Closing the MotionMark/Suits gap between LBSE and the legacy SVG engine

Update on what happened in WebKit in the week from October 12 to October 19.

Another busy week for the team! This week we had a variety of fixes, including the regular batch on the Layer-Based SVG Engine, a new pair of properties for WPE WebKit, and a new ApplicationManifest API which improves support for progressive web applications.

Cross-Port 🐱

Graphics 🖼️

WPE WebKit 📟

Apple and WebKit have shipped protections against web tracking for a long time. We put privacy protections in place for cookies in the very first version of Safari, we invented storage and cache partitioning and shipped it ten years before other major browsers, and we’re actively fighting device fingerprinting.

We do this because users deserve to not be tracked, not across websites and not covertly through fingerprinting, unless they explicitly opt in to it. See WebKit’s Tracking Prevention Policy for a comprehensive overview.

Identity Resolution, or the Post-Cookie Era

We fully blocked cross-site cookies six years ago. That was a huge step forward for privacy on the web.

However, the tracking industry has not sat idle since.

A “post-cookie” tracking method emerged, called identity resolution. In this scheme, third parties (i.e., not the website owner) invisibly collect your email address when you log in or sign up for a newsletter. They send the email address to their servers, create an opaque tracking ID permanently linked to your email address, and send that tracking ID back to the webpage. The tracking ID is stored on the website and can from thereon be used for arbitrary purposes linked to your email address, such as building a profile of your browsing or targeting ads at you across websites. Logging out or unsubscribing from that newsletter does not remove the tracking ID or your email address stored with the third party.

Over time, these third parties collect even more data as you log in using your email address or fill in forms with personal data. They use this to create a data profile of you, known as an identity graph. Here’s an illustrative example of what such a graph may look like:

Email addresses almost always constitute Personally Identifiable Information, or PII. Another example is your phone number. Such information not only allows for cross-site tracking, but also cross-device tracking. For the majority of users, their email address serves as a globally unique ID that they keep for years, even decades. When users provide information for one purpose, it breaks their expectation to use it for another unstated purpose. For example, a user who logs in or signs up for a newsletter is not expecting to have their information sent to a third party for other, potentially long-term, intents.

First party personalization is not tracking, and is not what our technologies seek to prevent. But even if identity graphs are only scoped to data from a single company, i.e. a first party, the central identity resolver is a third party and it holds cross-site, cross-device, and cross-party data about the user and can perform matching and targeting functions in the capacity of a clearinghouse. That is a tracking capability that each first party does not have on their own.

What We Are Doing To Protect Users Against Identity Resolution

Some companies serve as third-party infrastructure to facilitate identity resolution. They are present but invisible on many webpages where you enter your email address or use your email address for login purposes. They are not themselves login providers or newsletter services, they’re just there to track you.

In our iOS, iPadOS, macOS, and visionOS 27 releases, Safari and WebKit block network access to identity resolution infrastructure to prevent cross-site tracking. This stops them from sending your email address to their servers and all the downstream effects of that. The blocking is done on the domain level, meaning they can’t just change the structure of the network request to work around the protection.

Hide My Email

As an iCloud+ subscriber, you are offered the service Hide My Email which enables you to submit unique, randomized email addresses to every new website while still getting their messages in your inbox. Unique, random email addresses provide additional protection against email-based tracking.

Our Commitment to Web Privacy

It’s not enough to block cross-site cookies to prevent cross-site tracking today because the tracking industry has not stopped trying to track users on the web. They have ushered into what they call the post cookie era and in our latest releases we have put strong protection in place. We will continue to prevent covert and cross-site tracking by default, while maintaining the ability for websites to provide first-party personalization to their users.

Update on what happened in WebKit in the week from October 5 to October 12.

A CSS invalidation bugfix, moving steps for optgroup and hr elements, and a handful of fixes to the Layer-Based SVG Engine compose this week's bag of updates, changing to a calmer pace compared to the packed weeks we've had recently!

Cross-Port 🐱

Graphics 🖼️

Safari Technology Preview Release 254 is now available for download for macOS Golden Gate and macOS Tahoe. If you already have Safari Technology Preview installed, you can update it in System Settings under General → Software Update.

This release includes WebKit changes between: 321068@main…322634@main.

Accessibility

Resolved Issues

• Fixed VoiceOver on iOS not identifying date, time, and color inputs as pop-up buttons. (321384@main) (187696500)
• Fixed VoiceOver being unable to press buttons, links, and form controls styled with pointer-events: none. (322472@main) (188003870)
• Fixed VoiceOver announcing every focused ARIA menuitem, menuitemcheckbox, and menuitemradio as “selected”. (322397@main) (188185386)
• Fixed an issue on iOS where an error message made of several pieces of text was read in reverse order with some text repeated. (322318@main) (188764297)

Animations

Resolved Issues

• Fixed view timeline animations freezing once a sticky-positioned inline ancestor sticks to the scroll container. (321094@main) (187300111)
• Fixed an issue where accelerated animations of opacity to 0, including scroll-driven animations, could leave elements fully visible instead of transparent. (322355@main) (187682187)

CSS

New Features

• Added support for the size, min-size, and max-size shorthand properties. (321710@main) (187495014)
• Added support for the border-*-radius side shorthands, such as border-top-radius, which set the radii of both corners on one side of a box at once. (322537@main) (187605885)
• Added support for the interpolate-size property, which allows animations and transitions to and from intrinsic sizing keywords such as auto, min-content, and fit-content. (321370@main) (187701518)
• Added support for the symbols() function for defining anonymous counter styles. (321624@main) (188048446)
• Added support for CSS linked parameters, including the link-parameters property and param(), for passing values into linked SVG images. (321822@main) (188217737)
• Added support for the calc-size() function, which allows calculations on intrinsic sizes such as auto, fit-content, and max-content. (322574@main) (188996389)

Resolved Issues

• Fixed CSS Grid relayout cost growing quadratically with the number of grid items that have distinct order values. (321853@main) (173962596)
• Fixed CSS Grid track sizing for items that span multiple tracks to follow the current specification for distributing extra space, including to non-affected tracks. (322402@main) (182725333)
• Fixed table cells after an empty width: 0 column being placed off-screen. (322376@main) (183452074)
• Fixed the rendering of outlines with a negative outline-offset on elements that use corner-shape. (321259@main) (186820849)
• Fixed line-clamp and -webkit-line-clamp to share the same underlying values and cascade correctly against each other, with -webkit-line-clamp now treated as a shorthand. (322292@main) (187100061)
• Fixed sibling-index() and sibling-count() returning 1 for children of a shadow root. (321182@main) (187201634)
• Fixed line-clamp, max-lines, and block-ellipsis to match the latest specification syntax, allowing max-lines and line-clamp to combine auto with an integer and block-ellipsis to accept no-ellipsis, ellipsis, or a string. (321832@main) (187371224)
• Fixed grid track sizing for items that span multiple tracks so that they are sized in groups by span count, as the CSS Grid specification requires. (321194@main) (187413690)
• Fixed a min-content inline size to give both the min-content and max-content contributions of an element that size. (321278@main) (187601903)
• Fixed an issue where a stretched grid item whose padding exceeded its grid area was sized narrower than its own padding. (321295@main) (187612019)
• Fixed implicit named grid lines created by grid-template-areas sometimes being empty. (321401@main) (187753954)
• Fixed fit-content() grid tracks growing beyond their limit when distributing extra space. (321720@main) (187757242)
• Fixed grid layout to use a grid item’s margin box, rather than its border box, for its minimum size contribution so items with margins size their tracks correctly. (321614@main) (187850851)
• Fixed clip-path with a <geometry-box> value ignoring corner-shape and clipping to rounded corners instead. (321557@main) (187891292)
• Fixed a flex item’s base size ignoring the space available to it when its main size is fit-content. (322557@main) (187932371)
• Fixed a box with a fixed width ignoring max-width: max-content when contributing its intrinsic size. (322298@main) (188008779)
• Fixed grid track sizing so a track’s growth limit is never initialized smaller than its base size. (321616@main) (188023571)
• Fixed the intrinsic width of grid containers with contain: inline-size, container-type: inline-size, or content-visibility: hidden so it comes from contain-intrinsic-size rather than the grid items. (321612@main) (188029152)
• Fixed missing repaints in CSS Grid layouts when grid items move. (321737@main) (188142676)
• Fixed table-layout: fixed being ignored when a table’s width is intrinsic, min-intrinsic, or a calc-size() value. (322409@main) (188201473)
• Fixed relative color syntax to preserve none channel values that are referenced directly, so oklab(from oklab(none none none) l a b) resolves to oklab(none none none). (321724@main) (188215354)
• Fixed color serialization so that sRGB colors with none components serialize using color(srgb ...), and hsl() and hwb() colors serialize their saturation, lightness, whiteness, and blackness components as percentages. (321758@main) (188254602)
• Fixed relative color syntax so that missing (none) components are preserved instead of becoming 0 when the origin color is converted to a different color space. (321802@main) (188300348)
• Fixed relative alpha() colors to serialize in the most precise form using color() syntax, matching color-mix() and other relative color expressions. (321829@main) (188323511)
• Fixed relative alpha() color functions to require an alpha parameter, so values like alpha(from red) are now invalid, following a CSS Working Group resolution. (321852@main) (188339902)
• Fixed deprecated CSS system colors, such as ActiveBorder, Menu, Scrollbar, ThreeDFace, and Window, to compute to their CSS Color 4 equivalents on macOS. (322193@main) (188365953)
• Fixed border-image-repeat: round to round the tile count to the nearest whole number instead of rounding it down. (321996@main) (188369219)
• Fixed a regression where elements with aspect-ratio inside a column flex container did not shrink when the container got narrower. (321951@main) (188393652)
• Fixed line-clamp to make room for the block ellipsis during line breaking, moving content that doesn’t fit next to the ellipsis to the next line, including nowrap content. (322495@main) (188393991)
• Fixed line-clamp so that when the block ellipsis displaces all content on the clamped line, only the ellipsis remains and the line is not made taller by inline boxes. (322500@main) (188440163)
• Fixed an issue where grid items with aspect-ratio and a percentage height did not shrink when the grid got narrower. (322176@main) (188444964)
• Fixed CSS color conversion to follow the latest specification rules for missing hue components on achromatic colors, including in hsl() and hwb(). (321984@main) (188471496)
• Fixed line-clamp adding a block ellipsis to the last line when all of the content fits within the line limit. (322510@main) (188500712)
• Fixed line-clamp to count the lines of nested blocks towards the maximum number of lines. (322521@main) (188535368)
• Fixed an issue where a justified line came up short when its hanging trailing whitespace was inside an inline box. (322224@main) (188548682)
• Fixed line-clamp to remove hanging trailing whitespace before the block ellipsis. (322531@main) (188551752)
• Fixed an issue where line-clamp was ignored on floats and absolutely positioned boxes. (322551@main) (188552622)
• Fixed an issue where ruby annotations lost their text inside a line-clamp container. (322578@main) (188552871)
• Fixed an issue where text inside a display: contents element inherited the wrong style after its parent’s style changed. (322092@main) (188591349)
• Fixed line-clamp incorrectly clamping lines on a multi-column container. (322584@main) (188595965)
• Fixed an issue where changing the width of a line-clamp container showed the lines past the clamp point. (322600@main) (188596942)
• Fixed aspect-ratio being ignored on absolutely positioned boxes with height: fit-content, min-content, or max-content. (322178@main) (188597811)
• Fixed line-clamp: auto to clamp at the container’s block size. (322603@main) (188621599)
• Fixed an issue where changing shape-image-threshold did not update the shape when the shape image was a gradient. (322232@main) (188772999)
• Fixed grid items ignoring their ::first-line styles in certain cases. (322319@main) (188830233)
• Fixed fit-content() grid tracks with a percentage argument being stretched when the grid’s size is indefinite. (322421@main) (188848301)
• Fixed overflow-wrap: anywhere keeping extra characters on a line, or breaking inside a surrogate pair, next to punctuation that is prohibited at the start of a line. (322554@main) (188884467)
• Fixed the initial value of position-visibility to be anchor-visible. (322565@main) (188939499)

Canvas

Resolved Issues

• Fixed rect() using the wrong winding direction when given a negative width or height. (322101@main) (188036092)
• Fixed TextMetrics emHeightAscent and emHeightDescent to add up to the font’s em size, and updated the top, hanging, middle, ideographic, and bottom baselines to match when drawing text. (322077@main) (188368945)
• Fixed sizing of image sources, such as SVG images without a natural size, used by canvas drawImage() and createPattern(), createImageBitmap(), WebGL, and VideoFrame to follow CSS object size negotiation. (322003@main) (188524860)

Deprecations

• Removed support for the non-standard darker value of globalCompositeOperation. (321811@main) (188035440)

Editing

Resolved Issues

• Fixed an issue where the caret was hard to see after pasting wrapped text whose color contrasts poorly with the editor’s background, such as dark text pasted into a dark-mode editor. (321615@main) (186543233)
• Fixed drag-selecting text that starts inside a position: fixed element so that the page autoscrolls when the pointer moves past the edge of the window. (322310@main) (188330363)
• Fixed an issue where converting a bulleted list to a numbered list left a stray type attribute on the resulting <ol>. (322170@main) (188445470)

Forms

Resolved Issues

• Fixed ::picker-icon on <select> elements to draw the dropdown arrow as a built-in glyph instead of a text character positioned with a negative margin, so authors no longer need to reset margins when styling it. (321110@main) (185952359)
• Fixed setting valueAsNumber to throw a TypeError for infinite values and to clear the value when set to NaN, instead of throwing a NotSupportedError for both. (321668@main) (188047421)
• Fixed missing icons in search fields, including the magnifying glass in <input type="search"> and the filter field icons in Web Inspector. (322219@main) (188297101)

HTML

Resolved Issues

• Fixed an iframe whose src changed before its first load committed being missing from the back/forward list, which could show the wrong frame content after navigating back. (321768@main) (149977268)
• Fixed navigating a subframe that still shows its initial about:blank document to replace the history entry instead of adding a new one, so the back button works as expected. (321285@main) (187298226)
• Fixed changes to the scrolling attribute on an <iframe> not taking effect immediately when overlay scrollbars are in use. (321994@main) (188326221)

Images

Resolved Issues

• Fixed top-level image viewer to support dark-mode. (322117@main) (97965029)
• Fixed a broken <img> with an empty alt attribute to have no natural size or aspect ratio, so block-level images no longer show a broken-image icon. (321251@main) (155149701)
• Fixed the bitmap image naturalWidth and naturalHeight to return the image metadata size rather than the decoded size; this fixed layout of the image for different sizes. (322220@main) (172477431)
• Fixed image-rendering not applying to generated images, such as cross-fade(), used in the CSS content property. (322533@main) (189024049)
• Fixed the bitmap image naturalWidth and naturalHeight to return the density-corrected natural rather than the layout size which can be affected the style such as image-orientation. (322534@main) (189024238)

JavaScript

Resolved Issues

• Fixed BigInt("-") and BigInt("0x ") to throw a SyntaxError. (321129@main) (187423917)
• Fixed an issue where optimized code could read a stale value of a module variable after an import cycle. (321135@main) (187432418)
• Fixed spreading or applying a strict mode arguments object truncating its length to 32 bits. (321213@main) (187527803)
• Fixed stack trace capture to read Error.stackTraceLimit from the Error constructor. (321296@main) (187633441)
• Fixed named backreferences (\k<name>) inside regular expression lookbehinds incorrectly matching the empty string in some cases. (321355@main) (187741552)
• Fixed RegExp.prototype.test() skipping the observable read of lastIndex for some anchored regular expressions. (321363@main) (187754780)
• Fixed ArrayBuffer.prototype.slice() to correctly look up Symbol.species on the constructor, including for ArrayBuffer objects from other realms. (321451@main) (187853060)
• Fixed Intl.DateTimeFormat.prototype.resolvedOptions() reporting a dayPeriod value for 12-hour formats that was never requested, which caused formatters recreated from those options to output text like “in the morning” instead of “AM”. (321443@main) (187860472)
• Fixed Intl.Segmenter containing() returning a segment that also included the preceding segment when the index was at a boundary before a surrogate pair, such as an emoji. (322218@main) (187863002)
• Fixed Intl.DurationFormat dropping zero minutes and seconds that follow a numeric unit. (321755@main) (188252937)
• Fixed Promise.prototype.then(), catch(), finally(), Promise.resolve(), and Promise.reject() creating promises and errors in the wrong realm when used with a Promise from another realm, such as an iframe. (321864@main) (188345846)
• Fixed (a?.b)(x) skipping the call and returning undefined when a is null or undefined, instead of evaluating the arguments and throwing a TypeError. (321867@main) (188347937)
• Fixed Intl.DurationFormat dropping a fractional value folded into a zero unit, so formatting { milliseconds: 500 } with milliseconds: "numeric" returns 0.5 sec instead of an empty string. (321878@main) (188362824)
• Fixed Intl.DurationFormat dropping the minus sign for fractional values between -1 and 0. (321988@main) (188478180)
• Fixed String.prototype and RegExp.prototype methods such as match(), replace(), split(), and test() incorrectly running with the caller’s realm when used with a RegExp or function from another realm. (321990@main) (188478512)
• Fixed tagged templates with a parenthesized optional chain as the tag to keep the correct this value. (322141@main) (188677696)
• Fixed tagged templates that use a super property as the tag so the tag function is called with the current this value. (322253@main) (188790013)
• Fixed TypedArray constructors creating an empty array when passed a Proxy that wraps an array-like object. (322260@main) (188794129)
• Fixed the ArrayBuffer constructor to throw a RangeError for an invalid length before reading the prototype of newTarget. (322281@main) (188822488)
• Fixed the Array constructor to read the prototype of newTarget before throwing a RangeError for an invalid length. (322282@main) (188822747)

Media

New Features

• Added support for the transfer option in WebCodecs EncodedAudioChunk, EncodedVideoChunk, AudioData, VideoFrame, and ImageDecoder constructors, allowing ownership of ArrayBuffer data to be transferred instead of copied. (321548@main) (187834056)
• Added support for the hevc option in VideoEncoder configurations so that WebCodecs can produce HEVC video in Annex B format. (322385@main) (188387670)

Resolved Issues

• Fixed paused media with audio in a hidden page being able to start playing again without a user gesture. (322266@main) (169468617)
• Fixed video disappearing while audio continued after returning from Picture-in-Picture to element fullscreen and then exiting to inline on iOS. (321751@main) (181656299)
• Fixed an issue where text tracks whose mode was set with JavaScript could be overridden by automatic caption selection, preventing multiple text tracks from showing at the same time. (321838@main) (183472153)
• Fixed an issue where media range responses could drop the last byte of a requested range. (321101@main) (187225949)
• Fixed a mirrored VideoFrame being flipped vertically instead of horizontally when its rotation is applied. (321697@main) (187300986)
• Fixed an issue where the play() promise never resolved and the playing event never fired for Media Source Extensions content mixing clear and encrypted media when the decryption key was already available. (321495@main) (187850389)
• Fixed WebCodecs VideoEncoder and VideoDecoder hanging on flush() when the underlying codec buffers more than four frames. (321682@main) (188165426)
• Fixed incorrect colors in 8-bit 4:2:2 VP9 video decoded in software, where the chroma channels were swapped and caused a visible color cast. (322477@main) (188857520)
• Fixed the software VP9 decoder used by WebCodecs and media playback to report a decode error instead of silently dropping 4:4:4 frames or producing corrupted 12-bit frames. (322513@main) (188868857)

Networking

Resolved Issues

• Fixed cookies with non-ASCII characters set using document.cookie or cookieStore.set() getting truncated, and changed reading them to decode as UTF-8 to match other browsers. (322447@main) (124266311)
• Fixed resources from app-registered custom URL schemes failing to load because of stricter cross-origin checks. (321782@main) (182251092)
• Fixed a regression on iOS where Apple Wallet passes delivered through a data: URL navigation did not open in Wallet. (322096@main) (184582548)
• Fixed an issue where a speculation rules prefetch that hit a cross-origin redirect also cancelled a real navigation to the same URL. (321796@main) (187701208)
• Fixed an issue where a failed speculative prefetch could break the actual navigation, sometimes prompting users to download the page instead of displaying it. (322091@main) (188119964)
• Fixed structured header field parsing rejecting the entire header when a dictionary or parameter key begins with *. (321835@main) (188260300)
• Fixed cross-origin stylesheets loaded without CORS never being reused from the parsed stylesheet cache, improving page load performance. (322418@main) (188872969)

PDF

Resolved Issues

• Fixed the context menu for selected text in PDFs on macOS not offering the Translate option. (322064@main) (186553741)

Performance

Resolved Issues

• Fixed unnecessary style resolution for ::before and ::after rules that cannot generate content, such as box-sizing resets, improving performance. (322517@main) (186807298)
• Fixed synthetically bolded text always using the slower text measurement path. (321394@main) (187588326)
• Fixed a regression where items with a percentage flex-basis inside deeply nested column flex containers could make layout time grow exponentially and freeze the page. (321866@main) (187727635)

Rendering

New Features

• Added live pinch-to-zoom on macOS, so content stays sharp during the gesture and fixed and sticky elements follow the zoom. (322535@main) (106728296)

Resolved Issues

• Fixed synthetic bold text being measured wider than the font’s real metrics, which caused letter-spaced text to overflow and wrap and skewed ch units and tab-size. (321206@main) (55307109)
• Fixed a retriggered overlay scrollbar expansion animation jumping instead of animating smoothly from its current progress. (321389@main) (183216907)
• Fixed the intrinsic width of replaced elements with a percentage width and a resolvable percentage height. (321748@main) (187522214)
• Fixed floats and inline-blocks being sized incorrectly when a child sets min-width: min-content or min-width: max-content. (321332@main) (187621931)
• Fixed hit testing on 3D-transformed elements rotated so far that part of them is behind the viewer, where the visible portion did not receive pointer events. (321633@main) (188120032)
• Fixed an issue where white-space: nowrap content containing spaces overflowed the line instead of wrapping to the next line. (322209@main) (188406135)
• Fixed an issue where inline box borders were drawn closed on a fragment where the inline box continues past a line-clamp clamp point. (322345@main) (188471367)
• Fixed unnecessary rendering and compositing work when a frame moves without resizing, improving scrolling performance on pages with fixed-position iframes. (322194@main) (188665149)

SVG

Resolved Issues

• Fixed calling clear() on a pattern’s patternTransform.baseVal so the patternTransform attribute is ignored. (321124@main) (170518953)
• Fixed getComputedTextLength() and the character position methods to account for lengthAdjust="spacingAndGlyphs". (321445@main) (187473448)
• Fixed SVG angle values to serialize numbers using CSS number formatting, consistent with SVG lengths and CSS values. (321460@main) (187757273)
• Fixed a regression where an SVG without a viewBox had zero width as a flex item. (321446@main) (187794543)
• Fixed the transform attribute on the outermost <svg> element being ignored or applied in the wrong position. (321441@main) (187854814)
• Fixed pointer-events values stroke, visibleStroke, visible, and all missing the stroke area of SVG shapes when stroke is none. (322143@main) (188285211)
• Fixed paused SVG image animations restarting from the beginning instead of resuming, matching the behavior of animated bitmap images. (322303@main) (188834229)

Security

Resolved Issues

• Fixed navigator.hardwareConcurrency returning unusual core counts to known fingerprinting scripts, which could trigger bot detection challenges, by alternating between 4 and 8 instead. (321431@main) (177211562)
• Fixed Content Security Policy violations in workers not firing securitypolicyviolation events or notifying a ReportingObserver. (322099@main) (188368580)

Web API

Resolved Issues

• Fixed Navigation API dispose events for entries removed by another frame’s navigation seeing stale navigation.entries(), and fixed a crash when a frame is detached during a dispose event. (321726@main) (184961466)
• Fixed an issue where ending a worker with both a readwrite and a readonly IndexedDB transaction in flight could leave that database permanently unable to run any transaction. (321564@main) (187349025)
• Fixed window.outerWidth and window.outerHeight returning 0 in some apps that embed WebKit. (321417@main) (187603389)
• Fixed pagehide, visibilitychange, and unload event handlers having no effect, such as beacons and messages never arriving, when navigating to a cross-site page that loads in a different process. (321626@main) (188113419)
• Fixed memory growth when reading Blob data, such as with Blob.arrayBuffer() or FileReader, by no longer storing completed reads in the memory cache. (321948@main) (188322145)
• Fixed an issue where calling preventDefault() in a navigate event handler did not cancel a cross-site navigation.navigate(). (322591@main) (188636761)
• Fixed Largest Contentful Paint to use an image’s natural dimensions when computing its effective visual area, so SVG images with only one natural dimension are no longer reported as candidates. (322624@main) (189112402)

Web Extensions

Resolved Issues

• Fixed webRequest events not firing for subframes loaded inside an extension’s action popup. (321290@main) (167403221)
• Fixed an issue where a web extension’s background service worker could handle messages before it finished registering after being reloaded, causing checks for existing offscreen documents to fail. (321556@main) (186304610)
• Fixed webRequest event listeners filtered by types so that main_frame and sub_frame match top-level and iframe loads respectively instead of being swapped. (321074@main) (187214709)
• Fixed webRequest events reporting the wrong parentFrameId for subframes whose parent is the main frame, which now correctly report 0. (321079@main) (187227773)
• Fixed an issue where HTTP and HTTPS iframes loaded inside a web extension page incorrectly received the extension’s Content Security Policy. (322449@main) (188407446)
• Fixed an issue where an extension offscreen document calling window.close() did not close the document. (321974@main) (188408957)

Web Inspector

Resolved Issues

• Fixed very large values, such as border-radius: calc(infinity * 1px), overflowing the box model diagram. (322462@main) (174246956)
• Fixed a regression where the Sources tab showed no scripts when inspecting an older remote target. (322286@main) (187134944)
• Fixed JavaScript breakpoints showing an incorrect resolved state on pages with multiple frames when one frame navigates or reloads. (322410@main) (187726262)
• Fixed exported Timeline recordings losing the DOM node associated with layout and rendering events when imported again. (321679@main) (188164899)

WebAssembly

New Features

• Added support for WebAssembly wide arithmetic, which adds instructions for 128-bit integer addition and subtraction and for multiplying two 64-bit integers into a 128-bit result. (321926@main) (188342106)

Resolved Issues

• Fixed an inefficiency in the WebAssembly in-place interpreter by making its instruction handlers smaller, improving performance by about 5% on Apple silicon. (321217@main) (187291986)
• Fixed redundant work when compiling WebAssembly code that uses garbage-collected structs and arrays, improving compile times. (322019@main) (188134232)

WebDriver

New Features

• Added initial support for the WebDriver BiDi browsingContext.captureScreenshot command, which captures the page viewport as a PNG. (321353@main) (145987196)

Resolved Issues

• Fixed WebDriver key actions so that the Insert, Pause, and Cancel keys report the correct DOM key and code values, and so that keypad keys on iOS report Numpad* codes and the numpad key location. (322405@main) (187036197)
• Fixed WebDriver to queue classic commands for a session so they run one at a time, preventing hangs when commands overlap. (322485@main) (187215746)
• Fixed an issue where a WebDriver command waiting for navigation to complete could hang indefinitely when another command on the same page also started waiting, by returning an error for the replaced command. (321165@main) (187217320)
• Fixed returning a stale element from a script to report a “stale element reference” error instead of “no such element”. (322221@main) (187510557)

WebGL

Resolved Issues

• Fixed a regression where WebGL texImage2D() and texSubImage2D() uploads from image sources handled premultiplied alpha incorrectly. (321143@main) (187093618)

WebGPU

Resolved Issues

• Fixed copyExternalImageToTexture() to preserve alpha values instead of passing lossy premultiplied data, which caused some textures with transparency to render incorrectly. (321601@main) (142087137)
• Fixed createComputePipelineAsync() and createRenderPipelineAsync() never settling when the device was lost or destroyed. (321466@main) (187846864)
• Fixed fragment shaders that discard before loops writing NaN values to the render target on some Apple silicon GPUs. (321870@main) (187997601)
• Fixed WebGPU content permanently dropping to a fraction of the display refresh rate after a few slow frames. (322439@main) (188257377)
• Fixed an issue where render pipelines created from an already-used GPUShaderModule always missed the shader cache, making repeated pipeline creation as slow as a cold compile. (321998@main) (188501171)
• Fixed an issue where reusing a render bundle with executeBundles() lost the bind group dynamic offsets after the first execution. (322002@main) (188524116)
• Fixed setBindGroup() on render pass encoders doing redundant sampler registration work. (322005@main) (188530801)

WebRTC

Resolved Issues

• Fixed H.265 video encoded or decoded through WebRTC and WebCodecs always being tagged as BT.709 limited range instead of preserving its actual color space. (321788@main) (187787801)
• Fixed full-range color handling for H.264 video in WebRTC and WebCodecs by decoding it with WebKit’s own VideoToolbox decoder. (322034@main) (188171149)
• Fixed H.264 video encoding and decoding to preserve the video’s color space, and fixed frames from a canvas to use the sRGB color space when encoded. (322056@main) (188373969)

With the 2.54 release, WPEPlatform became the default way of integrating WPE WebKit with the underlying platform, and its API is now considered stable. At the same time, the libwpe-based API that WPE has relied on since its beginnings is now deprecated. In this article we explain why this change was made, how applications use the new API, and what is involved in migrating an existing application from libwpe.

Back in 2022 we published an overview of the WPE WebKit project, describing the different components of WPE and how they fit together. Most of what that article explains about WebKit and the WPE API is still valid, but the way WPE connects to the platform has changed considerably since then, so this is a good moment to revisit that part of the picture.

How WPE used to integrate with the platform

Since its beginnings, WPE has delegated graphics and input to code that lives outside of WebKit. libwpe defined a generic interface for these, and a backend, loaded at runtime, implemented that interface for a given platform. WPEBackend-fdo, based on Wayland and other freedesktop.org technologies, was the reference backend, while Cog provided a convenience layer on top for those writing browsers.

This design achieved its main goal: hardware vendors and integrators could support WPE on their platforms without having to modify WebKit itself. However, it also meant that a good part of the platform work was left to the application. To show a web page on screen using WPEBackend-fdo, an application had to:

• Load a libwpe backend with wpe_loader_init() and initialize it, usually by passing it an EGL display.
• Create a view backend through the “exportable” API of WPEBackend-fdo, wrap it in a WebKitWebViewBackend, and pass that to the web view.
• Receive, in a set of callbacks, the buffers exported by WebKit for each frame, present them on screen, release them, and notify WebKit when the frame had been displayed.
• Collect input events from the windowing system and forward them to WebKit with the wpe_view_backend_dispatch_*_event() family of functions.

As a result, even a simple browser required a fair amount of knowledge of the graphics pipeline, and the code involved was split across three repositories (WebKit, libwpe, and WPEBackend-fdo) that had to be kept in sync. Much of this code was the same from one application to the next, and Cog provided a ready-made implementation of it for applications that did not want to write their own.

What WPEPlatform changes

WPEPlatform is a GObject-based library that lives in the WebKit repository and is built as part of WPE WebKit. It replaces both libwpe and the backends written against it, and it moves the responsibility of rendering and input handling away from the application and into WebKit and the platform implementation.

The library is only used by WebKit’s UI process. As before, the web process renders the page into buffers that are shared with the UI process (DMA-BUF buffers on Linux, AHardwareBuffer on Android, or shared memory when rendering in software). The difference is that WebKit now hands these buffers directly to the platform implementation, which takes care of presenting them, without the application having to take part in the process.

The API is built around four classes:

• WPEDisplay: the connection to the platform, and the object that creates all the others.
• WPEToplevel: a top-level surface, which is normally a window, or the whole output on platforms that have no windows.
• WPEView: the surface where a single web view is rendered, hosted in a toplevel. It also receives the input events for that web view.
• WPEBuffer: the pixel data produced by WebKit and handed to the view, with a subclass for each type of buffer.

These are complemented by smaller classes for screens, keymaps, settings, input methods, gestures, gamepads, the clipboard, and accessibility. Several of them, such as screens, settings, input methods, and gestures, had no equivalent in libwpe.

WPE WebKit ships with three built-in platform implementations: Wayland, DRM/KMS (for devices that drive the display directly, without a compositor), and headless (for testing and offscreen rendering). Other implementations can be developed out of tree and installed as modules, which WPE WebKit discovers at runtime. wpe-platform-gtk, which embeds WPE web views in GTK 4 applications, is an example of this.

Using WPEPlatform in an application

For most applications, WPEPlatform is not visible at all. A WebKitWebView created without a backend selects a platform automatically: WPE WebKit tries the available platform implementations in order of priority and uses the first one that connects successfully. The following program is a complete, if minimal, browser:

#include <wpe/webkit.h>
#include <wpe/wpe-platform.h>

static void
on_view_closed (WPEView *view, gpointer user_data)
{
    g_main_loop_quit (user_data);
}

int
main (int argc, char *argv[])
{
    g_autoptr(GMainLoop) loop = g_main_loop_new (NULL, FALSE);
    g_autoptr(WebKitWebView) web_view = g_object_new (WEBKIT_TYPE_WEB_VIEW, NULL);

    WPEView *view = webkit_web_view_get_wpe_view (web_view);
    g_signal_connect (view, "closed", G_CALLBACK (on_view_closed), loop);

    webkit_web_view_load_uri (web_view, argc > 1 ? argv[1] : "https://wpewebkit.org");
    g_main_loop_run (loop);

    return 0;
}

It only needs the wpe-webkit-2.0 pkg-config module to build, which pulls in wpe-platform-2.0 when WPE WebKit is built with WPEPlatform support (the default since 2.54). Note that the closed signal is emitted when the user closes the window, and of the built-in platforms, only Wayland emits it. On DRM and headless the application decides by itself when to exit.

The platform API comes into play when an application needs more than these defaults. The most common cases are the following.

Choosing a platform. The WPE_PLATFORM environment variable (wayland, drm, or headless) forces a given platform without any changes to the code. An application that is meant to run on a single platform can also create the display itself and pass it to the web view:

#include <wpe/wayland/wpe-wayland.h>

g_autoptr(GError) error = NULL;
g_autoptr(WPEDisplay) display = wpe_display_wayland_new ();
if (!wpe_display_connect (display, &error))
    g_error ("Could not connect to Wayland: %s", error->message);

WebKitWebView *web_view = g_object_new (WEBKIT_TYPE_WEB_VIEW,
                                        "display", display,
                                        NULL);

The Wayland-specific API is available with the same wpe-webkit-2.0 module, but an application that depends on it can check for the wpe-platform-wayland-2.0 pkg-config module, which is only installed when WPE WebKit is built with the Wayland platform enabled. The DRM and headless implementations work the same way, with wpe_display_drm_new() and wpe_display_headless_new().

Handling input. Input events are delivered to the WPEView through the event signal before they reach the web page. An application can connect to it to implement keyboard shortcuts, returning TRUE to stop the event from reaching the page:

static gboolean
on_view_event (WPEView *view, WPEEvent *event, gpointer user_data)
{
    if (wpe_event_get_event_type (event) == WPE_EVENT_KEYBOARD_KEY_DOWN
        && (wpe_event_get_modifiers (event) & WPE_MODIFIER_KEYBOARD_CONTROL)
        && wpe_event_keyboard_get_keyval (event) == WPE_KEY_q) {
        g_main_loop_quit (user_data);
        return TRUE;
    }
    return FALSE;
}

g_signal_connect (view, "event", G_CALLBACK (on_view_event), loop);

Controlling the window. The toplevel that hosts the view is available through wpe_view_get_toplevel(), and provides functions to set the title (wpe_toplevel_set_title()), resize, maximize, or switch to fullscreen (wpe_toplevel_fullscreen()). Changes in its state are reported by the toplevel-state-changed signal of the view. How much of this is supported depends on the platform: Wayland implements all of it, the headless implementation only keeps track of size and fullscreen state, and DRM does not support them, since its toplevel always covers the whole screen.

Finally, wpe_display_get_settings() gives access to WPESettings, where applications can override platform settings such as the dark mode preference, reduced motion, or contrast. The prefers-color-scheme, prefers-reduced-motion, and prefers-contrast CSS media queries follow these settings.

