108 lines
9.6 KiB
Markdown
108 lines
9.6 KiB
Markdown
---
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tags:
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- work
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- cpm
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- summary
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updated: '2026-11-03'
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status: draft
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---
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# CPM stuck-messaging project: where we are, Nov/3
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Internal metrics, keep out of public PRs. Task: [CPM: root-cause the stuck embedded extension messaging](https://app.asana.com/1/137249556945/project/72649045549333/task/1216761517055116?focus=true). Details: [[cpm-post-release-analysis-2026-10-27]], [[cpm-status-2026-10-15]].
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Goal: permanent stuck reports below 1% of DAU (0.2-0.5% counts as success).
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## What the project has achieved
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Success criteria: permanent stuck reports below 1% of DAU (0.2-0.5% counts as success). Permanent = no response for 5 minutes, confirmed by a repeat or a reload.
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Progress against it (1.213 / 7.243 days 1-2 → 1.214 / 7.244 day 1):
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- iOS: 0.43% → 0.44% of DAU. Inside the target.
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- macOS: 2.87% → 1.89% of DAU (any failure 28.5% → 15.1%). Target not reached yet. Nov/9 fixes bring it to about 1.6%.
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Breakage measurement, built and corrected:
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- Production telemetry for the stuck extension: one episode report with failure groups, tab scope, repeat count, and rates against DAU. Before it we could not separate stuck from recovered failures or attribute a cause. [Improve telemetry](https://app.asana.com/1/137249556945/task/1219531810004069?focus=true), [TD: failure pixels attribution](https://app.asana.com/1/137249556945/task/1218619301158188?focus=true).
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- Error pages were reported as breakages on macOS. Fixed, so the macOS figure is now accurate: any failure 28.5% → 15.1%, permanent 2.87% → 1.89% of DAU. [Fix false-positive breakage reports for error pages](https://app.asana.com/1/137249556945/task/1220003778559452?focus=true).
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Breakage fixes shipped, with what each did:
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- Stable extension origin ([P3: stable baseURL fix](https://app.asana.com/1/137249556945/task/1219643764290826?focus=true), [Disable stable baseURL fix for OS<26.6](https://app.asana.com/1/137249556945/task/1220003778559448?focus=true), OS 26.6+): removes a 1.5 to 32 s startup blackout after an origin change. iOS 26.6+ startup-missing and no-view reports down over 90%.
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- macOS pinned tab lost on window close ([P5: pinned tab after windowDidClose](https://app.asana.com/1/137249556945/task/1219643712648486?focus=true)) and tab merging ([Fix Tab Merging causing CPM failure](https://app.asana.com/1/137249556945/task/1218356681060823?focus=true)): reproduced and fixed. P5 tests 9 pass with fix → 5 expected failures with it off → 27 pass.
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- Wake and startup recovery ([P1&P2[&P4]: Fix init loss on background unload](https://app.asana.com/1/137249556945/task/1219531810004072?focus=true)): applied to 2,026 iOS / 89 macOS episodes on Oct/26.
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- Network process restart ([Fix CPM breakage on network process crash](https://app.asana.com/1/137249556945/task/1219531810004073?focus=true)): applied 476 iOS / 277 macOS times on Oct/26.
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- Public Nov/9: [Restart extension context when error 6 leaves the background view alive](https://app.asana.com/1/137249556945/task/1219939142983214?focus=true) (up to 0.08% DAU iOS) and [Upgrade Web Extensions before loading](https://app.asana.com/1/137249556945/task/1220004977087625?focus=true) (macOS 0.26%, iOS 0.05% DAU).
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Causes proved by reproduction:
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- iOS error-6 loop: stale failed background ([WebExtensions breakage harness](https://app.asana.com/1/137249556945/task/1219531810004071?focus=true)). Fixed by the Nov/9 error 6 restart.
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- Origin change cleaning the cache before startup (fixed by P3).
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- macOS P6: a tab without a controller never answers. 0.42% of DAU, no fix yet.
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Hypotheses tested and rejected:
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- [Deallocation race fix](https://app.asana.com/1/137249556945/task/1217907325352233?focus=true), [A/B](https://app.asana.com/1/137249556945/task/1218356681060819?focus=true), [flag activation](https://app.asana.com/1/137249556945/task/1219036128743441?focus=true): flag never activated, data showed no relation.
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- Hung or crashed background process: under 1% of failures show it.
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- Lost message after wake: 0 lost in ~1,500 wakes in WebKit tests ([Reproduce the issue](https://app.asana.com/1/137249556945/task/1217907325352231?focus=true)).
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- [Reload/recover on the Stuck signal](https://app.asana.com/1/137249556945/task/1218744813699968?focus=true): 46% of macOS episodes still got no response after it. Late page reload: 0 fires in production.
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- Memory pressure, feature flag toggling, "failed load blocks forever": not reproduced.
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- Graveyard mitigation: not supported by the data.
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## Fixes going public next week (Nov/9)
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- [Upgrade Web Extensions before loading](https://app.asana.com/1/137249556945/task/1220004977087625?focus=true): load the new extension version first on launch, instead of an outdated one.
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- Expected: removes part of the "extension updated" group (macOS 0.26% DAU, iOS 0.05%). Launch upgrades only, so partial.
