[MWPW-199159] Lingo web performance: re-apply #6210 with iconography.css fix#6316
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Restores "perf: improve lingo performance — personalization, geo, lingo, XLG" (#6210), which was reverted in #6267 because it broke iconography.css rendering on stage. The icon regression is fixed in the following commit; every other optimization from #6210 is preserved unchanged. This is a clean revert-of-the-revert applied on top of current stage, so it also carries the intervening loadPostLCP/lenis change from #6274. Co-authored-by: Okan Sahin <39759830+mokimo@users.noreply.github.com>
The iconography.css/breakpoint-theme.css rel=preload hints added to preloadBlockResources() in #6210 caused icons to disappear on almost all stage pages, forcing the #6267 revert. Root cause: loadLink() dedupes by href alone, ignoring rel. iconography.css and breakpoint-theme.css are applied later via loadStyle() (hero-marquee, notification, editorial-card, aside). Once preloadBlockResources() inserted a <link rel="preload" as="style"> for those hrefs, the subsequent loadStyle() -> loadLink() call found an existing link by href and no-oped (callback('noop')) instead of creating the rel=stylesheet link — so the CSS downloaded but was never applied. Removing just these two preloads restores icon rendering while keeping every other optimization from #6210. Making the preload work would require rel-aware activation in the shared loadLink() (ecosystem-wide blast radius, fiddly onload/callback semantics) and only warms a small CSS fetch a few ms early — not worth the risk, so the micro-optimization is dropped.
#6210 added in-flight promise memoization to getEntitlementMap() but only cleared config.mep.entitlementMapFetch on the success path. When the XLG tags fetch failed (fetchData returns falsy), the handle stayed set to a resolved promise, so every later call returned the consumerEntitlements fallback and never retried for the rest of the page session — a behavior change from the pre-#6210 code, which re-fetched on each call. Clear the handle on the failure branch too so a transient failure can recover. Concurrent callers still share one in-flight fetch. Surfaced by devil's-advocate review of the #6210 resurrection.
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Reinstate the barrier that holds cross-site (Wave 2) query-index fetches
until the priority wave lands, made priority-aware:
- Wave 1 (primary + base) and any cross-site index flagged fetchPriority:"yes"
in lingo-site-mapping.json are fetched first, at default (auto) priority.
- The barrier awaits that whole priority wave.
- Remaining cross-site indexes fetch after, at { priority: 'low' }, so they
don't compete for bandwidth during the LCP window.
- lingo-site-mapping.json now fetches at default priority (was 'low') so the
flagged indexes are discovered promptly rather than gated behind a
low-priority map fetch.
…etchPriority test - getEntitlementMap: restore #6210's failure branch (drop the in-flight-handle reset). It only added retry-on-transient-failure, which is not a correctness fix and costs a repeated fetch on deterministic failures; falling back to consumerEntitlements for the page is acceptable graceful degradation. - utils.js: remove explanatory comments (keep the shared file lightweight). - utils.test.js: cover the new fetchPriority:"yes" branch — flagged cross-site index is fetched before the low-priority remainder and without { priority: 'low' }. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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Root-cause fix for the #6210 icon regression, replacing the earlier approach of deleting the preloads. #6210 preloaded iconography.css / breakpoint-theme.css (rel=preload, as=style) then applied them via loadStyle; loadLink deduped by href alone, so the preload link shadowed the loadStyle and the stylesheet was never created — CSS fetched, never applied, icons broke. Fix: a stylesheet request now dedups only against an existing stylesheet link, so a preload no longer shadows it. The block's loadStyle creates a fresh rel=stylesheet link (fires load reliably in every engine — no swap, no dependency on preload load semantics) that reuses the preloaded bytes via HTTP cache (the canonical preload -> stylesheet pattern). Non-stylesheet rel requests keep href-only dedup unchanged. Okan's two preloads restored. Reviewed by a devil's advocate (GO, strictly safer than swap-based alternatives which carried a cross-engine hang risk). Cross-repo audit: no adobecom consumer preloads a CSS URL then loadStyles it. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Closes the two coverage gaps a devil's-advocate PR review flagged (both were correct-by-reading but had zero guarding tests): - geo.test.js (new): getAkamaiCode success + sessionStorage cache, concurrent-caller dedup (single in-flight fetch), post-failure re-fetch (in-flight handle cleared in finally, no poisoning), non-ok rejection, and the 5s AbortController timeout -> reject. - personalization.test.js: categorizeActions last-write-wins for config.mep.replacepage / updateframework under the same Promise.all(experiments.map(...)) shape applyPers uses, plus the default-variant early return. Pins the parallelization ordering contract. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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Looks good to me, found just one NIT.
