pwa-offline-sync

version	1.0.0
name	pwa-offline-sync
description	Design Cache Storage + IndexedDB strategy and sync queue per ADR-005. Activate for service worker, cache, or offline bug investigation.
category	workflow
allowed-tools	Read Write Edit Grep Glob
license	MIT

Skill: pwa-offline-sync

Purpose: design, implement, and validate offline/PWA behavior (service worker, caches, IndexedDB, sync queue) per ADR-005.

When to run

• Editing service worker, cache strategies, or sync orchestration.
• Touching IndexedDB schema, permission caching, or zombie detection.
• Investigating offline bugs or data conflicts.

Inputs

• plans/005-adr-offline-sync.md
• plans/007-implementation-phases.md (Phase 3)
• docs/offline.md (when available)

Workflow

1. Assess entity rules – confirm table of offline-first entities + conflict strategy.
2. Plan caches – map shell/static/EPUB/cover assets to Cache Storage policies (cache-first vs stale-while-revalidate vs network-first).
3. IndexedDB schema – define stores for progress, annotations, sync queue, permission cache; version migrations carefully.
4. Service worker – implement install/activate/fetch with trace logging, offline fallback page, and error handling.
5. Sync manager – queue writes locally, dedupe via mutation IDs, replay when online, implement exponential backoff + zombie detection.
6. Testing – simulate offline/online in Playwright; unit-test queue reducers; verify revoked grants are blocked after reconnect.

Checklist

• Cache + DB version numbers bumped intentionally (no silent clears).
• Accept-Language, X-Trace-Id, and capability headers sent even when offline data queued.
• Zombie detection notifies user + stops further reads upon revocation.
• Service worker cleans up old caches.
• Memory-safe listeners (remove event handlers on self when replaced).