Migrating from libwpe

For an application, most of the migration consists of removing code. With WPEBackend-fdo, creating a web view looked roughly like this, with most of the actual work happening in the callbacks of exportable_client:

struct wpe_view_backend_exportable_fdo *exportable =
    wpe_view_backend_exportable_fdo_egl_create (&exportable_client, app, width, height);
struct wpe_view_backend *wpe_backend =
    wpe_view_backend_exportable_fdo_get_view_backend (exportable);
WebKitWebViewBackend *backend =
    webkit_web_view_backend_new (wpe_backend, destroy_backend, exportable);
WebKitWebView *web_view = webkit_web_view_new (backend);

With WPEPlatform, the same is achieved with a single line:

WebKitWebView *web_view = g_object_new (WEBKIT_TYPE_WEB_VIEW, NULL);

webkit_web_view_new() is only available when WPE WebKit is built with the legacy API, so applications need to switch to g_object_new(). The rest of the application code that uses the WebKit API (settings, network sessions, navigation, and so on) does not need any changes. The diagram below summarizes what moves out of the application:

The rest of the libwpe code in an application maps to WPEPlatform as follows:

libwpe / WPEBackend-fdo	WPEPlatform
wpe_loader_init() and backend initialization	Automatic, or WPE_PLATFORM, or creating a WPEDisplay
Exportable client callbacks, buffer release, frame completion	Handled by WebKit and the platform implementation
wpe_view_backend_dispatch_*_event()	Handled by the platform; intercept with the WPEView::event signal
Fullscreen handler	wpe_toplevel_fullscreen() and the toplevel state

There are a few things in libwpe and WPEBackend-fdo that have no equivalent in WPEPlatform. The process provider API of libwpe is gone, since WebKit is again in charge of launching its auxiliary processes. The only exception is Android, which has its own WPEProcessManager API. The audio extension of WPEBackend-fdo has not been supported since 2.46, and the video plane extension, used to display video frames on hardware overlay planes, has no equivalent yet.

Those who maintain a custom backend for WPEBackend-fdo, rather than an application, will need to port it to a WPEPlatform implementation. This means subclassing WPEDisplay, WPEToplevel, and WPEView, and optionally the input method, keymap, and screen classes. The tutorial on writing a platform implementation covers this in detail. In many cases, extending one of the built-in implementations might be enough: the Wayland one, for example, exposes its wl_display, wl_compositor, and wl_surface objects, which makes it possible to add support for additional Wayland protocols.

On the build side, the legacy API is still built by default in 2.54 and will continue to be maintained while applications migrate. Once an application no longer needs it, it can be disabled at build time with the ENABLE_WPE_LEGACY_API=OFF CMake option. As for Cog, it will not have further stable releases beyond the 0.18.x series, so we recommend that new applications use the WebKit and WPEPlatform APIs directly.

Further reading

The reference documentation for WPEPlatform has been considerably extended for this release, and is the best place to continue from here:

• The overview of the API.
• A tutorial on writing a browser with WPEPlatform.
• A guide on migrating from libwpe, with more examples than this article.
• A mapping table with the WPEPlatform equivalent of every public symbol in libwpe and WPEBackend-fdo.

For an example of a platform implementation that lives entirely outside of WebKit, Alex has written about WPE WebKit on Android with WPEPlatform, which shows how far the API can be taken.

If you run into problems while migrating, or find that something you relied on in libwpe is missing, please let us know, either by filing a bug in WebKit’s Bugzilla, on the webkit-wpe mailing list, or in the #wpe Matrix channel.

Update on what happened in WebKit in the week from September 28 to October 5.

Another week populated with updates! This time we sweep through a new crypto backend, more layer-based SVG engine updates, better filters, and some miscellaneous updates.

Cross-Port 🐱

Graphics 🖼️

WPE WebKit 📟

Update on what happened in WebKit in the week from September 21 to September 28.

Following the stable releases last week, we have the first security advisory covering fixes included in them; the flurry of fixes and polish for the Skia compositor continues; SharedArrayBuffer gets re-enabled, and more.

Cross-Port 🐱

JavaScriptCore 🐟

Graphics 🖼️

WebKitGTK 🖥️

WPE WebKit 📟

WPE Platform API 🧩

Releases 📦️

Safari Technology Preview Release 253 is now available for download for macOS Golden Gate and macOS Tahoe. If you already have Safari Technology Preview installed, you can update it in System Settings under General → Software Update.

This release includes WebKit changes between: 320113@main…321067@main.

Accessibility

Resolved Issues

• Fixed an issue where VoiceOver announced aria-keyshortcuts values containing Meta or Alt literally instead of using the macOS terminology Command and Option. (320424@main) (186342070)
• Fixed an issue where VoiceOver could repeatedly announce the same live region content as it streamed into a page. (320576@main) (186694747)

Animations

New Features

• Added support for style-originated scroll timelines to match globally, allowing them to be defined outside of the target’s hierarchy or that of an element with a timeline-scope property. (320183@main) (186261285)

Resolved Issues

• Fixed an issue where an animation attached to a view timeline’s scroll range was not updated when the scroll container’s scrollable overflow changed. (320244@main) (185328465)
• Fixed an issue where an animation could attach to a style-originated timeline made visible by timeline-scope instead of one established by an ancestor, which now takes priority. (320223@main) (186265325)
• Fixed an issue where a style-originated timeline defined outside of a timeline-scope hierarchy could remain active instead of yielding an inactive timeline. (320227@main) (186330965)
• Fixed an issue where changing a timeline-scope value did not update timelines for animations outside of its hierarchy. (320231@main) (186331685)
• Fixed a regression where a paused and seeked animation incorrectly finished when resumed after a separate animation running at a non-default playback rate. (320238@main) (186339093)
• Fixed an issue where the ViewTimeline constructor did not require a subject parameter. (320969@main) (187200265)

CSS

New Features

• Added support for the extended numeric range in longhand East Asian counter styles. (320887@main) (109875198)
• Added support for CSSContainerRule.conditions. (320762@main) (182257864)
• Allow combining safe and unsafe keywords with normal alignment, and change safe behavior for absolutely (and fixed positioned) boxes to keep the box within their original containing block (the viewport). (185952139)
• Added support for using sibling-index() and sibling-count() within container query conditions. (320493@main) (186564084)

Resolved Issues

• Fixed an issue where a near-zero fixed background-size value collapsed the image tile to nothing. (320169@main) (140387662)
• Fixed an issue where the [class~=foo] attribute selector did not perform as well as an equivalent class selector. (320862@main) (164128575)
• Fixed an issue where highlight colors, such as those used by ::selection, did not inherit as a StyleColor, which could prevent values like color-mix(in oklab, teal 50%, currentcolor) from resolving correctly. (320228@main) (184495338)
• Fixed an issue where a second CSS custom highlight sharing a Range with an already-registered highlight never painted. (320355@main) (185173794)
• Fixed an issue where outside list markers were only repositioned after layout when their first formatted line was in a descendant block, instead of for every outside list marker. (320561@main) (185529863)
• Fixed an issue where an inset box-shadow with a large spread on a wrapped inline element painted outside the element as full-width bands. (320150@main) (185651318)
• Fixed an issue where CSS.highlights iterated in hash order instead of registration order after its wrapper was garbage collected. (320343@main) (185754041)
• Fixed an issue where corner-shape rendered incorrectly when inner corners intersected. (320287@main) (185931169)
• Fixed an issue where a grid item with an aspect-ratio could keep a stale inline size contribution when the grid container shrank. (320117@main) (186101273)
• Fixed an issue where flexible grid tracks did not respect the grid container’s minimum and maximum size. (320160@main) (186103325)
• Fixed an issue where fixed grid track sizing functions were overridden to zero while sizing tracks to fit non-spanning items. (320168@main) (186117142)
• Fixed an issue where explicitly-placed grid items advanced the auto-placement cursor. (320253@main) (186118858)
• Fixed an issue where the propagated root background was painted in the wrong position in vertical-rl writing mode. (320167@main) (186274088)
• Fixed an issue where opening a <details> element made its <summary> one pixel shorter. (320461@main) (186413478)
• Fixed an issue where a typed parameter of a CSS custom function did not keep its type. (320340@main) (186439114)
• Fixed an issue where attr() stopped invalidating on attribute changes after a view transition. (320420@main) (186467515)
• Fixed an issue where unicode-bidi and direction had no effect on an inside ::marker. (320504@main) (186468752)
• Fixed an issue where fit-tolerance did not interpolate between <length-percentage> values. (320383@main) (186509338)
• Fixed an issue where a grid item’s automatic minimum size was not clamped to a fixed maximum track sizing function. (320750@main) (186606479)
• Fixed a regression where the line-height quirk in quirks mode was not applied to line boxes inside a nested inline-block element that had no line-height of its own. (320514@main) (186614663)
• Fixed an issue where interpolating a <length-percentage> from a calc() value to a pure <length> dropped the percentage component at 100% progress. (320585@main) (186628152)
• Fixed an issue where text-decoration-thickness and text-underline-offset did not preserve percentage values when interpolating. (320584@main) (186628810)
• Fixed an issue where align-content left the list marker behind. (320532@main) (186676835)
• Fixed an issue where text-indent moved an outside list marker along with the indented text. (320533@main) (186678552)
• Fixed an issue where a float in a list item’s content pushed the outside list marker inward with the line. (320549@main) (186680551)
• Fixed an issue where a tab character rendered too narrow when tab-size was small in a proportional font. (320671@main) (186698040)
• Fixed an issue where a gradient in the content property painted blank. (320620@main) (186742805)
• Fixed an issue where some combinations of corner-shape with thick borders rendered incorrectly. (320826@main) (186808871)
• Fixed an issue where fit-content() grid tracks could be stretched beyond their argument instead of capping the track’s growth limit. (320780@main) (186961437)
• Fixed an issue where an orthogonal <caption>‘s margins were missing from the table. (321056@main) (187137359)
• Fixed an issue where an orthogonal <caption> ignored its margin against the table edge. (321060@main) (187139068)
• Fixed an issue where transforming a table row group could misplace its absolutely positioned children. (321065@main) (187252945)
• Fixed an issue where the resolved right and bottom values of an out-of-flow positioned element were wrong inside a vertical inline containing block. (321061@main) (187295559)
• Fixed an issue where the identity and translation fast path of a transformation matrix ignored the w component when mapping a 4-component point. (321030@main) (187297446)

Canvas

Resolved Issues

• Fixed an issue where a placeholder <canvas> element with no pushed OffscreenCanvas frame would fail instead of returning a transparent black image. (320202@main) (186229685)
• Fixed an issue where an off-by-one error in the bottom-row check caused canvas noise injection to misclassify the bottom-left pixel. (320510@main) (186640624)
• Fixed a performance regression where drawing a canvas onto itself with drawImage prevented its backing surface from being recycled. (320735@main) (186731221)
• Fixed an issue where a canvas 2D context remained unusable after a temporary failure to allocate its backing store. (320605@main) (186799597)
• Fixed an issue where drawing to <canvas> computed path bounds unnecessarily when the whole backing store was already marked dirty. (320709@main) (186946552)

Editing

Resolved Issues

• Fixed an issue where the context menu in PDFs with copying disabled was missing text selection options. (320444@main) (186527750)
• Fixed an issue on macOS where the Copy option was enabled in the edit menu after selecting text in a PDF that disallows copying. (320534@main) (186648332)

Forms

Resolved Issues

• Fixed an issue where a large picker for a base-appearance <select> could render outside the viewport, by applying safe alignment to keep it within its original containing block. (320564@main) (185952139)

HTML

Resolved Issues

• Fixed an issue where the window load event could fail to fire if a readystatechange handler triggered a new load during page completion. (320331@main) (186373617)

JavaScript

New Features

• Added support for BigInt values in Intl.PluralRules.prototype.select and Intl.PluralRules.prototype.selectRange. (320396@main) (186534585)
• Added support for a faster Toom-3 multiplication algorithm for large BigInt values. (321013@main) (187336927)

Resolved Issues

• Fixed an issue in JavaScriptCore where a stale inline cache for a custom accessor on a previously flattened dictionary could persist after the accessor was shadowed, which could cause code that replaces built-in properties at runtime (such as a test mocking library overriding XMLHttpRequest) to keep using the original value. (320742@main) (180048596)
• Fixed an issue where Intl.DurationFormat in digital style included a stray separator when minutesDisplay was set to "auto" and minutes ended up hidden. (320182@main) (180722012)
• Fixed an issue where Array.prototype.toSpliced threw a TypeError instead of a RangeError when the array’s length was Infinity. (320554@main) (184438837)
• Fixed an issue where TypedArray setFromTypedArray could not use memmove when the region was intentionally overlapping and the spec algorithm needed to read back the modified result. (320130@main) (186145219)
• Fixed an issue where the TypedArray constructor could produce incorrect results when copying Array content whose element access has side effects. (320185@main) (186227333)
• Fixed a performance issue where String.prototype.toLowerCase and String.prototype.toUpperCase did not scan strings inline in the DFG and FTL JIT tiers. (320293@main) (186301688)
• Fixed an issue where a character following a class set operand in a /v mode regular expression class incorrectly added U+0000 to the class. (320216@main) (186319779)
• Fixed an issue where Temporal.ZonedDateTime.prototype.round resolved the rounded wall-clock time using a minute-rounded offset instead of the correct offset. (320217@main) (186319834)
• Fixed an issue where Object.freeze() did not invalidate the megamorphic inline cache epoch, which could cause stale property accesses on a frozen object. (320276@main) (186393610)
• Fixed an issue where deleting a property of a dictionary prototype in place did not invalidate the megamorphic store cache. (320375@main) (186513123)
• Fixed a performance issue where RegExp.prototype.test did not fast-fail when the input string was shorter than the pattern’s minimum possible match length. (320487@main) (186534079)
• Fixed an issue where regular expression lookbehind assertions could fail to match, or match at an invalid position, due to incorrect handling of surrogate pairs in the regular expression interpreter. (320492@main) (186536137)
• Fixed an issue where Atomics.isLockFree() converted its argument with a 32-bit integer conversion instead of ToIntegerOrInfinity, which could cause it to incorrectly return true for large size values. (320715@main) (186610789)
• Fixed an issue where a stack frame for a script loaded from a data: URL included the entire script in Error.stack instead of a truncated URL. (320770@main) (186614179)
• Fixed an issue where a JIT fast path for RegExp.prototype.test could skip the required read of lastIndex, silently dropping observable side effects. (320582@main) (186792229)
• Fixed an issue where tail-call optimization was skipped for eval calls that didn’t resolve to the real eval function, and incorrectly applied inside generator and async function bodies, which could produce incorrect results. (320687@main) (186840477)
• Fixed an issue where RegExp.escape incorrectly narrowed supplementary code points to 16 bits. (320682@main) (186962453)
• Fixed an issue where a \- following a class set operand in a /v mode regular expression class incorrectly threw a SyntaxError. (320683@main) (186962513)
• Fixed an issue where RegExp::deleteCode() cleared a regular expression’s cached pattern atom, which could cause incorrect values from static RegExp properties such as leftContext and rightContext after the compiled code was reclaimed while idle. (320817@main) (187104089)
• Fixed an issue where String.prototype.at and String.prototype.codePointAt could return an incorrect value for an out-of-bounds or negative index because the JIT compiler could eliminate their bounds check. (321014@main) (187336661)

Media

Resolved Issues

• Fixed an issue where wireless playback could create a remote media session helper too eagerly, which could delay switching an active playback route to a wireless device. (320748@main) (184536781)
• Fixed an issue where MediaRecorder could hold back a lone video keyframe indefinitely instead of using it to start a new recording segment. (320219@main) (186229843)
• Fixed an issue where an AV1 sequence header that exactly filled the buffer was incorrectly rejected due to an off-by-one bounds check. (321041@main) (187306821)
• Fixed an issue where black video-range pixel buffers were produced with super-black values instead of legal black. (321040@main) (187309125)

Networking

Resolved Issues

• Fixed an issue where custom scheme CORS checks incorrectly blocked subresources loaded from an HTML document opened via a file: URL. (320685@main) (179999480)
• Fixed an issue where reading a file-backed Blob range larger than 2GB truncated the read length due to an integer overflow. (320981@main) (187207663)
• Fixed an issue where validation of an HTTP header value did not check its final character, allowing control characters and DEL to be accepted as valid. (321019@main) (187288970)

Performance

Resolved Issues

• Fixed an issue where navigation could redundantly parse and decode a page’s URL multiple times, causing significant hangs for pages with very long URLs. (320292@main) (185796614)
• Fixed excessive CPU and power usage caused by IntersectionObserver observation on pages with many observed elements. (320395@main) (185839711)
• Fixed an issue where style resolution for elements sharing a scroll-timeline name could block the main thread for multiple seconds. (320902@main) (186090970)
• Fixed an issue where ScrollingStateTree::insertNode performed redundant work reordering children on pages with many sibling scrolling nodes. (320527@main) (186143008)
• Fixed an issue where ordinary property changes, such as toggling overflow: hidden, could trigger an unnecessary full-layer repaint. (320296@main) (186422878)

Rendering

Resolved Issues

• Fixed an issue where a layer with a negative z-index inside a stacking context failed to composite correctly when overlapping an externally composited layer. (320473@main) (130595406)
• Fixed an issue where the <mo> operator dictionary was consulted even when the element contained non-text content. (320730@main) (173078723)
• Fixed an issue where accents and other combining marks could be painted outside their base letter when letter-spacing, word-spacing, expansion, or synthetic bold were applied. (320957@main) (186013305)
• Fixed a regression that caused extra spacing to appear between an image and surrounding content near the bottom of a page. (320115@main) (186102748)
• Fixed an issue where hovering links could trigger unnecessarily wide repaints, by repainting ink-overflow-only style changes without running inline layout. (320128@main) (186104270)
• Fixed an issue where text nodes inside a display: contents element received redundant updates during style resolution. (320144@main) (186246705)
• Fixed an issue where content changing inside an element with a blur() filter did not properly repaint, leaving stale pixels around the edge of the filtered region. (320398@main) (186278957)
• Fixed an issue where a MathML rowspan="0" attribute was incorrectly clamped to 1. (320324@main) (186420659)
• Fixed an issue where non-MathML children of <annotation> and <annotation-xml> were not rendered. (320334@main) (186429768)
• Fixed an issue where drawing a native image did not respect the requested InterpolationQuality, affecting image scaling across canvas, SVG, and PDF rendering paths. (320429@main) (186439811)
• Fixed an issue where a layer with clip-path or mask could be treated as fully opaque, causing incorrect rendering. (320634@main) (186722177)
• Fixed an issue where a position: sticky element with -webkit-box-reflect applied could composite its reflection incorrectly. (320712@main) (186812790)
• Fixed an issue where an optimization to text matrix handling when drawing glyphs could cause text to render upside down. (321067.5@safari-7626.1.8-branch) (187588379)

SVG

New Features

• Added support for the SVG 2 path attribute on <textPath>, which lets text follow an inline path without referencing a separate <path> element via href. (321038@main) (185831618)

Resolved Issues

• Fixed an issue where SVG conditional processing attributes on clipPath, mask, and pattern elements incorrectly prevented the resource from being referenced. (320207@main) (19103270)
• Fixed an issue where SVG number attributes did not revert to their initial value when removed or set to an invalid value. (320226@main) (165378154)
• Fixed an issue where a SMIL animation of a presentation attribute was never released after the animated element was detached from the document, permanently freezing the animated value. (320199@main) (185452156)
• Fixed an issue where SVGLength resolved ex units by rounding the font’s x-height up to a whole pixel, causing the SVG DOM and getComputedStyle to disagree. (320606@main) (185984854)
• Fixed an issue where additive color animations in SVG lost precision due to per-layer 8-bit rounding. (320166@main) (186223510)
• Fixed an issue where an SVG transform change could leave an ancestor layer’s cached repaint rects stale, resulting in incorrect repainting. (320722@main) (187005898)
• Fixed an issue where SVGImage::isAnimating() returned true for SVG images that had no animations. (320839@main) (187106396)

Security

Resolved Issues

• Fixed an issue where a click in a backgrounded window could result in an action being taken. (320186@main) (186280350)
• Fixed an issue where CredentialStorage::removeCredentialsWithOrigin failed to purge HTTPS credentials that used the default port. (320968@main) (187210150)

Web API

New Features

• Added support for QuotaExceededError as a DOMException subclass, exposed on window and worker global scopes. (320856@main) (141586555)

Resolved Issues

• Fixed an issue where scrollWidth and clientWidth returned inconsistent values when the page was zoomed in or out due to rounding. (320773@main) (121879134)
• Fixed an issue where rotating the device to landscape orientation could pause a video playing in full screen, by adding a site-specific quirk. (320318@main) (148284059)
• Fixed several URLPattern matching issues affecting Service Worker routing, including incorrect encoding of the username and password components and unhandled unclosed pattern groups. (320122@main) (183434701)
• Fixed an issue where WebDriver reported an empty URL instead of about:blank for a browsing context that had not yet navigated. (320428@main) (183468933)
• Fixed an issue where WKWebView.magnification reported the pre-gesture scale for a few moments after a pinch-to-zoom gesture ended, instead of the scale about to commit. (320341@main) (185381317)
• Fixed an issue where Cache.delete() and Cache.keys() swallowed exceptions thrown while constructing a Request from a URL string. (320524@main) (186636105)
• Fixed a regression where WebXR hit testing failed with a TypeError when offsetRay was not specified. (320717@main) (186997100)
• Fixed an issue where interrupting a scroll with a tap could incorrectly trigger navigation of the link under the pointer. (321053@main) (187268555)
• Fixed an issue where click events did not include the modifier keys that were pressed at the time of the click. (320984@main) (187270584)

Web Extensions

New Features

• Added support for the offscreen API. (318833@main) (184269255)

Resolved Issues

• Fixed an issue where i18n.getMessage() dropped non-string substitution arguments instead of coercing them to strings. (320931@main) (149855718)
• Fixed an issue where webRequest.onBeforeRequest reported the resource type main_frame instead of sub_frame for subframe document loads. (321067@main) (167403388)
• Fixed an issue where a high priority static declarativeNetRequest redirect rule was not favored over a low priority session redirect rule. (320739@main) (176176246)
• Fixed an issue where webRequest events did not fire for loads blocked by a declarativeNetRequest rule. (320336@main) (176177851)
• Fixed an issue where webRequest events did not fire for page loads created with tabs.create. (320430@main) (177727052)
• Fixed an issue where an extension’s service worker lost its clients after being unloaded and reloaded, preventing it from finding an existing offscreen document. (320198@main) (186116488)
• Fixed an issue where an extension’s popover could be cut off because vh, svh, and lvh units resolved to the popover’s minimum height instead of its actual size. (320726@main) (186391990)

Web Inspector

New Features

• Added support for network throttling of the inspected page. (320893@main) (144892477)

Resolved Issues

• Fixed an issue in Web Inspector where WebSocket handshake headers were missing when using the Network.framework loader. (320156@main) (185255819)
• Fixed an issue in Web Inspector where a Debugger.globalObjectCleared event from a subframe cleared every target’s script map instead of only the affected target’s. (320787@main) (187042936)

WebAssembly

Resolved Issues

• Fixed an issue where JS string builtins and imported string constants were not applied when compiling WebAssembly modules loaded as ES modules. (320174@main) (186037843)
• Fixed an issue where the WebAssembly.Exception constructor rejected null options and incorrectly accepted non-object options. (320215@main) (186319813)
• Fixed an issue where the WebAssembly validator rejected i31.get_s and i31.get_u when the operand’s static type was a bottom reference type. (320578@main) (186660590)

WebDriver

Resolved Issues

• Fixed an issue where WebDriver BiDi’s script.call_function trimmed error messages incorrectly, cutting off part of the message. (320205@main) (186311752)
• Fixed an issue where WebDriver’s deleteAllCookies command could report success before cookies had actually finished being deleted. (320440@main) (186410147)
• Fixed an issue where WebDriver reported a stale element reference error instead of a no such element error for a node reference belonging to a different browsing context. (320518@main) (186615759)
• Fixed an issue where WebDriver did not properly handle the right-hand variants of modifier keys, such as ShiftRight and ControlRight, on Cocoa platforms. (320741@main) (186961436)
• Fixed a regression where WebDriver returned no such element instead of stale element reference for a node reference from a previous document. (320729@main) (187042183)
• Fixed an issue where WebDriver’s Add Cookie command dropped the cookie when the request did not include a sameSite attribute. (320916@main) (187193380)

WebGL

Resolved Issues

• Fixed an issue where WebGL contexts created with premultipliedAlpha: false were composited incorrectly. (320650@main) (53509398)

WebGPU

Resolved Issues

• Fixed an issue where uploading a canvas as a WebGPU texture had very poor performance. (320765@main) (153642354)
• Fixed an issue where GPUDevice.createBindGroup()‘s fast path failed to reuse bind groups containing a GPUBuffer entry alongside an external texture, forcing an unnecessary full rebuild. (320309@main) (186379208)
• Fixed an issue where a WebGPU external texture imported from a video element using WebM or MSE playback rendered as a black placeholder instead of the video frame. (320427@main) (186470526)
• Fixed an issue where using WebGPU render bundles on some GPUs could cause the device to be unexpectedly lost. (320689@main) (186688781)
• Fixed an issue where WebGPU could report the primitive-index feature as available on GPUs that don’t support it, resulting in an uncaptured error. (320691@main) (186690340)
• Fixed an issue in WebGPU where an array value constructor referenced through a type alias could generate invalid Metal Shading Language, silently producing incorrect compute results. (320690@main) (186803296)
• Fixed an issue in WebGPU where inlining three or more calls to a function operating on a large struct could silently miscompile on some devices, producing incorrect results. (320697@main) (186804865)
• Fixed an issue where asynchronous pipeline creation could stall rendering. (321042@main) (187296614)

WebRTC

Resolved Issues

• Fixed an issue where a WebRTC UDP connection to an unresolved remote address was incorrectly restricted to IPv6. (320716@main) (186844205)
• Fixed an issue where a TURN UDP connection could fail unnecessarily when DNS resolution failed, by allowing the socket to open directly to the host. (320720@main) (186847964)

Update on what happened in WebKit in the week from September 14 to September 21.

Following up to last week, we have a handful of exciting fixes to WebKitGTK and WPE WebKit covering Sysprof, rendering of CSS "filter" and "backdrop-filter", and the Layer-Based SVG Engine. We also have optimizations, stable releases, and new blog posts!

Cross-Port 🐱

Graphics 🖼️

Releases 📦️

Community & Events 🤝

WPE WebKit and WebKitGTK 2.54 have been released with a bunch of improvements and new APIs as usual, but there’s one point that kept the Igalia WebKit graphics team busy for the whole cycle: the new Skia-based compositor. The replacement of Cairo with Skia for content rendering has been a success and it’s already well integrated and optimized. We thought we could try to use Skia for the composition too and replace TextureMapper with Skia. TextureMapper was introduced in 2010 for the Qt port and later adopted by other ports. It uses the OpenGL ES API and maintains a collection of shader programs to paint different content. Nowadays TextureMapper is mostly the same code and shader programs, and it’s unmaintained and missing features. However, the performance was good and it has served us really well all these years. So, this time the goal was not to get better results in benchmarks, but to modernize the implementation, reduce the amount of code to maintain ourselves (like all shader programs) and make it easier to implement the missing features and fix existing bugs. This post is a summary of all the work we have done this cycle to implement the new Skia compositor.

SkiaCompositingLayer

The first step was adding an SkiaCompositingLayer class to replace TextureMapperLayer and adapt all the code to use one or the other depending on an environment variable. The initial implementation was based on the TextureMapper one for the things that are common like iterating the layer tree, computing transformations, etc. The way layers produced their contents didn’t change, so we were receiving textures for tiled content, video buffers, WebGL, accelerated 2D canvas, etc. SkiaCompositingLayer created a Ganesh Skia surface to draw those textures using SkCanvas::drawImageRect(). This initial implementation was enough to run the default MotionMark test suite, since it doesn’t use other composition features. Even though performance was not the goal, we had to make sure we didn’t regress. This initial implementation was neutral in MotionMark. We needed tests to implement those features and measure performance at the same time, so we decided to add a new set of tests to MotionMark, just extending the existing tests to require composition, which makes sure that filters, masks, path clipping, transformations, etc. were done by the compositor.

Filters

We first tried implementing filters using an intermediate surface like TextureMapper does. It worked, but the MotionMark score in the filters test was much worse. We realized that with Skia we could implement most of the filters without using an intermediate surface. All filter types except blur and drop shadow can be simplified to an SkColorFilter with SkImageFilter::asAColorFilter() which can be implemented without an intermediate surface, just by setting the color filter in the SkPaint we pass to SkCanvas::drawImageRect(). This not only fixed the performance regression, but also gave better results than TextureMapper, which always needs an intermediate surface.

Masks

There are two different kinds of masks: image mask, where the source mask is an image already, and clip path, where the mask is represented by a path to be clipped. In TextureMapper both are implemented the same way using intermediate surfaces. The mask is painted into a surface and then the masked layer creates an intermediate surface where its contents are first painted and then the mask contents on top using DstIn blend mode. Skia has APIs that allowed us to implement both cases in a much simpler and more efficient way. In the case of image masks, where we already have an image, we paint the mask contents once and keep it cached, and then the masked layer creates an SkShader for the image mask that is passed to SkCanvas::clipShader() without having to paint into an intermediate surface. Clip path masks are even easier, because we can just take the path we get and build an SkPath we can pass to SkCanvas::clipPath(), without having to paint the mask as an image at all or use any other intermediate surface. Once again, masks were not only easier to implement but they ended up being more performant too.

3D contexts

The implementation of 3D layer contexts is fairly independent of TextureMapper and OpenGL, so we could just take it almost as it was, using SkPath to build the clips and a few other adaptations. We could also fix existing bugs like the z-ordering that has always been broken in TextureMapper.

Blend modes

TextureMapper never supported blend modes and they were easy to implement with Skia just using the SkPaint property for it. This made several layout tests start passing.

Batched painting

After implementing all the features we were at a point in which we had the same or better performance in all tests except for three MotionMark compositing tests that were giving much worse results. Those tests use small layers and give a high result which means we end up adding a lot of layers to the scene before we start skipping frames. The root cause was the large number of layers filling the command queue of Ganesh. Skia Ganesh queues the GL drawing operations instead of sending them to the GPU right away. When the surface is flushed for whatever reason, the queued GL drawing operations are then processed and sent to the GPU. This allows Skia to apply nice optimizations like merging several tasks and reducing the amount of draw operations we end up sending to the GPU. In those tests where a lot of layers are created and painted to the compositor Skia surface the internal command queue ends up being huge too. Processing and analyzing such a long queue to optimize what we send to the GPU required more CPU work than what we save by optimizing the GL draw operations. Skia provides an API that allows us to do the batching ourselves. Since the compositor already has information to decide what operations could be merged together, we could reduce the internal queue size in many cases. We can merge SkCanvas::drawImageRect() operations as long as they share the same color filter, blend modes and sampling options. In the best case scenario we could reduce the whole internal queue to just one operation. This time the change improved the results of those tests getting them to about 93% of the TextureMapper score, but still a bit behind.

Promise images

The Skia Ganesh backend requires that an SkImage backed by a texture is created for the current thread GrDirectContext, even if it’s borrowing an existing texture. In WebKit all textures are created with a sharing GL context so that they can be accessed and destroyed from different threads with the same sharing GL context. So, for a layer whose content is an image we had to create a texture in the compositing thread to upload the pixels if the image was not accelerated, or for accelerated images get the texture identifier of the image, and then create another SkImage from the compositing thread borrowing the texture for the current GrDirectContext. The Skia Ganesh backend provides an API to create promise images, which can be created from any thread but targeting a specific thread, providing a fulfill callback that will be called on the target thread when the SkImage is first used to retrieve the wrapped texture. This way we can create the SkImage from the main thread for the compositing thread without using OpenGL at creation time. For non-accelerated images we realized we don’t need to manually create the texture and upload the pixels in the compositor, we can just pass the unaccelerated SkImage to the compositor SkCanvas and Skia will handle it internally much more efficiently than we did. And this change improved those compositing tests much further than we expected. The reason turned out to be the batching from the previous section: Skia merges the entries of an image set by comparing texture proxy pointers, and until now we were wrapping the texture in a new SkImage on every frame for every layer, so hundreds of layers drawing the very same image produced hundreds of different proxies that Skia could not merge. Passing the same SkImage every time collapses all of them into a single draw operation, which is the best case we described above. With batched painting and promise images together we could beat TextureMapper significantly.

Deferred Display Lists (DDL)

When we switched to Skia for painting, we kept the threaded rendering model, just using a separate smaller queue for GPU rendering workers. The GPU workers created their own GrDirectContext to paint the layer tiles. The resulting textures were re-wrapped in the compositing thread for the compositor GrDirectContext using fences for the proper synchronization. We knew this was not the recommended way to use Skia Ganesh from multiple threads, but with TextureMapper we had no other option. However, with the Skia compositor we can do it the recommended way by using a single GrDirectContext in the compositing thread and use Deferred Display Lists (DDL) and promise images to paint the tiles. With DDL, GPU workers no longer use GL at all and they don’t need a GrDirectContext, they paint tiles into a display list that records the GL drawing operations, but without touching GL. For image drawing operations recorded into the DDL, promise images are used too. Since this is now all CPU work we can remove the smaller GPU worker queue and use a single queue with more workers. The compositor replays the DDL into an SkSurface that is then passed to the compositor SkCanvas.

This change fixed rendering glitches on Android and was performance neutral for the whole composition suite and for most of the MotionMark tests, but in MotionMark 1.3 at 15fps it cost 29% in Suits and 14% in Leaves, while improving Images by 9%. Correctness and the other benefits of DDL made us accept those regressions.

Damage

TextureMapper already supported using damage information to optimize the painting while compositing, but it has always been disabled at run time because there were issues we never managed to fix. With the Skia compositor we decided to start from scratch and properly handle the damage information while compositing to render only the parts of the frame that actually changed. I’m not going to go into detail here because Nikolas Zimmermann has written an amazing blog post about it with all the details.

Current situation

The Skia compositor is finished and enabled by default in 2.54. Even though it was not the main goal, it performs better than TextureMapper in most of the benchmarks we run: the composition suite we added is 45% faster, and MotionMark 1.3.1 is 35% faster. The exception is MotionMark 1.3 at 15fps with GPU rendering, which comes out flat, because the Suits and Leaves tests are still about 26% and 10% behind due to the deferred display lists trade-off described above.

We are already working on fixing existing issues in composition that we never fixed in TextureMapper. In the main branch TextureMapper is now disabled by default at build time, and support will be removed soon for the GTK and WPE ports. In 2.54 it’s still a run-time decision so if you find any issue with 2.54, you can check if it’s a Skia compositor regression by trying TextureMapper with WEBKIT_USE_SKIA_FOR_COMPOSITION=0 environment variable.

Future plans

We are already working on further improvements like using promise images for all external textures we have to pass to the compositor. We will explore the possibility of using Vulkan with the Ganesh backend instead of GL and eventually try the new Graphite backend. And of course we will continue fixing any existing issues related to the compositor.

Teaching the new Skia compositor to recomposite only what changed

Our Safari release notes have never been as long as they are for this version. The number of features alone rose from 58 to 80 since the first beta in June.

Safari MCP makes working with coding agents dramatically easier. Customizable select turns the real <select> element into something you can fully restyle — now with new UA default styles that provide an even-better starting place. Scroll anchoring stops content from jumping when something loads in above. The <model> element comes to iOS, iPadOS, and macOS, giving 3D a powerful HTML element. Websites can now provide immersive environments on visionOS. And much more.

Safari MCP

Are you developing websites using coding agents? The Safari MCP server, now available in Safari 27.0 will make your workflow faster and more powerful. Give Claude Code, Codex, or the agent of your choice control over the browser window so it can see how your code renders. Safari MCP provides access to the DOM, network requests, screenshots, and console output. Your agent can do more on its own while you do less hopping between windows, less dropping screenshots in your terminal, and less typing prompts to describe what’s not working.

The Safari MCP server enables your agent to:

• see how your code renders in Safari
• verify user states in forms, checkout flows, selections & more
• compare computed styles and layout to results in other browsers
• test for accessibility issues like missing labels, improper ARIA attributes, and poor contrast
• analyze performance with navigation timing and resource load times

And much more. The MCP server runs entirely on your local machine. It makes no network calls of its own. It does not have access to your personal information in Safari. And any captured data goes directly to the agent you’re running, not to Apple.

