Android home screen widget (revival of PR #7124)

Implements #3818. Based on ilvez's POC (PR #7124, closed) plus the 2026-06-08 review punch-list. Re-implemented on current master (the PR's April base has drifted heavily).

Architecture (unchanged from POC — confirmed sound)

• Snapshot bridge: Angular pushes a compact JSON snapshot of today's tasks into the existing native KeyValStore (SQLite) under key widget_data. The native RemoteViewsFactory reads it. No new storage mechanism.
• Done actions: SharedPreferences-backed WidgetDoneQueue (mirrors WidgetTaskQueue / ReminderDoneQueue patterns), drained by Angular.

Improvements over the POC (mapped to the punch-list)

1. Title tap opens app (bug fix). A collection has one setPendingIntentTemplate; the POC's second fill-in intent silently fell into the done-template. Fix: one broadcast template, fill-ins carry either EXTRA_TASK_ID (→ done) or EXTRA_OPEN_APP (→ startActivity), branch in onReceive.
2. Manifest hardening. Custom actions removed from the exported receiver's intent-filter (explicit-component PendingIntents don't need filter entries; listing them let any app mark tasks done / launch us). Only APPWIDGET_UPDATE remains.
3. Queue-only done path. Widget tap → enqueue + widget refresh + contentless "drain now" LocalBroadcast. Angular always reads via getWidgetDoneQueue() (get-and-clear). Single delivery path; no double setDone(); retires the '$sanitizedId' string-interpolated JS call.
4. Single-writer blob (replaces the proposed ts-guard). Native never writes widget_data. For instant checkbox feedback while the app is dead, the factory overlays isDone=true for IDs currently in WidgetDoneQueue at render time (peek(), non-clearing). The Angular-vs-native write race disappears structurally; markDoneInWidgetData is deleted.
5. Memoized snapshot selector. selectAndroidWidgetData projects todayIds + task entities + project colors into the exact blob shape. Project color changes now propagate (POC pulled colors in but excluded them from the distinct key). Dedupe happens in WidgetDataService via a last-pushed-JSON cache, so all trigger paths share it.
6. Post-sync freshness push (new — gap found in review). The hydration-guard filter drops all emissions during remote-op apply and nothing re-emits after, so the widget would miss synced changes until the next local edit. Added push on the isSyncInProgress$ falling edge. (Push-on-pause kept as belt-and-braces.)
7. Typed contract. AndroidWidgetData interface (TS) + WidgetData.kt parser as the two named ends of the v:1 contract, locked by a golden-shape unit test on the serializer and a JVM parse test on the Kotlin side. (typia writer-side assert was considered and skipped: the object is constructed from typed state, so an assert is tautological, and a throw would leave the widget stale — worse than pushing.)
8. Drain hygiene. Dedupe IDs, skip missing/already-done tasks (no duplicate ops, no op-log noise from stale queue entries), gate on initial data load. One aggregated translated snack (T/en.json) instead of one hardcoded snack per task.
9. KeyValStore per-call db.close() removal (correct SQLiteOpenHelper pattern, avoids churn from widget reads) — redone against the current chunked-read code. All access is @Synchronized on the App-level singleton, so widget-vs-bridge concurrency stays serialized. Backup-ring round trip must be manually verified on device (no Robolectric in the project).
10. Kotlin JSON parsing extracted to WidgetData.kt (single parse site, JVM-testable via org.json:json test dep). optString("projectId", null) JSON-NULL→"null" footgun avoided via isNull() checks; Angular omits projectId when absent.

Known limitations (deliberate, documented)

• Widget reflects the app's last known state; cross-client freshness while the app is dead is phase 2 (WorkManager + SuperSync).
• Day rollover while the app process is dead shows yesterday's list until next open (native can't recompute "today"; selector handles rollover whenever JS is alive).
• Hardcoded dark styling; Jetpack Glance / Material You is a follow-up view-layer swap.
• Widget chrome strings are native strings.xml (English) — accepted for v1.
• No task creation / undo from widget.

Files

Native: widget/{TaskListWidgetProvider,TaskListWidgetService,WidgetData,WidgetDoneQueue}.kt, CapacitorMainActivity.kt (drain receiver), webview/JavaScriptInterface.kt (getWidgetDoneQueue, updateWidget), app/KeyValStore.kt, manifest, layouts, xml/appwidget_info.xml, values/strings.xml, build.gradle (test dep), test/.../widget/WidgetDataTest.kt.

Angular: features/android/android-widget.model.ts, features/android/store/android-widget.selectors.ts (+spec), features/android/widget-data.service.ts (+spec), features/android/store/android-widget.effects.ts (+spec), android-interface.ts, root-store/feature-stores.module.ts, en.json (+npm run int).