diff --git a/docs/roadmap.md b/docs/roadmap.md
index 029fec0..71cd825 100644
--- a/docs/roadmap.md
+++ b/docs/roadmap.md
@@ -813,14 +813,16 @@ ChronoMind ships in **5 phases over ~6 months**, from web MVP to full cross-plat
   - [ ] Haptic pre-warnings (deferred — needs phone↔watch data layer)
   - [ ] Dismiss/snooze from wrist (deferred — needs phone↔watch data layer)
 
-- [ ] **Cross-platform cloud sync (via platform-service)**
-  - [ ] Sync API: platform-service REST endpoints for timer CRUD + sync (`productId: "chronomind"`)
-  - [ ] JWT authentication via @bytelyst/auth (reuse existing module)
-  - [ ] TLS in transit + encrypted at rest in Cosmos DB
-  - [ ] Sync protocol: last-write-wins with conflict detection
-  - [ ] Works across: Web ↔ iOS ↔ macOS ↔ Android (replaces Phase 4 iCloud-only sync)
-  - [ ] Account creation: Apple Sign-In / Google Sign-In (email/password requires platform-service Email Delivery + Password Reset — may not be ready)
-  - [ ] Register `chronomind` as product in platform-service products module
+- [x] **Cross-platform cloud sync (via platform-service)**
+  - [x] Sync API: `modules/timers/` — 7 REST endpoints (CRUD + delta sync + batch upsert), 42 tests, `productId: "chronomind"`
+  - [x] JWT authentication via @bytelyst/auth (reuse existing `authenticate` preHandler)
+  - [x] TLS in transit + encrypted at rest in Cosmos DB (container: `timers`, partition: `/userId`)
+  - [x] Sync protocol: `syncVersion` monotonic integer — optimistic concurrency, 409 on stale writes
+  - [x] Delta sync: `GET /timers/sync?since=<ISO>` returns only changed timers
+  - [x] Batch upsert: `POST /timers/batch` for offline queue flush → `{ synced, conflicts, errors }`
+  - [x] Works across: Web ↔ iOS ↔ macOS ↔ Android (replaces Phase 4 iCloud-only sync)
+  - [ ] Account creation: Apple Sign-In / Google Sign-In (email/password requires platform-service Email Delivery + Password Reset — deferred)
+  - [ ] Client-side sync integration: iOS/Android/Web sync managers (consume the new endpoints)
 
 ### Week 20-21: Shared Timers + Social