To give it a try, go to Safari > Settings > Developer > check “Allow remote automation and external agents.” (If the Developer pane is not available, first go to Advanced, and check “Show features for web developers”.)

If you’re using Claude:

claude mcp add safari-mcp -- "/usr/bin/safaridriver" --mcp

If you’re using Codex:

codex mcp add safari-mcp -- "/usr/bin/safaridriver" --mcp

For other agents, you put the following in your mcp.json or config.json file.

{
  "mcpServers": {
    "safari-mcp": {
      "command": "/usr/bin/safaridriver",
      "args": ["--mcp"]
    }
  }
}

Let us know what you think, especially if you have any feature requests. Learn more by reading Introducing the Safari MCP server for web developers, or by referencing documentation.

Quality

The biggest feature of Safari 27.0 isn’t a feature at all. It’s the tremendous effort that went into improving the quality of existing features. At WWDC, we were proud to announce 525 fixes. Then we added 60% more, reaching a total of 844. Plus the majority of feature work improves existing features.

When we look at the efforts we made to improve quality, the story can be seen in several themes.

Compatibility. Our team made many changes to help make specific websites work correctly for their users. For example, Hindi InScript typing in an online document editor, images vanishing from search results on a restaurant reservation site, and Pahawh Hmong text misrendering in an online encyclopedia.

Foundations. Sometimes the best way to improve quality is to start over. Safari 27.0 has an all-new ES module loader. We rebuilt CSS Zoom. And now inline layout places elements with subpixel precision.

Depth. We got deep into specific technologies. There are 66 fixes to SVG in this release alone, including an end-to-end review of the SMIL animation engine. HTML tables got a systematic pass, with absolutely positioned tables now handling percentage-sized children, min-height, and max-height correctly. Plus deep work on Media Source Extensions (MSE) and Encrypted Media Extensions (EME). And much more.

Alignment. Much of the work is to better match exactly what web standards prescribe. For example, we corrected the MathML Core operator dictionary and its spacing values across several fixes. Fixes to innerText bring Safari’s rendered-text output better in line with standards for display, visibility, white-space, and form controls. And we improved how HTTP cache obeys Cache-Control.

Integration. Sometimes two features each work perfectly alone, but combined, something starts to go wrong. We fixed a lot of these this year. For example, -webkit-line-clamp shipped in WebKit in 2010, while text-wrap: balance arrived in 2024. Before Safari 27.0, if you applied both to the same element, the balancing simply didn’t happen. Now that’s fixed.

We truly hope all of these efforts throughout the last year make your work as a web developer a little easier. Read through the resolved issues at the end of this article to see specifics. And learn more about what we are doing to raise the quality of WebKit by watching What’s new in WebKit for Safari 27.

Customizable Select

The <select> element has been part of the web since the very beginning of HTML. But until recently, there wasn’t a lot you could to do style it or fill it with custom content. Customizable Select changes that. Now in Safari 27.0, it lets you build a fully custom drop-down menu to match the look and feel of your website or web app, without reaching for JavaScript or a pile of <div>. You can even push far beyond a typical drop-down menu to a very different UI. Because it’s a real form control, you get automatic, reliable support for keyboard navigation, screen readers, form submission, validation, change events and more.

Start by applying appearance: base-select in your CSS. This immediately switches to the look and feel provided by new UA styles, and enables the new powers in HTML.

select, 
select::picker(select) { 
    appearance: base-select 
}

You might notice that the default UA styles in Safari 27.0 are different than they were for the first beta back in June. The summer gave us the opportunity to reflect on what it will be like for web developers to write custom styles on top of the new defaults. We realized after 30 years of web developers struggling with form control styling, we wanted to provide something even better.

These defaults set you up with all the basics. You won’t be left with homework to do to get the select into a usable state. You can simply switch to the new control with appearance: base-select, and apply as little or as much additional code as you’d like. Don’t like the new defaults? You are in luck, it’s very easy to override them. Feel fine keeping any of these pieces like the new drop shadow, 4px rounded corners, touch-friendly line height, cleaner hover states, user-ready chevron & checkmark, subtle opt group styling, etc? Great! It’s already done for you, with support for all the variations like light & dark modes, forced color mode, disabled states and more.

We brought this new design to the CSS Working Group, where it’s being further discussed and refined. Once other browsers update their implementations, we will together reach our shared commitment for all browsers to support an identically interoperable starting place.

New pseudo-elements like ::picker-icon and ::checkmark let you easily target parts of the control that were previously unstylable. Plus, you can now insert HTML elements inside each <option> to add more detail. The new <selectedcontent> element can be used to adjust what gets displayed as the currently-selected option’s content. Learn more watching Rediscover the HTML Select Element from WWDC26.

HTML

Model

Originally shipped a year ago in visionOS, the HTML <model> element is now also available in Safari on iOS, iPadOS, and macOS. This new element is a lot like video, audio, and img — this time embedding a 3D model in the page.

<model src="mallet.usdz"></model>

Just like the other HTML elements for media, you can link to multiple source files, including a fallback.

<model>
    <source src="boot.usdz" type="model/vnd.usdz+zip">
    <source src="boot.glb" type="model/gltf-binary">
    <img src="boot.png" alt="workboot in light tan leather">
</model>

You can optionally include attributes like environmentmap to provide custom lighting for your model. Or stagemode, which sets the default interaction behavior. Target your model with JavaScript and open up a wide range of possibilities.

Learn all about it, including where to get a 3D model, how to optimize it for the web, and what can be done with JavaScript by watching Get started with the HTML Model Element from WWDC26. And check out these demos in Safari.

Safari 27.0 also adds support so the CSS dynamic-range-limit property can be applied to the <model> element, giving you control over HDR tone mapping and rendering range for 3D content on iOS and macOS.

Responsive images

Responsive image techniques get easier with the auto keyword for sizes.

<img src="photo.jpg"
     srcset="photo-400.jpg 400w, photo-800.jpg 800w, photo-1200.jpg 1200w"
     sizes="auto"
     loading="lazy"
     width="1200"
     height="800"
     alt="A mountain landscape">

Using sizes="auto" on an image with loading="lazy" tells the browser to automatically calculate the size based on the actual layout width once it’s known. This means you don’t have to predict the rendered layout width ahead of time.

Web Components

Safari 27.0 adds support for the shadowrootslotassignment attribute on declarative shadow roots. This lets you configure the slot assignment mode (named or manual) directly in HTML when defining a shadow root declaratively, matching the JavaScript attachShadow({ slotAssignment: "manual" }) option.

Spatial Web

Immersive environments

Environments in visionOS are an incredible part of the experience of Vision Pro. They let you transform your physical surroundings into a different place—like Yosemite, Mount Hood, or the Moon. It’s been possible for Apple developers creating immersive apps for visionOS to provide custom environments with their app. Now in Safari 27.0, environments can be provided as part of a website.

You can provide an immersive environment with a simple <model> element and one JavaScript API call. The Immersive API on the model element works similarly to how the Fullscreen API does on video elements. Learn all about it in Explore immersive website environments in visionOS.

By the way, this new Immersive API replaces the developer preview originally called Spatial Backdrop. If you built anything using Spatial Backdrop, migrate it to the Immersive API on the <model> element.

Image controls

Now the <img> element has a controls attribute in HTML. It works just like the controls attribute on the video and audio elements. When present, the browser offers controls to allow the user to adjust or more fully experience the media.

<img controls src="panorama.jpg" alt="A panorama of the Dolomites" >  

In Safari 27.0 in visionOS when the controls attribute is present, Safari provides a user interface for interacting with spatial and panorama photos. This gives users an easy and consistent mechanism to view photos spatially or immersively, and eliminates the need for web developers to build their own UI.

WebXR

Safari 27.0 adds support for texture array projection layers in WebXR Layers. When creating a projection layer with XRWebGLBinding.createProjectionLayer(), you can now request textureType: "texture-array" so each eye’s view renders into its own layer of a single texture array.

Scroll Anchoring

Many websites inject content into the page as the user is reading or viewing that content. The new content often appears above where the user is currently looking — like images, ads, or comments being injected into the page. In the past, this caused the content the user was reading to be suddenly pushed down, causing a disorienting jump to a random place on the page.

Now with support for Scroll Anchoring, Safari 27.0 instead adjusts the scroll position and keeps the content exactly where it was before the content insertion. As a web developer, you don’t have to do anything to enable this on your site. It just works.

Scroll anchoring is controlled by the overflow-anchor CSS property, which defaults to auto. If you have a specific need where you need to opt out of scroll anchoring, you can use overflow-anchor: none.

CSS

The stretch keyword for sizing

Safari 27.0 adds support for using stretch with the properties width, height, min-width, max-width, min-height, max-height, and flex-basis. The stretch keyword tells an element to fill the available space in the relevant axis.

.card {
    width: stretch;
}

It’s just like using width: 100% — but this time accounting for margins, which prevents overflow. If you’ve been using -webkit-fill-available to solve this need, now is a good time to switch.

Anchor positioning improvements

Safari 27.0 makes three updates to anchor positioning, as the web standard evolves and the tool becomes more powerful.

First, we added support for transform-aware anchor positioning. Now, when an anchor element has a CSS transform applied — scale, rotate, translate, or any combination — elements positioned relative to that anchor follow its transformed position instead of its pre-transform layout position. This works for transforms applied via the transform property as well as through the individual translate, rotate, and scale properties. If you use anchor positioning to attach a tooltip, popover, or annotation to a transformed element, it now tracks correctly, even with animated transforms.

Second, the default value for position-anchor changes from auto to normal, fixing a potential side effect where the positioning behavior of elements that don’t even use Anchor Positioning could be impacted. The new value none opts out entirely. The new default, normal, behaves the same as none unless position-area is also set, in which case it behaves like auto did, as originally intended.

And third, Safari 27.0 also adds support for anchor-valid and anchor-visible . Originally, position-visibility: anchors-valid hid an element if any of its required anchor references couldn’t be resolved. However, it wasn’t clear what constituted “required anchor references”. So the CSS Working Group changed the behavior to only look at the default anchor box. To match, some keywords were renamed to drop the plurality. The anchors-valid value is now anchor-valid , while anchors-visible is now anchor-visible. Safari 27.0 aligns with the new behavior, and temporarily supports the old keywords for compatibility.

Color improvements

The new alpha() relative color function is a shorthand for adjusting just the alpha channel of an existing color, without repeating the rest of its channels: alpha(from var(--mycolor) / 80%). It keeps the origin color in its own color space and only changes the alpha value — useful when you want a more transparent or more opaque version of a color you already have, without writing out the full relative color syntax.

The color-mix() function now accepts more than two colors, so you can blend several colors together at once, like color-mix(in oklab, teal 20%, olive 30%, blue 50%). If you leave out the percentages, each color contributes equally.

The image(<color>) function lets you use a solid color anywhere an <image> value is expected. Unlike background-color, which sits underneath all background layers, image(<color>) behaves like a real image layer — it can stack above other background images, get sized with background-size, and be positioned and clipped like any image.

Safari 27.0 also adds support for forwarding missing color components when interpolating between analogous color spaces. Previously, a color with an intentionally missing component (none), like an achromatic gray with no meaningful hue, could get incorrectly assigned a hard 0 when converted into an analogous space for interpolation, producing a subtly wrong blended color. Now the missing component is carried forward as missing instead, so interpolation behaves the way you’d expect.

And more CSS

The light-dark() function now accepts <image> values, not just colors, so you can specify different images for light and dark color schemes in a single declaration: background-image: light-dark(url(day.png), url(night.png)). Gradients work here too.

Safari 27.0 adds support for the :heading pseudo-class, which matches any heading element — <h1> through <h6>. Instead of writing h1, h2, h3, h4, h5, h6 in your selector list, you can just write :heading. Plus, :heading also has a functional form for targeting specific levels, for example, :heading(1, 2) matches only <h1> and <h2>.

The revert-rule keyword is now supported in Safari 27.0. Like revert and revert-layer, revert-rule rolls back the cascade — but specifically to the state as if the current style rule had not been present. It gives you a more precise tool for working with overrides, especially in component libraries and design systems where you want to selectively undo declarations within a rule without losing the rest.

The CSS progress() function now supports a no-clamp option in Safari 27.0. By default, progress() returns how far a value sits between two bounds as a ratio from 0 to 1, clamped to that range. Adding no-clamp removes the clamp, so the result can fall below 0 or above 1, which is useful when you want an effect to keep scaling past its defined bounds instead of flattening out at the edges.

Safari 27.0 adds support for contain: style applying to CSS quotes. This allows you to scope effects of quotes to a certain subtree.

Safari 18.4 added support for text-autospace to control spacing between Chinese/Japanese/Korean (CJK) and non-CJK characters. Safari 27.0 now adds the insert keyword, making text-autospace: ideograph-alpha ideograph-numeric and text-autospace: ideograph-alpha ideograph-numeric insert equivalent.

The Dutch IJ digraph is now supported in Safari 27.0. When the content language is Dutch (lang="nl"), text-transform: capitalize and ::first-letter now correctly titlecase “ij” to “IJ” at the start of words.

Safari 27.0 adds support for the case-sensitive s modifier in CSS attribute selectors. Adding s after the value forces a case-sensitive match — for example, a[href$=".PDF" s] matches only a literal uppercase .PDF. This is the counterpart to the i modifier you may already be using to force case-insensitive matching (a[href$=".pdf" i] matches .pdf, .PDF, .Pdf, and so on); s lets you go the other way when you need an exact-case match on an attribute HTML would otherwise treat as case-insensitive.

Safari 27.0 also adds support for the :host:has() compound selector, letting a shadow host style itself based on what’s inside its own shadow tree. Because :has() can compound onto any selector, :host:has(:checked) or :host:has(::slotted(img)) let a custom element’s host change its own appearance depending on the state of its shadow content — useful for web component authors who want the host to react to what’s inside it without reaching for JavaScript.

Animations

Safari 27.0 adds the animation property to the AnimationEvent and TransitionEvent interfaces, letting event handlers directly access the Animation object associated with the event.

SVG

Safari 27.0 adds quite a few improvements to SVG.

Now the lang and xml:lang attributes are supported inside SVG. Use it to specify the language of text content to ensure correctness of both text rendering and accessibility announcements.

Safari 27.0 adds support for <use> referencing an external SVG file without a # fragment identifier. Previously, in order to point <use href="…"> at another SVG document, you had to name a specific element inside it with a fragment but now <use> can reference the external file on its own. There’s also a fix so <a> elements in SVG are treated consistently with HTML <a> elements for origin/security checks.

Several non-standard and legacy SVG interfaces have been removed to better align with the SVG 2 specification:

• SVGLocatable and SVGTransformable interfaces
• nearestViewportElement and farthestViewportElement properties on SVGGraphicsElement
• viewTarget property on SVGViewSpec
• glyph-orientation-horizontal property

Plus, there are a huge number of SVG fixes shipping this year. See the list below for what’s improved in Safari 27.0.

WebAssembly

Safari 27.0 adds support for WebAssembly JavaScript Promise Integration (JSPI). JSPI lets synchronous-looking WebAssembly code suspend and wait for JavaScript Promises, making it much easier to port existing C, C++, Rust, and other language code to the web where that code expects synchronous I/O.

Before JSPI, porting code that called synchronous APIs to Wasm required rewriting everything on top of a callback or async state machine. With JSPI, the Wasm module can suspend at a call site and resume when the Promise resolves — the rest of the module sees straight-line synchronous code. This is a significant capability for the Wasm ecosystem.

JavaScript

Safari 27.0 includes a complete standards-compliant rewrite of the ECMAScript module (ESM) loader. The new loader is implemented in native C++ and conforms directly to the ECMAScript specification’s module loading algorithms, replacing an earlier implementation based on an abandoned 2016 WHATWG Loader proposal that predated top-level await entirely.

The rewrite fixes module execution ordering and initialization issues that could cause imports to access exports before they were fully evaluated. It was validated against test262, the Web Platform Tests, and additional test cases.

Top-level await is a foundational feature of modern JavaScript module authoring, and it’s been a real pain point in Safari for a while — a known source of cross-browser bugs that developers building module-based apps had to work around. This fix closes that gap. To learn more, read Fixing Top-Level Await in Safari.

Web API

Safari 27.0 adds support for the Service Worker static routing API. This lets a service worker declare routing rules that the browser can use to bypass the service worker entirely for certain requests, reducing overhead for high-performance PWAs.

Safari 27.0 adds three improvements to ReadableStream. First, the async iteration with for await...of:

const response = await fetch("/data");
for await (const chunk of response.body) {
  process(chunk);
}

Second, the ReadableStream.from() static method for creating a stream from any async iterable or iterable:

const vegetables = ["Carrot", "Broccoli", "Tomato", "Spinach"];
const asyncIterator = (async function* () {
  yield 1;
  yield 2;
  yield 3;
})();
// Create ReadableStream from the array
const myReadableStream = ReadableStream.from(vegetables);
// Create ReadableStream from async iterator
const asyncReadableStream = ReadableStream.from(asyncIterator);

And third, the ability to transfer a ReadableStream , WritableStream and TransformStream across contexts via postMessage().

Web Inspector

Several Web Inspector updates in Safari 27.0 make common debugging tasks easier.

The Color Picker now shows color contrast information inline as you edit. No more switching tools mid-decision to check whether a color combination is accessible. This works when you’re editing both foreground and background colors at the same time.

The Color Picker’s format and gamut controls are also now visible upfront instead of hidden. If you’ve ever gone hunting for those options, this will help.

In the Network tab, when a resource redirects, you can now see every request in the chain rather than just the final destination. It’s much easier to figure out what’s actually happening.

The Elements tab adds Subgrid and Grid-Lanes badges that make it easy to identify subgrid and grid-lanes layout contexts as you explore a page.

The Timeline tab now includes the layout root element in Layout event details, so you can see which element triggered a layout pass. The Timeline view also uses distinct colors for style events like “Style Invalidated” and “Style Recalculated”, making them easy to tell apart from layout events at a glance, and adds a separate column showing the node associated with each layout and rendering event.

Media

Safari 27.0 supports setting TextTrackCue.endTime to Infinity to represent an unbounded cue duration. It’s useful for captions or data cues of live streams.

Safari 27.0 adds support for synchronized video playback on macOS displays using genlock. Genlock synchronizes the timing signal across multiple displays or capture devices, which is important for broadcast, live-event, and multi-display installation setups. Even a few frames of misalignment between screens is visible. When genlock is available, video played in Safari stays in lockstep with the rest of the signal chain instead of drifting on its own clock.

Safari 27.0 improves how HDR images with gain maps are decoded and rendered, decoding them into accelerated backing stores in the GPU process. This is a rendering-pipeline improvement rather than a new API — HDR photos with gain maps (the format used by iPhone’s Adaptive HDR photos) should render more correctly and efficiently, building on gain-map rendering fixes from recent releases.

Safari 27.0 lets you override the color space a hardware VideoDecoder uses when decoding video with WebCodecs. This helps when a stream’s embedded color space metadata is missing or wrong. Now, you can tell the decoder which color space to interpret the frames in instead of being stuck with an incorrect result.

Networking

Safari 27.0 adds support for Secure cookies on loopback hosts. For loopback hosts using plaintext HTTP, cookies marked Secure can now be set via JavaScript and Set-Cookie headers, matching the behavior of other browsers, simplifying local development and testing with Secure cookies.

WebGPU

Safari 27.0 now supports the clip_distances built-in value in WGSL shaders. Clip distances are a WebGPU feature that allows vertex shaders to define custom clipping planes, enabling you to discard geometry on one side of an arbitrary plane before rasterization occurs.

Canvas

The radii argument of CanvasPath.roundRect() is now optional in Safari 27.0. Calling roundRect(x, y, width, height) without radii draws a plain rectangle with square corners which is the same as calling rect() , matching the behavior of other browsers.

Rendering

Safari 27.0 adds srgb-linear and display-p3-linear to predefined color spaces, making these linear-light color spaces available in Canvas, WebGL, and other APIs.

MathML

Safari 27.0 updates its MathML operator dictionary to match the MathML Core specification, adding support for multi-character operators (like ++, :=, and /=). This improves spacing and layout for these operators in complex mathematical notation.

In addition, Safari 27.0 supports tabindex, focus(), blur(), and autofocus on MathML elements, improving MathML feature parity with HTML. This makes math content fully participate in keyboard navigation and focus management, which supports interactive educational content and accessibility.

Safari 27.0 also adds support for detecting embellished operators through <mrow> for underover layout. In MathML, an operator wrapped in a grouping element like <mrow> — for example, <mrow><mo>∑</mo></mrow> used as the base of a <munder> or <munderover> — still counts as that operator for layout purposes.

And the href attribute is now deprecated on all MathML elements except <a>, matching how HTML already restricts href to elements built for navigation rather than treating it as a global attribute.

WebRTC

Safari 27.0 adds support for the targetLatency attribute in WebRTC, for specifying a target latency on a receiver. It adds support for the RTCRtpCodec dictionary and related constructs, improving the ability to inspect and configure codecs. It adds support for RTCRtpReceiver.jitterBufferTarget, for tuning the jitter buffer. And it adds video source width and height to RTC stats.

Storage

Safari 27.0 now supports specifying maxAge when setting a cookie via the Cookie Store API.

await cookieStore.set({
  name: "session",
  value: "abc123",
  maxAge: 60 * 60 * 24 * 7, // one week, in seconds
});

Editing

Safari 27.0 now supports menu items that convert editable text between Simplified and Traditional Chinese characters. It’s available in the “Transformations” submenu of the context menu for relevant text selections.

WebDriver

Safari 27.0 adds WebDriver support for the Digital Credentials API, with commands that let automated tests simulate wallet payloads, wait indefinitely for a credential response, and simulate a user rejecting the request. This lets you write end-to-end tests for Digital Credentials flows without needing a real wallet or person to drive the interaction.

Web Extensions

The runtime.getDocumentId() Web Extension API now has support in Safari 27.0. It adds reporting of uncaught JavaScript exceptions and unhandled promise rejections in Web Extension scripts, making extensions easier to debug. It adds support for propagating user gestures through sendMessage(), connect(), postMessage(), and executeScript() — so extensions can reliably perform actions like media playback that require user activation. And it adds support for the tabId key in chrome.windows.create(), letting an extension move an existing tab into a newly created window instead of only creating new tabs from scratch.

WKWebView

Safari 27.0 helps native app developers do even more using the WKWebView public API for native app developers. Build advanced browser and web-hosting experiences on top of WebKit more easily with the following new features:

• WKJSHandle — use JavaScript object references from native code.
• WKContentWorldConfiguration — configure content world properties such as autofill scripting, shadow root access, and inspectability when creating a WKContentWorld.
• alternateRequest and overrideReferrerForAllRequests on WKWebpagePreferences — modify the main resource request during navigation and apply custom referrer headers across all resource loads.
• willSubmitForm callback on WKNavigationDelegate — receive notification of HTML form submissions via a new WKFormInfo object.
• mainFrameNavigation on WKNavigationAction and mainFrameNavigation on WKNavigationResponse — correlate navigation actions and responses with each other and their originating loads.
• WKWebView.load(_ url:) — load a URL directly without wrapping it in an NSURLRequest.
• WKDOMNodeSnapshot — clone DOM nodes, including shadow roots, between different WKWebView instances.
• WKHTTPCookieStore.cookies(for:) — retrieve cookies matching a specific URL without fetching the entire cookie store.
• WKWebpagePreferences.globalPrivacyControlEnabled — let a native app enable or disable sending the Global Privacy Control (GPC) Sec-GPC HTTP header on outgoing requests for a given page load.

Resolved issues

Accessibility

• Fixed an issue where calling speechSynthesis.cancel() removed utterances queued by subsequent speechSynthesis.speak() calls. (46151521)
• Fixed an issue where SVG <use> elements referencing <symbol> elements inside an <img> were incorrectly included as unnamed images in VoiceOver’s Images rotor. (98999595)
• Fixed an issue where changing the id attribute of an element targeted by aria-owns did not update the accessibility tree. (107644248)
• Fixed slot elements referenced by aria-labelledby to correctly use their assigned slotted content for accessible names and ignore hidden slotted nodes. (114500560)
• Fixed <meter> element to have consistent labels between aria-label and title attributes. (127460695)
• Fixed elements with display: contents and content in a shadow root to have their content properly read when referenced by aria-labelledby. (129361833)
• Fixed aria-labelledby to use the checkbox name instead of its value when the checkbox name comes from an associated <label> element. (141564913)
• Fixed VoiceOver cursor positioning for elements focused via the drawFocusIfNeeded() canvas API. (146323788)
• Fixed grid elements with child rows in a shadow root to properly work with VoiceOver. (153134654)
• Fixed an issue where VoiceOver read text within images that have role="presentation". (159304061)
• Fixed an issue where content within dynamically expanded <details> elements was not exposed in the accessibility tree. (159865815)
• Fixed an issue where the contextmenu event was not fired for elements inside iframes when triggered by keyboard or assistive technology actions such as VoiceOver’s VO+Shift+M. (164128676)
• Fixed an issue where changes to <input type="button"> elements inside live regions were not announced by assistive technologies. (168200460)
• Fixed ::first-letter text not being exposed in the accessibility tree when no other text accompanies it. (168458291)
• Fixed an issue where VoiceOver was unable to access aria-owned rows and their cells in grids and tables. (168770938)
• Fixed an issue where VoiceOver could not find focusable splitter elements when navigating to the next or previous form control. (170187464)
• Fixed an issue where color picker inputs could not be activated using VoiceOver’s press action. (172218114)
• Fixed an issue where interactive elements containing an <svg> named by a child <title> element did not expose an accessible name. (172559238)
• Fixed an issue where incorrect bounding boxes were computed for MathML table rows and cells. (172851295)
• Fixed an issue where comboboxes did not forward focus to their aria-activedescendant, preventing assistive technologies from interacting with list items. (172931277)
• Fixed VoiceOver on Safari unable to navigate to content revealed by disclosure widgets using hidden="until-found". (173228707)
• Fixed an issue where aria-owns was not respected when computing the accessible name from element content. (173249317)
• Fixed VoiceOver line-by-line reading skipping content in read-only documents. (174349841)
• Fixed invalidation of aria-hidden=”true” when focus lands inside the aria-hidden subtree. (174449524)
• Fixed VoiceOver’s “Skip redundant labels” setting not being respected on certain web pages. (176297111)
• Fixed an issue preventing VoiceOver from following focus() calls for newly added elements. (177167634)
• Fixed role computation for elements with prefixes. (178399441)
• Fixed VoiceOver jumping to the top of the page when navigating to an element that immediately becomes accessibility-ignored via JavaScript. (179065364)
• Fixed VoiceOver reporting the Recent Events table on parks.wa.gov as empty. (179156593)
• Fixed an <a> element with a click handler but no href not being exposed as a link. (179398579)
• Fixed VoiceOver not announcing the selected state of the day-of-month button when configuring a monthly notification. (180294912)
• Fixed stale aria-labelledby when the referenced element dynamically changes its aria-label. (180319221)

Animations

• Fixed an issue where animation-fill-mode did not correctly apply viewport-based units after the viewport was resized. (80075191)
• Fixed an issue where !important declarations did not override CSS animation values when CSS transitions were also running on the same property. (174367827)
• Fixed an issue where identity matrix decomposition generated invalid quaternions, resulting in incorrect transform animations. (174813328)

