fix(agent-office): node_monitor 루프 예외 방어 + 테스트 보강 (B2 리뷰)

- per-worker 루프 전체를 try/except로 감싸 Redis 예외 시 redis_ok=False+break (Blocker)
- heartbeat 파싱 except에 UnicodeDecodeError 추가 (Important)
- hb.get('ts') or '' 로 null ts 안전 처리 (Minor)
- 테스트 3개 추가: paused 폴백·processing 집계·llen 예외 회귀

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019LV86jBozkNhSFXJA412fq

agent-office/app/node_monitor.py

@@ -55,6 +55,7 @@ async def collect_status(redis=None) -> dict:
         return out
 
     for w in WORKER_REGISTRY:
+        try:
             info = {"name": w["name"], "kind": w["kind"], "alive": False, "state": None,
                     "last_beat_age_s": None, "queue_depth": 0, "dead_letter": 0,
                     "processing": 0, "jobs_done": 0, "jobs_failed": 0, "last_job_at": None}
@@ -65,10 +66,10 @@ async def collect_status(redis=None) -> dict:
                     info.update(alive=True, state=hb.get("state"),
                                 jobs_done=hb.get("jobs_done", 0), jobs_failed=hb.get("jobs_failed", 0),
                                 last_job_at=hb.get("last_job_at"),
-                            last_beat_age_s=_beat_age(hb.get("ts", ""), now))
+                                last_beat_age_s=_beat_age(hb.get("ts") or "", now))
                     if w["kind"] == "watcher" and hb.get("mode"):
                         out["paused_reason"] = hb["mode"]
-            except json.JSONDecodeError:
+                except (json.JSONDecodeError, UnicodeDecodeError):
                     logger.warning("heartbeat JSON 파싱 실패 name=%s", w["name"])
             if w["queue"]:
                 info["queue_depth"] = await r.llen(w["queue"])
@@ -78,6 +79,10 @@ async def collect_status(redis=None) -> dict:
                     proc += await r.llen(key)
                 info["processing"] = proc
             out["workers"].append(info)
+        except Exception:
+            logger.exception("워커 상태 수집 실패 name=%s", w["name"])
+            out["redis_ok"] = False
+            break
 
     for w in out["workers"]:
         if w["kind"] == "trader":

agent-office/tests/test_node_monitor.py

@@ -62,3 +62,37 @@ async def test_trader_http_pull_link():
     st = await node_monitor.collect_status(redis=r)
     link = next(l for l in st["links"] if l["from"] == "ai_trade")
     assert link["type"] == "http-pull" and link["status"] == "healthy"
+
+@pytest.mark.asyncio
+async def test_paused_no_watcher_heartbeat_fallback_reason():
+    """paused=True인데 watcher heartbeat 없으면 paused_reason == 'trading' 폴백."""
+    r = FakeRedis(kv={"queue:paused": b"1"})  # watcher heartbeat 없음
+    st = await node_monitor.collect_status(redis=r)
+    assert st["paused"] is True
+    assert st["paused_reason"] == "trading"
+
+@pytest.mark.asyncio
+async def test_processing_count_image_render():
+    """processing:<queue>:<worker_id> 리스트가 있으면 processing 필드에 합산된다."""
+    worker_id = "abc123"
+    proc_key = f"processing:queue:image-render:{worker_id}"
+    r = FakeRedis(
+        kv={"worker:image-render:heartbeat": _hb("image-render", "render", "busy")},
+        lists={proc_key: 3},
+    )
+    st = await node_monitor.collect_status(redis=r)
+    img = next(w for w in st["workers"] if w["name"] == "image-render")
+    assert img["processing"] == 3
+
+@pytest.mark.asyncio
+async def test_llen_exception_returns_redis_ok_false():
+    """워커 루프 중 llen 예외 발생 시 예외를 전파하지 않고 redis_ok=False 반환 (Blocker 회귀)."""
+    class BrokenLlenRedis(FakeRedis):
+        async def llen(self, key):
+            raise ConnectionError("Redis 연결 끊김")
+
+    r = BrokenLlenRedis(
+        kv={"worker:music-render:heartbeat": _hb("music-render", "render", "idle")}
+    )
+    st = await node_monitor.collect_status(redis=r)
+    assert st["redis_ok"] is False