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- [Restart extension context when error 6 leaves the background view alive](https://app.asana.com/1/137249556945/task/1219939142983214?focus=true): restart the stuck background when the failed view is still retained.
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- Expected: up to 0.08% DAU on iOS, negligible on macOS. Partial, most error 6 reports only have it in history.
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- Together: macOS 1.89% to about 1.6%, iOS 0.44% to about 0.3-0.35%. Upper bounds, not measured.
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## Data now (% of DAU, 1.214 / 7.244, Nov/2)
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One day, early adopters, macOS has about 9k DAU. Treat as a rough picture.
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- Permanent stuck = no response for 5 minutes, confirmed by a repeat or a reload. Browser-wide = 2+ tabs, one-tab = single tab.
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- macOS: any failure 15.1%, permanent 1.89%. The earlier 28.5% / 2.87% on 1.213 included error pages, so the drop is the metric fix. Mature 1.213 is also at ~1.9%.
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- Browser-wide 1.22%, one-tab 0.68%.
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- Idle wake 0.68%, tab not connected (P6) 0.42%, other 0.30%, extension updated 0.26%, recent load 0.19%.
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- iOS: any failure 8.0%, permanent 0.44% (0.39% on 7.243 days 1-2).
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- Browser-wide 0.26%, one-tab 0.18%.
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- Recent load 0.18%, error 6 0.08%, idle wake 0.06%, extension updated 0.05%, other 0.04%.
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- iOS is already under the 1% target. macOS stays above it after the Nov/9 fixes.
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- Unaddressed on macOS: idle wake (35% of permanent) and P6 (22%). Nothing in flight for either.
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- Extension install and load errors are rare (thousandths of a percent), not worth the time.
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## Plan
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Cleanup, this week:
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- [Feature flags cleanup](https://app.asana.com/1/137249556945/task/1220159402040629?focus=true) (task is empty in Asana, content below). Registry tasks per flag:
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- Remove the fix and the flag, they did not work or never ran:
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- [cpmBackgroundGraveyardTreatment](https://app.asana.com/1/137249556945/task/1218860893478440?focus=true): graveyard mitigation, not supported by data.
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- [cpmLateBackgroundDocumentRecovery](https://app.asana.com/1/137249556945/task/1219588497257482?focus=true): late page reload, default off, 0 fires.
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- [cpmMessagingHangRecovery](https://app.asana.com/1/137249556945/task/1218855001659655?focus=true): reload on the stuck signal, 46% still no response; decide keep or remove.
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- [cpmBackgroundLoadRecovery](https://app.asana.com/1/137249556945/task/1219701603183698?focus=true): P1/P2 wake and retry, no measurable effect.
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- Remove the diagnostics flags together with the diagnostics layer:
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- [cpmDiagnosticsRecorder](https://app.asana.com/1/137249556945/task/1218785444896174?focus=true): recorder and unresponsive token.
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- [cpmBackgroundDelegateProxy](https://app.asana.com/1/137249556945/task/1218782530802146?focus=true): delegate proxy for diagnostics.
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- Keep the fix, remove the failsafe flag once its effect is measured:
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- [cpmNetworkProcessRecovery](https://app.asana.com/1/137249556945/task/1219701603183695?focus=true): network restart.
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- [cpmStableBaseURL](https://app.asana.com/1/137249556945/task/1219728649844711?focus=true): stable origin; flag state is not visible in pixels, check the remote config first.
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- [webExtensionSharedPinnedTabWindowClose](https://app.asana.com/1/137249556945/task/1219660990760563?focus=true): P5.
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- [webExtensionStateRestorationGate](https://app.asana.com/1/137249556945/task/1218931841045393?focus=true): session restoration race.
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- [cpmBackgroundLoadRestart](https://app.asana.com/1/137249556945/task/1219970564251181?focus=true): error 6 restart, after Nov/9 data.
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- [Pixel data cleanup](https://app.asana.com/1/137249556945/task/1220159402040630?focus=true) (task is empty in Asana, content below):
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- Remove the treatment pixels that only say "applied": background_wake, background_load_retry, install/upgrade readiness, late_document_reload, network_process_recovery_applied, startup_response_missing.
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- Remove the temporary episode parameters that only served the investigation (bg_events and the other debug fields), after the new metrics are live.
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Metrics, next two weeks:
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- Permanent small set: one episode report with a fixed format, rates against DAU, a sample of healthy navigations as baseline. Old and new formats published together for one release to keep the trend. Added to the health indicators dashboard. Task to create.
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- Extension lifecycle metrics to diagnose the wake problem: where the init message stops (page, background, native checks, dashboard update, answer back to the page), plus a background state check when a failure is reported. Needs a privacy review and extension and app releases, data in 1-2 release cycles. Task to create.
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- Data check of the Nov/9 fixes: [Analyze attribution data after stage 3](https://app.asana.com/1/137249556945/task/1220159402040627?focus=true).
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Decide later:
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- Mitigations that do not need the cause: retry the init from the page when no answer arrives, keep-warm A/B for the background.
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- P6 has no fix. The wake group will not be solved without the new metrics. If they show nothing actionable, close the project and reset the target.
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