(The automated email removed my message formatting, and its a bit confusing
to read through the full history. For your benefit, here is a formatted
copy focusing on the new request)
Requesting a 3 milestone extension to the Origin Trial for this feature
(m147 - m149).
Reason:
- Provide developers the opportunity to test several significant changes
to the API shape following the most recent Origin Trial (OT) feedback
(details below).
- Also, multiple developers have requested the opportunity to
participate in a new OT period, as they were unable to complete testing
before the previous deadline.
- While we considered moving directly to shipping, the substantial
implementation changes following the first OT will benefit from another
round of developer feedback to ensure a stable launch.
- (We also have remaining specification and documentation work to
complete).
Major changes since the end of the previous OT:
- InteractionContentfulPaint performance entry now reports for ALL
interactions, and reports before the soft navigation performance entry is
emitted.
- I.e. It's a general responsiveness metric as well as a navigation
loading metric.
- Integrated with Event Timing interactions, and both SoftNavigation and
InteractionContentfulPaint now receive an `interactionId` value to match.
- Added support for `replaceState` and exposed `navigationType` to the
API (a top developer-requested feature change)
Minor changes:
- Adjusted the navigation startTime to match the interaction event
timing startTime (i.e. Event hardware timeStamp).
- This will make reported timings appear larger, but be more
consistent with existing Interaction metrics (and existing interaction
performance measurement tooling).
- Many more "under the hood" improvements further improve detection
rates and paint reporting quality.
Field data results from the latest versions look incredibly promising (and
we hope to share some insights publicly at BlinkOn, soon).
On Wed, Apr 1, 2026 at 3:21 PM Chromestatus <[email protected]>
wrote:
> *Contact emails*
> [email protected], [email protected], [email protected]
>
> *Explainer*
> https://github.com/WICG/soft-navigations
> https://github.com/WICG/soft-navigations/blob/main/Design.md
>
> *Specification*
> https://wicg.github.io/soft-navigations
>
> *Summary*
> Exposes the (experimental) soft navigation heuristics to web developers,
> using both PerformanceObserver and the performance timeline. This feature
> reports two new performance entries: - "soft-navigation", for user
> interactions which navigate the page. Defines a new timeOrigin to help
> slice the performance timeline. - "interaction-contentful-paint", which
> reports on the loading performance of interactions (beyond just next
> paint), used as LCP for soft-navigations.
>
> *Blink component*
> Blink>PerformanceAPIs
> <https://issues.chromium.org/issues?q=customfield1222907:%22Blink%3EPerformanceAPIs%22>
>
> *Web Feature ID*
> *No information provided*
>
> *TAG review*
> https://github.com/w3ctag/design-reviews/issues/879
>
> *TAG review status*
> Issues addressed
>
> *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
>
> *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://github.com/WICG/proposals/issues/71#issuecomment-1325856231
> 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?
> *No information provided*
>
>
> *Reason this experiment is being extended*
> Requesting a 3 milestone extension to this feature. Reason: provide
> developers the opportunity to test several significant changes to the API
> shape following the most recent Origin Trial (OT) feedback (details below).
> Also, multiple developers have requested the opportunity to participate in
> a new OT period, as they were unable to complete testing before the
> previous deadline. While we considered moving directly to shipping, the
> substantial implementation changes that followed the first OT we think will
> benefit from another round of developer feedback to ensure a stable launch.
> (We also have remaining specification/documentation work to do). Major
> changes since end of previous OT: - InteractionContentfulPaint performance
> entry now reports for ALL interactions, and reports BEFORE soft navigation
> performance entry is emitted. I.e. its a general responsiveness metrics as
> well as a navigation loading metric. - Integrated with Event Timing
> interactions, and both SoftNavigation and InteractionContentfulPaint now
> receive an `interactionId` value to match. - Added support for
> replaceState, and expose `navigationType` to the api (top developer
> requested feature change) Minor changes: - Adjusted the navigation
> startTime to match the interaction event timing startTime (i.e. Event
> hardware timeStamp). This will make reported timings look larger, but more
> consistent with existing Interaction metrics (and existing tooling) - Many
> more "under the hood" improvements that further improve detection rates and
> paint reporting quality. Field data results from the latest versions look
> incredibly promising (and we hope to share some insights publicly at
> BlinkOn, soon).
>
> *Reason this experiment is being extended*
> We are still collecting feedback from partners, who are evaluating the
> suitability of this API to replace existing ad-hoc methods of measuring
> soft navigations, including some who were only recently able to start
> experimenting. Additionally, we have made changes to the heuristics, in
> response to testing and feedback, to eliminate some false-positive
> detections, and better match the behaviour of real-world single-page apps.
> Some of these changes initially went out in Chrome 120, and were refined in
> Chrome 121; some will be released with Chrome 122. We'd like to give
> developers a chance to experiment with these changes, to help inform any
> future adjustments that need to be made. After Chrome 123, we intend to
> pause the experiment while we act on all of the feedback, and decide
> whether further changes to the heuristics are necessary, or if the API is
> in good enough shape to consider shipping.
>
> *Reason this experiment is being extended*
> This feature has already gone through two origin trials which ended in
> milestone 123 a year ago. We took developer feedback and communicated with
> web developers at the end of the trial with the following status: "The
> Chrome team are taking time to review the experiment feedback and consider
> the next steps for this API. We want to address some accuracy issues and
> believe another origin trial will be required before the feature is ready
> to progress." Over the next year we investigated the reasons for the
> deficiencies, updated the implementation, and revamped the proposed API
> slightly. I have created a description of these changes here:
> https://github.com/WICG/soft-navigations/issues/47 Early results (local
> lab testing, and field histograms in aggregate) from the current version of
> the feature shows a significant improvement from a year ago, and we've
> gotten positive anecdotal feedback from some early testers on Canary with
> experimental features enabled. Although this feature has already had 2
> Origin trials, because there has been over a year of gap since the last
> trial, we request permission for another 6 milestones extension, rather
> than 3, which are necessary as we expect it will take developers some time
> ramp up and collect sufficient field data to analyze give feedback, and for
> us to iterate on this feedback.
>
> *Ongoing technical constraints*
> None.
>
> *Debuggability*
> *No information provided*
>
> *Will this feature be supported on all six Blink platforms (Windows, Mac,
> Linux, ChromeOS, Android, and Android WebView)?*
> No
>
> *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*
> *No information provided*
>
> *Finch feature name*
> SoftNavigationHeuristics
>
> *Requires code in //chrome?*
> False
>
> *Tracking bug*
> https://bugs.chromium.org/p/chromium/issues/detail?id=1338390
>
> *Estimated milestones*
> 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
> Origin trial Android first 139
> Origin trial Android last 144
> Origin trial WebView first 139
> Origin trial WebView last 144
>
> *Link to entry on the Chrome Platform Status*
> https://chromestatus.com/feature/5144837209194496?gate=5090983379337216
>
> *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 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>.
>
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