Weekly hardening: v152/v153 coverage + v147 MDN-shape upgrades

[PaulKinlan]

Weekly hardening run (2026-09-06), one page per commit. Channels refreshed from the live API: stable=153, beta=154, dev=155. Six pages: four coverage (one MDN stub, three full references) and two v147 MDN-shape upgrades. All research dated 2026-09-06.

Coverage — new pages (4)

• f959b6d — v153/iterator-join (5095183554314240), Case A MDN stub. MDN's Iterator.prototype.join() page verified substantive, so gendn carries only the shipping metadata MDN doesn't track: V8 js_iterator_join in the shipped-flag tier at trunk, BCD rows (Chrome 153 / Firefox 154 / Safari preview, with per-engine bug evidence), test262 count, honest Baseline absence, four live showcase concept demos (all HEAD 200).
• ae43547 (+ schema fix 1aa265f) — v153/xml-parsing-in-rust-for-non-xslt-scenarios (5309598397497344), full reference for the libxml2→Rust parser swap. No web-exposed API, so the documented surface is the migration/behavior contract: verbatim Document::CreateParser selection algorithm, the four covered scenarios, error-reporting deltas, bisect recipe. Data-integrity finding disclosed on-page: the chromestatus record's intent_thread_url points at an unrelated thread (the Device Memory intent); the correct blink-dev thread is linked. The generator's misfired warn-block assertion (regex hit the diagnostic flag recipe; the feature ships enabled-by-default) was removed before the suite's first commit, with rationale in the commit message.
• fd31087 — v152/user-agent-image-replacement-api (5076374013476864), full reference + 2 child member routes. Surface traced verbatim from Chromium html_image_element.idl (replacedByUserAgent, onuareplacestart/onuareplaceend; event types confirmed in event_type_names.json5). Origin trial 152–157: warn-block carries the exact OT token + --enable-blink-features steps and the explicit negative that the Experimental Web Platform features flag does not enable it.
• f2feb96 — v152/suspicious-site-warnings (5427561449521152), full reference for a browser-UI feature with no author-facing API: verbatim Safe Browsing real-time-lookup trigger (fails open), desktop bubble / Android dialog flows, 30-day host-keyed bypass allowlist, chrome://flags entry (expiry M155), both enterprise policies quoted from canonical YAMLs. Stale chromestatus metadata disclosed on-page.

MDN-shape upgrades (2 of the ~156 old-shape backlog)

• 6d96bf1 — v147/update-device-memory-api-limits: Baseline banner (device-memory is Baseline-limited), verbatim IDL + Sec-CH-Device-Memory ABNF from the W3C WD, coarsening algorithm with Chrome trunk clamp constants, real per-version BCD table (4 keys), live showcase iframe (memory-inspector). Evidence-backed fixes: unlinked msg15601 citation resolved; Finch flag reframed as kill switch; lede corrected (floor rises on every platform).
• 2395971 — v147/css-update-decoupling-of-width-and-style-properties: Baseline banner, verbatim before/after propdefs from the merged EDs, computed/resolved/used-value model, per-browser WPT stable-run results, live showcase iframe (computed-value-inspector). Factual error fixed: the old page claimed getComputedStyle().borderWidth returns the authored width — per css-backgrounds-3 only outline-width/column-rule-width changed resolved values; border-width still reads 0px under border-style: none.

Both upgraded pages gained reference-contract.json (implementation-sufficient) + _questions.json; routes, identities, and immutable conformance suites preserved.

Gates (all green at the final head)

check-routes, validate-artifacts, test-reference-contract, check-conformance, deno fmt --check, deno check server.ts; per-page conformance 0 fail everywhere (blocked = the runner's manual-evidenced assertions, resolved by integrator screenshot/source review); mobile+desktop matrix run with screenshots read for all six routes (ok/ok recorded; coverage 56/200, up from 51). Showcase iframes HEAD-verified 200; in-sandbox visual render blocked by proxy TLS egress, disclosed per page (consistent with prior runs).

⚠ Overlap with open PRs #6/#7

Open, unmerged PRs #6 and #7 contain earlier versions of four of these pages (iterator-join in #7; suspicious-site-warnings, user-agent-image-replacement-api, and the css-decoupling upgrade in #6). Because main is the baseline for each weekly run, this branch re-covers them with fresher 2026-09-06 research — e.g. BCD now has Iterator.join rows (Chrome 153 / Firefox 154 / Safari preview) that predate-gap the #7 version, and the UA-image-replacement OT window is confirmed 152–157. Merging this PR makes those overlapping parts of #6/#7 redundant; merging #6/#7 first will conflict here.

Not done / next

v154 (22 features) and v155 (17) have no pages yet; v152 still misses 3 (sub-apps-for-iwas, unframed-display-mode-for-iwas, IAMF dev-trial dup of the v153 page) and v153 misses 4. ~154 pages remain in the old (pre-Baseline-banner) shape; the batch continues next run, tracked in goals.json.

🤖 Generated with Claude Code

https://claude.ai/code/session_011mT9PcQJACXLp8xDcpAe2g

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Generated by Claude Code

[Copilot]

🟡 Changes recommended

The v153 xml-parsing conformance suite has a ChromeStatus identity mismatch, and the committed conformance rollup artifacts appear to be from a single-suite run, degrading conformance verdict visibility site-wide.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

This PR is a weekly “hardening” batch that adds new Chrome 152/153 reference coverage (including an MDN stub) and upgrades two older v147 pages to the current MDN-shaped lifecycle (reference-contract + critique), along with refreshed responsive/conformance artifacts.

