feat(interviews): auto-trigger lifecycle hooks + bridge SimulationRunner→Manager on COMPLETED

- Add backend/app/services/interviews/lifecycle.py with install_hooks() that
  registers on_ready (pre-survey) and on_completed (post-survey + synthesis)
  daemon-thread callbacks on a SimulationManager.
- Add SimulationRunner.register_on_completed() / _fire_on_completed() so
  external callbacks can be notified when _monitor_simulation transitions to
  COMPLETED (both exit-code-0 path and simulation_end event path).
- Wire both in app/__init__.py: create singleton SimulationManager, install
  lifecycle hooks, and register its _notify_on_completed with SimulationRunner.
- Add test_lifecycle.py: verifies install_hooks registers one callable for each
  of ready and completed.
- All 40 unit tests + 2 integration tests pass.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend/app/__init__.py

@@ -47,6 +47,19 @@ def create_app(config_class=Config):
     SimulationRunner.register_cleanup()
     if should_log_startup:
         logger.info("已注册模拟进程清理函数")
+
+    # Install interview lifecycle hooks on a singleton SimulationManager.
+    # The singleton's _notify_on_completed is also wired into SimulationRunner
+    # so that the runner's monitor thread fires the completed hooks when a
+    # simulation process exits successfully.
+    from .services.simulation_manager import SimulationManager
+    from .services.interviews.lifecycle import install_hooks
+
+    _simulation_manager_singleton = SimulationManager()
+    install_hooks(_simulation_manager_singleton)
+    SimulationRunner.register_on_completed(_simulation_manager_singleton._notify_on_completed)
+    if should_log_startup:
+        logger.info("已安装面试生命周期钩子")
     
     # 请求日志中间件
     @app.before_request

backend/app/services/interviews/lifecycle.py

@@ -0,0 +1,72 @@
+"""
+Interview lifecycle hook installer (Task 20).
+
+install_hooks(manager) registers two callbacks on a SimulationManager:
+  - on_ready  → spawn T0 longitudinal pre-survey in a background thread
+  - on_completed → spawn full post-sim batch + synthesis in a background thread
+
+Both hooks are best-effort: failures are logged but never propagate to the
+calling thread.
+"""
+
+from __future__ import annotations
+
+import threading
+
+from app.utils.logger import get_logger
+
+logger = get_logger(__name__)
+
+
+def install_hooks(manager) -> None:
+    """Attach interview lifecycle callbacks to a SimulationManager.
+
+    on_ready  → spawn T0 longitudinal in a background thread
+    on_completed → spawn full post-sim batch in a background thread
+    Hooks are best-effort; failures only log.
+    """
+
+    def _on_ready(state) -> None:
+        sim_id = (
+            getattr(state, "simulation_id", None)
+            or getattr(state, "sim_id", None)
+            or getattr(state, "id", None)
+        )
+        if not sim_id:
+            return
+        threading.Thread(target=_run_pre, args=(sim_id,), daemon=True).start()
+
+    def _on_completed(state) -> None:
+        sim_id = (
+            getattr(state, "simulation_id", None)
+            or getattr(state, "sim_id", None)
+            or getattr(state, "id", None)
+        )
+        if not sim_id:
+            return
+        threading.Thread(target=_run_post, args=(sim_id,), daemon=True).start()
+
+    manager.register_on_ready(_on_ready)
+    manager.register_on_completed(_on_completed)
+
+
+def _run_pre(sim_id: str) -> None:
+    try:
+        from app.api.interview import _build_orchestrator
+
+        orch = _build_orchestrator(sim_id)
+        orch.run_pre()
+    except Exception as e:
+        logger.warning(f"auto pre-survey failed for {sim_id}: {e!r}")
+
+
+def _run_post(sim_id: str) -> None:
+    try:
+        from app.api.interview import _build_orchestrator
+        from app.services.interview_synthesizer import InterviewSynthesizer
+
+        orch = _build_orchestrator(sim_id)
+        orch.run_post()
+        InterviewSynthesizer(store=orch.store).run()
+    except Exception as e:
+        logger.warning(f"auto post-survey failed for {sim_id}: {e!r}")

backend/app/services/simulation_runner.py

@@ -226,7 +226,29 @@ class SimulationRunner:
     
     # 图谱记忆更新配置
     _graph_memory_enabled: Dict[str, bool] = {}  # simulation_id -> enabled
-    
+
+    # Completion callbacks registered from outside (e.g. SimulationManager lifecycle hooks).
+    # Each callable receives the SimulationRunState that just transitioned to COMPLETED.
+    _on_completed_callbacks: list = []
+
+    @classmethod
+    def register_on_completed(cls, fn) -> None:
+        """Register a callback invoked when a simulation transitions to COMPLETED.
+
+        The callback receives the SimulationRunState instance.  It is called from
+        the monitor daemon thread, so keep it short or hand off to another thread.
+        """
+        cls._on_completed_callbacks.append(fn)
+
+    @classmethod
+    def _fire_on_completed(cls, state: SimulationRunState) -> None:
+        """Invoke all registered on_completed callbacks; exceptions are isolated."""
+        for fn in list(cls._on_completed_callbacks):
+            try:
+                fn(state)
+            except Exception as e:
+                logger.warning(f"on_completed callback failed: {e!r}")
+
     @classmethod
     def get_run_state(cls, simulation_id: str) -> Optional[SimulationRunState]:
         """获取运行状态"""
@@ -528,6 +550,7 @@ class SimulationRunner:
                 state.runner_status = RunnerStatus.COMPLETED
                 state.completed_at = datetime.now().isoformat()
                 logger.info(f"模拟完成: {simulation_id}")
+                cls._fire_on_completed(state)
             else:
                 state.runner_status = RunnerStatus.FAILED
                 # 从主日志文件读取错误信息
@@ -638,6 +661,7 @@ class SimulationRunner:
                                         state.runner_status = RunnerStatus.COMPLETED
                                         state.completed_at = datetime.now().isoformat()
                                         logger.info(f"所有平台模拟已完成: {state.simulation_id}")
+                                        cls._fire_on_completed(state)
                                 
                                 # 更新轮次信息（从 round_end 事件）
                                 elif event_type == "round_end":

backend/tests/interviews/test_lifecycle.py

@@ -0,0 +1,26 @@
+"""
+Tests for interview lifecycle hook installer (Task 20).
+"""
+
+from app.services.interviews.lifecycle import install_hooks
+
+
+class _StubMgr:
+    def __init__(self):
+        self.ready = []
+        self.completed = []
+
+    def register_on_ready(self, fn):
+        self.ready.append(fn)
+
+    def register_on_completed(self, fn):
+        self.completed.append(fn)
+
+
+def test_install_hooks_registers_two_callables():
+    mgr = _StubMgr()
+    install_hooks(mgr)
+    assert len(mgr.ready) == 1
+    assert len(mgr.completed) == 1
+    assert callable(mgr.ready[0])
+    assert callable(mgr.completed[0])