fix(agent): add model request timeouts and empty-response fallback

docs/plans/state.json

@@ -1,6 +1,6 @@
 {
   "version": "1.0",
-  "updated_at": "2026-02-17",
+  "updated_at": "2026-02-18",
   "description": "Tracks the status of all Flynn plans and implementation phases",
   "plans": {
     "makefile-skills-convenience-targets": {
@@ -5076,10 +5076,22 @@
         "docs/plans/state.json"
       ],
       "test_status": "pnpm test:run src/session/manager.test.ts src/gateway/handlers/handlers.test.ts + pnpm typecheck passing"
+    },
+    "native-agent-model-timeout-hardening": {
+      "status": "completed",
+      "date": "2026-02-18",
+      "updated": "2026-02-18",
+      "summary": "Added hard per-request model timeouts in `NativeAgent` (`modelTimeoutMs`, default 120000ms) to fail fast when providers hang, covering both single-turn and tool-loop model calls. Also added empty-final-response normalization to avoid silent blank replies and added regression tests for timeout and empty-response cases.",
+      "files_modified": [
+        "src/backends/native/agent.ts",
+        "src/backends/native/agent.test.ts",
+        "docs/plans/state.json"
+      ],
+      "test_status": "pnpm test:run src/backends/native/agent.test.ts passing"
     }
   },
   "overall_progress": {
-    "total_test_count": 1887,
+    "total_test_count": 1889,
     "all_tests_passing": true,
     "p0_completion": "3/3 (100%)",
     "p1_completion": "4/4 (100%)",