docs: mark Phase 6 complete in phase6-scheduler-integration-plan

src/docs/apiserver-backend-tasks.md

@@ -105,10 +105,12 @@
 
 ## P1-3: Heartbeat Keep-Alive
 
-- [ ] **#13 P1-3: Heartbeat keep-alive implementation**
-  - `backend/clib.go` — Add `heartbeatIntervalSecs int32` (default 30), `SetHeartbeatInterval()`, `heartbeatFn` var, `StartHeartbeat(ctx context.Context)`
-  - `backend/handler.go` — `OnClusterUpdated` calls `SetHeartbeatInterval(cluster.HeartbeatInterval)` after store update
-  - `cmd/main.go` — Call `backend.StartHeartbeat(ctx)` after `backend.RegisterToBackend(...)`
+- [x] **#13 P1-3: Heartbeat keep-alive implementation**
+  - `backend/clib.go` — Added `heartbeatIntervalSecs int32` (default 30), `SetHeartbeatInterval()`, `heartbeatFn` var, `StartHeartbeat(ctx context.Context)` goroutine with ticker
+  - `backend/handler.go` — `OnClusterUpdated` calls `SetHeartbeatInterval(cluster.HeartbeatInterval)` after store update (zero-preserve: skips if interval==0)
+  - `cmd/main.go` — Calls `backend.StartHeartbeat(ctx)` after `backend.RegisterToBackend(...)`
+  - `backend/handler_test.go` — Tests for heartbeat interval update, zero-preserve, timer leak, test drain, store consistency
+  - Commits: `ffc5b20` (goroutine), `0a3de8b` (leak/drain/consistency fixes)
 
 ---
 
@@ -119,4 +121,11 @@
   - `ninja -C build` for C components passes — required meson reconfigure + CGO val_helpers.h fix
   - RBAC verification — `host:control` (cluster_admin) and `host:view` (all authenticated) confirmed in routes + rbac.yaml
   - Input safety — comment limit 512 chars; select expression limit 4094 chars (1024 reduction deferred to P1-2b)
-  - **CGO fix applied:** extracted `static` val helpers from `clib.go` preamble into `val_helpers.h` shared header; `convert.go` now includes it; added explicit `float64()` cast for `C.double` return
+  - **CGO fix applied:** extracted `static` val helpers from `clib.go` preamble into `val_helpers.h` shared header; `convert.go` now includes it; added explicit `float64()` cast for `C.double` return
+
+- [x] **#15 Integration test suite** — see [`apiserver-backend-integration-test-plan.md`](apiserver-backend-integration-test-plan.md)
+  - `backend/integration_test.go` — §1 (config push), §3 (resource values), §4 (heartbeat), §5 (cross-feature): 17 tests
+  - `controllers/integration_test.go` — §2 (host control), §6 (RBAC), §8 (input safety): 17 tests + 1 skip (§8.1 pending P1-2b)
+  - `store/concurrency_test.go` — §7 (thread safety): 3 concurrent-access tests
+  - All use `//go:build !cgo`; run with `CGO_ENABLED=0 go test ./backend/... ./controllers/... ./store/...`
+  - Commit: `86a65d6`