Intent to Ship: Speculation rules: tag field
Domenic Denicola
Contact emails
robe...@chromium.org, dom...@chromium.orgExplainer
https://github.com/WICG/nav-speculation/blob/main/speculation-rules-tags.mdSpecification
https://wicg.github.io/nav-speculation/speculation-rules.htmlSummary
This enables developers to add tag field to speculation rules. This optional field can be used to track the source of speculation rules, e.g. to treat them differently at an intermediary server. Any tags associated with a speculation will be sent with the Sec-Speculation-Tags header.
Blink component
Internals>PreloadSearch tags
speculationrules, prerendering, prefetchTAG review
https://github.com/w3ctag/design-reviews/issues/721 The TAG is generally dissatisfied with speculation rules, claiming that the syntax is too complicated. As such, we don't believe asking for review of this additional small field would be fruitful.TAG review status
Not applicableRisks
Interoperability and Compatibility
The entire speculative loading feature is a progressive enhancement, so in general risks are low in this area.
Gecko: No signal (https://github.com/mozilla/standards-positions/issues/1172) Mozilla is neutral on speculation rules syntax in general (https://github.com/mozilla/standards-positions/issues/620), although positive on prefetching. We opened a new request for this specific feature to ensure we captured any of their input.
WebKit: No signal (https://github.com/WebKit/standards-positions/issues/54) WebKit has not yet responded to our 2022 request for a position on speculation rules in general. We have updated the thread to point them to this latest addition anyway.
Web developers: Positive (https://github.com/WICG/nav-speculation/blob/main/speculation-rules-tags.md#stakeholder-feedback)
Other signals:
Activation
Due to how new fields in speculation rules are interpreted in older versions of Chromium, using this field on the rule level can cause the rules to be dropped. A workaround is using it on the ruleset level only during this transition period. https://github.com/WICG/nav-speculation/blob/main/speculation-rules-tags.md#location-of-the-tags-within-the-json
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
Debuggability
We would like to use the presence of ruleset-level tags to improve DevTools's existing display of speculation rules rulesets: https://issues.chromium.org/issues/393408589
Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, ChromeOS, Android, and Android WebView)?
NoGeneral support for speculation rules on WebView remains unavailable. There is nothing specific about this feature that is incompatible with WebView, however, so if speculation rules starts working on WebView this feature will "just work".
Is this feature fully tested by web-platform-tests?
YesWe have a large set of tests planned, and are actively landing them now. They should show up in https://wpt.fyi/results/speculation-rules?label=master&label=experimental&aligned&q=tags once they have landed. (Some already have but more are on the way.)
Flag name on about://flags
NoneFinch feature name
SpeculationRulesTagRequires code in //chrome?
FalseTracking bug
https://issues.chromium.org/issues/381687257Adoption expectation
Major platforms start using this feature shortly after it launches in Chromium.Adoption plan
Reaching out to major platforms directly, via already-established communications channels such as the spec issue tracker.Estimated milestones
| Shipping on desktop | 136 |
| Shipping on Android | 136 |
We are hoping to launch this in 136, despite the branch cut already having passed, by backporting the flag-flipping CL or (less preferred) turning it on using Finch. If there are concerns that prevent approvals from coming in quickly enough for this, then we might slip to 137.
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).
NoneLink to entry on the Chrome Platform Status
https://chromestatus.com/feature/6503137340555264?gate=5074975754813440Links to previous Intent discussions
Intent to Prototype: https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAM0wra8a%2B4uVDq1V1ZvrkUj9Jg3tbnbnqNXfeHhxZSSMj1mXVg%40mail.gmail.com
Yoav Weiss (@Shopify)
Contact emails
robe...@chromium.org, dom...@chromium.orgExplainer
https://github.com/WICG/nav-speculation/blob/main/speculation-rules-tags.mdSpecification
https://wicg.github.io/nav-speculation/speculation-rules.htmlSummary
This enables developers to add tag field to speculation rules. This optional field can be used to track the source of speculation rules, e.g. to treat them differently at an intermediary server. Any tags associated with a speculation will be sent with the Sec-Speculation-Tags header.
Blink component
Internals>PreloadSearch tags
speculationrules, prerendering, prefetchTAG review
https://github.com/w3ctag/design-reviews/issues/721 The TAG is generally dissatisfied with speculation rules, claiming that the syntax is too complicated. As such, we don't believe asking for review of this additional small field would be fruitful.TAG review status
Not applicableRisks
Interoperability and Compatibility
The entire speculative loading feature is a progressive enhancement, so in general risks are low in this area.
Gecko: No signal (https://github.com/mozilla/standards-positions/issues/1172) Mozilla is neutral on speculation rules syntax in general (https://github.com/mozilla/standards-positions/issues/620), although positive on prefetching. We opened a new request for this specific feature to ensure we captured any of their input.
WebKit: No signal (https://github.com/WebKit/standards-positions/issues/54) WebKit has not yet responded to our 2022 request for a position on speculation rules in general. We have updated the thread to point them to this latest addition anyway.
Web developers: Positive (https://github.com/WICG/nav-speculation/blob/main/speculation-rules-tags.md#stakeholder-feedback)
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Alex Russell
- why do we keep doing this these JSON-ish declarative forms without adding any sort of DOM? It's maddening.
LGTM1
On Tue, Apr 1, 2025 at 5:25 AM Domenic Denicola <dom...@chromium.org> wrote:
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Vladimir Levin
Chris Harrelson
LGTM2, with some disappointment on two fronts:
- why do we keep doing this these JSON-ish declarative forms without adding any sort of DOM? It's maddening.- we're backing into many things that effectively map to headers. Why not just add a "headers" sub-field to the structure and allow a full set, ala the Request() ctor?Both of those can happen as compatible additions, so not going to block here.Best,Alex
On Tuesday, April 1, 2025 at 12:51:45 AM UTC-7 Yoav Weiss wrote:
LGTM1
On Tue, Apr 1, 2025 at 5:25 AM Domenic Denicola <dom...@chromium.org> wrote:
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