CSS

• Fixed an issue where -webkit-text-fill-color incorrectly overrode text-decoration-color. (47010945)
• Fixed shape-outside computing incorrect text wrapping in RTL writing modes. (56890238)
• Fixed aspect-ratio intrinsic-size handling in flex layout to align with the specification. (83240099)
• Fixed flex layout to use the used flex-basis instead of the specified value for definiteness evaluation. (85707621)
• Fixed an issue where the outline offset was too large for outline: auto on macOS. (94116168)
• Fixed an issue where element positioning was incorrect when the containing block was an anonymous block. (96548847)
• Fixed an issue where box-shadow did not work on display: table-row elements. (96914376)
• Fixed text-indent with calc() containing percentages to correctly treat percentage components as zero for intrinsic size contributions. (97025949)
• Fixed an issue where out-of-flow content had an incorrect height when set to fit-content. (97492632)
• Fixed an issue with percentage size resolution in flex items in quirks mode. (100183902)
• Fixed an issue where clip-path: inset() border-radius values did not render correctly at certain element and clip-path sizes. (110847266)
• Fixed text-decoration-thickness propagation to inner spans with non-inline style. (111015539)
• Fixed -webkit-box flexbox emulation not sizing children correctly inside <fieldset> elements. (114094538)
• Fixed: Improved performance on pages using :where and :is selectors. (114904007)
• Fixed an issue where elements with display: table could have incorrect layout when borders were present. (116110440)
• Fixed aspect-ratio not being respected on flex children when the flex container has position: absolute. (117807518)
• Fixed aspect-ratio not working correctly on flex children that also have overflow set. (118926827)
• Fixed font-family serialization to preserve quotes around family names that match CSS-wide keywords or generic families. (125334960)
• Fixed an issue where elements with border, position: absolute, and aspect-ratio: 1 were not rendered as squares. (126292577)
• Fixed an issue where perspective-origin failed to resolve var() references when used as the second value, preventing animations from being applied. (131288246)
• Fixed :focus-visible incorrectly matching after a programmatic focus() call triggered by clicking a button with child elements. (134337357)
• Fixed an issue where the bottom margin of a last child element collapsed out of a parent with min-height. (134356544)
• Fixed a performance issue where pages with many DOM manipulations and complex :has() selectors could freeze. (138431700)
• Fixed an issue where a font was downloaded despite no characters in the document falling within its unicode-range. (140674753)
• Fixed an issue where @media (prefers-color-scheme: dark) inside an iframe did not match when the iframe’s color-scheme was set to dark. (142072593)
• Fixed an issue where background-clip: text did not work on table header elements. (142812484)
• Fixed an issue where width: 0 did not collapse a table cell to its minimum size. (142814603)
• Fixed an issue where :has(:empty) continued to match after the targeted element’s content was dynamically changed to no longer be empty. (143864358)
• Fixed an issue where floats and out-of-flow objects could be incorrectly adjacent to anonymous blocks. (144481961)
• Fixed an issue where text gradually disappeared when toggling text-transform on elements with ::first-letter styling. (145550507)
• Fixed an issue where height: max-content resolved to zero on absolutely positioned elements when a child had max-height: 100%. (147333178)
• Fixed unnecessary text truncation that could occur with always-on scrollbars. (148428628)
• Fixed an issue where tables with collapsed borders incorrectly calculated the first row width, causing excess border width to spill into the table’s margin area. (149675907)
• Fixed an issue where an inline-flex container with flex-direction: column did not update its width to match the intrinsic size of a child image when the image was not cached. (150260401)
• Fixed CSS zoom interacting incorrectly with font-weight, font-style, and font-variant on iPad. (152173269)
• Fixed an issue where non-replaced elements with aspect-ratio enforced the automatic minimum size even when min-width was explicitly set to 0. (156837730)
• Fixed image aspect-ratio not being preserved when width: 100% and height: 100% are set but no ancestor has a defined width. (162373271)
• Fixed an issue where an element can’t anchor to its previous sibling. (162903640)
• Fixed :has() style invalidation performance for selectors where :has() is in non-subject position. (163512170)
• Fixed CSS Container Style Queries to work when the container has display: contents. (164414720)
• Fixed CSS Style Container Query to recognize the default value of a custom property in multiline cases. (165627262)
• Fixed an issue where RTL grid scrollable areas did not correctly account for grid layout and scrollbars. (167792896)
• Fixed pixel snapping to be applied consistently for all border-width value types. (168240347)
• Fixed rendering of linear gradients when all color stops are at the same position. (169063497)
• Fixed an issue where inset box-shadow was incorrectly positioned on table cells with collapsed borders. (169254286)
• Fixed position-try-order to interpret logical axis values using the containing block’s writing mode instead of the element’s own writing mode. (169501069)
• Fixed CSS Anchor Positioning so that absolutely positioned elements no longer anchor to viewport-fixed-position elements unexpectedly. (170323196)
• Fixed an issue where children with percentage heights inside absolutely positioned elements using intrinsic height values (fit-content, min-content, max-content) incorrectly resolved against the containing block’s height instead of being treated as auto. (171179193)
• Fixed an issue where percent-height replaced elements computed stale preferred widths in shrink-to-fit containers. (171184282)
• Fixed a regression where @scope styles did not apply to slotted elements in web components. (171383788)
• Fixed an issue where the table cell nowrap minimum width calculation quirk was applied outside of quirks mode. (171410252)
• Fixed an issue where display property transitions caused popovers and <dialog> elements to animate incorrectly when closing. (171454696)
• Fixed a performance issue where contain: layout caused significantly slower forced layouts when all siblings created their own formatting context. (171545381)
• Fixed an issue where dynamically inserting text before existing content did not update ::first-letter styling. (171649994)
• Fixed an issue where underlines were split when a ruby base was expanded due to long ruby text. (171653095)
• Fixed an issue where changing color-scheme did not repaint iframe background. (171658244)
• Fixed an issue where nested children of a popover element failed to render when using position: absolute. (171735933)
• Fixed an issue where color: initial resolved to the wrong color when the system is in dark mode. (172320282)
• Fixed an issue where an element with display: contents did not establish an anchor scope when using anchor-scope. (172355302)
• Fixed an issue where ordered list numbers with large starting values were clipped off-screen. (172515216)
• Fixed <general-enclosed> in media queries to reject content with unmatched close brackets per the <any-value> grammar. (172575115)
• Fixed an issue where the rlh unit was double-zoomed with evaluation-time CSS zoom. (172798163)
• Fixed an issue where anchor-positioned elements anchored to children of sticky-positioned boxes did not stick correctly. (172884148)
• Fixed an issue where pseudo-elements were not sorted correctly when sorting anchor elements by tree order. (173032203)
• Fixed outline: auto to correctly respect zoom. (173068660)
• Fixed transferred min/max block-size constraints not being applied for intrinsic keyword widths on replaced elements. (173128588)
• Fixed outline-offset to work correctly with outline: auto on iOS. (173130230)
• Fixed :active, :focus-within, and :hover pseudo-classes to correctly account for elements in the top layer. (173145294)
• Fixed a regression where the ic length unit was incorrectly affected by page scaling. (173198587)
• Fixed the shape() function to omit default control point anchors in computed value serialization per the CSS Shapes specification. (173233716)
• Fixed: Updated SVG and MathML user agent style sheets to use :focus-visible instead of :focus. (173321368)
• Fixed an issue where lh and rlh units resolved with double-zoom when line-height was a number value. (173448638)
• Fixed outline-width to be ignored when outline-style is auto, matching the specification. (173567890)
• Fixed :in-range and :out-of-range pseudo-classes for time inputs with reversed ranges. (173589851)
• Fixed :placeholder-shown to correctly match input elements that have an empty placeholder attribute. (173604635)
• Fixed an issue where ligatures caused a non-zero layout width for text with font-size: 0. (173840866)
• Fixed computed value of auto insets or margins as returned by getComputedStyle() to be zero, if the element uses position-area or anchor-center. (173885561)
• Fixed position-area not being able to anchor to an element positioned using anchor functions. (173964030)
• Fixed :in-range and :out-of-range pseudo-classes to correctly update when the readonly attribute changes. (173978657)
• Fixed scroll overcompensation of fixed, nested anchor-positioned elements, so they no longer lose their position when scrolling. (174010503)
• Fixed an issue where view-timeline-inset serialization failed to coalesce identical values. (174096313)
• Fixed CSS variable cycle detection to match the CSS Values Level 5 specification. (174105259)
• Fixed url() token serialization in CSS custom properties. (174144616)
• Fixed text-autospace to correctly handle supplementary Unicode characters. (174148315)
• Fixed an issue where flex items with different order values caused incorrect baseline alignment. (174241817)
• Fixed an issue where hovering over ::first-letter text showed a pointer cursor instead of the expected I-beam cursor. (174258447)
• Fixed an issue where display: grid on a <fieldset> element added extra unnecessary space below its content. (174301311)
• Fixed outline radii rendering for elements with a non-auto outline-style. (174328839)
• Fixed an issue where aspect-ratio was not honored when the page was zoomed in. (174361289)
• Fixed replaced elements to use the transferred size through intrinsic aspect ratio for min-content and max-content sizing. (174386310)
• Fixed an issue where height: 100% on a child element altered the layout when the parent’s height was defined via aspect-ratio. (174448267)
• Fixed margin collapse to be allowed when the preferred block size behaves as auto, per the CSS Sizing specification. (174547610)
• Fixed an issue where document.styleSheets and shadowRoot.styleSheets incorrectly included adopted style sheets, which per the CSSOM specification should only appear in the final CSS style sheets list used for style resolution. (174583340)
• Fixed the CSSOM preferred style sheet set name to be established at sheet creation time based on insertion order rather than tree order. (174586058)
• Fixed -webkit-box-pack to account for -webkit-box-direction and to handle overflow repositioning correctly. (174588996)
• Fixed highlight pseudo-elements such as ::selection and ::highlight to disallow vendor-prefixed properties, aligning with the CSS Pseudo-Elements specification. (174590593)
• Fixed cycle detection and nested function call handling in CSS custom functions. (174609179)
• Fixed FontFace.loaded to reject when a local() font source fails to load. (174631384)
• Fixed an issue where word-break: break-all incorrectly allowed CJK close punctuation to appear at the start of a line. (174656971)
• Fixed an issue where word-break: keep-all incorrectly suppressed line break opportunities at CJK punctuation characters. (174658701)
• Fixed the FontFace constructor to reject with a SyntaxError instead of a NetworkError when a BufferSource fails to parse, per the CSS Font Loading specification. (174669738)
• Fixed the FontFace family attribute to return the serialization of the parsed value. (174698351)
• Fixed grid layout to correctly handle percentage and calc() values for the specified size suggestion. (174863227)
• Fixed :has() sibling invalidation issues related to relation forwarding. (175006235)
• Fixed an issue where min-width: auto was not correctly computed for flex items. (175157619)
• Fixed an issue where percentage heights inside flex items did not resolve correctly in quirks mode. (175158571)
• Fixed an issue where margin-trim: block-start did not apply to blocks nested inside inline boxes. (175162899)
• Fixed an issue where dynamically changing display: contents on a <fieldset> legend caused incorrect rendering. (175163337)
• Fixed: Improved :has() invalidation performance by including the full selector context in invalidation selectors. (175177078)
• Fixed :hover state to repaint correctly on the customizable <select> element. (175273152)
• Fixed the CSS preload scanner to resolve relative @import URLs against the <base> element URL. (175305190)
• Fixed -webkit-box flex distribution for children with orthogonal writing modes. (175323734)
• Fixed calc(infinity) as a flex-grow factor not stretching a flex item to 100% width. (175431146)
• Fixed :has() sibling invalidation failing due to an internal bitfield overflow, causing stale styles when siblings are added or removed. (175433733)
• Fixed :has() invalidation for sibling combinators when elements are inserted or removed from the DOM. (175441568)
• Fixed transition-property not preserving the specified case of <custom-ident> values during serialization. (175467206)
• Fixed the will-change property not serializing correctly when used with non-property identifiers or identifiers in a non-standard case. (175482352)
• Fixed percentage top and bottom values on relatively positioned elements not resolving when the containing block has aspect-ratio. (175502356)
• Fixed: Updated the enhanced <select> element to use self- keywords for anchor positioning. (175505107)
• Fixed serialization of multi-word font family names that were always incorrectly quoted due to treating the full string as a single identifier. (175522811)
• Fixed text-indent computation when tab stop positions are involved. (175529961)
• Fixed calc() margin computations in flex layout. (175532405)
• Fixed calc() margin computations for block, fieldset, and table caption layouts. (175548980)
• Fixed handling of <li> value attributes in reversed ordered lists. (175558324)
• Fixed CSS trigonometric functions to correctly convert degrees to radians. (175575617)
• Fixed sibling-index() and sibling-count() inside calc() functions to be correctly simplified. (175590806)
• Fixed sibling-index() and sibling-count()to correctly return 0 when used in cross-tree ::part() styling. (175592607)
• Fixed the CSS resize handle not working on an element when the handle overlaps a child iframe. (175621855)
• Fixed flex container baseline alignment being incorrectly computed for scroll containers by clamping to the border edge. (175631095)
• Fixed an issue where inline-level boxes with calc() margins or padding lost the fixed component during intrinsic width computation. (175669222)
• Fixed floats with margin-start incorrectly overlapping adjacent floats. (175669464)
• Fixed aspect-ratio calculations for block-level elements with size constraints. (175669713)
• Fixed aspect-ratio calculations for flex items with percentage cross-size constraints. (175669774)
• Fixed aspect-ratio calculations for flex items with definite cross-size values. (175690028)
• Fixed revert-layer computing incorrectly when there is a leading empty or space substitution value. (175729680)
• Fixed :has() invalidation incorrectly resetting sibling relation bits, causing style invalidation failures for first-in-sibling-chain elements. (175738008)
• Fixed text in nested CSS Subgrid with overflow: hidden clipping content on subsequent items. (175877530)
• Fixed CSSStyleDeclaration.setProperty() failing to apply !important priority to an existing inline style property when the value was an integer of 255 or lower. (176099619)
• Fixed an issue where flex items with explicit min-height: min-content were incorrectly treated as scrollable, zeroing out their minimum size. (176173688)
• Fixed :has() invalidation performance when used inside nested :is() selectors. (176354723)
• Fixed sibling-count() & sibling-index() used in @keyframes to re-resolve when siblings change. (176531901)
• Fixed :has() style invalidation failing in complex nested cases involving :is(). (176719780)
• Fixed -webkit-perspective not establishing a containing block for fixed-positioned descendants. (176729670)
• Fixed nested multi-column layouts with three or more levels failing to paginate content across pages. (176741498)
• Fixed :has() selector performance by using scope selectors to limit style invalidation traversal for class, attribute, and pseudo-class changes. (176771971)
• Fixed non-replaced blocks with aspect-ratio and a percentage max-width collapsing to zero width during intrinsic sizing. (176873776)
• Fixed percentage max-width on elements with aspect-ratio resolving against the wrong axis in perpendicular writing modes. (176879597)
• Fixed z-index not applying to statically-positioned display: -webkit-box items to align with Firefox and Chrome behavior. (176886461)
• Fixed an interaction between an img with max-width and surrounding elements that caused the parent’s layout to compute incorrectly. (176889859)
• Fixed flex containers using box-sizing: border-box providing the wrong cross size to stretched flex items. (176989934)
• Fixed flex containers with aspect-ratio-derived height not providing a definite cross size to their flex items. (177085129)
• Fixed SVG images with no intrinsic dimensions collapsing to zero height inside column flex containers. (177086497)
• Fixed incorrect margin offsets for inline <div> positioning to fix the broken layout of paragraph spacing on some sites. (177139092)
• Fixed shrink-to-fit boxes to update their width when they gain or lose a scrollbar. (177172896)
• Fixed CSS zoom to be animatable by the computed value. (177411607)
• Fixed preferred width to trim trailing whitespace before a preserved newline. (177426037)
• Fixed inline layout to apply margins of preceding block content at the line start eagerly when block-in-inline content is involved. (177438841)
• Fixed CSS attr() to align with disallowing the <url> type. (177540489)
• Fixed CSS attribute selector case-insensitivity handling for HTML attributes. (177547701)
• Fixed ::first-letter to use the correct definition of punctuation. (177599506)
• Fixed offset-path to respect <coord-box> when blending shape() and basic-shape paths. (177685457)
• Fixed stretch-fit width with aspect-ratio providing a definite cross size to flex items when it should not. (177705930)
• Fixed an aspect-ratio flex container resolving descendant percentage heights against a stale logical height. (177711905)
• Fixed inline-block baseline to fall back to the bottom margin edge when the content has no in-flow line boxes. (177753094)
• Fixed programmatic focus after keyboard interaction to match :focus-visible. (177850766)
• Fixed @font-face font-style to serialize ‘oblique 0deg’ as ‘normal’. (178185291)
• Fixed serialization of explicit font-variant longhands set after a system font. (178251443)
• Fixed CSSFontFeatureValuesRule.fontFamily to be settable rather than readonly. (178323504)
• Fixed font-style: oblique to be clamped against the font’s slant range rather than the @font-face weight range. (178324521)
• Fixed font-style: oblique angle being applied to the variable font ‘slnt’ axis with the wrong sign. (178326843)
• Fixed background and mask coordinated property list resolved values to match the specification. (178378309)
• Fixed longer hue interpolation when one input is none. (178476769)
• Fixed serialization of @font-face font-weight, font-width, and font-style oblique descriptor ranges with equal bounds to collapse to a single value, per CSSOM. (178517226)
• Fixed line-through to render with the correct thickness over a descendant inline box. (178547557)
• Fixed font-synthesis to avoid synthesizing styles outside of a font’s variable axis range. (178550149)
• Fixed font-style: italic to slant a variable font whose @font-face uses an oblique angle. (178566326)
• Fixed an issue where font-synthesis incorrectly applied synthetic oblique to variable fonts declared with @font-face. (178698772)
• Fixed SVG intrinsic sizing so that height: max-content uses the used width rather than the default width. (178712792)
• Fixed serialization of various CSS at-rules not escaping identifiers. (178750383)
• Fixed color-mix() to allow percentages that sum to zero. (178758710)
• Fixed color-mix() resolution for the new 0% rules. (178921722)
• Fixed a flex item with min-width: min-content being clamped to a smaller max-width. (178777567)
• Fixed :last-child and related selectors incorrectly gating on parser state outside of style resolution. (178879939)
• Fixed synthetic bold not being applied for a variable font whose @font-face font-weight descriptor explicitly restricts it to normal. (179001275)
• Fixed changing the color-scheme of an <iframe> not invalidating the appearance of the embedded document. (179177141)
• Fixed an issue where CSS math functions produced an incorrect signed zero for subtraction, min(), max(), clamp(), and mod(). (179534440)
• Fixed serialization of hsl() and hwb() colors that contain at least one none component value so they preserve their hsl()/hwb() function rather than converting to rgb(). (179854247)
• Fixed CSS scroll snap re-snap to prefer the fragment-targeted (:target) snap area over other aligned snap targets. (180108825)
• Fixed an issue where input[type=hidden] was not set to display: none !important in the user-agent stylesheet. (180137214)
• Fixed the CSS preload scanner failing to preload @import rules that follow an @layer statement rule. (180170656)
• Fixed serialization of CSSViewTransitionRule. (180170814)
• Fixed MediaList.deleteMedium() to parse its argument as a media query and remove all matching queries. (180270019)
• Fixed MediaList.appendMedium() to parse its argument as a single media query and suppress duplicates. (180291283)
• Fixed grid items with stretch or fit-content preferred sizes computing incorrect minimum-content contributions when sizing tracks. (180748205)
• Fixed inserting a CSS rule while a view transition is active causing the group animation to snap to its final state. (181100818)
• Fixed CSS var() to only resolve its fallback when the first argument resolves to the guaranteed-invalid value. (181114298)
• Fixed navigating away from a render-blocked document before its first rendering opportunity incorrectly firing pagereveal and starting an outbound cross-document view transition. (181191512)
• Fixed anchor-center in vertical writing modes not being scroll-adjusted along the block axis. (181413103)

Canvas

• Fixed an issue where a 2D canvas element unnecessarily forced a compositing layer. (172864747)
• Fixed canvas 2D context to set the origin-clean flag when reset. (177858398)
• Fixed canvas fillText with textAlign=center misplacing complex-shaped text. (178682402)

Editing

• Fixed an issue where characters styled with ::first-letter were not selectable. (5688237)
• Fixed an issue where explicitly setting a font size that matched a legacy <font> size would be incorrectly substituted with the legacy size, causing inconsistent rendering across different default font size configurations. (15292320)
• Fixed drag images of DOM elements with CSS transforms not rendering correctly. (99614217)
• Fixed an issue where the Font Picker style selection became unusable after changing fonts when editing multiple lines of text. (110651645)
• Fixed an issue where adjusting text selection with touch handles was prevented by JavaScript touch event handling on some websites. (151851274)
• Fixed an issue where execCommand('FormatBlock') did not preserve inline styles of replaced block elements, causing text formatting to be lost when pasting content. (157657531)
• Fixed opaque DOM mutations coming from dictation on iOS. (163454428)
• Fixed an issue where text-indent flickered or was ignored on contenteditable elements while typing. (170280101)
• Fixed an issue where text selection would jump unexpectedly when selecting absolutely-positioned content inside an element with user-select: none. (170475401)
• Fixed an issue where text selection was lost when focus transitioned from a contentEditable element to a non-editable target. (171221909)
• Fixed an issue where composition events were dispatched in the wrong order during IME input, causing incorrect character rendering with Devanagari and other input methods. (174330850)
• Fixed the Edit menu’s Copy item being incorrectly enabled when there was no selection in the web page. (176061974)
• Fixed a regression where Vietnamese and Korean keyboard input methods incorrectly exited modeless composition mode, requiring a double spacebar press to complete each word. (176847897)
• Fixed a recent regression that “Zhuyin – Traditional” input method stalling for multiple seconds when composing Chinese text. (177042301)
• Fixed typing Hindi (InScript) input on Google Docs. (177643899)
• Fixed iOS selection behavior so that selection is now possible while focus is inside editable content. (178846185)
• Fixed deletion in an editable table leaving an empty trailing table row behind. (180877315)
• Fixed vertical caret movement in editable content ignoring the requested editable-type parameter. (181000174)
• Fixed the page scrolling on its own while adjusting a text selection inside a fixed-position element, such as a search field pinned to the top of the page. (182770935)

Encoding

• Fixed an issue where CJK encoding state was not reset appropriately during text decoding. (174649963)

Fonts

• Fixed an issue where synthetic bold incorrectly added advance width to zero-advance glyphs. (179418570)

Forms

• Fixed an issue where keyboard commands such as paste did not work in form fields that restrict input to numbers. (4360235)
• Fixed an issue where keyboard tabbing position was lost when a focused button became disabled, causing focus to jump to the beginning of the page. (120676409)
• Fixed an issue where a positive margin-top on a <legend> element inside a <fieldset> did not shift the fieldset down. (141267953)
• Fixed an issue where small range input slider thumbs were difficult to interact with on iPadOS and visionOS by expanding their touch hit area. (147428926)
• Fixed <datalist> suggestions appearing with white text on a white background in dark mode after typing. (168676757)
• Fixed an issue on iOS where typing into an <input> element associated with a <datalist> was intercepted by type-to-select behavior. (173346270)
• Fixed: Made the <input type="checkbox" switch> control behave more like other controls with regards to native appearance CSS properties. (173487610)
• Fixed identically sized buttons to render with consistent corner radius. (173786057)
• Fixed an issue where <select multiple> did not always fire onchange when the mouse button was released far outside the element. (173882861)
• Fixed an issue where <select> control rendering was broken in vertical writing mode. (174068353)
• Fixed a performance issue where parsing <select> elements with thousands of <option> children via innerHTML caused O(n²) overhead due to repeated list recalculation. (174244946)
• Fixed an issue where date and time input types without min or max attributes incorrectly matched the :in-range pseudo-class. (174829899)
• Fixed an issue where cloned <input> and <textarea> elements did not preserve their user-modified state. (174892989)
• Fixed <option> elements to correctly implement the HTML specification’s dirtiness concept for tracking user-modified selected state. (175306111)
• Fixed the select picker appearing at an incorrect position when the <select> element is anchor positioned. (175454476)
• Fixed the default display value for <optgroup> and <option> elements to block, matching the behavior of other browsers. (175473184)
• Fixed field-sizing: content clipping the placeholder on number inputs that have no value. (175883299)
• Fixed <option> and <optgroup> elements to match the :disabled pseudo-class when inside a disabled <select>. (176559708)
• Fixed a box with percentage offset (e.g. top: 100%) being mispositioned when its containing block is out-of-flow with percentage height. (177181803)
• Fixed the concentric inner-button corner radius on horizontal text form controls incorrectly ignoring the bottom inset. (180869927)
• Fixed a number of issues with the default styles for customizable <select> with appearance: base-select, including spacing, borders, border-radius, overflow, cursors, optgroup styling, picker dialog shadow, and increased contrast colors. (183345556)

HTML

• Fixed an issue where an HTML map element without a name attribute did not match its associated image using the id attribute. (12359382)
• Fixed sequential focus navigation to skip elements that do not meet the specification’s focusability requirements. (103370883)
• Fixed viewport <meta> parsing to correctly treat form feed as ASCII whitespace per the HTML specification. (108440799)
• Fixed parsing of javascript: URLs to align with the specification. (147612682)
• Fixed a severe performance regression causing dynamic insertion of <img> elements with a src attribute to be dramatically slower than other browsers. (166201075)
• Fixed an issue where a third nested <iframe> using the srcdoc attribute did not render. (167917471)
• Fixed incorrect parsing of pixel-length margin attributes on <body>, <iframe>, and <frame> elements. (171240848)
• Fixed popover light dismiss to account for input buttons. (171352032)
• Fixed popover light dismiss to account for disabled command buttons. (171358576)
• Fixed an issue where replaceWith() stopped processing remaining nodes if a script in the replacement removed a sibling. (172753019)
• Fixed an issue where HEIC images were incorrectly converted to JPEG when uploaded via drag-and-drop or file input. (173206598)
• Fixed the HTML preload scanner to skip preloading stylesheets that have the disabled attribute. (173378582)
• Fixed an issue where setting the rel attribute on an <a> element multiple times did not clear prior link relations. (173567839)
• Fixed the HTML parser fast path to correctly process escaped attribute values longer than one character. (173673581)
• Fixed the HTML parser fast path to correctly detect nested <li> elements. (173983892)
• Fixed the HTML parser fast path to use the adjusted current node for MathML and SVG integration point checks. (174096305)
• Fixed document named item collection to include all <object> elements, aligning with other browser engines. (174537345)
• Fixed window.open() to correctly consume user activation when creating a new browsing context, aligning with the HTML specification. (174587258)
• Fixed remaining issues with <img sizes="auto"> to fully align with the specification. (174684058)
• Fixed nested calls to requestClose() incorrectly firing multiple cancel events and causing a stack overflow. (174850509)
• Fixed requestClose() incorrectly removing the open attribute when called on a disconnected dialog element. (174855725)
• Fixed an issue where dir=auto on <slot> elements did not update when slotted content changed. (174871706)
• Fixed an issue where <option> elements rendered incorrectly when the label attribute was empty. (174979446)
• Fixed an issue where the preload scanner incorrectly skipped <source> elements with an empty type attribute inside <picture>. (175094037)
• Fixed innerText to emit a newline for empty <option> or <optgroup> inside <select>. (175245381)
• Fixed HTML floating-point number parsing to correctly handle values with a leading + sign. (175300431)
• Fixed innerText to no longer emit newlines for visibility: hidden block elements. (175569426)
• Fixed innerText to correctly emit blank lines around <p> elements regardless of their CSS display value. (175729427)
• Fixed the speculative preload scanner to no longer incorrectly preload scripts inside SVG elements. (175800116)
• Fixed <a rel="ar"> elements wrapping <model> elements to correctly enter ARQL without extra steps and to display the AR badge. (176410897)
• Fixed innerText on tables to no longer emit spurious trailing newlines and to preserve row-exit newlines after empty rows. (176635985)
• Fixed the HTML preload scanner not preloading resources referenced by legacy <image> tags. (176712749)
• Fixed a regression that broke pushState with custom application URL schemes. (177547157)
• Fixed outerHTML setter to align with the HTML standard. (177788638)
• Fixed fragment parsing of xmlns="" inheritance and annotation-xml encoding. (177808494)
• Fixed createHTMLDocument() to no longer leave the body in a parsing state. (178440940)
• Fixed text fragment matching so that a prefix is no longer matched outside of a word boundary near the start of the document. (178467104)
• Fixed an issue where <link rel=preload as=json> incorrectly triggered a preload. (179843455)
• Fixed an issue where the deprecated align="center" attribute was not treated as identical to align="middle" per spec. (180128710)

Images

• Fixed an issue where inserting an image with a srcset attribute into a dynamically created iframe resulted in an invisible image. (66849050)
• Fixed naturalWidth and naturalHeight returning incorrect values for SVG images without intrinsic dimensions. (141196049)
• Fixed an issue where HDR images would flicker and lose their HDR appearance when overlapping layers animate. (163382580)
• Fixed an issue where adopting a standalone img element did not update its image data. (172856773)
• Fixed images appearing then quickly disappearing on OpenTable search results. (176275269)
• Fixed rendering performance of HDR images that have gain-maps by using GPU-backed surfaces. (176605566)
• Fixed <picture> <source> candidates being speculatively preloaded even when the inner <img> has loading=lazy. (177833110)
• Fixed HTMLImageElement.decode() to no longer resolve spuriously after adoption, src change, or cached-image reuse. (178118012)
• Fixed a regression where RGB gain map images were decoded to 8 bits per channel, causing a color shift and incorrect brightness. (179152566)
• Fixed handling of the gain-map target pixel format when decoding HDR images to fall back safely when the format cannot be parsed. (181180757)

JavaScript

• Fixed multiple top-level await correctness bugs with a rewrite of the ES module loader for standards compliance. (97370038)
• Fixed regular expressions in Unicode mode to not count non-capturing groups and modifiers toward the number of available backreferences. (167746769)
• Fixed %TypedArray%.prototype.subarray to calculate beginByteOffset correctly to align with ECMA-262. (168143600)
• Fixed the trace behavior of RegExp.prototype[Symbol.split] to align with ECMA-262. (168288878)
• Fixed Array.prototype.concat to correctly handle arrays with indexed accessors, preventing getter reentry from bypassing Symbol.isConcatSpreadable checks. (172237596)
• Fixed an issue where a greedy or non-greedy non-BMP character class in a regular expression could advance the index past the end of input. (172978772)
• Fixed an issue where class instance field initializers did not have the correct evaluation context when used inside arrow functions and nested scopes. (173296563)
• Fixed TypedArray [[Set]] to check the receiver before writing to the typed array. (173386404)
• Fixed %ArrayIteratorPrototype%.next() to return { done: true } instead of throwing a TypeError when the source TypedArray is detached and the iterator has already completed. (173759106)
• Fixed an issue where a fixed-count mixed-width character class in a regular expression did not correctly restore the index on backtrack. (173972458)
• Fixed an issue where regular expressions with non-BMP characters could skip valid match positions when alternating between patterns. (174200307)
• Fixed an issue where regular expression captures were not properly cleared when backtracking out of fixed-count parenthesized groups and negative lookaheads. (174201284)
• Fixed an issue where import { “``" as x } was incorrectly treated as a namespace import instead of a named import using the string “" as a ModuleExportName. (174314099)
• Fixed an issue where RegExp.prototype.exec and RegExp.prototype.test could match against a stale pattern if lastIndex has a valueOf that calls RegExp.prototype.compile. (174461752)
• Fixed an issue where async functions using module-scoped variables could fail when the DFG JIT optimized scope resolution. (174626957)
• Fixed an issue where Intl.Segmenter with granularity: "word" incorrectly reported isWordLike: false for numeric segments. (175057894)
• Fixed Object.defineProperties to call Proxy traps in the correct order. (175068687)
• Fixed an issue where Intl.Locale did not canonicalize before overriding the language. (175092327)
• Fixed time zone identifiers to return primary IANA time zone IDs instead of legacy ICU identifiers. (175098682)
• Fixed the Array ToPrimitive fast path incorrectly ignoring overrides of Object.prototype.valueOf. (175122250)
• Fixed input position corruption in regular expression backward matching when rewinding over a surrogate pair. (175122467)
• Fixed Intl.DateTimeFormat to preserve the original legacy timezone identifier instead of replacing it with the primary IANA ID. (175206605)
• Fixed Promise.prototype.finally to throw a TypeError when @@species is not a constructor, matching the behavior of other browsers. (175290627)
• Fixed the regular expression engine to reject dangling hyphens in character class syntax when using the /v flag. (175559808)
• Fixed a performance issue with module resolution by limiting cache population to star-resolution and indirect-resolution cases. (175826413)
• Fixed a performance issue with TypedArray.prototype.lastIndexOf by adding SIMD-accelerated reverse search for numeric types. (175904377)
• Fixed a performance issue where building a module namespace with many export statements was significantly slower than necessary. (175949532)
• Fixed DataView constructor to match specification-defined argument validation order and error throwing behavior. (176110210)
• Fixed an issue where Array.prototype.concat could produce incorrect results when combining arrays with incompatible indexing types. (176219964)
• Fixed multiple TypedArray constructor edge cases involving buffer sequences to align with the specification. (176724918)
• Fixed WebAssembly.Memory and WebAssembly.Module to align their cloning and transferring behavior with SharedArrayBuffer. (176792374)
• Fixed Array.prototype.join to include prototype elements added during element toString invocation. (178055452)
• Fixed an issue where Temporal.Instant operations were not aligned with the spec’s abstract operations. (179844859)

MathML

• Fixed the MathML operator dictionary to correct the stretchy property for several operators, resolving Web Platform Test failures. (170901728)
• Fixed an issue where symmetric non-stretchy large operators were not centered around the math axis. (170905663)
• Fixed an issue where dynamic changes to <mo> element attributes did not trigger a relayout. (170907029)
• Fixed an issue where minsize and maxsize defaults and percentages did not use the unstretched size as specified. (170908253)
• Fixed positioning of the <mprescripts> element within <mmultiscripts> layout. (170909975)
• Fixed an issue where the MathML fraction bar was not painted when its thickness was equal to its width. (170934351)
• Fixed an issue where <none> and <mprescripts> elements were not laid out as <mrow> elements in MathML. (170940035)
• Fixed an issue where MathML token elements ignored -webkit-text-fill-color when painting math variant glyphs. (172020318)
• Fixed padding and border rendering on <msqrt> and <mroot> elements and corrected token sizing for mathvariant. (173081436)
• Fixed absolute positioning of elements inside MathML by ensuring logical height is updated. (173088146)
• Fixed tabIndex values not being set correctly for MathML elements. (174734133)
• Fixed spacing values for prefix operators +, −, ±, ∓, ∇, and infix operator ⋉ in the MathML Core operator dictionary. (176652211)
• Fixed the operator dictionary entry for the ∂ prefix operator to use the correct spacing values (3, 0) instead of (2, 1). (176693587)
• Fixed nonce-hiding support for MathML elements to align with the HTML specification. (176875058)
• Fixed MathML operators routed through MathOperator being invisible when their glyph only exists in a fallback font. (178096170)
• Fixed MathML to use MathML Core fallback values for script layout constants. (179177178)

Media

• Fixed <audio> and <video> controls rendering incorrectly when rotated via CSS transform. (37516619)
• Fixed an issue where decoding WebM audio files with more than two channels would fail. (82160691)
• Fixed an issue where preservesPitch and playbackRate were not correctly handled on an HTMLMediaElement connected to an AudioContext via createMediaElementSource. (93275149)
• Fixed MediaCapabilities.decodingInfo() incorrectly reporting VP8 in WebM as not supported. (127339546)
• Fixed WebVTT to not display cues that are larger than the viewport. (136809012)
• Fixed an issue on iPad where exiting fullscreen on a media document incorrectly navigated back to the previous page instead of returning to the inline view. (137220651)
• Fixed an issue where the WebCodecs VideoDecoder API output frames in an incorrect order for videos containing B-frames. (145093697)
• Fixed an issue where the darkening overlay on inline video controls made accurate scrubbing difficult and displayed video content incorrectly on macOS. (161271114)
• Fixed an issue where WebM with VP9/Vorbis fallback would not play. (164053503)
• Fixed video playback failing when the declared MIME type in a <source> element does not match the actual content type served by the server. (166181001)
• Fixed an issue where text selection was broken after pausing a video when the media player ran in the content process. (167727538)
• Fixed HTMLMediaElement.currentTime to report smoothly progressing values instead of updating only at fixed intervals. (170115677)
• Fixed an issue where MP4 files containing Opus audio tracks could not be decoded with decodeAudioData. (170196423)
• Fixed an issue where the VideoFrame constructor did not handle the video color range correctly for NV12 (I420 BT601) video frames. (170299037)
• Fixed an issue where Live Text selection was unavailable on paused fullscreen videos. (170817667)
• Fixed an issue where FairPlay-protected VP9 content failed to play via MediaSource. (171210968)
• Fixed media controls not appearing when tapping videos in the LinkedIn feed on iPad. (171231918)
• Fixed an issue where autoplay would proceed before default text tracks finished loading. (171699293)
• Fixed the currentTime getter to return defaultPlaybackStartPosition when no media player exists. (171722368)
• Fixed HTMLMediaElement to fire a timeupdate event when resetting the playback position during media load as required by the specification. (171785463)
• Fixed an issue where the media player preload attribute was not properly updated when the autoplay attribute was set. (171883159)
• Fixed an issue where seeking in a WebM video did not work correctly while content was still loading. (172473039)
• Fixed an issue where media playback could not move to the next item in a playlist when the tab was in the background. (172676372)
• Fixed an issue where scrubbing a video in full-screen mode could cause it to exit full-screen. (172682230)
• Fixed an issue where HDR video content appeared washed out due to colorspace information being lost during processing. (172721079)
• Fixed Encrypted Media Extensions to check support for the full content type including codecs, rather than only the MIME type. (173852931)
• Fixed an issue where setting HTMLMediaElement.volume had no effect when the element was connected to an AudioContext. (174278899)
• Fixed ImageCapture to correctly queue takePhoto() and applyConstraints() requests to avoid concurrent capture session reconfiguration. (174950018)
• Fixed a regression where videos would stop playing and lose audio after a few seconds on some websites. (174966899)
• Fixed an issue where U+0000 (NULL) characters were not allowed in VTTCue text content. (175084171)
• Fixed video content disappearing after switching to another tab and back. (175257980)
• Fixed WebVTT cue settings line parsing failures. (175296476)
• Fixed subtitles and closed captions not appearing in fullscreen video on iOS. (175298523)
• Fixed <audio controls> to not show the “Subtitles” option when no subtitle track is present. (175357130)
• Fixed ::cue() selectors to correctly match the WebVTT root object in addition to child nodes. (175550173)
• Fixed currentTime on iOS to update more frequently during media playback. (175774587)
• Fixed Media Source Extensions readyState not being updated immediately when playback stalls due to a gap in buffered data. (176330683)
• Fixed timeupdate events being fired during seeking before the seek operation completes. (176861767)
• Fixed the ended event not always firing when the MediaSource duration is changed to match the current playback position. (176863546)
• Fixed a MediaSource issue where the decode-key cleanup in coded frame processing was incorrectly removing non-orphaned samples. (176971800)
• Fixed currentTime() returning a stale value after the playback rate was changed from zero to a non-zero value. (177046564)
• Fixed MSE SourceBuffer.remove() to no longer remove an extra sample, and fixed buffered ranges to cover the correct ranges. (177065364)
• Fixed an HTMLMediaElement that doesn’t display in an infinite scrolling webpage to use a viewport listener that notifies the media player about the visibility of the element. (177081214)
• Fixed EME to use a 10 second key wait timeout. (177936893)
• Fixed EME OCDM to prevent a spurious keystatuses event when all keys have expired. (177939767)
• Fixed getSupportedCapabilitiesForAudioVideoType (EME) to no longer include unsupported capabilities. (178142768)
• Fixed MediaSession.setActionHandler to not throw an exception when called. (178167294)
• Fixed AudioData.copyTo to throw RangeError when frameOffset equals numberOfFrames. (178609688)
• Fixed MIDI and AVI MIME signature matching due to a typo in MIME sniffing. (178661530)
• Fixed PannerNode to no longer produce non-finite samples for edge-case distance parameters. (178784571)
• Fixed the VP codec parameters string to no longer zero-pad bitDepth based on transferCharacteristics. (179210193)
• Fixed an issue where the MediaSource text-track removal loop always processed only the last track. (179508398)
• Fixed an issue where isValidVideoFrameBufferInit() tested displayWidth and displayHeight presence against themselves instead of the correct properties. (179514279)
• Fixed an issue where MediaMetadata artwork sizes parsing read the wrong substring for the height value. (179523057)
• Fixed an issue where the pictureInPictureElement getter inverted the shadow-host connectivity check. (179675087)
• Fixed ArrayBuffer-backed YUV VideoFrame with a visibleRect rendering with offset chroma channels. (180202939)
• Fixed video playback of streams from certain sources such as security cameras not working. (180411019)
• Fixed transient device rotation resulting in captured video frames having the wrong orientation. (180429147)
• Fixed Media Source Extensions playback and seek by loosening the gap tolerance between buffered ranges. (180439090)
• Fixed being unable to enter Picture-in-Picture again after navigating to another video. (182971786)
• Fixed video showing a black screen while audio continued to play after the video decoder was invalidated. (184041554)

Model Element

• Fixed setting the entityTransform on a <model> element while the model is unloaded or hidden. (179114750)
• Fixed <model> elements losing gesture interactivity after the model player is reloaded (for example, when the model scrolls out of and back into the viewport). (179249565)

Navigation

• Fixed a <meta http-equiv="refresh"> to a URL differing only in fragment identifier being incorrectly treated as a page reload. (176933795)

Networking

• Fixed redirects to data: URLs to be blocked for subresources such as images and scripts, aligning with the Fetch specification. (74165956)
• Fixed XMLHttpRequest incorrectly dropping the request body during redirects. (98459882)
• Fixed X-Frame-Options to only strip tab or space characters, not vertical tabs. (126915315)
• Fixed an issue where Safari’s address bar could display an internationalized domain name (IDN) homograph as a visually identical legitimate Latin domain, enabling potential phishing attacks. (166796168)
• Fixed an issue where the preload scanner did not include integrity metadata in requests, causing incorrect Integrity-Policy violation reports. (168280745)
• Fixed range request validation to properly handle HTTP 416 (Requested Range Not Satisfiable) responses. (168487440)
• Fixed a regression where the referrer could be missing after a process-swap navigation. (169006635)
• Fixed incorrect URL query percent-encoding when using non-UTF-8 character encodings such as iso-8859-2, windows-1250, and gbk. (169566553)
• Fixed an issue where the multipart form data parser incorrectly required CRLF after the closing delimiter, causing some web applications to fail to render correctly. (174348783)
• Fixed an issue where partitioned cookies could not be deleted via WKHTTPCookieStore. (174557252)
• Fixed URL parsing for sendBeacon() and the Media Session API. (177330315)
• Fixed an issue where WebKit refused to load valid ASCII domains starting with xn-- that did not pass strict IDNA 2008 validation, aligning behavior with the WHATWG URL Standard. xn-- is the prefix of a punycode-encoded non-ASCII domain. (177686282)
• Fixed an issue where arbitrary Content-* headers from 304 responses were not used to update cached entries. (179864251)
• Fixed an issue where the Cache-Control request directives max-age, min-fresh, and no-store were not honored. (179865576)
• Fixed an issue where Cache-Control: public was not honored on responses with unknown status codes. (179870099)
• Fixed an issue where the HTTP cache did not store responses with explicit freshness for all status codes. (179871690)
• Fixed URL path separators being encoded as %2F following a percent-encoded Armenian path segment. (180067095)

PDF

• Fixed an issue where panning a zoomed-in PDF on iOS would frequently rubber band back to the starting position. (156854435)
• Fixed broken text underlines in PDFs created by WKWebView‘s PDF export API. (180631575)
• Fixed only one PDF HUD responding to mouse clicks on pages with multiple embedded PDFs. (183273642)

Performance

• Fixed an extremely slow page load on iPhone caused by blur filters with large radii (172480480)

Printing

• Fixed an issue where animations were ignored during print, causing missing content on animated pages. (36901701)
• Fixed an issue where printing light text on a dark background with backgrounds disabled could result in invisible text. (170070133)
• Fixed a regression where printing a WebView embedded in an enclosing NSPrintOperation dropped all text. (174756900)

