LGTM1. Extremely excited about this; congrats on the launch. On Tuesday, June 23, 2026 at 1:26:11 PM UTC-7 Michal Mocny wrote:
> Contact emails > > [email protected], [email protected], [email protected] > > Explainer > > https://github.com/WICG/soft-navigations > > Specification > > https://wicg.github.io/soft-navigations > > Summary > > Adds "soft-navigation" and "interaction-contentful-paint" PerformanceEntry > types to the web performance timeline to track interaction-driven page > performance, including for "soft" navigations (JS-driven navigations in > Single Page Apps (SPAs)). This work expands on metrics like Largest > Contentful Paint (LCP) and Interaction to Next Paint (INP). > > The "interaction-contentful-paint" entry reports on new contentful paints > within parts of the page modified by a user interaction, helping developers > understand interaction loading latency. This proposal tracks the effects of > interactions across async tasks (like fetch requests). > > The "soft-navigation" entry reports same-document history state changes > initiated by interactions, establishing a new time origin to correctly > attribute subsequent performance data to the active route rather than the > initial document URL. > > Blink component > > Blink>PerformanceAPIs > <https://issues.chromium.org/issues?q=customfield1222907:%22Blink%3EPerformanceAPIs%22> > > Web Feature ID > > No information provided > > Motivation > > Web developers have been asking for a way to measure the loading > performance of "soft navigations" (JS-driven navigations in Single Page > Apps (SPA)), and to integrate such navigations into the web performance > timeline in general. > > Besides getting useful new performance insights for these, having a shared > standard definition for such navigations helps attribution for all existing > performance timeline data (i.e. resource timings), and provides better > default aggregation for metrics like INP or CLS with better URL attribution. > > Initial public proposal > > https://github.com/WICG/proposals/issues/71 > > TAG review > > https://github.com/w3ctag/design-reviews/issues/879 > > TAG review status > > Pending > > Origin Trial Name > > Soft Navigation Heuristics > > Goals for experimentation > > 1. Gaining insights on the quality of the heuristic and how it compares to > current heuristics employed, from web developers, spa-framework authors, > and by existing RUM providers; Focusing specifically on the initial > "soft-navigation" reporting and the "interaction-contentful-paint" loading > entries that follow. > > 2. Learning if developers find the correlation of various existing > performance entries (i.e. Resource Timings, CLS or INP entries) to these > soft navigation entries more useful than without them. > > Chromium Trial Name > > SoftNavigationHeuristics > > Link to origin trial feedback summary > > https://github.com/WICG/soft-navigations/issues/47 > > Origin Trial documentation link > > https://github.com/WICG/soft-navigations#soft-navigations > > Risks > > > Interoperability and Compatibility > > No information provided > > Gecko: No signal ( > https://github.com/mozilla/standards-positions/issues/854) > > WebKit: No signal ( > https://github.com/WebKit/standards-positions/issues/235) > > Web developers: Strongly positive > > https://issues.chromium.org/issues/40229587 > > https://github.com/WICG/proposals/issues/71 > > https://twitter.com/yoavweiss/status/1575191332775026688 > > Other signals: > > WebView application risks > > Does this intent deprecate or change behavior of existing APIs, such that > it has potentially high risk for Android WebView-based applications? > > None known. This feature is part of the standard performance timeline, > which is available in WebView in the same way as non-webview. The feature > is entirely implemented within blink + renderer. > > > Debuggability > > No information provided > > Will this feature be supported on all six Blink platforms (Windows, Mac, > Linux, ChromeOS, Android, and Android WebView)? > > Yes > > Is this feature fully tested by web-platform-tests > <https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md> > ? > > Yes > > > Flag name on about://flags > > soft-navigation-heuristics > > Finch feature name > > SoftNavigationHeuristics > > Rollout plan > > Will ship enabled for all users > > Requires code in //chrome? > > False > > Tracking bug > > https://bugs.chromium.org/p/chromium/issues/detail?id=1338390 > > Availability expectation > > Feature is available only in Chromium browsers for the foreseeable future. > This is relatively common for Performance APIs, where the