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| const selector = rel === 'stylesheet' | ||
| ? `link[href="${href}"][rel="stylesheet"]` | ||
| : `link[href="${href}"]`; |
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NIT:
Suggested change
| const selector = rel === 'stylesheet' | |
| ? `link[href="${href}"][rel="stylesheet"]` | |
| : `link[href="${href}"]`; | |
| const selector = `link[href="${href}"]${rel === 'stylesheet' ? '[rel="stylesheet"]' : ''}`; |
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Reminder to set the |
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Verified. Ready for Stage.
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July 22, 2026 20:01 — with 
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Re-applies the reverted Lingo web-performance PR #6210, with the iconography regression that caused the revert fixed at the root cause.
Background
#6210 (perf: improve lingo performance — personalization, geo, lingo, XLG) was merged to
stageand reverted ~3h later by #6267 becauseiconography.cssstopped being applied — icons broke on almost all stage pages (milo-dev thread). This PR restores #6210 and fixes that regression properly.Root cause of the icon regression
loadLink()(libs/utils/utils.js) deduped existing links byhrefalone, ignoringrel. #6210 addedrel=preload, as=stylehints foriconography.cssandbreakpoint-theme.cssinpreloadBlockResources()(formarquee/hero-marquee). Those stylesheets are applied later vialoadStyle()(hero-marquee, notification, editorial-card, aside). Because a<link>with that href already existed (the preload), the laterloadStyle()→loadLink()found it and no-oped instead of creating the applyingrel=stylesheetlink — so the CSS downloaded but was never applied.Changes
more details
stage. All personalization / geo / lingo / XLG optimizations preserved unchanged.loadLink()rel-aware. Arel=stylesheetrequest now dedups only against an existing stylesheet link, so a preload no longer shadows theloadStyle(). The block'sloadStyle()creates a fresh<link rel=stylesheet>(firesloadreliably in every engine — no rel-swap, no dependency on preloadloadsemantics) that reuses the preloaded bytes via HTTP cache — the canonicalpreload → stylesheetpattern (MDN). Non-stylesheetrelrequests keep href-only dedup, unchanged. This keeps Okan's non-render-blocking early fetch and applies the CSS — rather than discarding the optimization.fetchPriorityinlingo-site-mapping.json(today onlyupp) are fetched first; the remaining cross-site indexes wait behind a barrier and then fetch at{ priority: 'low' }so they don't compete during the LCP window.lingo-site-mapping.jsonitself fetches at default priority so the flagged indexes are discovered promptly.Design note (why the root-cause fix, not a rel-swap)
more details
An alternative — swap the preload link's
reltostylesheeton load — was designed and rejected after a devil's-advocate review: it depends onrel=preload as=stylefiringloadin every engine (unverified on Safari/WebKit; our suite is Chromium-only), and if it doesn't, the awaitedloadStylecallback can never fire → block decoration hangs (worse than the bug). The rel-aware-dedup fix has no such dependency: worst case is a benign double-fetch (perf, not correctness); icons always apply. Cross-repo audit: no adobecom consumer preloads a CSS URL thenloadStyles it, so the shared-fn change is behavior-preserving for every non-broken caller.Verification
test/**run green (3702 passed at last full run; the sole failure is a pre-existing floating-promise flake —fetchAndProcessPlainHtml with MEP,utilities.test.js:42, asserts inside a non-awaited.then(), proven non-deterministic by isolation and outside the CSS/loadLinkpath). New/added coverage for every risk-bearing change: theloadLinkpreload-dedup fix (aloadStylefor a preloaded href creates a distinct applying stylesheet, not shadowed), thefetchPriority: "yes"query-index branch,geo.jsgetAkamaiCode(concurrent-caller dedup, post-failure re-fetch, 5s abort→reject), andcategorizeActionslast-write-wins ordering underPromise.all. Lint clean./creativecloud,?milolibs=mainvs?milolibs=MWPW-199159, confirmed on this build: the branch showsiconography.cssandbreakpoint-theme.csseach as two links — arel=preload as=style(not applied) plus an appliedrel=stylesheet(link.sheetnon-null) — the canonical preload→stylesheet pair; main has the single applied stylesheet. 0 unstyled icons on both (9 visible icons each). Confirms the preload optimization is preserved and the CSS applies.Resolves: MWPW-199159
Test URLs:
Icon / perf comparison (consumer page):