Rendering

• Fixed an issue where table cells with rowspan values exceeding the actual number of rows were incorrectly computing heights. (3209126)
• Fixed changes to a filter: drop-shadow() not repainting the area outside the element’s boundaries. (49387957)
• Fixed an issue where ::first-letter styles caused Range.getClientRects() and Range.getBoundingClientRect() to return incorrect dimensions. (71546397)
• Fixed incorrect distributed height in table rows when a <td> element has an explicit height set. (78549188)
• Fixed an issue where U+2028 LINE SEPARATOR was not rendered as a forced line break. (88470339)
• Fixed an issue where a block formatting context with margin-start could overlap an adjacent float. (93187697)
• Fixed position: relative on table rows (<tr>) to correctly establish a containing block for absolutely positioned descendants. (94294819)
• Fixed <marquee> elements causing incorrect table width calculations. (99826593)
• Fixed Google search-suggestion font sizes increasing on rotation from portrait to landscape. (113801810)
• Fixed boxes in the top layer to use the initial containing block as their static-position rectangle. (155495104)
• Fixed an issue where a flex item containing a percentage-height image did not shrink correctly around the image. (156902823)
• Fixed an issue where form controls with height: 100% in auto-height containers incorrectly resolved to zero height. (161699543)
• Fixed incorrect box sizing on inline elements when they have no siblings and their padding-left plus margin-left equals zero. (162376969)
• Fixed a regression where an element inside an iframe gaining its own compositing layer could cause an iframe’s semi-transparent background to appear darker.(163509267)
• Fixed an issue where space-taking scrollbars did not trigger a proper re-layout when the box size depends on content size. (166836126)
• Fixed misrendering of Pahawh Hmong text on Wikipedia. (167446860)
• Fixed an issue where View Transition snapshots were incorrectly stored in sRGB, causing rendering issues with non-sRGB colors. (167634138)
• Fixed an issue where font subpixel quantization was unnecessarily disabled in some cases, improving text rendering quality. (168088611)
• Fixed table layout to properly handle visibility: collapse on columns. (168556786)
• Fixed intrinsic sizing for absolutely positioned replaced elements. (168815514)
• Fixed text being incorrectly truncated in RTL containers when combined with text-overflow: ellipsis and an inline-block pseudo-element. (168875614)
• Fixed percentage padding in table cells to resolve against column widths. (168940907)
• Fixed a regression where hovering over elements could leave repaint artifacts on the page. (169112402)
• Fixed table height distribution to apply to tbody sections instead of only the first section. (169154677)
• Fixed an issue where table sections with explicit heights did not properly constrain and distribute space among contained rows. (169235210)
• Fixed an issue where images with min-width: fit-content rendered at an incorrect width. (169359566)
• Fixed an issue where height: 100% was incorrectly calculated for replaced elements like images serving as grid items nested inside a flexbox. (169431440)
• Fixed an issue where images were incorrectly stretched in certain page layouts. (170270187)
• Fixed an issue where Find in Page scrolled to the wrong location when matching text inside elements with user-select: none. (170477571)
• Fixed the baseline calculation for inline-block elements so that when overflow is not visible, the baseline is correctly set to the bottom margin edge. (170575015)
• Fixed an issue where replaced elements did not correctly apply min-height and min-width constraints in certain configurations. (170765025)
• Fixed an issue where overlay backgrounds would briefly dim incorrectly when de-compositing in a scrollable container. (171024685)
• Fixed a regression where sticky-positioned elements inside overflow containers could appear in front of content that should overlap them. (171179878)
• Fixed an issue where auto table layout did not honor max-width on table cells when distributing width between them. (171459245)
• Fixed an issue where border-spacing incorrectly included collapsed columns in auto table layout calculations. (171468102)
• Fixed an issue where percentage-height children of table cells with unresolvable percentage heights were not sized intrinsically. (171469500)
• Fixed an issue where cell backgrounds in collapsed-border tables extended into adjacent cells’ border space at table edges. (172068907)
• Fixed an issue where if a document in an iframe uses @prefers-color-scheme, it does not follow the color-scheme set by grandparents of the iframe. (172229372)
• Fixed an issue where list item margins were computed incorrectly when the page was zoomed in or out. (172312498)
• Fixed an issue where about:blank iframes did not always have a transparent background. (172400258)
• Fixed an issue where a right-floated table could overlap another table. (172655655)
• Fixed an issue where grid containers failed to avoid float boxes. (172655720)
• Fixed an issue where an anonymous block created for list markers was not properly collapsed when block content prevented line-box parenting. (172686060)
• Fixed text-wrap: balance not being applied to content with -webkit-line-clamp. (172715503)
• Fixed an issue where checkboxes could overlap with adjacent text. (172741572)
• Fixed an issue where checkbox outlines appeared misaligned. (172742551)
• Fixed an issue where list markers rendered on the wrong line when list items started with empty inline elements. (172762578)
• Fixed an issue where U+2029 PARAGRAPH SEPARATOR was not treated as a forced line break. (173106856)
• Fixed a black region appearing on the right side of swift.org when the sidebar is open. (173191807)
• Fixed an issue where tiles were missing after navigating back in history. (173288233)
• Fixed an issue where view transition snapshots could capture stale transform values for accelerated CSS transform animations. (173323193)
• Fixed an issue with outside list markers when blockification prevents line-box parenting. (173417560)
• Fixed a regression where nested empty inline boxes accumulated an incorrect vertical offset, causing inline elements to stack as block-level elements. (173723162)
• Fixed an issue where pseudo-elements were incorrectly included in outline rect collection. (174033087)
• Fixed an inverted Y-axis comparison that could cause incorrect caret positioning. (174144220)
• Fixed <legend> to mask the <fieldset>‘s border correctly when it has a negative left margin. (174185071)
• Fixed an issue where <br> elements with line-height: 0 still created extra vertical space, failing to respect the declared line height. (174400946)
• Fixed auto outlines to more closely follow the border radii of elements. (174466854)
• Fixed how gradients are rendered to improve performance. (174880197)
• Fixed image-orientation being ignored for background-image, border-image, and list-style-image. (174894122)
• Fixed a white-space: pre-wrap layout issue with justified text. (174937310)
• Fixed an image with min-height: min-content inside a column flex container not shrinking to preserve its aspect ratio. (174999995)
• Fixed an issue with flex-wrap and flex factor computation for wrapping flex items. (175012395)
• Fixed vertical writing-mode content incorrectly wrapping when the parent has auto height. (175123356)
• Fixed a column-wrap flex container with flex-basis: 0 wrapping items into extra columns instead of stacking them when nested inside another column flex container. (175195518)
• Fixed incorrect bounding box position for newline characters. (175243361)
• Fixed an issue where a child element with filter: blur() ignored border-radius overflow clipping from its parent. (175519148)
• Fixed an issue where absolutely positioned tables with content exceeding their declared width were incorrectly positioned. (175755871)
• Fixed height calculations for absolutely positioned tables with percentage-sized children. (175762381)
• Fixed an issue where containers with block-in-inline content did not expand when max-height was removed. (175799547)
• Fixed an issue where absolutely positioned tables with explicit percentage or fixed heights did not resolve correctly against their containing block. (175852400)
• Fixed always-on scrollbar thumbs not rendering on the root element of nested documents with display: flex. (175866046)
• Fixed absolutely positioned tables ignoring min-height and shrinking below their content height. (175883577)
• Fixed drop-shadow filters and transform: translate() incorrectly clipping nested elements after a regression. (175905543)
• Fixed absolutely positioned tables ignoring max-height constraints. (175932457)
• Fixed scrollbar-gutter placement on the root element in RTL layouts. (175939512)
• Fixed an issue where a flex item with aspect-ratio and content-box padding computed the wrong height in a column flex container. (176033726)
• Fixed a repaint issue where table rows did not repaint their previous position after a preceding row changed size, causing content to appear at both the old and new locations. (176172404)
• Fixed an issue where block-level boxes nested within inline elements were not properly aligned when using align-content: center. (176173122)
• Fixed a regression that caused incorrect layout in some content using stretch. (176398251)
• Fixed intrinsic sizing for non-replaced elements with percentage dimensions. (176493856)
• Fixed justification expansion to apply around CJK Unified Ideographs Extensions E, F, G, and H. (176759766)
• Fixed RTL position-fixed elements losing their contents when the document is scrolled on iOS. (177454608)
• Fixed the background of a composited <html> element not being repainted when the <body> background changed. (177975964)
• Fixed an issue where text changes that did not modify the text element’s size in a flex layout on a new compositing layer did not trigger re-rendering. (179292409)
• Fixed an issue where an underline was drawn twice on <sup> elements. (179537119)
• Fixed an issue where an underline under a <sup> element was offset by one device pixel from the rest of the line on subpixel displays. (179586525)
• Fixed an issue where the ex unit in text-box-edge misplaced the propagated underline, causing it to be painted twice. (179769451)
• Fixed an issue where min-width was not honored over max-width when sizing a shrink-to-fit container around a replaced element. (179935558)
• Fixed an issue where an <img> embedding an SVG with a near-integral intrinsic width rendered one device pixel narrower than expected. (180490343)
• Fixed elements with filter: drop-shadow() not being fully repainted when a child is resized. (181284741)

SVG

• Fixed SVG applying text-decoration to elements with display: contents. (85691104)
• Fixed SVG <text> with textLength scaling each glyph separately when x or y is a list. (94161279)
• Fixed an issue where backslash-escaped dot characters in SVG animation timing attribute ID references were not parsed correctly. (94260935)
• Fixed an issue where SMIL animations of href or xlink:href on SVG <image> elements had no visual effect. (96316808)
• Fixed the resolved value for the width and height properties on SVG <rect>, <image>, <svg>, and other elements. (96320059)
• Fixed an animated GIF freezing when referenced by SVG <use> and the opacity was adjusted. (96837306)
• Fixed an issue where SVG animation did not clear the animated CSS property when attributeName was dynamically changed. (97097883)
• Fixed an issue where box-shadow was not drawn on fixed-positioned SVG elements. (97098951)
• Fixed :visited link color to properly propagate to SVG through currentColor. (98776770)
• Fixed an issue where a CSS filter referencing an SVG filter via url(#id) was not invalidated when the filter content changed. (101870430)
• Fixed vector-effect to apply a transform to path geometry rather than to stroke geometry. (103573160)
• Fixed negative stroke-dashoffset values rendering with incorrect offsets when stroke-dasharray has an odd number of values. (103596361)
• Fixed <animateMotion> non-path animations to apply the rotate attribute. (110915794)
• Fixed SVG2 systemLanguage attribute to improve parsing and compliance with the specification. (116427520)
• Fixed removing an item from SVGTransformList to properly allow attribute removal. (117840533)
• Fixed SVG SMIL length animations to reject invalid to, from, and by values such as those with leading whitespace. (118537155)
• Fixed Unicode text with complex scripts not rendering correctly along a curved <textPath>. (120284006)
• Fixed an issue where the XML document parser did not defer inline script execution until pending stylesheets had loaded. (122574381)
• Fixed an issue where animated SVG images referenced via an <img> tag did not animate correctly due to repaint artifacts with object-fit. (141815698)
• Fixed SVG elements with display: contents being visually hidden. (141825746)
• Fixed an SVG <tspan> positioning bug with xml:space="preserve" that caused multi-line text to render incorrectly. (143722975)
• Fixed an issue where SVG elements referencing non-existent filter IDs were not rendered. (164046592)
• Fixed SVGPathElement.getTotalLength() and . SVGPathElement.getTotalLength.getPointAtLength() to respect the CSS d property. (167195297)
• Fixed offsetX and offsetY for SVG elements to use the outermost SVG as the base for coordinate calculation. (168548585)
• Fixed an issue where URL fragments were not percent-decoded before being used for SVG references. (169582378)
• Fixed: Updated the default values of fx and fy attributes on SVGRadialGradientElement to 50% to align with the SVG2 specification. (169645572)
• Fixed SVGAnimatedRect.baseVal to ignore invalid values set on the viewBox attribute, such as negative width or height, aligning with Firefox and Chrome. (170214971)
• Fixed SVG length attributes to reset to their default values when removed, rather than retaining previously set values. (170360351)
• Fixed an issue where getScreenCTM() did not include CSS transforms and zoom contributions in the legacy SVG rendering path. (171525696)
• Fixed a rounding issue for SVG rect height with em and percentage values. (171587382)
• Fixed SVGLength.convertToSpecifiedUnits() failing when converting from px to %, em, or ex. (172056830)
• Fixed an issue where an SVG <image> element was not repainted when the href attribute was removed. (172530834)
• Fixed an issue where an invalid attribute type in one SVG animation group prevented all subsequent animation groups from running. (172593109)
• Fixed a regression where wheel events were not dispatched to an empty <svg> root element. (172909441)
• Fixed an issue where SMIL parseClockValue did not reject out-of-range minutes and seconds values per the SMIL timing specification. (173577212)
• Fixed the SMIL values attribute to preserve empty values and handle trailing semicolons. (173594455)
• Fixed SMIL repeat(n) event conditions not triggering animations. (173599629)
• Fixed SVG2 getStartPositionOfChar and getEndPositionOfChar to be more compliant with the specification. (174145885)
• Fixed SVG intrinsic sizing so that max-content and min-content use the viewBox aspect ratio when intrinsic sizes are missing. (174568894)
• Fixed glyph-orientation-vertical: auto to use UTR#50 Vertical Orientation properties for correct character orientation in vertical text. (175064567)
• Fixed SVG intrinsic aspect ratio being incorrectly suppressed when preserveAspectRatio is set to none. (175173375)
• Fixed SVG images without complete intrinsic dimensions incorrectly using ratio-based scaling for background-size. (175345107)
• Fixed glyph-orientation-vertical: auto to decode surrogate pairs for UTR#50 lookup. (175570881)
• Fixed the SMIL clock value parser to accept hours greater than 99 and reject malformed seconds values. (175593583)
• Fixed stroke-dasharray interpolation to use least common multiple for list length matching and corrected composition behavior. (175598175)
• Fixed SVG geometry presentation attributes like cx, cy, r, rx, ry, x, y, width, and height being incorrectly applied to elements such as <g> on which they are not permitted. (175672111)
• Fixed handling of pathLength="0" and negative pathLength for stroke dashing. (175928827)
• Fixed an issue where @prefers-color-scheme in an SVG image will sometimes not follow the system color appearance. (176413340)
• Fixed getScreenCTM() returning an incorrect matrix when the document is scrolled under a CSS-transformed ancestor. (176814876)
• Fixed an issue where an SVG filter applied via CSS to an element positioned below the viewport rendered a spurious black square at the viewport origin. (177482001)
• Fixed hit-testing of clip-path with nested objectBoundingBox <clipPath> to use the correct reference box. (177605894)
• Fixed SVG overflowing edges when offset by a fractional value. (177630386)
• Fixed IntersectionObserver not computing intersections for SVG element roots. (177807041)
• Fixed feGaussianBlur not applying when stdDeviation contains a 0 in the second component. (177906905)
• Fixed SVG vertical <text> to honor the CSS text-orientation property instead of only the deprecated glyph-orientation-vertical presentation attribute. (178044217)
• Fixed an issue where the per-character rotate attribute was discarded on a <textPath>, so it now composes with the path tangent angle. (178044478)
• Fixed an issue where getRotationOfChar() returned approximately 360° instead of 0° for full-turn rotations after normalisation into the [0°, 360°) range. (178044934)
• Fixed an issue where a non-BMP character before a <tspan> boundary shifted the x and y value lists by one position. (178360036)
• Fixed interpolation of arc flags in the d property to treat them as non-zero booleans. (178950624)
• Fixed pathFromEllipseElement to honor auto values for rx and ry, so APIs such as getTotalLength() return the correct length for ellipses. (178959205)
• Fixed animated GIFs freezing when presentation attributes are changed on an SVG image referenced by a <use> element. (179414226)
• Fixed an issue where getBoundingClientRect() on an SVG <tspan> element returned the bounds of the entire <text> element instead of the <tspan>‘s own area. (179626476)
• Fixed an issue where a nested clip-path on a <clipPath> element ignored css zoom. (180162723)
• Fixed several SVG styling spec-compliance failures. (181052042)
• Fixed dynamic changes to orient and markerUnits on <marker> not repainting elements that reference it. (181106538)
• Fixed SVG SMIL number, integer-optional-integer, number-optional-number, and path animations to not apply when their from, to, or by values fail to parse. (181308150)

Scrolling

• Fixed an issue on iOS where calling scrollTo during a momentum scroll incorrectly interrupted the scroll, ensuring that momentum scrolling continues as expected and smooth scrolling behaves properly. (41949531)
• Fixed scrolling of the “Add Contacts” drop-down on outlook.live.com by narrowing the scope of a quirk. (48008837)
• Fixed an issue on iOS where programmatic smooth scrolling with scroll-snap-type: mandatory failed after the browser chrome was hidden. (100727098)
• Fixed an issue where scrollIntoView with nearest alignment incorrectly aligned to the far edge for an oversized target positioned before the scrollport. (106356373)
• Fixed an issue where interrupting scroll momentum caused the scrolling container to stop rendering and hit-testing to be misplaced. (116205365)
• Fixed an issue on iOS where restored scroll position was incorrect after relaunching Safari. (127308062)
• Fixed a passive: false wheel event listener combined with overscroll-behavior: contain preventing scrolling. (137757208)
• Fixed an issue where tabbing in a scroll container with scroll-padding did not scroll the focused element into view. (147513379)
• Fixed pan gestures incorrectly passing through scroll containers laid over vertical-rl body text. (160788907)
• Fixed a regression on macOS 26 where horizontal rubber-banding interfered with vertical scrolling. (165449829)
• Fixed an issue on macOS where custom CSS scrollbars could be cut off and the scrollbar corner rect was sized incorrectly. (168566468)
• Fixed rubberbanding behaving incorrectly when a site triggers a smooth scroll to the top during a rubberband. (170705188)
• Fixed an issue where pages could become blank and jump to the top after dynamically loading new content when scroll anchoring was enabled. (170889205)
• Fixed an issue where scroll anchoring could cause pages to scroll to negative offsets. (171221075)
• Fixed an issue where pages using the Navigation API could have offset hit test locations, making elements unclickable. (171752650)
• Fixed CSS scroll snap points inside zero-sized elements not working correctly. (172863699)
• Fixed an issue on iOS where composited layers would briefly flash blank when window.scrollTo() was called synchronously with a DOM layout change. (173197381)
• Fixed occasional flashes of an incorrect scroll position when scroll anchoring adjusts content while scrolling. (173456210)
• Fixed an issue where sticky-positioned elements could flicker rapidly after scrolling. (173680821)
• Fixed an issue where scroll anchoring could cause a page to scroll to the top or bottom automatically. (173885027)
• Fixed an issue where calling scrollIntoView() on a scrollable element incorrectly scrolled the element’s own contents. (174173683)
• Fixed scroll anchoring interfering with rubberbanding on some websites. (175195943)
• Fixed an issue on iOS where scroll position was not preserved correctly when rotating the device on right-to-left pages. (175910769)
• Fixed top and bottom fixed-position elements flickering during rubber-band scrolling. (176226179)
• Fixed the scroll anchoring behavior so that the comments panel on Quip is no longer blank when expanded. (178255628)
• Fixed an issue where scroll snapping selected a snap point that overshot the destination instead of the closest one in the scroll direction. (179549119)
• Fixed an issue where interrupting a smooth scroll with a new scrollTo() call to a different target fired the scrollend event at the wrong position. (179551854)
• Fixed an issue where re-snapping after a layout change moved away from a valid scroll position when the snap area was larger than the snapport. (179553122)
• Fixed CSS scroll snap re-snap to prefer a snap area that contains the focused or fragment-targeted element. (180707984)
• Fixed the scroll position jumping when a page changes scroll-padding while scroll anchoring is active. (183145868)

Security

• Fixed an issue where Content Security Policy 'self' did not match script sources in opaque-origin HTTP(S) documents. (178638597)
• Fixed <object> elements that load images being incorrectly blocked by the img-src Content Security Policy directive. (178772677)
• Fixed a regression where some websites failed to display and logged Content Security Policy errors in the console. (179684592)
• Fixed an issue where Content Security Policy incorrectly applied script-src to JSON module imports instead of connect-src. (180006320)
• Fixed same-page navigations being incorrectly checked against Content Security Policy. (180342503)
• Fixed Content Security Policy frame-ancestors violations in report-only policies being ignored instead of reported. (180447621)
• Fixed Content Security Policy parsing to reject trailing characters after the closing quote on nonce-source and hash-source values. (180903857)
• Fixed Content Security Policy trusted-types expressions to reject trailing characters after keywords and the wildcard. (180973793)

Spatial Web

• Fixed spatial and panoramic image controls to support RTL language layout and localization of type labels. (161690817)
• Fixed <model> elements displaying at 100x the expected size for assets authored in tools that use centimeter units. (167805672)
• Fixed an issue where WebXR viewports did not get an initial value until getViewport() was called. (168125694)
• Fixed an issue where the <model> element stagemode orbit physics behaved differently between iOS and visionOS. (172189776)
• Fixed an issue on visionOS where fullscreen video would sometimes jump when exiting fullscreen if the browser window was narrower than the video. (174454557)
• Fixed an issue where removing all text from the URL bar on Safari in visionOS showed an empty completion list. (176499710)
• Fixed XRProjectionLayer to return correct values for width, height, and layer count. (178444052)
• Fixed an issue where transforming the camera instead of the model in a <model> element led to undesirable lighting effects. (179522538)

Storage

• Fixed an issue where IndexedDB could incorrectly return a version 0 database after an abort during the initial onupgradeneeded event. (176195526)
• Fixed IndexedDB connections in workers to recover after a network process crash. (177219395)
• Fixed an issue where IndexedDB transactions could be blocked for an extended period before starting when another page’s transaction was suspended in the background. (178769599)

Tables

• Fixed an issue with a collapsed border color mismatch when the table cell has a different writing-mode. (173655092)

Text

• Fixed a line break appearing after a U+201D Right Double Quotation Mark. (177952069)

UI Events

• Fixed boundary events not being dispatched when a hovered element is removed from the DOM, so the Full Screen button on bsky.app no longer remains stuck in a hover state. (176507648)

Web API

• Fixed the parent window’s history.state being set to null when history.pushState is called from a child iframe. (50019069)
• Fixed the Async Clipboard API to request paste access asynchronously. (75969974)
• Fixed clicking on a scrollbar of an overflow container blurring the current activeElement. (92367314)
• Fixed an issue where the change event was not fired on <input> and <textarea> elements when they lost focus while another application was in the foreground. (98526540)
• Fixed Web IDL bindings to correctly reject SharedArrayBuffer where [AllowShared] is not specified. (107786134)
• Fixed Content Security Policy to only recognize ASCII whitespace excluding vertical tabs to align with the specification. (108559413)
• Fixed emoji input on Google Docs and similar web applications by suppressing keypress events for supplementary characters. (122678873)
• Fixed an issue where MouseEvent.offsetX and MouseEvent.offsetY were not relative to the padding edge as specified. (125763807)
• Fixed an issue on visionOS where the gamepadconnected event did not fire unless gamepad permission had already been granted. (141623162)
• Fixed an issue where CSPViolationReportBody did not include the source line number in Content Security Policy violation reports. (152607402)
• Fixed IntersectionObserver to no longer notify targets in detached documents. (162699098)
• Fixed an issue where selecting credentials in the Digital Credentials API sometimes required a second click to trigger verification. (163295172)
• Fixed window bar visibility properties (toolbar.visible, statusbar.visible, menubar.visible) to return static values per the HTML specification for privacy and interoperability. (166554327)
• Fixed handling of unknown DigitalCredential protocols by gracefully filtering them out and showing a console warning instead of throwing an error. (166673454)
• Fixed: Updated the Digital Credentials API to rename DigitalCredentialRequest to DigitalCredentialGetRequest per the latest specification. (167115220)
• Fixed an issue where Service Worker routes were not matched when no fetch event handler was set. (167753466)
• Fixed spec conformance issues in the Streams API piping and abort behavior. (167841090)
• Fixed Service Worker static routing rules to enforce limitation checks as required by the specification. (167977145)
• Fixed layerX and layerY to return correct values with CSS transforms. (168968832)
• Fixed location.ancestorOrigins returning stale origins after an iframe is removed from the document. (169097730)
• Fixed NavigateEvent.canIntercept to correctly return false when navigating to a URL with a different port, aligning with the Navigation API specification. (169845691)
• Fixed NavigateEvent.navigationType to return "replace" when navigating to a URL that matches the active document’s URL. (169999046)
• Fixed an issue where the dragend event had incorrect coordinates when dragging within a nested <iframe>. (170750013)
• Fixed an issue where navigation.currentEntry.key did not change in private browsing windows after calling history.pushState(). (171147417)
• Fixed an issue where touch event properties values were sometimes swapped with neighboring values. (171567543)
• Fixed a performance issue where ResizeObserver callbacks became increasingly sluggish over time. (172718139)
• Fixed a performance issue where IntersectionObserver became sluggish over time when observing many elements due to O(n²) iteration. (172727210)
• Fixed an issue where navigation.currentEntry.id did not change in private browsing windows after calling history.replaceState(). (172897962)
• Fixed an issue where document.open() incorrectly aliased the caller’s security origin. (173369038)
• Fixed an issue where history.replaceState() on a traversed history entry incorrectly changed navigation.currentEntry.key to a new UUID instead of preserving the original key. (173388766)
• Fixed an issue where Object.prototype could not be serialized by structuredClone(). (173728983)
• Fixed an issue where backslashes were not handled correctly in non-special URLs. (173757759)
• Fixed a URL parsing bug in the special relative or authority state. (173772241)
• Fixed an issue where event listener once and passive flags were not preserved when copying listeners between elements. (173834642)
• Fixed: Preserved existing listener options (such as passive defaulting) when overwriting event handler attributes. (173842822)
• Fixed the Credential Management API to properly define which credential types are allowed in the same get() request. (173918198)
• Fixed an issue where event.target was not set after dispatching an event in a shadow tree with no listeners. (174136382)
• Fixed an issue where navigator.credentials.create() and navigator.credentials.get() discarded the AbortSignal reason and always rejected with a generic AbortError. (174220589)
• Fixed Range.extractContents() to not extract out-of-bounds nodes when the end container is removed during extraction. (174307275)
• Fixed Digital Credentials to surface OperationError for platform-cancellation and unknown errors instead of AbortError or UnknownError. (174308268)
• Fixed document.createEvent() to throw an exception for "MutationEvents", "MutationEvent", "PopStateEvent", and "WheelEvent", aligning with other browser engines. (174339775)
• Fixed ParentNode.append() to correctly de-duplicate nodes when the same node is passed multiple times. (174365465)
• Fixed an issue where MutationObserver delivered childList records in the wrong order when script ran during node insertion. (174368989)
• Fixed an issue where setting a URL object’s port property to whitespace behaved incorrectly. (174484035)
• Fixed a missing return in the Navigation API’s performTraversal that caused incorrect behavior when traversing to an unknown key. (174513305)
• Fixed Blob.slice() to correctly clamp fractional start and end parameters using round-half-to-even rounding per the File API specification, which may change how edge-case fractional values like 0.5 are rounded. (174555334)
• Fixed postMessage() to validate transferable object states after serialization, aligning with the HTML specification. (174558047)
• Fixed structuredClone() and window.postMessage() to correctly throw a DataCloneError when serializing a SharedArrayBuffer outside of cross-origin isolated contexts. (174562553)
• Fixed an issue where calling Element.blur() on an <iframe> did not reset document.activeElement to <body>. (174591529)
• Fixed document.styleSheets to be accessible on documents created by DOMParser. (174625774)
• Fixed innerText getter to correctly handle trailing newlines and blank lines for <p> elements and headings. (174642704)
• Fixed innerText whitespace handling at inline-block boundaries. (174713114)
• Fixed XMLSerializer namespace handling to correctly serialize elements with namespace prefixes. (174726401)
• Fixed the innerText getter to preserve newlines for elements with white-space: pre-line. (174727341)
• Fixed service worker registrations to be unregistered when the main script is missing. (174755909)
• Fixed innerText handling of replaced elements at block boundaries. (174816319)
• Fixed EventSource to be closed when window.stop() is called. (174830925)
• Fixed service worker registrations to be unregistered when failing to retrieve stored imported scripts. (174833692)
• Fixed calling preventDefault() during a pointerdown event to correctly suppress mousedown and mouseup events on iOS. (174864309)
• Fixed innerText to not fall back to textContent for elements with display: contents. (174883499)
• Fixed Digital Credentials rejecting with the wrong error code and synchronously; rejections are now queued as a task with the correct error. (174895437)
• Fixed innerText to preserve the contents of <option> elements inside <select>. (175006854)
• Fixed Element.innerText to collect option text when called directly on a <select> element. (175156630)
• Fixed worker scripts to always be decoded as UTF-8, as per the specification. (175327455)
• Fixed an issue where an Event object’s target property could lose its JavaScript wrapper due to premature garbage collection. (175439759)
• Fixed an issue where ancestors of TreeWalker.currentNode could be prematurely garbage collected. (175442228)
• Fixed FileSystemDirectoryHandle.resolve() to return the correct path array for child entries. (175645387)
• Fixed PerformanceNavigationTiming.domInteractive and domContentLoadedEventEnd incorrectly returning 0 instead of the correct timestamps. (175739835)
• Fixed FileSystemDirectoryHandle.removeEntry() to correctly remove entries. (175745157)
• Fixed CryptoKey to correctly remain associated with its secure context. (176157712)
• Fixed: Improved cross-origin isolation enforcement for workers. (176175488)
• Fixed SharedArrayBuffer cloning and agent cluster ID assignment. (176465817)
• Fixed missing custom element callbacks for the role attribute. (176713992)
• Fixed incorrect URL parser invocation on the Notification object. (176762955)
• Fixed requestAnimationFrame() not providing sub-millisecond timestamp precision in cross-origin isolated contexts. (176967366)
• Fixed IntersectionObserverEntry.boundingClientRect to honor CSS zoom aware getBoundingClientRect. (177250323)
• Fixed IntersectionObserver to report correct bounds for SVG element targets. (177260411)
• Fixed Web Locks API to remove the AbortSignal abort algorithm after a lock request settles. (178589067)
• Fixed an issue where the URL Pattern tokenizer emitted a spurious zero-length Regexp token for empty regexp groups. (179452346)
• Fixed KeyboardEvent.getModifierState("AltGraph") and MouseEvent.getModifierState("AltGraph") always returning false. (180597374)
• Fixed Credential.type returning "digital-credential" instead of "digital" for digital credentials. (180618646)
• Fixed aborting navigator.credentials.get() leaving the digital-credentials document picker stuck on screen. (180812397)
• Fixed FileReader.readAsText() ignoring the charset parameter of the Blob‘s MIME type. (180890703)
• Fixed DOMMatrix and IntersectionObserver correctly enforcing absolute-length unit requirements when parsing values. (181453666)

Web Audio

• Fixed Web Audio PannerNode orientation-only changes not updating the directional cone gain. (181413407)

Web Extensions

• Fixed cross-origin XMLHttpRequest from a Safari Web Extension to no longer trigger an additional permissions request. (154866064)
• Fixed browser.i18n.getMessage() to correctly substitute named placeholders when they appear adjacent to non-space characters. (169146196)
• Fixed browser.i18n.getMessage() to correctly substitute two adjacent named placeholders. (175315700)
• Fixed an issue where web extension service worker registration database files accumulated on each Safari launch, causing performance degradation. (175484888)
• Fixed loading Web Extensions breaking Cloudflare bot challenge pages. (176618014)

Web Inspector

• Fixed hovering over a node in a preview for a collection to highlight the node in the inspected page. (20341722)
• Fixed showing ES2022 class private fields, methods, and accessors when inspecting object instances in the Console. (88527162)
• Fixed an issue where CSS properties added to new rules were not applied and were marked as invalid. (103548968)
• Fixed an issue in the Network panel where the Request / Response menu did not remember the user’s previously selected value. (108231795)
• Fixed a JavaScript breakpoint on a line containing only a semicolon not being triggered. (126707973)
• Fixed the Console REPL to allow redefinition of variables declared with let and const. (143140659)
• Fixed the Timeline exporting and importing the wrong timestamp for performance.mark() records. (145226764)
• Fixed editing inline style attribute values in the Elements panel resulting in truncated or malformed content. (149523483)
• Fixed local response overrides mapped to a file being interpreted as Latin-1 (ISO-8859-1) instead of their actual encoding. (149847746)
• Fixed the Media Logging setting not persisting across page loads. (154766890)
• Fixed symbolic breakpoints to work with native constructors such as Array, Date, EventTarget, and Worker. (157178256)
• Fixed an issue where the input field for recording canvas frames in the Graphics tab was sometimes too small to type in and only allowed typing one character at a time. (157787230)
• Fixed the Network tab filtering by resource type not working after clearing a filter that had no matches. (161570940)
• Fixed an issue where CSS rules added via the “Add New Rule” button in the Styles panel were intermittently not applied or would vanish after entering a property. (164971557)
• Fixed the Status column in the Network tab to be visible by default. (167348733)
• Fixed missing stack traces for MIME type errors when importing modules. (169396940)
• Fixed an issue where tree outlines in Web Inspector would intermittently show blank content while scrolling when a filter was active. (169502061)
• Fixed an issue where an active recording in the Timelines tab would stop when navigating or reloading the current page even when the setting to stop recording once the page loads was turned off. (169732727)
• Fixed an issue in the Timelines tab where rows containing object previews were sometimes not visible in the heap snapshot data grid. (170164522)
• Fixed context menu items in the Elements tab to only display relevant options when multiple DOM nodes are selected. (170307979)
• Fixed an issue where previewing resources in the Network tab displayed an error upon navigating away and Preserve Log was enabled. (171216835)
• Fixed an issue where selected DOM node keys in a Map in the Scope Chain sidebar had unreadable white text on a light background. (171840122)
• Fixed the Safari Develop menu and WebDriver to launch Device Hub instead of Simulator when available in Xcode. (174276041)
• Fixed the Layers 3D view to correctly map textures to composited bounds and use proper selection highlighting instead of tinting textures. (174355052)
• Fixed the Layers 3D view to re-snapshot preserved layers after a repaint instead of displaying stale textures. (174358757)
• Fixed an issue where the WebAssembly debugger had no source bytes for modules compiled via WebAssembly.instantiateStreaming, preventing source-level debugging in LLDB. (174362152)
• Fixed the WebAssembly debugger to generate human-readable module names from the WebAssembly name section and fetch URL, replacing bare address-based fallback names in LLDB’s image list. (174465437)
• Fixed an issue where all folder tree elements were expanded after filtering for a resource in the Sources panel. (175009135)
• Fixed an erroneous “There are unread messages that have been filtered” banner appearing in the Console when console.groupCollapsed() is used. (175279759)
• Fixed an issue in the Storage tab where filtering by storage type did not reveal the popup with options. (175444192)
• Fixed Timeline recordings showing unrelated events incorrectly nested inside longer events. (176309164)
• Fixed clearing the Console tab search field to dismiss the Clear Filters button. (176388155)
• Fixed Web Inspector toolbar buttons rendering at incorrect sizes. (176508343)
• Fixed the Event Listeners sidebar to populate for cross-origin iframe nodes. (177011541)
• Fixed properties added to an element’s Style Attribute sometimes disappearing momentarily. (178053421)
• Fixed the Accessibility sidebar being empty for nodes inside cross-origin iframes. (178562336)
• Fixed inline style invalidation to batch DOM.getAttributes commands per tick in cross-origin iframes instead of issuing one command per node. (178830496)
• Fixed DOM Storage read and write commands to resolve against the frame’s own origin in cross-origin iframes. (179249711)
• Fixed a moved breakpoint reverting to its original location after closing and reopening Web Inspector. (180083858)
• Fixed showing the formatted parameters string for prototype objects such as Map.prototype. (180298712)
• Fixed missing formatted parameter strings for object shorthand methods and arrow functions. (180466459)
• Fixed an unnecessary colon appearing in front of non-class function properties. (180476445)
• Fixed a self-canceling ternary that produced an incorrect cross-axis direction in the flex overlay. (181198803)
• Fixed the color picker force-converting picked colors to Display P3. (181201503)
• Fixed Page.searchInResources silently omitting cache-backed resources from search results. (181202027)
• Fixed duplicate invalid CSS declarations both incorrectly displaying as Active in the Styles sidebar. (181203080)
• Fixed adopted constructable stylesheets being misclassified as User Agent stylesheets in cross-origin iframes. (181204768)
• Fixed an unsigned underflow that caused the DOM agent to spuriously report power-efficient playback. (181205602)
• Fixed Network.setExtraHTTPHeaders to replace previously set headers instead of accumulating them. (181282814)
• Fixed zero-width joiners and other hidden Unicode characters not being displayed in text nodes. (182968570)

WebAssembly

• Fixed WebAssembly.Suspending and WebAssembly.SuspendError to be data properties instead of getter functions, aligning with other WebAssembly attributes like WebAssembly.Module. (170155726)
• Fixed incorrect IntegerOverflow exceptions thrown by i32.rem_s, i64.rem_s, i32.div_u, i64.div_u, i32.rem_u, and i64.rem_u when both operands are constants. (175122462)
• Fixed a regression where RegisterSet::normalizeWidths() lost vector-width information, causing v128 argument corruption in WebAssembly SIMD thunks. (176035764)

WebDriver

• Fixed an issue where the WebDriver full page screenshot was clipped to the viewport dimensions instead of the full page. (179840186)

WebGL

• Fixed a regression where a WebGL canvas was filled with opaque content that hid stacked canvases beneath it. (175352260)
• Fixed compressedTexImage not validating whether the compressed texture format extension has been enabled. (175652171)
• Fixed some texImage functions reporting errors with incorrect function names. (175652807)
• Fixed some WebGL context state properties not being correctly reset on context loss. (176190808)

WebGPU

• Fixed GPUDevice.onuncapturederror event handler attribute not working. (149577124)
• Fixed: Restored maxStorageBuffersInFragmentStage and related WebGPU limits. (160800947)
• Fixed rendering failing when using direct GPUTexture objects instead of GPUTextureView with multisampled resolve targets in render passes. (175452924)
• Fixed a WGSL shader validation failure in binary arithmetic expressions. (176473479)
• Fixed WGSL parser handling of identifiers per the latest specification. (177008615)
• Fixed WGSL validation of binary expressions involving short-circuit and/or operators. (177012957)

WebRTC

• Fixed an issue where I420 BT709 VideoFrame was encoded in an incorrect color space when encoding to VP9. (169425608)
• Fixed an issue where RTCPeerConnection.addIceCandidate() did not reject when the connection was already closed. (170470988)
• Fixed outgoing video feeds freezing when the Safari window is obscured by another window while a virtual background is active. (170720729)
• Fixed an issue where RTCDataChannel did not check the SCTP buffered amount synchronously. (172386678)
• Fixed an issue where MediaStreamTrack could have incorrect settings if the source settings changed while the track was being transferred. (172657570)
• Fixed an issue where a remote WebRTC track was not unmuted when the first packet was received. (172904930)
• Fixed validation of RTC send encodings to better align with the specification. (172997814)
• Fixed an issue where RTCRtpSender.setParameters did not clear parameters that were unset by the web application. (173678165)
• Fixed WebRTC VP9 encoders to correctly propagate frame colorspace information. (174008548)
• Fixed WebRTC media capabilities to report power-efficient AV1 decoding when supported. (174686183)
• Fixed a regression where RTCPeerConnection with iceTransportPolicy: "relay" failed to gather ICE candidates. (174794660)
• Fixed RTCInboundRtpStreamStats.trackIdentifier to match MediaStreamTrack.id. (174938984)
• Fixed audio issues when joining Cisco Meeting Server meetings using Safari. (175260977)
• Fixed screen sharing via getDisplayMedia() starting at extremely low quality and taking up to 30 seconds to become legible for remote participants. (175425085)
• Fixed the WebProcess AudioSession to remain active while microphone capture is live. (180505014)
• Fixed OverconstrainedError to inherit from DOMException and expose a code attribute per the Media Capture spec. (180728516)
• Fixed the configurationchange event being dropped when a source-side change occurred while a MediaStreamTrack was muted; the event is now deferred until unmute. (180728609)

Updating to Safari 27

Safari 27.0 comes automatically with macOS 27 Golden Gate, iOS 27, iPadOS27 and visionOS 27. Plus, you can update to Safari 27.0 on macOS 26 Tahoe and macOS 15 Sequoia, separate from macOS.