Changes:

• Added new v152/v153 feature coverage pages (mix of stub + full references) with lifecycle artifacts.
• Upgraded two v147 legacy pages to the new MDN-shaped structure and lifecycle sidecars.
• Updated responsive support tracking and refreshed conformance rollup outputs.

File summaries

File	Description
v153/xml-parsing-in-rust-for-non-xslt-scenarios/reference-contract.json	Adds implementation-sufficient contract inventory/mapping for the internal XML parser migration page.
v153/xml-parsing-in-rust-for-non-xslt-scenarios/conformance.json	Adds immutable conformance suite for the new v153 page (currently has an identity mismatch issue).
v153/xml-parsing-in-rust-for-non-xslt-scenarios/_questions.json	Adds critique + guidance consulted record for the new v153 page.
v153/iterator-join/index.html	Adds a v153 MDN stub page for Iterator.prototype.join with shipping metadata + links.
v153/iterator-join/conformance.json	Adds immutable conformance suite for the v153 stub page.
v153/iterator-join/_questions.json	Adds critique + guidance consulted record for the v153 stub page.
v152/user-agent-image-replacement-api/replacedbyuseragent/index.html	Adds/updates member page for replacedByUserAgent with detailed contract + examples (one example needs a null guard).
v152/user-agent-image-replacement-api/reference-contract.json	Adds implementation-sufficient contract inventory/mapping for UA Image Replacement API.
v152/user-agent-image-replacement-api/events/index.html	Adds/updates member page documenting uareplacestart/uareplaceend events.
v152/user-agent-image-replacement-api/conformance.json	Adds immutable conformance suite for the v152 feature page.
v152/user-agent-image-replacement-api/_questions.json	Adds critique + guidance consulted record for the v152 feature page.
v152/suspicious-site-warnings/reference-contract.json	Adds implementation-sufficient contract inventory/mapping for a browser-UI (non-web-API) feature.
v152/suspicious-site-warnings/conformance.json	Adds immutable conformance suite for the v152 feature page.
v152/suspicious-site-warnings/_questions.json	Adds critique + guidance consulted record for the v152 feature page.
v147/update-device-memory-api-limits/reference-contract.json	Adds implementation-sufficient contract inventory/mapping for the v147 MDN-shape upgrade.
v147/update-device-memory-api-limits/_questions.json	Adds critique + guidance consulted record for the v147 MDN-shape upgrade.
v147/css-update-decoupling-of-width-and-style-properties/reference-contract.json	Adds implementation-sufficient contract inventory/mapping for the v147 MDN-shape upgrade.
v147/css-update-decoupling-of-width-and-style-properties/_questions.json	Adds critique + guidance consulted record for the v147 MDN-shape upgrade.
responsive-support.json	Updates mobile/desktop support records for touched routes.
reports/conformance/results.json	Updates last conformance runner output (currently appears to be a single-suite run, not run-all).
reports/conformance/responsive.json	Updates responsive runner output.
reports/conformance/index.html	Updates the conformance rollup HTML (currently reflects only 1 suite).
goals.json	Rolls new follow-up goals from critiques into the aggregated backlog.

Review details

• Files reviewed: 28/28 changed files
• Comments generated: 3
• Review effort level: Lite

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[Copilot]

🔵 Needs a closer look

v153/xml-parsing-in-rust-for-non-xslt-scenarios/conformance.json advertises a live Chrome Platform Showcase demo contract despite the page documenting that the CPS route is 404, creating inconsistent lifecycle metadata.

Review details

Suppressed comments (1)

v153/xml-parsing-in-rust-for-non-xslt-scenarios/conformance.json:12

• This suite claims a Chrome Platform Showcase demo exists (demo URL + cpsFeature metadata), but the page itself states the CPS route is HEAD-checked 404 (index.html #examples). Keeping demo/cpsFeature non-null here makes the conformance metadata misleading and may cause downstream tooling to treat the page as having a live CPS contract.

• Files reviewed: 29/30 changed files
• Comments generated: 0 new
• Review effort level: Lite

[PaulKinlan]

Re the follow-up Copilot note on v153/xml-parsing-in-rust-for-non-xslt-scenarios/conformance.json (demo/cpsFeature non-null while the CPS route is 404): no change made, deliberately.

schema/conformance.schema.json defines cpsFeature as "when this page wraps/links a chrome-platform-showcase feature, the canonical CPS identity" — an identity reference, not a liveness claim. The page links the CPS feature route as the demo's future home (with the HEAD-checked 404 disclosed and date-stamped in #examples), so recording the canonical identity is what the field is for, and it matches the committed precedent on main: v153/scroll-axis-lock/conformance.json carries identical demo + cpsFeature metadata for the same not-yet-built CPS route. Liveness is what demo-embed-loads assertions claim, and this suite intentionally has none — downstream tooling that treats non-null cpsFeature as "live demo" would misread the schema (and already misreads scroll-axis-lock on main). Keeping the identity stable also serves the durable embedded-demo contract: when the showcase builds the demo, the identity is already correct and nothing needs repointing.

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