[State Sync Redesign] Epic 1: Transport optimization

Optimize the background-to-UI state delivery transport: remove dead code, eliminate 200ms debounce, add frame-aligned batching. Introduces per-controller transport subscriptions as a new path alongside the existing memStore.subscribe(sendUpdate) (dual-write); Epic 2 later extends per-controller subscriptions to all consumers and removes memStore. No downstream migration (no selector, component, or test changes). Each issue is independently shippable.

Key Benefits

• UI latency 200ms to 17ms: microtask batching + requestAnimationFrame replaces background debounce
• Remove publicConfigStore, dead EventEmitter events; repurpose PatchStore as PatchBuffer (keyed-patch accumulator for microtask batching)
• Controller keys preserved in transport: enables Epics 2 and 3

ADR Option

A1 (transport optimization)

Phase

A1 (background cleanup)

Dependencies

None

Enables

• Epic 2 (background cleanup) — within A1
• Epic 3 (UI-controller subscriptions) — A2 phase, after A1 complete

Prior art

#29600 Phase 1 (controller-keyed hydration) is reusable.

Issues

• 1.1: Remove publicConfigStore — #40034
• 1.2: Delete dead EventEmitter events — #40035
• 1.3: Per-controller transport subscriptions (dual-write), remove debounce, add requestAnimationFrame batching, repurpose PatchStore as PatchBuffer — #40036
• 1.4: Send keyed initial state on START_UI_SYNC — #40037
• 1.5: Add port disconnect detection for UI contexts — #40177
• 1.6: UI reconnect logic after port disconnect — #40178

Validation criteria

• publicConfigStore removed, dapp connectivity unaffected (1.1)
• Latency improvement measurable in React DevTools profiler (1.3)
• E2E tests pass with requestAnimationFrame batching (1.3)
• Controller keys visible in transport (debug logging) (1.3)
• Keyed initial state available on startUISync (1.4)
• Port disconnect detected and surfaced to user (1.5)
• Long-lived UI contexts reconnect and rehydrate after service worker restart (1.6)

Start with the transport work described in subissue #40036 and the prior art in #29600; this epic does not name implementation files or tests. Confirm completion against the listed validation criteria: measurable latency improvement, passing E2E tests with requestAnimationFrame batching, and preserved controller keys in transport.