v144 · capabilities (fugu)

Web App Manifest: specify update eligibility, icon urls are Cache-Control: immutable

Specify an update eligibility algorithm in the manifest spec. This makes the update process more deterministic and predictable, giving the dev more control over whether (and when) updates should apply to existing installations, and allowing removal of the 'update check throttle' that user agents currently need to implement to avoid wasting network resources.

concepts

  1. Manifest Update Rules

    Manifests can opt icons into immutable caching — Chrome treats the icon URL as content-addressed and skips the eligibility check on update. Speeds up update detection on slow networks.

  2. Cache-Control Decision

    Paste any icon URL; the page fetches HEAD and shows whether Chrome 144 would treat it as immutable for PWA updates.

  3. Eligibility Simulator

    Paste old and new manifests — the simulator runs the v144 eligibility algorithm field by field and predicts whether Chrome will refetch, update, or skip.

  4. Icon Hash Strategy

    Enter an icon filename and see the content-addressed URL pattern with Cache-Control: immutable — and how a hash change forces a re-fetch. Generates the manifest JSON fragment and HTTP headers needed.

why it shipped

- Consistency: Provide a consistent way to detect when a manifest update should happen. - Preventing unnecessary user interruption: Users should not see an update dialog more than necessary to confirm security-sensitive changes. - User agent flexibility: It should be possible for users agents to use their judgement to block updates for known bad sites, allow known trusted apps to update without UX, or allow tiny visual changes to icons without requiring UX. - Developer control: Developers should have more control over when the update dialog may show to users. - Reduce network traffic: Unnecess

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