requirement for > Baseline support is lower. A performance API can be feature detected and > used only on Chromium and still give developers great value. > > That said, there is existing Baseline support for the foundations of this > work: Event Timing, Paint Timing, and LCP-- and it seems there is > relatively positive support for the nascent AsyncContext and Container > Timing features which may make interop progress in the next year. Thus we > expect a future where this set of APIs also reaches interop/Baseline status. > > Adoption expectation > > At least 3 major abstractions replace their use of an existing feature > with this feature within 24 months of reaching mainline. Specifically, > several RUM measurement products and/or frameworks rely on custom > instrumentation, web platform api monkey-patching, and/or developer hints > in order to measure interactions and soft-navigations. These APIs have been > fairly widely deployed during origin trial by many partners/abstractions, > and we expect that these APIs are broadly adopted over the next few years. > > Adoption plan > > This feature has been in demand for years, and has been widely discussed > in relevant web performance groups (w3c web perf working group, rum > community group, slack, conferences, etc). Many organizations have already > participated in multiple rounds of OT. This feature is also expected to > power the next major update to the Core Web Vitals program, and has already > been integrated into an experimental branch of the web-vital.js library > which has wide industry adoption (making it an easier integration/upgrade). > > Non-OSS dependencies > > Does the feature depend on any code or APIs outside the Chromium open > source repository and its open-source dependencies to function? > > No. > > Estimated milestones > > Shipping on desktop > > 151 > > Origin trial desktop first > > 139 > > Origin trial desktop last > > 144 > > Origin trial extension 1 end milestone > > 123 > > Origin trial extension 2 end milestone > > 149 > > Origin trial extension 3 end milestone > > 123 > > Origin trial extension 4 end milestone > > 144 > > Shipping on Android > > 151 > > Origin trial Android first > > 139 > > Origin trial Android last > > 144 > > Shipping on WebView > > 151 > > Origin trial WebView first > > 139 > > Origin trial WebView last > > 144 > > > Anticipated spec changes > > Open questions about a feature may be a source of future web compat or > interop issues. Please list open issues (e.g. links to known github issues > in the project for the feature specification) whose resolution may > introduce web compat/interop risk (e.g., changing to naming or structure of > the API in a non-backward-compatible way). > > The API shape has gone through multiple rounds of iteration and is > expected to be in its final form. There may be future API extensions added > to expose more features (i.e. to add more "container timing" details) but > the API was designed to gracefully support this. > > Note: the spec currently does not limit this API only the main frame top > level document, but the chromium implementation does. We expect to change > the implementation to expose InteractionContentfulPaint also to frames, but > may change the spec to limit SoftNavigation entries (due to complexity of > history stack). > > Link to entry on the Chrome Platform Status > > https://chromestatus.com/feature/5144837209194496?gate=4820517475844096 > > Links to previous Intent discussions > > Intent to Prototype: > https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAL5BFfV3qRFx0i-eGJFSzqE8bnbX8XYJCvXAj0LfvO0icPo_jA%40mail.gmail.com > > Intent to Experiment: > https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAL5BFfUb_Gn_5gGy8SnChg5KH2JN57Gv0NhnHN7Q_kH0Aa17CQ%40mail.gmail.com > > Intent to Extend Experiment 1: > https://groups.google.com/a/chromium.org/g/blink-dev/c/xxrmKr-6X38/m/48Hri1cnAgAJ > > Intent to Extend Experiment 2: > https://groups.google.com/a/chromium.org/d/msgid/blink-dev/69cd703e.050a0220.319665.006a.GAE%40google.com > > Intent to Extend Experiment 3: > https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAL5BFfULP5d3fNCAqeO2gLP56R3HCytmaNk%2B9kpYsC2dj4%3DqoQ%40mail.gmail.com > > Intent to Extend Experiment 4: > https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAEeF2TfyN4LMy2DQwjPrsTekEw8dNXgcqiogvznagjtWyfqixA%40mail.gmail.com > > > This intent message was generated by Chrome Platform Status > <https://chromestatus.com/>. > > -- You received this message because you are subscribed to the Google Groups "blink-dev" group. 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