Feedback

We love hearing from you. To share your thoughts, find our web evangelists online: Jen Simmons on Bluesky / Mastodon, Saron Yitbarek on Bluesky, and Jon Davis on Bluesky / Mastodon. You can follow WebKit on LinkedIn. If you run into any issues, we welcome your feedback on Safari UI (learn more about filing Feedback), or your WebKit bug report about web technologies or Web Inspector. If you run into a website that isn’t working as expected, please file a report at webcompat.com. Filing issues really does make a difference.

The WebKit team at Igalia is happy to announce a new release series of WPE WebKit. This release has two main highlights: the new WPEPlatform API, now stable and enabled by default, and a web process compositor built on the Skia graphics library, replacing the TextureMapper-based one. Read on for the details on both, along with a summary of the other most noteworthy changes from the latest release cycle.

WPEPlatform: the new WPE API

WPEPlatform, the API that has been in the works for the past several release cycles, takes center stage in 2.54: it is now enabled by default and its API is considered stable, so applications can build on it without expecting breaking changes in future releases. Consequently, the traditional libwpe-based API is officially deprecated: it remains available and maintained, but new code should target WPEPlatform, and existing embedders are encouraged to plan their migration. This also applies to Cog, which will not have stable releases beyond the 0.18.x series.

The best part of the new API is how much simpler it is. Under libwpe, an application had to create a view backend (usually through WPEBackend-fdo’s “exportable” backend) and drive rendering, buffer management, and input dispatch itself through its callbacks. WPEPlatform moves all of that into WebKit and the platform implementation, so migrating an application is mostly a matter of deleting code: in the common case, the application constructs its WebKitWebView without a backend, WebKit selects a suitable platform automatically, and everything built on top of the web view carries over unchanged. The platform API only surfaces when an application wants more than the defaults: pinning to a particular platform, handling raw input events, or driving the toplevel window. Each of those is a few lines against a small GObject API rather than a set of C callbacks to implement.

To help embedders make the move, WPEPlatform is now extensively documented. The reference documentation includes an overview of the platform API (covering its relationship to libwpe and what is intentionally not part of the new API), a guide on compiling against it, a tutorial on writing a browser, and a tutorial on writing a WPE platform implementation. A guide on migrating from libwpe, with a symbol-by-symbol mapping table, walks embedders through the process step by step.

Since WPEPlatform is now built by default, the wpe-platform-2.0 pkg-config module is available in regular builds. Conversely, the legacy API can be disabled at build time with ENABLE_WPE_LEGACY_API=OFF when it is not needed.

Additions and final adjustments

New platform APIs added this cycle include:

• WPEProcessManager and WPEProcessLaunchOptions, which allow the embedder to control how the auxiliary WebKit processes are launched and terminated. This is particularly important on Android, where each process is a service that must be started with bindService(), and it removes the last reason a WPEPlatform-only build could not work there. Note that, unlike the rest of WPEPlatform, the process management API is only built when targeting Android and remains experimental: it is not yet generic enough to be enabled everywhere, and it may still change in future releases.
• Gamepad rumble support, through wpe_gamepad_has_rumble() and wpe_gamepad_rumble(), with a built-in implementation based on libmanette. This enables the Gamepad API vibrationActuator for web content.
• A new WPE_SETTING_OVERLAY_SCROLLBARS setting, enabled by default, which may be disabled by applications to opt into classic, always-visible scrollbars.
• A new WPE_INPUT_PURPOSE_SEARCH input purpose, allowing input methods to detect when the values of an input field are expected to be search terms.

A few final adjustments were made to the API before declaring it stable, which may require updates to platform implementations and applications developed against the earlier previews:

• The WPE_SETTING_DISABLE_ANIMATIONS setting has been replaced by WPE_SETTING_REDUCED_MOTION, matching the dedicated reduced-motion setting introduced in GNOME 50, and a new tri-state WPE_SETTING_INTERFACE_CONTRAST setting has been added. Together with the existing WPE_SETTING_DARK_MODE setting, these make the prefers-reduced-motion, prefers-contrast, and prefers-color-scheme media queries follow the platform settings.
• wpe_gesture_controller_handle_event() now returns a boolean indicating whether the event was consumed.
• The WPE_DMABUF_BUFFER_FORMAT environment variable has been renamed to WPE_BUFFER_FORMAT.

Beyond Linux: Android

A good measure of the new API’s maturity is wpe-android, which has been rebuilt this year as a WPEPlatform platform implementation living entirely outside the WebKit tree: Android’s display system now looks to the engine like any other WPE platform, and applications get a convenience Java API modeled after android.webkit.WebView. The new WPEProcessManager API removed the last dependency on libwpe there. You can read more about it in this post.

On the WebKit API side

The shared WebKit API has also seen additions this cycle:

• A new API for page icons: webkit_favicon_database_get_page_icons() retrieves all the icons declared by a page as a list of WebKitImage objects, and the WebKitWebView:page-icons property exposes the icons of the currently loaded page. Each icon implements GLoadableIcon, so applications can pick the size that best fits their needs. With this, the favicon database is available in WPE for the first time; it can be enabled with webkit_website_data_manager_set_favicons_enabled().
• A new WebKitWebView:magnification property to handle visual scaling of the page, independent of the zoom level.
• WebKitWebsitePolicies:custom-user-agent allows setting a custom User-Agent for a single navigation, by passing the policies to webkit_policy_decision_use_with_policies().
• webkit_feature_list_find() is a convenience function to look up a feature by identifier in a feature list.

Graphics improvements

A new Skia-based compositor

This cycle brings the largest overhaul of the rendering architecture since the adoption of Skia for 2D rendering: the web process compositor now uses the Skia API instead of the venerable TextureMapper. Layers are composed into the final frame using Skia, which allows sharing a single rendering infrastructure across the whole graphics stack and enables several optimizations:

• Tile contents are recorded into deferred display lists and replayed on the compositor thread, so painting worker threads no longer need to touch the GPU at all.
• Batched painting groups the drawing of many layers into a single Skia call, which improves performance on pages with many layers that can be painted in the same operation.
• Unnecessary clip operations are avoided whenever possible, keeping the batched paths effective.

Beyond raw performance, expressing compositing as Skia draw calls made several features simpler and faster: filters and masks no longer require intermediate offscreen surfaces in most cases, and CSS blend modes, which TextureMapper never implemented, now work in composited layers. And since Skia can target both OpenGL and Vulkan, the compositor no longer stands in the way of Vulkan-based rendering in the future.

The new compositor also works when using the legacy libwpe-based API.

The consolidation on Skia goes beyond compositing: the option to use Cairo for 2D rendering has been removed, making Skia the only 2D rendering implementation. Rendering tiles in the main thread is no longer supported either, so threaded rendering is now the only tile painting path.

Damage-aware compositing

Damage tracking has seen substantial work this cycle. The damage is the region of the view that changed since the previous frame and therefore requires repainting; Paweł Lampe’s introduction to damage propagation covers the concept in depth. Compositing itself now uses this information: each draw the compositor issues is restricted to the damaged rectangles, in a way that preserves the batched painting described above, and damage propagation to the platform is now enabled by default. A new DamageRectangleThreshold preference allows embedders to tune the balance between damage precision and bookkeeping cost.

The performance impact

What drove the compositor rewrite was making it simpler and easier to maintain, as Carlos García Campos explained at the Web Engines Hackfest 2026; performance came later, since TextureMapper started out ahead after more than a decade of tuning. By now the optimization work has more than closed that gap. The public WPE performance dashboard, which continuously runs benchmarks on Raspberry Pi 4 devices, tells the story: comparing the last TextureMapper-based revisions against the current ones, and thus measuring the cumulative effect of the graphics work described in this section, the MotionMark score is up by around 36%. On the composition-focused variant of the benchmark, where the compositor dominates the workload, the score is up by around 45%.

The dashboard also records the GPU load during each run, and there the difference is even more telling. MotionMark increases scene complexity until the browser can no longer sustain the target frame rate, so a higher score already means more work per frame; the Skia compositor delivers that while keeping the GPU markedly less busy. On embedded devices, where the GPU is typically the scarcest resource, this headroom translates directly into smoother pages.

One part of the work goes largely unmeasured here, though. MotionMark animates nearly the entire viewport, so there is hardly anything for damage tracking to save. Real-world content behaves differently: usually a small area of the page is changing while everything else stays still, and skipping all of that quiet area cuts the per-frame GPU work to a fraction.

Other rendering improvements

A GPU atlas is now used for batched raster image uploads, regardless of the compositor in use, and it is reused across frames when the image set does not change, avoiding needless texture allocation and pixel uploads.

Asynchronous scrolling is smoother: several synchronization issues between the main, scrolling, and compositing threads that caused glitches while scrolling have been fixed, and the scrolling thread no longer blocks the compositor to flush its state, removing input-latency stalls on pages with many layers.

Finally, more animations can now run on the compositing thread: CSS animations using the steps() and linear() timing functions no longer force main-thread animation.

Better multimedia on embedded hardware, and a WebRTC transition

Let’s start with the transition: the GStreamer-based WebRTC backend is being replaced with a LibWebRTC-based implementation, which is expected to be available in the next release cycle. As a consequence, WebRTC support, which in previous releases required building with experimental features enabled, is disabled in 2.54.

The rest of the multimedia work moved forward at full speed, with a strong focus on embedded hardware:

• Hardware video decoding and encoding for platforms with a Qualcomm GPU has been added, leveraging the qtic2vdec and qtic2venc GStreamer elements.
• Video decoding limits are now respected in MediaCapabilities queries, and can be overridden with the WEBKIT_GST_VIDEO_DECODING_LIMIT environment variable, so a single build can serve devices with different capabilities.
• Resource usage on pages containing many videos has been improved, by stopping the pipelines of muted, invisible video elements.
• A new feature flag, enabled by default, allows low-end devices to skip caching pages with multimedia content in the back-forward cache, so that a suspended pipeline cannot hold a scarce hardware decoder hostage.
• Media capability reporting is more accurate: non-AAC mp4a codecs (MP3, AC-3, E-AC-3) are correctly reported as supported when decoders are present, xHE-AAC support is auto-detected, and Dolby AC-4 is advertised for MSE on systems that support it.
• Experimental support for SourceBuffer.changeType() has been added to the MSE backend, along with a fix for playback stalling at ad transitions on Twitch.
• Persistent licenses are now supported in the Thunder CDM for encrypted media.

On top of this, the GStreamer backend has received a substantial amount of memory-safety and lifetime-correctness work that translates into a more stable multimedia experience.

WebXR

The OpenXR-based WebXR implementation continues to progress. The main highlight is support for the WebXR Layers API: quad, cylinder, equirect, and cube layers are now implemented, in addition to the already supported projection layers. Layers can be backed by texture arrays, and XRSession.maxRenderLayers lets content query the compositor’s layer budget.

The backend has also been decoupled from OpenGL ES through an abstract graphics binding, paving the way for a future Vulkan-based binding.

WebXR support remains a build-time option, enabled with the ENABLE_WEBXR=ON CMake option; the Layers support additionally requires ENABLE_WEBXR_LAYERS=ON.

Other improvements to the WPE port

Several long-standing gaps in the WPE port have been closed this cycle:

• A built-in popup menu is now used as the default implementation for <select> elements when the WebKitWebView::show-option-menu signal is left unhandled, so option menus work out of the box.
• Initial drag-and-drop support has been added: web views now handle drags driven by the mouse events they already receive.
• Spell checking is now supported using the Enchant library, enabled by default, and can be toggled at build time with the ENABLE_SPELLCHECKING CMake option.
• The on-screen keyboard is no longer shown when an element is focused programmatically; it only appears as a result of user interaction.
• Initial support for the Pointer Lock API can be enabled at build time with the ENABLE_POINTER_LOCK CMake option.
• Saving files from the Web Inspector now works in WPE.

Web Platform support

As usual, this list is not exhaustive as WebKit continuously progresses in its support for new standards. Some of the highlights for this release are:

• The Temporal API, a modern replacement for Date, is now enabled.
• WebAssembly JavaScript Promise Integration (JSPI) is now enabled, along with the WebAssembly Multi-Memory and Relaxed SIMD proposals.
• Customizable select elements (appearance: base-select) are now supported.
• The CloseWatcher API and the closedby attribute for <dialog> are now enabled.
• CSS scroll anchoring is now enabled.
• The CSS @function rule and the if() function are now available.
• Advanced attr() substitution is now available.
• The Origin-Agent-Cluster header is now supported.
• Transferable streams and ReadableStream.from() are now enabled.
• IndexedDB getAllRecords() is now supported.
• Time zone changes in the host system are now picked up at runtime by Date and Intl.

What’s new for WebKit developers?

WebKit can now use mimalloc as its memory allocator, as an alternative to its own bmalloc. For now it is the default only on some architectures (32-bit ARM, MIPS, RISC-V, and builds supporting 64 KB memory pages); everywhere else bmalloc remains the default, and mimalloc can be enabled with the USE_MIMALLOC build option.

Logging now falls back to the standard error output when journald is not reachable, which is common in minimal containers, and the new WEBKIT_DEBUG_OUTPUT environment variable allows choosing the log destination explicitly.

Profile-guided optimization is now supported in regular CMake builds with Clang, through the ENABLE_LLVM_PROFILE_GENERATION and USE_PGO_PROFILE options.

Finally, a note for packagers: building WPE WebKit now requires Ninja, as the CMake Makefile generator is no longer supported.

Looking forward to 2.56

The 2.56 release series will bring even more improvements, and we expect it to be released during the spring of 2027. Until then!

Update on what happened in WebKit in the week from September 7 to September 14.

In this week's edition, the PNG image decoder received a much needed cleanup, as well as another swipe of unassorted graphics improvements, most notably in the Layer-Based SVG Engine. Finally, we also have an exciting and informative article about how to use the WPE Platform API on Raspberry Pi.

Cross-Port 🐱

Graphics 🖼️

Community & Events 🤝

• Bug: 318938 – Support touch event asynchronous scrolling
• Commit: 319347@main

The WPE and GTK ports have supported touch events for a long time, but asynchronous scrolling only worked for wheel events. Scrolling driven by touch still depended on the web process main thread. This change puts touch events on the asynchronous scrolling path too.

Let’s start with the background: what asynchronous scrolling is and why it needs to be built differently here.

What is asynchronous scrolling? #

Why it is needed #

A naive implementation of scrolling looks like this:

1. The UI process receives an input event (wheel or touch).
2. It sends the event to the web process main thread.
3. The main thread runs the page’s JavaScript event listeners.
4. If nothing called preventDefault(), the scroll position is updated.
5. The page is rendered at the new scroll position.

Step 3 is the problem. The main thread is easily blocked for hundreds of milliseconds by JavaScript execution or layout, and scrolling is frozen for that whole time. Your finger moves, the screen does not. That is what synchronous scrolling feels like.

Asynchronous scrolling moves the work off the main thread: the scrolling thread updates the scroll position, and the compositor thread composites and presents the frame. Neither needs the main thread, so scrolling keeps running at 60fps even when the main thread is busy.

The scrolling tree and event regions #

Two data structures make this possible.

The scrolling tree is a tree of the scrollable areas of a page. The main frame, overflow: scroll elements, position: fixed/sticky elements and so on each become a node holding its own scroll position and a reference to its layer. The scrolling thread updates scroll positions by looking only at this tree, and the compositor thread then draws the layers at their new positions — the main thread is not involved in either step.

But there are places where scrolling on its own would be wrong, because the page might call preventDefault() from an addEventListener("touchstart", ...) handler. That is what event regions are for.

An event region records, per layer and at rendering time, “this rectangle has a listener for this kind of event”. EventRegion keeps separate regions for touchstart, touchmove, pointerdown, mousedown and friends, and for any given point it yields a TrackingType:

enum class TrackingType : uint8_t {
    NotTracking = 0,   // No listener. The event does not even need to be delivered.
    Asynchronous = 1,  // Passive listeners only. Scroll now, notify the page later.
    Synchronous = 2    // A non-passive listener may call preventDefault(). We must wait.
};

The passive distinction is what makes Asynchronous possible. preventDefault() cancels an event only if the listener was registered with passive: false; from a passive listener it does nothing. And on window, document and document.body, touchstart/touchmove (and wheel) default to passive: true — see MDN: Using passive listeners. So Asynchronous is the case “there are listeners, but none of them can cancel the scroll”: start scrolling now, deliver the event to the main thread afterwards.

Because this information travels to the scrolling thread along with the layer tree, an incoming input event can be classified without waking the main thread. That is the heart of asynchronous scrolling.

Why the iOS implementation could not be reused #

The iOS port already implements asynchronous scrolling for touch events, but it could not be reused, because the process layout is different.

iOS:
  UI process:  platform layer tree + scrolling tree + touch event input
  Web process: main thread (DOM, layout)

WPE / GTK (Coordinated Graphics):
  UI process:  touch event input only
  Web process: main thread (DOM, layout)
               + EventDispatcher thread / scrolling thread
               + platform layer tree + scrolling tree

On iOS both the platform layer tree and the scrolling tree live in the UI process — the very process that receives touch events — so the classification and the scroll both happen right there. On WPE and GTK we use Coordinated Graphics, and both trees live in the web process instead. The classification therefore has to happen after sending the event to the web process, but before touching the main thread.

Fortunately the same problem was already solved for wheel events. The web process has an EventDispatcher thread that receives wheel events from the UI process without going through the main thread and consults the scrolling tree directly. This change builds the same shape for touch events.

How a touch becomes a scroll in WPE #

One more piece of background: in WPE a touch does not scroll the page directly. Touch events are first offered to the page; only if the page does not consume them does the UI process turn the touch sequence into scrolling.

The decision point is PageClientImpl::doneWithTouchEvent(). If the page handled the event, gesture detection is cancelled with wpe_gesture_controller_cancel() so the engine does not also act on it. If it was not handled, the event is fed to the WPE platform gesture controller via ViewPlatform::handleGesture(), and a recognized WPE_GESTURE_DRAG is turned into a synthetic scroll event pushed back into the page as a wheel event:

GRefPtr<WPEEvent> simulatedScrollEvent = adoptGRef(wpe_event_scroll_new(
    m_wpeView.get(), WPE_INPUT_SOURCE_TOUCHSCREEN, 0, static_cast<WPEModifiers>(0), dx, dy, TRUE, FALSE, x, y));
page().handleNativeWheelEvent(WebKit::NativeWebWheelEvent::create(simulatedScrollEvent.get(), phase));

That TRUE is precise_deltas: touch-driven scrolling in WPE reaches the engine as precise-delta wheel events, which becomes relevant later.

The important consequence is this: the UI process cannot start scrolling until it knows whether the page is going to consume the touch. That answer used to come from the web process main thread — so when the main thread was busy, scrolling did not start. That is the problem this change fixes.

The change #

Enabling touch event regions #

A new ENABLE(COORDINATED_TOUCH_EVENTS) is introduced in PlatformEnableGlib.h, and it turns on ENABLE(TOUCH_EVENT_REGIONS) whenever touch events are enabled on WPE/GTK. The AlwaysUseTouchEventRegions preference now defaults to true under that flag, so Document::shouldUseTouchEventRegions() returns true and touch regions are actually recorded on the layers during rendering.

UI process: send to the EventDispatcher instead of the main thread #

The old WebPageProxy::handleTouchEvent() consulted a touchEventTracking state kept in the UI process and sent Messages::WebPage::TouchEvent, i.e. straight to the web process main thread.

The new version delegates all classification to the web process and only queues events and delivers answers. One event is in flight at a time; the next is sent when the reply arrives. The flood of touchmove events produced while a finger moves is coalesced into the newest queued event when that is also a touchmove, and the coalesced events are flushed to doneWithTouchEvent() together with the reply.

The destination is now Messages::EventDispatcher::TouchEvent.

Web process: classification on the EventDispatcher thread #

EventDispatcher::touchEvent() runs on the EventDispatcher thread, where it looks up the page’s scrolling tree, asks it for a TrackingType, and splits three ways:

• NotTracking — no listeners. Reply handled = false immediately, without bothering the main thread at all. The UI process can start scrolling right away.
• Asynchronous — passive listeners only, so nothing can cancel the event. Reply handled = false first so scrolling starts, then deliver the event to the main thread.
• Synchronous — a non-passive listener may call preventDefault(), so wait for the main thread result as before.

Replying without a main thread round trip is possible because the new TouchEvent message is declared AnyThread in EventDispatcher.messages.in. The iOS equivalent is MainThreadCallback, which always replies from the main thread.

If there is no scrolling tree for the page yet, the event goes to the main thread as before.

Classifying a touch in the scrolling tree #

The classification itself is ScrollingTreeCoordinated::eventTrackingTypeForTouchEvent(). It works in two stages.

First, for each newly pressed touch point: convert the point from view to contents coordinates, hit test the layer tree down from the root contents layer, take the frontmost layer whose event region contains the point, and query that region. It is queried for many event types, because a touch fires more than the DOM touch* events — pointer*, compatibility mouse events and gesture* too, and a non-passive listener for any of them forces synchronous handling. The results are folded into a small TouchEventTracking struct with four fields: start, move, end and force-change.

Second, the tracking type of the event as a whole is derived from the touch point states, merging the per-field values. Merging picks the stronger of two types (NotTracking < Asynchronous < Synchronous), so if any single point needs synchronous handling, the whole event is synchronous.

TouchEventTracking persists for the lifetime of a touch sequence and is reset once all points are released, so the hit test done at touchstart is reused for the following touchmove/touchend. That guarantees a sequence never flips from synchronous to asynchronous halfway through just because a finger moved off a listener’s area.

<input type=range> #

A slider handles touches internally even with no JavaScript listener, so looking at the event region alone would classify it as NotTracking. HTMLInputElement::updateTouchEventHandler() now sets the HasInternalTouchEventHandling flag on EventTarget for range inputs, and StyleAdjuster turns that flag into the full set of touch region types for the element.

Keeping the animation running on the scrolling thread #

The last piece is in ScrollingEffectsController::handleWheelEvent(). As shown above, WPE synthesizes wheel events from touch gestures with precise deltas. Precise-delta events only need immediateScrollBy() to move the scroll position — but then nothing drives screen updates while the main thread is busy.

The fix is that, while a scroll gesture is in progress, a scroll animation is also started — from one ULP short of the destination (std::nextafter()) to the destination. Visually it finishes instantly — the real scroll is still done by immediateScrollBy() — but a scroll animation is now running, which starts display link monitoring and keeps compositing driven regardless of the main thread.

The event flow, summarized #

Before:

After (no listeners, or passive listeners only):

Where a non-passive listener exists, we still wait for the main thread as before. The spec requires preventDefault() to be honoured, so that is unavoidable.

Layout test updates #

As a side effect, the tests under fast/events/touch/ had to be updated.

Event regions are computed during a rendering update and propagated to the scrolling tree via the platform layer tree. Which means a test like this:

target.addEventListener("touchstart", handler);
tapSoon(20, 20);   // ← the region has not been updated yet!

taps immediately after registering the listener, while the scrolling tree still believes there is no listener and returns NotTracking. The event never reaches the main thread and the test fails.

A new UIHelper.renderingComplete() was added for this:

static async renderingComplete()
{
    // Wait for the platform layer tree to be updated
    await UIHelper.animationFrame();
    await UIHelper.animationFrame();
}

Two animation frames are needed because the first one runs the rendering update that computes the regions, and a second is needed for the result to reach the layer tree.

Summary #

• On WPE and GTK both the layer tree and the scrolling tree live in the web process (Coordinated Graphics), so the iOS touch asynchronous scrolling implementation could not be reused directly.
• Instead, touch events were given the same shape that already works for wheel events: ask the scrolling tree from the EventDispatcher thread.
• The keys were enabling touch event regions, and making the IPC reply AnyThread so it can be sent without waiting for the main thread.
• Anywhere the page has no non-passive listener, scrolling now starts regardless of what the main thread is doing.

Acknowledgements #

Many thanks to Alejandro G. Castro and Carlos Garcia Campos for their insightful reviews of this work, and to Claude for writing this blog post.

Safari Technology Preview Release 252 is now available for download for macOS Golden Gate and macOS Tahoe. If you already have Safari Technology Preview installed, you can update it in System Settings under General → Software Update.

This release includes WebKit changes between: 319252@main…320112@main.

Accessibility

Resolved Issues

• Fixed the accessible name of a display: contents element incorrectly including text from its siblings. (319287@main) (185108892)
• Fixed list marker text being included in accessible names and values that requested text without list markers. (319615@main) (185422271)

Animations

Resolved Issues

• Fixed an unresolved current time for a progress-based timeline being treated as a progress timeline boundary. (319442@main) (183902668)
• Fixed a newly encountered animation frame rate being aligned with the lowest compatible frame rate instead of the highest. (319362@main) (185152473)
• Fixed an animation of width or height being incorrectly accelerated when only some keyframes have a size-dependent transform. (319363@main) (185153675)
• Fixed view timeline range boundaries discarding subpixel adjustments for sticky positioned elements. (319369@main) (185162728)
• Fixed keyframes using revert-layer or revert-rule no longer being recomputed after a KeyframeEffect is copied. (319368@main) (185164643)
• Fixed scroll-timeline-name and view-timeline-name to be loosely matched across shadow tree boundaries. (320040@main) (185206745)

CSS

New Features

• Added support for the named-feature() function in @supports conditions. (319412@main) (183688843)
• Added support for CSSConditionRule.supports. (319302@main) (184943650)
• Added support for the unprefixed user-select CSS property. (319562@main) (184964807)
• Added support for CSSMediaRule.matches. (319988@main) (185154835)
• Added support for percentage values in text-decoration-inset. (320052@main) (185850399)

Resolved Issues

• Fixed line-clamp not clamping content inside an inline block. (319848@main) (168534323)
• Fixed an unexpected ellipsis appearing when line-clamp is applied to content with a block inside an inline box. (319392@main) (182123153)
• Fixed the computed value of display for -webkit-box and -webkit-inline-box when combined with -webkit-box-orient: vertical and the continue property. (319370@main) (182288734)
• Fixed random() and random-item() with an auto caching key in the same property value producing the same random value. (319463@main) (182846761)
• Fixed margins trimmed by margin-trim being reflected in computed style. (319612@main) (184215336)
• Fixed subgrid columns ignoring the parent grid’s content distribution from justify-content. (319353@main) (184542148)
• Fixed the resolution of font-relative lengths when a minimum font size is in effect. (319340@main) (184727481)
• Fixed an issue where grid item margins were not included in the intrinsic size contributions of a grid container. (319836@main) (184789473)
• Fixed an issue where extra space was not distributed beyond growth limits when sizing grid tracks. (319837@main) (184933769)
• Fixed ::selection failing to repaint when its style changes. (319662@main) (184994906)
• Fixed invalidation and serialization of properties that use attr() with a number or percentage value. (319994@main) (185088893)
• Fixed anchor(right) not resolving to an inline anchor’s right edge in vertical-rl writing mode. (319286@main) (185108663)
• Fixed px values inside calc() expressions being serialized incorrectly in computed style when zoom is applied. (319320@main) (185156231)
• Fixed text-overflow: ellipsis not being shown on content that is not clamped when using line-clamp. (319597@main) (185348784)
• Fixed offset-path not respecting corner-shape when using a <coord-box> reference box. (319655@main) (185447602)
• Fixed corner-shape drawing square and notch corners as round and scoop on outlines and box-shadow spread. (319606@main) (185452130)
• Fixed font load status changes being reported with an incorrect previous state when script runs in response to a FontFace loaded promise. (319575@main) (185462848)
• Fixed incorrect style sharing between elements when a computed value depends on the lh unit. (319596@main) (185508307)
• Fixed interpolation of corner-shape for outset curves to match the updated specification algorithm. (319661@main) (185519894)
• Fixed: Removed the inline, inline-start, and inline-end values from margin-trim, which now accepts none | block | [ block-start || block-end ]. (319622@main) (185527437)
• Fixed: Changed calc() simplification so that clamp(none, a, b) becomes max(a, b) and clamp(a, b, none) becomes min(a, b). (319614@main) (185531467)
• Fixed align-content moving a floated child twice in block containers. (319665@main) (185536955)
• Fixed grid content not contributing to the scrollable overflow area. (319929@main) (185923265)
• Fixed background-size: contain, background-size: cover, and automatic sizing ignoring SVG images that have one intrinsic dimension and no aspect ratio. (319972@main) (185970333)
• Fixed arguments to registered custom functions so that they are evaluated in the calling context. (320022@main) (185975255)

CSS Grid Lanes

Resolved Issues

• Fixed: Renamed the flow-tolerance property to fit-tolerance. (319795@main) (185125327)

Canvas

Resolved Issues

• Fixed shadows rendering with a stale, incorrect transform in some cases. (319534@main) (185405205)

Editing

Resolved Issues

• Fixed pasted text being cut off in some web-based code editors. (319350@main) (184653264)
• Fixed typing a space in editable content inside a <summary> or <button> element also activating that element. (319628@main) (185479319)

Forms

Resolved Issues

• Fixed: Updated the default styling for appearance: base-select to center-align items, use lh units for padding, and reset all font properties on ::picker-icon and ::checkmark. (319816@main) (184843832)
• Fixed spin buttons for <input type="number"> not repainting when the window’s active state changes. (319683@main) (185625389)

HTML

Resolved Issues

• Fixed the dialog focusing steps not moving focus after calling show() because the <dialog> was still treated as unrendered. (319387@main) (185156091)
• Fixed dialog.close() restoring focus even when focus was not inside the dialog and the dialog was not modal. (319640@main) (185549474)
• Fixed documentElement.focus() to move focus to the viewport instead of doing nothing. (319730@main) (185567540)
• Fixed script elements parsed from XML by DOMParser executing after being cloned. (319922@main) (185943138)

Images

Resolved Issues

• Fixed ImageDecoder not applying an image’s EXIF orientation to the decoded frames. (319527@main) (184850407)
• Fixed ImageDecoder producing VideoFrame objects with a duration of zero. (319526@main) (185257570)

JavaScript

Resolved Issues

• Fixed worker.terminate() and page reloads not terminating a worker that is blocked in Atomics.wait or a WebAssembly atomic.wait. (319508@main) (147482360)
• Fixed Promise.try() to resolve its result with PromiseResolve, so a promise returned by the callback is no longer wrapped in an extra promise. (319276@main) (185064567)
• Fixed regular expression backreferences not restoring the input position when reading a surrogate pair fails. (319560@main) (185065533)
• Fixed Uint8Array.prototype.setFromBase64() so that nothing is read and no error is thrown when the target array has zero length. (319275@main) (185073630)
• Fixed a regular expression using the s flag matching from the start of the string instead of from lastIndex. (320086@main) (185814135)
• Fixed the Referer header sent for descendant and dynamically imported module script fetches. (319921@main) (185943042)
• Fixed String.prototype.replace with a unicode regular expression splitting a surrogate pair after an empty match. (320099@main) (186143674)

Media

Resolved Issues

• Fixed videos immediately exiting fullscreen back to inline after an earlier video had been played in fullscreen. (320084@main) (174807377)
• Fixed an issue where interacting with the inline media controls could dismiss a site’s custom video presentation. (319741@main) (181244652)
• Fixed video failing with MEDIA_ERR_ABORTED and restarting from the beginning after restoring a page from the back/forward cache. (319472@main) (183119720)
• Fixed ManagedMediaSource not firing the startstreaming event when seeking outside the buffered range. (319330@main) (183790572)
• Fixed an issue where a video could begin playing ahead of another video that requested playback earlier while audio session activation was still pending. (319455@main) (185043324)
• Fixed an unnecessary ended event being fired when seeking to the end of an HTMLMediaElement backed by a MediaSource. (319847@main) (185145277)
• Fixed an issue where audio could continue playing for several seconds after closing a tab. (319759@main, 319842@main) (185505597)

Networking

Resolved Issues

• Fixed cookies being stored as session cookies when their Expires date uses the month-before-day format produced by Date.prototype.toString(). (320016@main) (185840799)

Performance

Resolved Issues

• Fixed hidden page throttling heuristics not being applied to newly created pages. (319630@main) (185461584)

Rendering

Resolved Issues

• Fixed characters overlapping adjacent text when a space glyph’s base advance is substituted. (319556@main) (180227130)
• Fixed incorrect element dimensions being reported for content inside an iframe whose owner element generates no box. (319910@main) (181639379)
• Fixed content overlapping when an element gains a scrollbar during layout. (320066@main) (183465635)
• Fixed a list marker overlapping the list item content when the marker text is right-to-left. (319314@main) (185048387)
• Fixed an outside list marker keeping a line of its own when a block is appended to an empty list item. (319289@main) (185109123)
• Fixed a block-level box on a line being handed its own float as an intruding float. (319290@main) (185109160)
• Fixed list markers not updating when the list item’s font changes dynamically. (319476@main) (185330733)
• Fixed an issue where adjoining margins did not collapse when a container’s first child was a float or an out-of-flow box. (319696@main) (185591842)
• Fixed an issue where margins did not collapse after a self-collapsing block-level box on a line. (319697@main) (185598333)
• Fixed an issue where a list marker was painted on top of the list item’s content instead of behind it. (319818@main) (185741211)
• Fixed an issue where a block-level box on a line was left behind when a column break moved the line. (319821@main) (185787568)
• Fixed backdrop-filter being clipped to a rounded rectangle instead of following corner-shape. (320063@main) (185813432)
• Fixed an issue where a max-width length was not honored on an out-of-flow replaced element with an intrinsic aspect ratio. (319917@main) (185831651)
• Fixed a relatively positioned block-level box on a line reporting scrollable overflow as wide as the entire line. (319899@main) (185835450)
• Fixed an issue where an orthogonal block-level box inside an inline box made its container as wide as the box instead of as wide as its content. (319897@main) (185890940)
• Fixed the position of an orthogonal block-level box inside an inline box. (319895@main) (185895981)
• Fixed background-size: cover painting nothing for an SVG image with an extreme natural aspect ratio. (320008@main) (186006463)

SVG

New Features

• Added support for text-overflow as an SVG presentation attribute. (319563@main) (176146717)
• Added support for SVG external resources, allowing url() references to SVG resources such as filters, masks, and gradients in external documents. (319411@main) (183940963)

Deprecations

• Removed the use-script, no-change, and reset-size values from dominant-baseline to match SVG 2. (319256@main) (174635806)

Security

Resolved Issues

• Fixed an issue where navigations to external URLs in subframes were not consistently blocked. (319798@main) (185801936)

Web API

New Features

• Added support for a stack property on DOMException, matching other error objects. (319782@main) (185770735)

Resolved Issues

• Fixed the Digital Credentials API settling the navigator.credentials.get() promise synchronously instead of queuing a global task as required by the specification. (319421@main) (182678875)
• Fixed a streaming fetch() response body being withheld from the reader until the next network chunk arrived. (319981@main) (185883588)

Web Audio

Resolved Issues

• Fixed AudioBufferSourceNode ignoring the offset passed to start() when using a negative playbackRate. (319674@main) (184484940)
• Fixed AudioBufferSourceNode to clamp out-of-range loopStart and loopEnd values. (319755@main) (185752079)
• Fixed an issue where AudioBufferSourceNode rendered only silence when start() was called with an out-of-bounds offset and a negative playbackRate. (319779@main) (185769043)

Web Inspector

New Features

• Added logging of the site-specific quirks active on a page to the Web Inspector console. (319533@main) (185246801)

Resolved Issues

• Fixed an exception being thrown when selecting a CDATA section in the DOM tree. (319252@main) (185027124)

WebAssembly

New Features

• Added support for WebAssembly memory64 together with multiple memories. (319336@main) (185152671)

Resolved Issues

• Fixed inconsistent CompileError messages when compiling a WebAssembly module with more than one invalid function by always reporting the error for the lowest function index. (319430@main) (140651602)
• Fixed a re-exported imported WebAssembly.Tag not being the same object as the one that was imported. (319294@main) (185121644)
• Fixed re-exporting an imported immutable WebAssembly.Global so that the exports object returns the same object instead of a new wrapper. (319351@main) (185184951)
• Fixed WebAssembly.Module.imports() and WebAssembly.Module.exports() exposing the type field from the unfinished JS Type Reflection proposal. (319427@main) (185281658)

WebGL

Resolved Issues

• Fixed the orientation and improved the performance of WebGL canvas contents copied into an image, such as when drawing a WebGL canvas into a 2D canvas or an ImageBitmap. (319576@main) (184913852)
• Fixed getAttribLocation() and getUniformLocation() not reporting an INVALID_OPERATION error when querying an unlinked program with a reserved name prefix. (319903@main) (185565011)

WebGPU

New Features

• Added support for the snorm10-10-10-2 value of GPUVertexFormat. (319603@main) (185379686)

Resolved Issues

• Fixed a typo in WGSL diagnostics that named the sampler_comparison type incorrectly. (320037@main) (186031593)

WebRTC

Resolved Issues

• Fixed an issue where certificate fingerprints were not validated against the previously generated offer or answer when applying a local description. (319822@main) (183719203)
• Fixed TURN server URLs containing query-string parameters such as ?transport=tcp being rejected, which prevented relay ICE candidates from being gathered. (319365@main) (184556197)

WPE Platform API (also known as “new API”) is a redesigned, GObject-based platform-integration layer for WPE WebKit that replaces the older libwpe backend model. A few months ago, Kate and Simon published two closely related blog posts about it. The first one focuses more on the API and browser implementation details, while the second one focuses more on writing and integrating the browser within Linux distribution.

This article builds on top of the above ones, and showcases how to build and try a minimal WPE browser using WPE Platform API on Raspberry Pi. Moreover, as the WPE Platform API still evolves to some degree, this article also explains how to use and stick to the latest WPE WebKit from main branch. This way one can play with all the latest features straight on embedded hardware.

Before going further, one should be aware that in case of a simple release build (instead of one using latest main branch) it’s better to follow official instructions instead of this article.

Setup #

This article focuses on a certain setup using Raspberry Pi 3B but it should be fairly easy to adapt the config to any other Raspberry Pi model.

As for the work environment: the Linux-based host with ability to run containers was used along with WebKit Container SDK. The SDK version was precisely 2.53-v6-d535e88 as it uses Ubuntu 24.04.4 LTS that works well with Yocto scarthgap.

The Yocto scarthgap has been used to increase the chances that the config and commands demonstrated in this article will remain buildable for many years to follow.

Preparing the image #

The preparation of the image starts with a series of commands that create a main directory and clone important Yocto repositories along with some meta layer repositories. At this point already, it’s important to have the working directory shared between host and SDK.

# host
mkdir wpe-upstream
cd wpe-upstream
git clone https://git.yoctoproject.org/git/poky -b scarthgap
git clone git@github.com:openembedded/meta-openembedded.git -b scarthgap
git clone https://git.yoctoproject.org/git/meta-raspberrypi -b scarthgap
git clone https://github.com/Igalia/meta-webkit -b scarthgap
source poky/oe-init-build-env build

Once the build directory is created, it’s necessary to configure the meta layers in the build/conf/bblayers.conf file the following way:

# POKY_BBLAYERS_CONF_VERSION is increased each time build/conf/bblayers.conf
# changes incompatibly
POKY_BBLAYERS_CONF_VERSION = "2"

BBPATH = "${TOPDIR}"
BSPDIR := "${@os.path.abspath(os.path.dirname(d.getVar('FILE', True)) + '/../..')}"

BBFILES ?= ""
BBLAYERS ?= " \
  ${BSPDIR}/poky/meta \
  ${BSPDIR}/poky/meta-poky \
  ${BSPDIR}/poky/meta-yocto-bsp \
  ${BSPDIR}/meta-openembedded/meta-oe \
  ${BSPDIR}/meta-openembedded/meta-multimedia \
  ${BSPDIR}/meta-openembedded/meta-python \
  ${BSPDIR}/meta-raspberrypi \
  ${BSPDIR}/meta-webkit \
  "

With the above, the recipes from the meta layers cloned earlier will be considered by bitbake.

Next, the most important configuration step is appending the following to build/conf/local.conf:

MACHINE = "raspberrypi3-64" 
MACHINE_FEATURES:append = " vc4graphics"
GPU_MEM_256 = "128"
GPU_MEM_512 = "196"
GPU_MEM_1024 = "396"
DISTRO_FEATURES:append = " opengl egl wayland"
EXTRA_IMAGE_FEATURES = "debug-tweaks"
IMAGE_FEATURES:append = " ssh-server-dropbear hwcodecs"
IMAGE_INSTALL:append = " wpewebkit wpe-browser"
PREFERRED_VERSION_wpewebkit = "latest"
LICENSE_FLAGS_ACCEPTED = "synaptics-killswitch"

With that, wpewebkit latest will be preferred and installed in the image along with a dummy browser called wpe-browser.

To make the wpewebkit latest work, one needs to create meta-webkit/recipes-browser/wpewebkit/wpewebkit_latest.bb:

SUMMARY = "Lightweight WebKit port for embedded devices with OpenGL-ES acceleration"
DESCRIPTION = "WPE WebKit port pairs the WebKit engine with OpenGL-ES (OpenGL for Embedded Systems), \
               allowing embedders to create simple and performant systems based on Web platform technologies. \
               It is designed with hardware acceleration in mind, relying on EGL, and OpenGL ES."
HOMEPAGE = "https://wpewebkit.org/"
BUGTRACKER = "https://bugs.webkit.org/"
LICENSE = "BSD-2-Clause & LGPL-2.0-or-later"
LIC_FILES_CHKSUM = "file://Source/WebCore/LICENSE-LGPL-2.1;md5=a778a33ef338abbaf8b8a7c36b6eec80 "

REQUIRED_DISTRO_FEATURES = "opengl"

DEPENDS:append = " \
    libsoup \
    bison-native gperf-native harfbuzz-native libxml2-native ccache-native ninja-native ruby-native \
    fontconfig freetype glib-2.0 harfbuzz icu jpeg pcre sqlite3 zlib libpng libtasn1 \
    libwebp libxml2 libxslt virtual/egl virtual/libgles2 libepoxy libgcrypt \
    unifdef-native \
"

inherit cmake features_check pkgconfig perlnative python3native

export WK_USE_CCACHE = "NO"

PACKAGECONFIG ??= "accessibility avif dfg-jit gbm gpu-process \
                   jit jpegxl libbacktrace \
                   mediasource mediastream \
                   remote-inspector \
                   sysprof \
                   ${@' system-sysprof' \
                       if bb.utils.contains('BBFILE_COLLECTIONS', 'meta-gnome', True, False, d) \
                       else '' } \
                   unified-builds video webaudio woff2 wpe-platform \
                   ${@bb.utils.contains('DISTRO_FEATURES', 'systemd', 'journald', '' ,d)} \
                  "

PACKAGECONFIG[reduce-size] = "-DCMAKE_BUILD_TYPE=MinSizeRel,-DCMAKE_BUILD_TYPE=Release,,"
PACKAGECONFIG[release-with-debug-info] = "-DCMAKE_BUILD_TYPE=RelWithDebInfo,-DCMAKE_BUILD_TYPE=Release,,"

# WPE features
PACKAGECONFIG[accessibility] = "-DUSE_ATK=ON,-DUSE_ATK=OFF,atk at-spi2-atk"
PACKAGECONFIG[avif] = "-DUSE_AVIF=ON,-DUSE_AVIF=OFF,libavif"
PACKAGECONFIG[bubblewrap] = "-DENABLE_BUBBLEWRAP_SANDBOX=ON -DBWRAP_EXECUTABLE=${bindir}/bwrap -DDBUS_PROXY_EXECUTABLE=${bindir}/xdg-dbus-proxy,-DENABLE_BUBBLEWRAP_SANDBOX=OFF,bubblewrap xdg-dbus-proxy libseccomp"
PACKAGECONFIG[developer-mode] = "-DDEVELOPER_MODE=ON,-DDEVELOPER_MODE=OFF,wayland-native wayland-protocols wpebackend-fdo"
PACKAGECONFIG[deviceorientation] = "-DENABLE_DEVICE_ORIENTATION=ON,-DENABLE_DEVICE_ORIENTATION=OFF,"
PACKAGECONFIG[dfg-jit] = "-DENABLE_DFG_JIT=ON,-DENABLE_DFG_JIT=OFF,"
PACKAGECONFIG[documentation] = "-DENABLE_DOCUMENTATION=ON,-DENABLE_DOCUMENTATION=OFF, gi-docgen-native gi-docgen"
PACKAGECONFIG[encryptedmedia] = "-DENABLE_ENCRYPTED_MEDIA=ON,-DENABLE_ENCRYPTED_MEDIA=OFF,libgcrypt"
PACKAGECONFIG[experimental-features] = "-DENABLE_EXPERIMENTAL_FEATURES=ON,-DENABLE_EXPERIMENTAL_FEATURES=OFF,libavif libjxl"
PACKAGECONFIG[gamepad] = "-DENABLE_GAMEPAD=ON,-DENABLE_GAMEPAD=OFF,libmanette"
PACKAGECONFIG[gbm] = "-DUSE_GBM=ON,-DUSE_GBM=OFF,libdrm"
PACKAGECONFIG[geolocation] = "-DENABLE_GEOLOCATION=ON,-DENABLE_GEOLOCATION=OFF,geoclue"
PACKAGECONFIG[gpu-process] = "-DENABLE_GPU_PROCESS=ON,-DENABLE_GPU_PROCESS=OFF,"
PACKAGECONFIG[hyphen] = "-DUSE_LIBHYPHEN=ON,-DUSE_LIBHYPHEN=OFF,hyphen"
PACKAGECONFIG[introspection] = "-DENABLE_INTROSPECTION=ON,-DENABLE_INTROSPECTION=OFF, gobject-introspection-native"
PACKAGECONFIG[jit] = "-DENABLE_JIT=ON -DENABLE_C_LOOP=OFF,-DENABLE_JIT=OFF -DENABLE_C_LOOP=ON,"
PACKAGECONFIG[jpegxl] = "-DUSE_JPEGXL=ON,-DUSE_JPEGXL=OFF,libjxl"
PACKAGECONFIG[journald] = "-DENABLE_JOURNALD_LOG=ON,-DENABLE_JOURNALD_LOG=OFF,"
PACKAGECONFIG[lcms] = "-DUSE_LCMS=ON,-DUSE_LCMS=OFF,"
PACKAGECONFIG[spellcheck] = "-DENABLE_SPELLCHECK=ON,-DENABLE_SPELLCHECK=OFF,enchant"
PACKAGECONFIG[wpe-legacy-api] = "-DENABLE_WPE_LEGACY_API=ON,-DENABLE_WPE_LEGACY_API=OFF,libwpe virtual/wpebackend,"
PACKAGECONFIG[libbacktrace] = "-DUSE_LIBBACKTRACE=ON,-DUSE_LIBBACKTRACE=OFF,libbacktrace"
PACKAGECONFIG[minibrowser] = "-DENABLE_MINIBROWSER=ON,-DENABLE_MINIBROWSER=OFF,wayland-native wayland-protocols wpebackend-fdo"
PACKAGECONFIG[mediasource] = "-DENABLE_MEDIA_SOURCE=ON,-DENABLE_MEDIA_SOURCE=OFF,gstreamer1.0 gstreamer1.0-plugins-good"
PACKAGECONFIG[mediastream] = "-DENABLE_MEDIA_STREAM=ON,-DENABLE_MEDIA_STREAM=OFF,gstreamer1.0 gstreamer1.0-plugins-bad"
PACKAGECONFIG[pdfjs] = "-DENABLE_PDFJS=ON,-DENABLE_PDFJS=OFF,"

PACKAGECONFIG[speech-synthesis] = "-DENABLE_SPEECH_SYNTHESIS=ON,-DENABLE_SPEECH_SYNTHESIS=OFF,flite"

PACKAGECONFIG[sysprof] = "-DUSE_SYSPROF_CAPTURE=ON, -DUSE_SYSPROF_CAPTURE=OFF,"
PACKAGECONFIG[system-sysprof] = "-DUSE_SYSTEM_SYSPROF_CAPTURE=ON, -DUSE_SYSTEM_SYSPROF_CAPTURE=OFF, sysprof"
PACKAGECONFIG[video] = "-DENABLE_VIDEO=ON,-DENABLE_VIDEO=OFF,gstreamer1.0 gstreamer1.0-plugins-base"
PACKAGECONFIG[webaudio] = "-DENABLE_WEB_AUDIO=ON,-DENABLE_WEB_AUDIO=OFF,gstreamer1.0 gstreamer1.0-plugins-base gstreamer1.0-plugins-good"
PACKAGECONFIG[woff2] = "-DUSE_WOFF2=ON,-DUSE_WOFF2=OFF,woff2"
PACKAGECONFIG[remote-inspector] = "-DENABLE_REMOTE_INSPECTOR=ON,-DENABLE_REMOTE_INSPECTOR=OFF,"
PACKAGECONFIG[webrtc] = "-DENABLE_WEB_RTC=ON,-DENABLE_WEB_RTC=OFF,libvpx libevent libopus openh264"
PACKAGECONFIG[qtwpe] = "-DENABLE_WPE_QT_API=ON ${CMAKE_QT_OECONF},-DENABLE_WPE_QT_API=OFF,qtbase-native qtbase qtdeclarative libepoxy wpebackend-fdo ${QT_BUILD_DEPS}"
PACKAGECONFIG[unified-builds] = "-DENABLE_UNIFIED_BUILDS=ON,-DENABLE_UNIFIED_BUILDS=OFF,"
PACKAGECONFIG[thunder] = "-DENABLE_THUNDER=ON,-DENABLE_THUNDER=OFF,virtual/open-cdm"
PACKAGECONFIG[webxr] = "-DENABLE_WEBXR=ON,-DENABLE_WEBXR=OFF,openxr"

# Build option for WPE API 1.1
PACKAGECONFIG[wpe-1-1-api] = "-DENABLE_WPE_1_1_API:BOOL=ON,-DENABLE_WPE_1_1_API:BOOL=OFF,"

# Build option for WPE platform API
PACKAGECONFIG[wpe-platform] = "-DENABLE_WPE_PLATFORM=ON,-DENABLE_WPE_PLATFORM=OFF,libinput libxkbcommon wayland-native"

EXTRA_OECMAKE = " -DPORT=WPE -G Ninja"

# TODO: documentation and introspection are disabled by default because the are
# causing cross-compiling build errors
# PACKAGECONFIG:append = " ${@bb.utils.contains('DISTRO_FEATURES', 'api-documentation', 'documentation', '' ,d)} introspection"

# If SSE code compiles, assume it runs successfully (it can't actually run
# because of cross compiling)
EXTRA_OECMAKE:append:x86 = " -DHAVE_SSE2_EXTENSIONS_EXITCODE=0"
# Javascript JIT is not supported on ppc/arm/RISCV32/mips64
PACKAGECONFIG:remove:powerpc = "jit"
PACKAGECONFIG:remove:powerpc64 = "jit"
PACKAGECONFIG:remove:powerpc64le = "jit"
PACKAGECONFIG:remove:armv4 = "jit"
PACKAGECONFIG:remove:armv5 = "jit"
PACKAGECONFIG:remove:armv6 = "jit"
PACKAGECONFIG:remove:armv7a = "jit"
PACKAGECONFIG:remove:armv7ve = "jit"
PACKAGECONFIG:remove:riscv32 = "jit"
PACKAGECONFIG:remove:riscv64 = "jit"
PACKAGECONFIG:remove:mipsarchn64 = "jit"
PACKAGECONFIG:remove:mipsarchn32 = "jit"
PACKAGECONFIG:remove:loongarch64 = "jit"

# Javascript JIT is not supported on x86
PACKAGECONFIG:remove:x86 = "jit"

LDFLAGS:append:riscv64 = " -pthread"

FULL_OPTIMIZATION:remove = "-g"

LEAD_SONAME = "libWPEWebKit.so"
PACKAGES =+ "${PN}-web-inspector-plugin ${PN}-qtwpe-qml-plugin"
FILES:${PN} += "${libdir}/wpe-webkit*/injected-bundle/libWPEInjectedBundle.so"
FILES:${PN}-web-inspector-plugin += "${datadir}/wpe-webkit-*/inspector.gresource"
# nooelint: oelint.vars.insaneskip - ignored for convenience. We need to recheck if problem persist
INSANE_SKIP:${PN}-web-inspector-plugin = "dev-so"

# nooelint: oelint.vars.insaneskip - ignored for convenience. We need to recheck if problem persist
INSANE_SKIP:${PN}-qtwpe-qml-plugin = "dev-so"

# JSC JIT on ARMv7 is better supported with Thumb2 instruction set.
ARM_INSTRUCTION_SET:armv7a = "thumb"
ARM_INSTRUCTION_SET:armv7r = "thumb"
ARM_INSTRUCTION_SET:armv7m = "thumb"
ARM_INSTRUCTION_SET:armv7ve = "thumb"

# Extra runtime depends
# nooelint: oelint.vars.dependsordered - ignored for convenience
RDEPENDS:${PN} += "\
    ${@bb.utils.contains('PACKAGECONFIG', 'remote-inspector', '${PN}-web-inspector-plugin', '', d)} \
    ${@bb.utils.contains('PACKAGECONFIG', 'gst_gl', 'gstreamer1.0-plugins-base-opengl', '', d)} \
    ${@bb.utils.contains('PACKAGECONFIG', 'mediasource', 'gstreamer1.0-plugins-good-isomp4', '', d)} \
    ${@bb.utils.contains('PACKAGECONFIG', 'webaudio', 'gstreamer1.0-plugins-good-wavparse', '', d)} \
    ${@bb.utils.contains('PACKAGECONFIG', 'video', 'gstreamer1.0-plugins-base-app \
                                                    gstreamer1.0-plugins-base-audioconvert \
                                                    gstreamer1.0-plugins-base-audioresample \
                                                    gstreamer1.0-plugins-base-gio \
                                                    gstreamer1.0-plugins-base-playback \
                                                    gstreamer1.0-plugins-base-typefindfunctions \
                                                    gstreamer1.0-plugins-base-videoconvertscale \
                                                    gstreamer1.0-plugins-base-volume \
                                                    gstreamer1.0-plugins-good-audiofx \
                                                    gstreamer1.0-plugins-good-audioparsers \
                                                    gstreamer1.0-plugins-good-autodetect \
                                                    gstreamer1.0-plugins-good-avi \
                                                    gstreamer1.0-plugins-good-deinterlace \
                                                    gstreamer1.0-plugins-good-interleave \
                                                    ', '', d)} \
    libgles2 \
"

RDEPENDS:${PN}-web-inspector-plugin += "\
    shared-mime-info \
"

# Extra runtime recommends
RRECOMMENDS:${PN} += "\
    ca-certificates \
    ttf-dejavu-sans \
    ttf-dejavu-sans-mono \
    ttf-dejavu-serif \
    ${PN}-qtwpe-qml-plugin \
    ${@bb.utils.contains('PACKAGECONFIG', 'video', 'gstreamer1.0-plugins-base-meta gstreamer1.0-plugins-good-meta gstreamer1.0-plugins-bad-meta', '', d)} \
"

DEFAULT_PREFERENCE = "-1"

FILESEXTRAPATHS:prepend := "${THISDIR}/${PN}:"

# https://commits.webkit.org/319279@main
PR = "r319279"
SRCREV = "93472ec12ee947b30c7ec3c176ca0e2fb6ba6ace"
SRC_URI = "git://github.com/WebKit/WebKit.git;protocol=https;branch=main \
           file://0001-libpas-Only-include-stdatomic.h-when-compiling-with.patch \
           file://0002-WebDriver-Guard-LOG_CHANNEL-check-with-LOG_DISABLED.patch \
           "
S = "${WORKDIR}/git"

This file is self-contained on purpose; the idea is not to rely on any includes so that unpredictable behavior doesn’t happen in the future.

While the above file contains a lot of interesting details, the most interesting practical part is the last few lines. The SRCREV is set to point to the latest commit from the WebKit main branch (at the time of writing). Along with that comes SRC_URI that specifies two patches required to make WPE WebKit compile.

The problem with the patches is that advancing SRCREV will likely make them unusable due to merge conflicts. Therefore, when advancing the revision, it’s recommended to remove patches from SRC_URI and face the compilation problems from scratch as it’s very likely there will be new compilation problems anyway. Fortunately, nowadays LLMs can be used to fix any compilation problems by preparing custom patches just like the below ones (created by LLM as well). For example, most of the modern models should manage to prepare proper patches just by pointing them to the above recipe and the temp directory with the latest logs from build commands.

Assuming one uses the wpewebkit_latest.bb above, the first patch needs to be created in: meta-webkit/recipes-browser/wpewebkit/wpewebkit/0001-libpas-Only-include-stdatomic.h-when-compiling-with.patch with the following content:

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Pawel Lampe <plampe@igalia.com>
Date: Mon, 17 Aug 2026 00:00:00 +0000
Subject: [PATCH] [libpas] Only include stdatomic.h when compiling with Clang

Some libpas .c files (e.g. jit_heap.c) are compiled as C++ via
set_source_files_properties(... PROPERTIES LANGUAGE CXX) in
Source/bmalloc/CMakeLists.txt, for TZone heap support. pas_utils.h
unconditionally does `#include <stdatomic.h>`, but GCC's own
<stdatomic.h> relies on the C11-only `_Atomic` keyword and has no
support for being included from C++ translation units (this was only
addressed in much newer GCC releases). Compiling any of the
CXX-tagged libpas .c files with GCC 13 therefore fails with:

    error: '_Atomic' does not name a type

The header is only actually needed here for the Clang-specific
__c11_atomic_* intrinsics guarded by `#elif PAS_COMPILER(CLANG)`
further down in this file; the non-Clang (GCC) path uses the
__atomic_* builtins instead and does not need any of the types or
macros from <stdatomic.h>. Guard the include accordingly so GCC
builds (both plain C and the CXX-tagged libpas sources) are
unaffected by GCC's non-C++-aware <stdatomic.h>.

Upstream-Status: Pending
Signed-off-by: Pawel Lampe <plampe@igalia.com>
---
 Source/bmalloc/libpas/src/libpas/pas_utils.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/Source/bmalloc/libpas/src/libpas/pas_utils.h b/Source/bmalloc/libpas/src/libpas/pas_utils.h
index 962634080930..9b98fda54f43 100644
--- a/Source/bmalloc/libpas/src/libpas/pas_utils.h
+++ b/Source/bmalloc/libpas/src/libpas/pas_utils.h
@@ -42,7 +42,15 @@
 #endif
 
 #include <limits.h>
+#if PAS_COMPILER(CLANG)
+/* GCC's <stdatomic.h> relies on the C-only _Atomic keyword and is not
+ * usable when this header is included from a translation unit compiled
+ * as C++ (some libpas .c files are compiled as C++, see bmalloc's
+ * CMakeLists.txt). It is only needed here for the Clang-specific
+ * __c11_atomic_* intrinsics below; the GCC path uses __atomic_* builtins
+ * instead. */
 #include <stdatomic.h>
+#endif
 #include <stdbool.h>
 #include <stdint.h>
 #include <string.h>
--
2.43.0

The second patch should be: meta-webkit/recipes-browser/wpewebkit/wpewebkit/0002-WebDriver-Guard-LOG_CHANNEL-check-with-LOG_DISABLED.patch with:

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Pawel Lampe <plampe@igalia.com>
Date: Mon, 17 Aug 2026 00:00:00 +0000
Subject: [PATCH] [WebDriver] Guard LOG_CHANNEL check with
 LOG_DISABLED/RELEASE_LOG_DISABLED

WebDriverService::handleRequest() unconditionally checks
LOG_CHANNEL(WebDriverClassic).state to decide whether it is worth
building the request/response log strings. However,
Source/WebDriver/Logging.h only declares the WebDriverClassic (and
other WebDriver) log channels inside:

    #if !LOG_DISABLED || !RELEASE_LOG_DISABLED

On a release build (NDEBUG, so LOG_DISABLED is true) without journald
support and without OS_LOG/Android (so RELEASE_LOG_DISABLED is also
true) - the common configuration for an embedded Linux build without
the "journald" PACKAGECONFIG - that guard is false, so the channel is
never declared, and this direct, unguarded use of LOG_CHANNEL() fails
to compile:

    error: 'LOG_CHANNEL_PREFIXWebDriverClassic' was not declared in this scope

RELEASE_LOG_INFO() itself already collapses to a no-op in that
configuration (see wtf/Assertions.h), so guard this manual
LOG_CHANNEL() state check with the same condition used to declare the
channel in Logging.h.

Upstream-Status: Pending
Signed-off-by: Pawel Lampe <plampe@igalia.com>
---
 Source/WebDriver/WebDriverService.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Source/WebDriver/WebDriverService.cpp b/Source/WebDriver/WebDriverService.cpp
index 07ae385f33f4..2612d239a611 100644
--- a/Source/WebDriver/WebDriverService.cpp
+++ b/Source/WebDriver/WebDriverService.cpp
@@ -381,6 +381,7 @@ bool WebDriverService::findCommand(HTTPMethod method, const String& path, Comman
 void WebDriverService::handleRequest(HTTPRequestHandler::Request&& request, Function<void (HTTPRequestHandler::Response&&)>&& replyHandler)
 {
     Function<void (HTTPRequestHandler::Response&&)> actualReplyHandler = WTF::move(replyHandler);
+#if !LOG_DISABLED || !RELEASE_LOG_DISABLED
     if (LOG_CHANNEL(WebDriverClassic).state != WTFLogChannelState::Off) {
         RELEASE_LOG_INFO(WebDriverClassic, "HTTP request %s %s (body=%zu bytes)", request.method.utf8().data(), request.path.utf8().data(), request.dataLength);
         actualReplyHandler = [startTime = MonotonicTime::now(), replyHandler = WTF::move(actualReplyHandler)](HTTPRequestHandler::Response&& response) mutable {
@@ -388,6 +389,7 @@ void WebDriverService::handleRequest(HTTPRequestHandler::Request&& request, Func
             replyHandler(WTF::move(response));
         };
     }
+#endif
 
     auto method = toCommandHTTPMethod(request.method);
     if (!method) {
--
2.43.0

Once the patches are added, wpewebkit latest should build correctly. However, to make use of it one needs a browser.

To demonstrate how easy the browser for WPE WebKit with Platform API can be, a very minimalistic one will be prepared below.

The first step is to create a directory:

mkdir meta-webkit/recipes-browser/wpe-browser/

Then a file: meta-webkit/recipes-browser/wpe-browser/main.cpp that implements the whole browser:

#include <wpe/webkit.h>

int main(int argc, const char *argv[]) {
    g_autoptr(GMainLoop) loop = g_main_loop_new(nullptr, false);
    g_autoptr(WebKitWebView) view = WEBKIT_WEB_VIEW(g_object_new(WEBKIT_TYPE_WEB_VIEW,
        nullptr));
    webkit_web_view_load_uri(view,
        (argc > 1) ? argv[1] : "https://wpewebkit.org");
    g_main_loop_run(loop);
    return EXIT_SUCCESS;
}

Then a file: meta-webkit/recipes-browser/wpe-browser/CMakeLists.txt that describes how to build it:

cmake_minimum_required(VERSION 3.16)
project(wpe-browser CXX)

set(CMAKE_CXX_STANDARD 17)

include(GNUInstallDirs)

find_package(PkgConfig REQUIRED)

# The Wayland WPE Platform already depends on wpe-platform-2.0
pkg_check_modules(WebKitDeps REQUIRED
    IMPORTED_TARGET
    wpe-webkit-2.0
    wpe-platform-wayland-2.0
)

add_executable(wpe-browser main.cpp)

target_link_libraries(wpe-browser
    PRIVATE
        PkgConfig::WebKitDeps
)

install(TARGETS wpe-browser RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR})

and finally a recipe file: meta-webkit/recipes-browser/wpe-browser/wpe-browser_1.0.bb that allows bitbake to build the browser and install it in the image:

SUMMARY = "Minimal WPE WebKit browser launcher"
DESCRIPTION = "A minimal launcher built on the WPE Platform API, displaying \
               a URL given as its only argument (defaults to https://wpewebkit.org). \
               Based on https://simonpena.com/blog/2026/03/20/getting-started-with-wpe-webkit/"
HOMEPAGE = "https://simonpena.com/blog/2026/03/20/getting-started-with-wpe-webkit/"
LICENSE = "MIT"
LIC_FILES_CHKSUM = "file://${COMMON_LICENSE_DIR}/MIT;md5=0835ade698e0bcf8506ecda2f7b4f302"

FILESEXTRAPATHS:prepend := "${THISDIR}:"

SRC_URI = "file://main.cpp \
           file://CMakeLists.txt \
          "

S = "${WORKDIR}"

DEPENDS = "wpewebkit"
RDEPENDS:${PN} += "wpewebkit"

inherit cmake pkgconfig features_check

REQUIRED_DISTRO_FEATURES = "opengl wayland"

After all those steps, everything is ready to perform a build. This time the commands are executed in the SDK:

source poky/oe-init-build-env build
bitbake core-image-weston
cd tmp/deploy/images/raspberrypi3-64/
# flash to SD card based on preference

Trying the image #

Once the image is built and flashed to SD card, and the SD card has been used to boot the Raspberry Pi, one can SSH into it, basically by:

ssh root@<IP>

Then, the browser should work out of the box. The first command to try is the one that doesn’t need the network and therefore is the simplest:

XDG_RUNTIME_DIR=/run/user/1000 WAYLAND_DISPLAY=wayland-1 wpe-browser 'webkit://gpu/stdout'

If the network is available, it’s worth starting simple and loading some HTTP page:

XDG_RUNTIME_DIR=/run/user/1000 WAYLAND_DISPLAY=wayland-1 wpe-browser 'http://info.cern.ch'

If that works as well, one can try the HTTPS one:

XDG_RUNTIME_DIR=/run/user/1000 WAYLAND_DISPLAY=wayland-1 wpe-browser 'https://igalia.com'

If there’s an issue with certificates, it’s likely due to broken date/time, so the correct one needs to be set using a command like:

date -s '2026-09-02 22:34:56'

Conclusions #

Since the Platform API is the future of WPE, it’s worth using it already. As the above sections demonstrate, it hasn’t ever been easier to create a WPE-powered browser for embedded hardware. Moreover, nowadays as LLMs are at play, using latest sources from main branch and quickly patching on demand is a possibility worth utilizing. With that, a broad sea of experimenting possibilities becomes wide open. However, it must not be forgotten that while main branch is great for testing new web platform features implemented in WebKit, it’s not necessarily ideal for testing performance. In such case, it’s better to rely on releases and proper browser engine fine tuning for particular hardware one plays with.

Update on what happened in WebKit in the week from August 31 to September 7.

This was another week focused on ironing out graphics issues in preparation for the upcoming 2.54.x release series. Did we say release? Here we have another set of packaged release candidates as well!

Cross-Port 🐱

Graphics 🖼️

Releases 📦️

It’s that exciting time of year again when we start considering Interop proposals for next year! We’re thrilled to invite you to help shape the future of web interoperability.

Interop 2027 is just around the corner, and we want your ideas to make the web platform even more awesome. Whether you’re a seasoned pro or a newcomer with fresh perspectives, we want to hear from you.

Key Dates to Remember

• Proposal Submission Opens: September 3, 2026
• Submission Deadline: September 23, 2026

Don’t miss this opportunity to influence the direction of web standards and browser implementations.

Essential criteria

There are two essential criteria that all successful Focus Area proposals will have — testability and web standards. If an idea for a needed web technology doesn’t already have a mature web standard (from the W3C, TC39, etc), then it’s too early for it to be a Focus Area for Interop. Those standards are what make it possible to create automated Web Platform Tests, and the test results are what make the Interop Dashboard.

If you have an idea for cool new web technology that should exist, but doesn’t, then look into proposing it (or helping it along) in the appropriate web standards venue. For example, if you want a new CSS feature to exist, check out filing or commenting on an issue at the CSS Working Group. That is where new CSS gets invented, and the details of exactly how every piece should work get determined and written down.

If you want to propose technology that has insufficient tests or testing infrastructure — consider proposing it as an Interop Investigation. Interop Focus Areas are for web technology that can be tested and scored, while Interop Investigations are assignments the group behind the Interop Project gives themselves to encourage improvements for the future.

Writing a great proposal

The best submissions are typically:

• Specific: Identify a specific interoperability issue. One feature (or narrow group of related features) per proposal. Think font-size-adjust, not “typography”.
• Impactful: Provide a clear description of the interoperability problem that needs addressing. Use cases from your own experience are especially helpful.
• Valuable: Explain how web developers and/or users will benefit. Why is this more valuable than other existing options? Is there evidence this is a common need (perhaps survey results)?
• Stable: Link to the stable web standard that defines the technology you want improved. (Find it on the MDN web doc for that technology. Like here.)
• Tested: Look up and link to WPT test coverage. If more tests are needed, how can they be created this fall?

Read the Interop Proposers Guide to learn more.

Take the time needed to fully make your case. Why is the focus area you are proposing important? If there are hundreds of things that could be considered, why does this one stand out? How does the current state of affairs inhibit web developers? How are users affected? Is this technology something a lot of sites use? How critical is fixing this sooner rather than later? And what evidence can you provide that a lot of people share your belief that this is important?

Don’t assume everyone reading the proposals has full knowledge of last year’s proposals, or has had the time to follow all the details of how developers are using (or not using) every web technology out there. Make the case in your proposal. Convince the Interop team!

How to submit

Submit your proposal by filing an issue on Github. Feel free to collaborate with other people. If someone else has already proposed your idea, use the comments in GitHub issues to help further make the case. It’s far better to support an existing issue than have two issues for the same or very similar ideas. You can read proposals submitted in previous years to better understand the process.

Join the Interop Party!

The Interop Project is all about collaboration. By participating, you’re joining a global community of web developers, browser makers, and standards bodies working together to make the web more consistent and reliable across platforms. Share your insights as we make the web even more amazing together. We can’t wait to see your proposals.

WebKit for Safari 27 adds full spec compliance for top-level await. Before now, some of you may have run into unexpected “accessed before initialization” errors. We fixed it at the root by rewriting Safari’s module loader from the ground up so you can now confidently use await at the top level of your JavaScript modules. If top-level await wasn’t part of your toolkit before, this is a great time to give it another look.

What is top-level await?

Top-level await lets you use await at the top level of a module, enabling the same convenient use of Promises that async functions provide. Async functions provide support for await expressions to simplify complex Promise chains into linear sequences of code, and top-level await allows module authors to benefit from the same ease of use. Effectively, whenever an await expression is encountered, execution is paused until the awaited value is available, and in the meantime, control is returned to the caller of the async function. For ES modules, the analogy differs: when a module encounters a top-level await, any module that imports it is also suspended until the await resolves. However, sibling modules in the dependency graph that don’t depend on the awaiting module can still execute concurrently.

What this means for the web

You can try all of this today. Download Safari Technology Preview 251 or grab Safari 27 beta, and try integrating top-level await into your web apps. It just works! The improvements go beyond just top-level await: with the module loader rebuilt on the right foundation, ES modules as a whole are now something you can build on in Safari without a second thought. And once Safari 27 ships, you’ll be able to lean on top-level await and ES modules across your projects, in production, for everyone.

The problem

Top-level await is a complex feature implemented inside the module loader machinery. The ECMAScript specification’s section of modules leaves some parts up to the host—this includes the mechanism of fetching modules, which in practice will be done over the network by web browsers or from the local filesystem by JavaScript runtimes like Node.js and Bun. The WebKit team wrote Safari’s module loader long ago, back during the days of the WHATWG Loader proposal (last updated January 2016), and we relied on the proposal’s specification of the host-defined functionality. This worked during the early history of ES modules, when module execution was purely synchronous and top-level await didn’t exist. However, ECMAScript 2022 was later released, introducing top-level await as a feature. By this point, the WHATWG Loader proposal had effectively faded into obscurity after being superseded by the ECMAScript standard’s module section, but Safari’s module loader was still based on it. Top-level await was implemented in terms of a proposal that was abandoned before any support for async/await existed in ECMAScript, instead of in accordance with the ECMAScript standard’s algorithms for asynchronous module execution. This mismatch caused subtle bugs that we couldn’t fully resolve for years, despite multiple attempts. Instead of continuing to patch a foundation that couldn’t support the feature, we decided to rebuild it correctly.

An example

A major cause of Safari’s top-level await bugs was in how the module loader chose the order in which to load and evaluate modules. This code example demonstrates the issue:

// main.js

async function load(index) {
    try {
        print("Importing", index);
        const module = await import("./test-module.js");
        print("Imported", index);

        try {
            print(`Keys for ${index}:`, Object.keys(module));
        } catch (e) {
            print("Accessing", index, "failed:", e.message);
        }
    } catch (e) {
        print("Importing", index, "failed:", e.message);
    }
}

try {
    const imports = Array.from({ length: 3 }, (_, i) => {
        return load(i + 1);
    });

    await Promise.all(imports);
} catch (e) {
    print("Test failed:", e);
}

// test-module.js

await new Promise(resolve => setTimeout(resolve, 10));

export function someFunction() {
    return "Hello!";
}

export const someArray = [];

Its purpose is to dynamically load the same module three times in a row, printing the names of the module’s exports each time. It’s supposed to be ordered 1, 2, 3, but if the code is run with the old module loader, something unexpected occurs:

Importing 1
Importing 2
Importing 3
Imported 2
Accessing 2 failed: Cannot access 'someArray' before initialization.
Imported 3
Accessing 3 failed: Cannot access 'someArray' before initialization.
Imported 1
Keys for 1: someArray,someFunction

There are two things going wrong here. First, the order in which the imports complete is wrong. Instead of the expected 1, 2, 3, the order is 2, 3, 1. Second, there are strange errors about accessing a value before it’s initialized. Both problems are caused by the same bug.

When the module loader starts loading the module with top-level await the first time, it begins to execute it, and then pauses execution when it reaches the await. It then returns control to the main module, which begins the second import. The promise for the second import shouldn’t resolve until after the first import is done evaluating, but due to a bug in the old module loader, it resolves immediately. This leads to the second import finishing first, and because the evaluation of the imported module hasn’t completed yet, the code to print the module’s keys accesses uninitialized exports, causing an exception. The same happens with the third import. After those two fail, the first import finishes. This time, the evaluation has completed, so it’s able to successfully print the keys of the module’s exports.

With the new module loader, the output is what you’d expect:

Importing 1
Importing 2
Importing 3
Imported 1
Keys for 1: someArray,someFunction
Imported 2
Keys for 2: someArray,someFunction
Imported 3
Keys for 3: someArray,someFunction

Self-hosted JavaScript builtins vs. native C++

The old module loader was written in JavaScript as a self-hosted builtin. This had some advantages: unlike native code, JavaScript builtins can be inlined into the user code that invokes them, and it’s possible to avoid the performance penalty paid when crossing the boundary between JavaScript and C++. In addition, creation of objects is faster from JavaScript, as it’s sometimes possible to eliminate the heap allocation.

However, we later found multiple drawbacks with self-hosted JavaScript: it’s slower to start up because it has to be compiled at run time, unlike native code, which is fully compiled well in advance. In addition, builtins have inherently wide usage characteristics, which makes it harder for JavaScriptCore’s optimizing JIT compilers to exploit patterns in usage, and the module loader code isn’t a hot path, which further reduces the benefit of compiling at runtime. As a result, overall performance is less stable and predictable than it is for C++. When we rewrote the module loader, we chose to drop the self-hosted builtin approach in favor of fully native code.

The rewrite

In January 2026, we began rewriting the module loader. Because the consensus at that point had been that self-hosted JavaScript was not the ideal approach for the module loader, we started the process by deleting the entire JavaScript file that contained the old module loader.

After that, we began implementing the module loader operations one by one, translating the pseudocode defined in the ECMAScript specification into C++. As a guide through ordering which functions to implement first, given that the module loading machinery is a complex state machine, we read through the specification and took note of how the functions called each other and assembled a flow graph. This gave a starting point.

Leaf functions like ExecuteModule and ModuleRequestsEqual were ideal to implement early because they didn’t depend on any other functions. After a few weeks, the new module loader was able to handle the most common cases and a draft pull request was put up.

Testing the rewrite

Because the point of the rewrite was to improve the module loader’s reliability, thorough testing was essential. Engineers at Bun, whose runtime is built on JavaScriptCore and inherited the old module loader’s problems, graciously provided test cases they’d collected that demonstrated incorrect behavior. It was simple to adapt these to run with JavaScriptCore’s command line shell (jsc) and integrate them as tests.

To stress test the module loader’s performance and functionality, we wrote a fuzzer that produced complex graphs of modules (some with top-level await, others without) and import statements. The goal was to ensure that the observable effects of the module loading process were correct. We did this by generating large graphs and comparing the output of JavaScriptCore with the new module loader to the output of other JavaScript engines. If the text output matched byte-for-byte with other engines’ outputs, we could be sure that the new module loader was handling the test case correctly. And indeed we found in every tested example that the new module loader correctly handled the fuzzer output. Once all the module-related tests from test262 started passing and we fixed many previously failing module tests from WPT as well with no regressions, the new module loader was ready for merging. By this point, we had for a few weeks been daily driving a build of Safari with the new module loader integrated with no issues.

Give it a try

When we release Safari 27, you can start shipping web apps that take advantage of top-level await’s benefits. Until then, download the beta and try integrating top-level await into your projects. If you run into any issues, we’d love to hear your feedback. As always, bug reports can be submitted at bugs.webkit.org.

Update on what happened in WebKit in the week from August 24 to August 31.

After such a packed edition last week, we can relax with an even more packed installment this week! The team has been moving full steam ahead with the Layer-Based SVG Engine, and graphics improvements in general, but we also had a handful of other updates, such as SDK updates, a new WebsitePolicies API, and more.

Cross-Port 🐱

Graphics 🖼️

Infrastructure 🏗️

Safari Technology Preview Release 251 is now available for download for macOS Golden Gate and macOS Tahoe. If you already have Safari Technology Preview installed, you can update it in System Settings under General → Software Update.

This release includes WebKit changes between: 317935@main…319386@main.

Accessibility

Resolved Issues

• Fixed SVG anchors without an href being exposed as links. (318186@main) (181924326)

CSS

New Features

• Added support for @supports at-rule(...), which tests if a CSS at-rule is supported. (318482@main) (87884897)
• Added support for the object-view-box property. (318981@main) (132624217)
• Added support for property-scoped and property-index-scoped caching keywords in random(). (318960@main) (176395332)
• Added support for the random-item() function. (319180@main) (181816677)
• Added support for a comma-separated list of conditions in @container queries. (318233@main) (182249814)
• Added support for white-space-trim in the white-space shorthand. (318486@main) (182739052)
• Added support for external and data: URL filter references on HTML elements. (317991@main) (183059589)
• Added support for HighlightRegistry.highlightsFromPoint(). (318758@main) (184150480)
• Added support for random() in custom properties. (319039@main) (184715508)
• Added support for the ident() function. (319049@main) (184732904)
• Added support for the inherit() function. (319062@main) (184738624)
• Added support for the corner-shape property. (319205@main) (184950973)

Resolved Issues

• Fixed text overflowing a max-width constrained box when the page is zoomed out, by scaling the minimum font size with the zoom factor. (318509@main) (66569768)
• Fixed a background image not being repainted when only the URL fragment identifier changes. (318879@main) (105118256)
• Fixed a subgrid with a large column-gap overflowing a parent constrained by max-width. (318009@main) (137422489)
• Fixed nested @scope picking the wrong scoping roots when <scope-start> contains :has(:scope ...). (318711@main) (138495467)
• Fixed outside list markers disappearing or being mispositioned around line breaks. (318561@main) (159277763)
• Fixed the serialization of the size property in @page when both a page size and orientation are given. (318083@main) (162168233)
• Fixed the computed value of outline-offset not being snapped as a line width. (319236@main) (180054053)
• Fixed a flex item’s flex base size being clamped by its own min-width and max-width. (318264@main) (180064739)
• Fixed :focus-visible being shown after calling focus() inside an already focused ancestor. (318775@main) (181570771)
• Fixed multi-column height ignoring min-height when it exceeds max-height. (318676@main) (182381903)
• Fixed scroll snap selecting among equally aligned snap targets in the wrong order. (317997@main) (182571341)
• Fixed text-underline-offset being mispositioned for highlighted text in vertical writing modes. (318107@main) (182889143)
• Fixed the serialization of an unrecognized media query to preserve the original text as closely as possible. (318627@main) (182958311)
• Fixed the serialization of an unrecognized media query feature name to preserve the original casing. (318965@main) (183065105)
• Fixed @container style queries evaluating root-relative lengths incorrectly. (318144@main) (183094796)
• Fixed the originating element of ::part() in @container queries to be the element itself. (318620@main) (183154183)
• Fixed an anti-aliased fringe on ::highlight() background fills in vertical writing modes. (318177@main) (183496114)
• Fixed the first baseline of a wrap-reverse flex container coming from the wrong flex line. (318154@main) (183516222)
• Fixed a flex line’s cross size mixing the baseline and last baseline alignment groups. (318165@main) (183536181)
• Fixed the -webkit-border-image width flag being lost when a length edge precedes a non-length edge. (318214@main) (183584830)
• Fixed rounding of central baselines for atomic inline elements. (318268@main) (183584888)
• Fixed the block-ellipsis of a clamped block being styled from the wrong block formatting context. (318437@main) (183606151)
• Fixed ::highlight() pseudo-elements not inheriting from the parent element’s highlight. (318779@main) (183702060)
• Fixed clip on a child being ignored when determining whether an ancestor’s background is obscured. (318636@main) (183841775)
• Fixed var() not behaving as an arbitrary substitution function. (318912@main) (183913427)
• Fixed line-height units resolving incorrectly when the page is zoomed. (318558@main) (184032914)
• Fixed the computed value of line-height to more closely match how it was specified. (318710@main) (184232888)
• Fixed font-* properties resolving font-relative units against their own font instead of the parent element’s font metrics. (319052@main) (184336424)
• Fixed the rangeStart and rangeEnd animation attributes accepting length values that are not computationally independent when set from script. (318815@main) (184363719)
• Fixed -webkit-text-stroke not applying to highlighted text. (318976@main) (184375039)
• Fixed the ViewTimelineOptions inset member accepting length values that are not computationally independent when set from script. (318883@main) (184504829)
• Fixed ::highlight() not repainting after a CSS rule change. (319169@main) (184643272)
• Fixed ::highlight() not repainting when a highlight’s range is changed with CSS.highlights.set(). (319154@main) (184672580)
• Fixed a @function body not inheriting computed custom property values from the calling context. (319031@main) (184701762)
• Fixed arguments that invoke a @function being treated as a cycle. (319034@main) (184711017)
• Fixed the random() caching key not including the custom property name. (319096@main) (184722866)
• Fixed an auto <random-key> not being element-scoped, so every element shared the same item. (319153@main) (184845561)

Deprecations

• Removed the non-standard percentage value from -webkit-line-clamp. (318858@main) (159808285)
• Removed margin-trim support from flex containers, following the CSSWG resolution limiting it to block and multi-column containers. (318654@main) (184151309)
• Removed margin-trim support from grid containers, following the CSSWG resolution limiting it to block and multi-column containers. (318690@main) (184164505)

Canvas

Resolved Issues

• Fixed ctx.font not re-resolving relative font sizes when set to the same string after the canvas element’s style changed. (318753@main) (184194378)
• Fixed the canvas font keywords larger and smaller scaling by 1.02 instead of approximately 1.2. (318798@main) (184312611)

HTML

New Features

• Added support for popover=hint. (318958@main) (184548373)

Resolved Issues

• Fixed a color input with display: none not opening when its <label> is clicked. (318723@main) (100476630)
• Fixed createContextualFragment() leaving nested <head> and <body> elements behind when stripping a stray <html> element. (317962@main) (183163523)
• Fixed a <label> default action triggering when clicked interactive content removes itself. (318827@main) (184381262)
• Fixed clicking an element nested inside a checkbox or radio input wrongly activating the ancestor input. (318853@main) (184441087)
• Fixed focus not being restored to the correct element when a <dialog> is closed. (319173@main) (184751412)
• Fixed confirming an IME composition removing its containing positioned element. (319167@main) (184918934)

JavaScript

New Features

• Added support for Iterator.prototype.includes(). (318184@main) (173846280)
• Added support for the RegExp Buffer Boundaries proposal. (318415@main) (178287060)
• Added support for era and monthCode fields in Intl and Temporal calendars. (318428@main) (182753821)
• Added support for the traceStack option on WebAssembly.Exception and for Exception.stack. (318397@main) (183342491)
• Added support for WebAssembly Memory64. (318257@main) (183543404)
• Added support for deferred module evaluation with import defer. (318481@main) (183892394)
• Added support for Iterator.prototype.join(). (318502@main) (183892495)
• Added support for iterator chunking, including Iterator.prototype.chunks() and Iterator.prototype.windows(). (318479@main) (183892687)
• Added support for the joint iteration proposal, including Iterator.zip() and Iterator.zipKeyed(). (318477@main) (183892768)
• Added support for importing text modules with an import attribute of type: text. (318950@main) (184443879)

Resolved Issues

• Fixed a regular expression with ^ inside a group that can match empty failing to anchor the pattern. (317981@main) (183300022)
• Fixed incorrect matching for sticky regular expressions wrapped in .*. (317983@main) (183300106)
• Fixed a JSON.stringify() regression in how toJSON is checked. (318072@main) (183400665)
• Fixed Iterator.zip to use null-prototype objects for its options object and synthetic underlying iterator. (318061@main) (183418070)
• Fixed incorrect matching for regular expressions containing a negative lookahead. (318234@main) (183601444)
• Fixed module resolution ignoring the import attribute type in a module request. (318292@main) (183700464)
• Fixed the Array.from() fast path ignoring a Symbol.iterator override on set.keys() and set.values(). (318374@main) (183801651)
• Fixed stale character widths produced by v mode class set operations in regular expressions. (318416@main) (183879621)
• Fixed incorrect matching for regular expressions containing a lookbehind. (318418@main) (183881829)
• Fixed Temporal.PlainDate construction with years outside the supported range. (318504@main) (183960408)
• Fixed a TypeError regression when passing monthCode to Temporal calendar methods. (318566@main) (183980712)
• Fixed the order in which Temporal constructors read newTarget.prototype. (318635@main) (184072358)
• Fixed the String.prototype.localeCompare() collator cache going stale after a language change. (318616@main) (184096794)
• Fixed Temporal skipping the epoch range check when resolving a time inside a daylight saving time gap. (318663@main) (184140083)
• Fixed Temporal time zone identifier parsing to match the specification’s parse records. (318741@main) (184169471)
• Fixed Array.prototype.sort() not being stable when called without a comparator. (318682@main) (184189734)
• Fixed global object attribute getters and setters throwing when called as bare functions from global scope. (318748@main) (184273476)
• Fixed Iterator.prototype.join() to match the latest specification. (318806@main) (184321382)
• Fixed Iterator.prototype.chunks() and Iterator.prototype.windows() to match the latest specification. (318802@main) (184321801)
• Fixed Intl.Locale collections not being sorted. (318808@main) (184322384)
• Fixed formatToParts() omitting the era separator that format() inserts. (318847@main) (184382546)
• Fixed the import defer implementation to match the updated proposal. (318875@main) (184423667)
• Fixed \P{...} on the right side of a v mode && or -- operation being treated as a union. (318854@main) (184443379)
• Fixed Temporal.Duration rounding decisions being made on doubles instead of exact integers. (318901@main) (184472920)
• Fixed non-ISO calendar date field resolution at the edges of the supported range. (318940@main) (184478785)
• Fixed Temporal returning plausible values instead of throwing when an underlying calendar operation fails. (318953@main) (184567556)
• Fixed a regular expression string-list alternative containing a non-BMP character matching on only its leading code units. (318956@main) (184582034)
• Fixed the WebAssembly.Global value setter not treating a missing argument as undefined. (318967@main) (184608074)
• Fixed Unicode property escapes ignoring case-insensitive matching in u and v modes. (319064@main) (184762230)
• Fixed the Before Hijra era year being computed from rendered text instead of the calendar. (319172@main) (184853584)

Media

New Features

• Added support for HTMLMediaElement.removeTextTrack(). (318250@main) (183365541)

Resolved Issues

• Fixed WebVTT cue overlap avoidance to move a cue the shortest possible distance. (318012@main) (183151333)
• Fixed legacy EME generateKeyRequest() returning an incorrect destination URL. (317970@main) (183305929)
• Fixed requestFullscreen() and requestPictureInPicture() not consuming user activation. (318673@main) (183621577)
• Fixed selecting On in the media controls captions menu not turning on subtitles. (318468@main) (183776073)
• Fixed MediaRecorder dropping pending video frames when recording is stopped. (318595@main) (183975207)
• Fixed the auto position of a WebVTT cue with start or end text alignment to be 50%. (318610@main) (184039946)
• Fixed MediaRecorder dropping a frame whenever the writer input reports that it is not ready. (318778@main) (184271782)

Navigation API

New Features

• Added support for the to property on NavigationTransition. (319142@main) (184792753)
• Added support for intercepting a navigation with a precommit handler. (319208@main) (184893603)

Resolved Issues

• Fixed sourceElement reporting the deepest clicked element instead of the element responsible for the navigation. (319005@main) (184581613)
• Fixed NavigationHistoryEntry returning null instead of the empty string for url, key, and id when the document is not fully active. (319007@main) (184590003)
• Fixed navigateEvent.scroll() not scrolling to the beginning of the document when the fragment does not exist. (319068@main) (184595100)
• Fixed navigation.activation.from not being null when navigating away from the initial about:blank. (319217@main) (184624752)
• Fixed navigateerror not firing for a navigation started from a navigateerror handler. (319222@main) (184633618)

Networking

New Features

• Added support for backpressure when uploading a stream request body with fetch(). (318236@main) (183400867)

Resolved Issues

• Fixed a same-frame fragment navigation cancelling a download started by a download attribute click in the same task. (319105@main) (165498647)
• Fixed a page reloading continually by tracking the latest navigation action when considering Enhanced Security state changes. (318304@main) (183480452)
• Fixed XMLHttpRequest.getAllResponseHeaders() returning the previous response’s headers when the object is reused. (318217@main) (183561750)
• Fixed XMLHttpRequest.responseURL still returning the aborted request’s URL after calling abort(). (318241@main) (183587043)
• Fixed the CNAME-cloaking cookie expiry cap being applied to a top-level page’s own cookies instead of only subresources. (318332@main) (183664485)
• Fixed XMLHttpRequest.send() setting a Content-Type request header on GET and HEAD requests when passed a URLSearchParams. (318424@main) (183801778)
• Fixed imagesrcset not overriding href on <link rel="preload" as="image">. (318544@main) (183945535)
• Fixed <link rel=preload as> keywords not being matched ASCII case-insensitively. (318584@main) (184013239)
• Fixed PDF byte-range requests being blocked by the connect-src Content Security Policy directive instead of object-src. (318797@main) (184258237)
• Fixed a Content Security Policy host-source of the form *:*/path not matching. (318612@main) (184902666)
• Fixed a policy decision that outlives its navigation being applied to an unrelated load. (319378@main) (184974939)

Rendering

Resolved Issues

• Fixed text selection highlighting extending incorrectly when a float precedes the text. (319128@main) (109610452)
• Fixed text underlines rendering incorrectly for Urdu text. (319220@main) (161299983)
• Fixed a regression where editing text in some inputs stopped responding to backspace. (318095@main) (183391399)
• Fixed text-align: justify justifying the last line of a block. (318562@main) (183976364)
• Fixed Arabic letters in adjacent inline boxes not being joined. (319209@main) (184071471)
• Fixed a self-collapsing block nested in an inline box losing its margin when the root has a border. (318646@main) (184145672)
• Fixed trailing whitespace not being collapsed before a block nested in an inline box. (318653@main) (184151239)
• Fixed baseline alignment ignoring the offset of a block level box nested in an inline box. (318656@main) (184153324)
• Fixed an empty orthogonal block nested in an inline box stretching the line. (318659@main) (184158817)
• Fixed the margin after a block level box on a line being lost on relayout. (318660@main) (184159645)
• Fixed an empty editable container with only an out-of-flow child losing its line. (318671@main) (184176269)
• Fixed a float inside a block nested in an inline box intruding at the wrong position. (318678@main) (184184683)
• Fixed the baseline of an inline-block whose last line box holds a block level box dropping that line’s offset. (318702@main) (184222186)
• Fixed nested inline boxes around a block level box being stretched by their nesting depth. (318704@main) (184222677)
• Fixed an inline box with cloned decorations generating an extra line between two block level boxes. (318718@main) (184241600)
• Fixed a block whose content is a table being treated as self-collapsing. (318782@main) (184337051)
• Fixed a block level box’s margin after being counted twice when only that box needs layout. (318792@main) (184344633)
• Fixed an outside list marker making its list item’s children inline. (318891@main) (184380304)
• Fixed an excluded list marker aligning with a block level box on a line instead of the first line of text. (318908@main) (184405037)
• Fixed a block level box on a line reporting its scrollable overflow at its static position. (318885@main) (184505703)
• Fixed a block level box on a line not starting a new paragraph for unicode-bidi: plaintext and text-indent: each-line. (318886@main) (184505835)
• Fixed a highlight on the line after a block level box covering the box’s margin. (318887@main) (184506039)
• Fixed a block level box on a line switching off text-wrap: balance for the whole container. (318893@main) (184508888)
• Fixed inline boxes that are not relatively positioned offsetting their out-of-flow children by the position of the line. (318897@main) (184512485)
• Fixed a block level box on a line not contributing its margin box to its container’s overflow. (318906@main) (184526625)
• Fixed list-based hit testing reporting the container before a block level box on an earlier line. (318909@main) (184527135)
• Fixed selection gaps not being filled around a block level box on a line. (318911@main) (184527621)
• Fixed line-clamp not counting the lines of a block level box on a line. (318921@main) (184545926)
• Fixed a forced page break after a block level box on a line not moving the following content to the next page. (319029@main) (184712866)
• Fixed a float not being offered to the caret when its container has a block level box on a line. (319030@main) (184713698)
• Fixed a <fieldset> on a line taking its legend’s overhang twice. (319033@main) (184714637)
• Fixed a box that collapsed through with clearance on a line pushing the following content down by its margin. (319160@main) (184917509)
• Fixed intrinsic width computation when a line holds a block level box. (319212@main) (184968113)

SVG

New Features

• Added support for external and data: URL filter references on SVG elements. (317538@main) (114823248)
• Added support for passing a DOMMatrix2DInit dictionary to SVGMatrix.multiply(). (318109@main) (180896205)
• Added support for external SVG resource references, including clip-path, marker, and paint servers. (318543@main) (183941298)

Resolved Issues

• Fixed auto sizing of <svg:image> to follow the CSS default sizing algorithm. (318548@main) (122586485)
• Fixed SVGSVGElement.currentScale being a no-op on an outermost <svg> that is not the document root. (318762@main) (180889449)
• Fixed SVGLength.value returning negative numbers for r, rx, ry, width, height, and textLength, which disagreed with getComputedStyle(). (317963@main) (181108927)
• Fixed a clip-path basic shape being mispositioned on a <foreignObject> with a non-zero x or y. (318904@main) (182755161)
• Fixed feDropShadow ignoring an update to the Y component of stdDeviation when X changes. (318281@main) (183678196)
• Fixed <animateMotion> ignoring a numeric rotate value. (318565@main) (183832405)
• Fixed SVG enumerated attributes not reverting to their initial value when removed or set to an invalid value. (319093@main) (184076505)
• Fixed dynamic changes to x and y on <foreignObject> having no effect. (318669@main) (184172530)
• Fixed a clip-path basic shape being mispositioned on a rotated or scaled SVG element. (318924@main) (184494108)
• Fixed <animateMotion> ignoring a zero-length motion path. (318963@main) (184569273)

Deprecations

• Removed the SVGPathSegList collection and the SVGPathSeg family of interfaces from SVGPathElement, matching SVG 2. (318760@main) (115039851)

Scrolling

Resolved Issues

• Fixed re-snapping to prefer the block-axis box when the two scroll axes conflict. (318343@main) (183366125)
• Fixed scroll snapping when a scroll overshoots past the end of the scroll container. (318081@main) (183375912)
• Fixed element.scroll() and element.scrollTo() not scrolling inside a content-visibility: hidden subtree. (319219@main) (184935071)

Service Workers

New Features

• Added support for service workers reading stream upload data from a fetch event request body. (317964@main) (183108477)
• Added support for stream upload backpressure when a service worker reads the upload data. (318346@main) (183529369)

Resolved Issues

• Fixed a missing Sec-Fetch-Dest header on service worker script requests. (318237@main) (181909962)
• Fixed network fallback being allowed after a fetch event request body was already disturbed. (318042@main) (183125740)
• Fixed cancellation of a fetch event request body not being propagated to the original ReadableStream. (318043@main) (183317580)

Web API

Resolved Issues

• Fixed: Improved the InvalidStateError message thrown by selection methods to explain what is invalid. (318520@main) (134645414)
• Fixed a missing resize event when an iframe transitions from display: none to visible. (318713@main) (174638256)
• Fixed timeOrigin being skewed for Navigation Timing entries when the browsing context group changes. (318057@main) (179332119)
• Fixed the Digital Credentials API to consume transient activation before serializing the request. (318122@main) (182412996)
• Fixed the Cookie Store API not preserving the order of the cookie change subscription list. (318087@main) (183271849)
• Fixed notifications after the first persistent one not being closed. (318007@main) (183362637)
• Fixed getBoundingClientRect() returning a non-zero rect for SVG elements inside hidden containers. (318744@main) (183425103)
• Fixed quota accounting over-charging positioned writes through a FileSystemWritableFileStream. (318130@main) (183489019)
• Fixed an Apple Pay deferred payment request being dropped when the payment method changes. (318155@main) (183516996)
• Fixed Cache Storage size accounting underflowing and persisting a corrupt size. (318204@main) (183578693)
• Fixed FileReader.abort() being silently ignored on a reader reused after a completed read. (318288@main) (183695958)
• Fixed MathML and SVG elements not resetting tabIndex when tabindex is changed to an invalid value. (318303@main) (183696552)
• Fixed fullscreen state not being unwound when entering fullscreen fails. (319243@main) (184157871)
• Fixed the SharedWorkerGlobalScope prototype not being an immutable prototype exotic object. (318684@main) (184190755)
• Fixed the scrollend event not firing when wheel-scrolling a subframe. (318805@main) (184352772)

Web Audio

Resolved Issues

• Fixed a loss of precision in exponentialRampToValueAtTime() caused by accumulating the ramp value. (317955@main) (124498013)
• Fixed decodeAudioData() failing with an EncodingError for valid M4A files whose ftyp brand is not mp4. (318005@main) (183148186)
• Fixed registerProcessor() error messages so they name the offending AudioParam instead of the processor. (317948@main) (183189781)
• Fixed an OscillatorNode with a-rate automation starting out of phase by honoring sub-sample start times. (317953@main) (183194827)
• Fixed the AudioBufferSourceNode output channel count to account for whether the node is actively processing. (317956@main) (183245229)
• Fixed stale audio being played instead of silence when the audio destination ring buffer underruns. (317968@main) (183305574)
• Fixed an AudioScheduledSourceNode not firing the ended event when it is not connected to the destination. (318515@main) (183986981)
• Fixed a k-rate AudioParam input to AudioBufferSourceNode.detune diverging from the equivalent automation. (318516@main) (183987621)
• Fixed AudioContext.close() not rejecting when called on an already-closed context. (318522@main) (183989479)
• Fixed AudioWorkletGlobalScope.currentFrame reporting 0 for a worklet created while the context is suspended. (318601@main) (184081765)
• Fixed an AudioWorkletProcessor being torn down too early after process() returns false. (318621@main) (184107806)
• Fixed the AudioWorkletNode processorerror event missing filename, lineno, and colno. (318705@main) (184224032)
• Fixed MediaStreamAudioSourceNode capturing the wrong track and continuing to play after the track ends. (318706@main) (184224142)
• Fixed a zero-duration exponentialRampToValueAtTime() at a non-frame-aligned time rendering NaN. (318868@main) (184434164)
• Fixed setting ConvolverNode.buffer to null not releasing the impulse response. (318870@main) (184434803)
• Fixed reverse playback of buffers longer than 2^23 frames extrapolating outside the source samples. (318869@main) (184439324)

Web Extensions

New Features

• Added support for wildcard domains and subdomains in externally_connectable.matches. (318361@main) (183642164)
• Added support for setAccessLevel() on the local and sync storage areas. (318980@main) (183680404)
• Added support for scripting.ExecutionWorld. (319009@main) (184284891)

Resolved Issues

• Fixed several inconsistencies in the browser.alarms API. (318493@main) (183770530)
• Fixed a significant delay loading web extensions when the browser is launched cold. (318756@main) (183827503)

Web Inspector

New Features

• Added icons for recorded WebGL and WebGPU actions in the Canvas tab. (318517@main) (42777850)
• Added support for recording WebGPU devices in the Canvas tab. (318407@main) (183538409)
• Added support for instrumenting WebGPU devices in the Canvas tab. (318336@main) (183757645)
• Added support for WebGPU content previews in the Canvas tab. (318363@main) (183785306)
• Added support for instrumenting WebGPU pipelines in the Canvas tab. (318366@main) (183790749)
• Added support for disabling WebGPU render pipelines in the Canvas tab. (318403@main) (183857257)
• Added support for using the WebGPU label of devices and pipelines as their name in the Canvas tab. (318409@main) (183876768)
• Added support for exposing client metadata for WebGPU devices. (318467@main) (183939079)
• Added support for recording WebGL extension actions in the Canvas tab. (318474@main) (183945866)
• Added support for mapping WebAssembly byte offsets to original sources with source maps. (318546@main) (184017160)
• Added support for editing WebGPU shaders in the Canvas tab. (318633@main) (184128414)
• Added support for highlighting WebGPU render pipelines in the Canvas tab. (318668@main) (184169419)
• Improved the estimated memory use reported for WebGL and WebGPU canvases to include their graphics resources. (318915@main) (184535731)
• Added support for recording object arguments and result objects in the Canvas tab. (319059@main) (184759172)
• Added support for showing names for recorded WebGPU bitfields. (319174@main) (184928178)
• Added support for snapshotting WebGPU element image copies. (319176@main) (184928370)
• Added syntax highlighting to recording actions in the Canvas tab. (319189@main) (184936730)

Resolved Issues

• Fixed canvas recordings retaining memory by pruning recordings that are no longer in use. (318613@main) (35893620)
• Fixed searching resources returning duplicate results for the same resource. (319061@main) (42879586)
• Fixed resource data for non-buffered resources persisting across navigations. (318035@main) (181210169)
• Fixed WebAssembly module scripts not being associated with the resource that fetched them. (318207@main) (183583149)
• Fixed stale frame navigation event timestamps being shown after initializing. (318213@main) (183584784)
• Fixed a selected details sidebar panel not being restored when it becomes available again. (318353@main) (183778380)
• Fixed detaching a child frame also detaching its parent frame. (318355@main) (183778531)
• Fixed stale execution contexts being kept when their identifiers change. (318356@main) (183779166)
• Fixed response end times being dropped for resources without request timing data. (318360@main) (183783292)
• Fixed recorded WebGPU object arguments not being swizzled correctly. (318545@main) (184017109)
• Fixed missing console.record() options being treated as if they were present. (318555@main) (184029716)
• Fixed recorded object identifiers colliding by assigning them per type. (318567@main) (184040370)
• Fixed configured WebGPU <canvas> elements not being distinguished from CSS canvas client nodes. (318794@main) (184346714)

WebCodecs

New Features

• Added support for the WebCodecs ImageDecoder API. (319179@main) (184857272)

WebGPU

Resolved Issues

• Fixed a WGSL miscompilation when swizzling a packed vec3 value. (318098@main) (183426431)
• Fixed a large frame-rate drop when executeBundles() is called with bundles containing indirect draws. (318538@main) (183458069)
• Fixed textureDimensions(t, level) clamping the mip level one past the last valid level. (318273@main) (183673818)
• Fixed GPUQueue.copyExternalImageToTexture() uploading indexed PNG images incorrectly. (318952@main) (184529653)

WebRTC

New Features

• Added WebRTC AV1 software fallback support. (317986@main) (182789617)

Resolved Issues

• Fixed a valid current value being ignored when both min and max are given in a capture constraint range. (318046@main) (182968516)
• Fixed setSinkId() reporting success without switching audio output for a single-track MediaStream. (318149@main) (183147942)
• Fixed getUserMedia() interrupting the microphone system-wide when echoCancellation is disabled. (318164@main) (183517329)
• Fixed ImageCapture.takePhoto() failing permanently after a single transient capture error. (318260@main) (183640839)