Restore pending user message during active replay

backend/api/server.py

@@ -354,6 +354,7 @@ class RunRecord:
     updated_at: float
     cancel_event: threading.Event
     process_registry: RunProcessRegistry
+    pending_prompt: str = ''
     current_stage: str = ''
     error: str = ''
     events: list[dict[str, Any]] = field(default_factory=list)
@@ -365,7 +366,7 @@ class RunManager:
         self._runs: dict[str, RunRecord] = {}
         self._latest_by_session: dict[tuple[str, str], str] = {}
 
-    def start(self, account_key: str, session_id: str) -> RunRecord:
+    def start(self, account_key: str, session_id: str, pending_prompt: str = '') -> RunRecord:
         now = time.time()
         record = RunRecord(
             run_id=uuid4().hex,
@@ -376,6 +377,7 @@ class RunManager:
             updated_at=now,
             cancel_event=threading.Event(),
             process_registry=RunProcessRegistry(),
+            pending_prompt=pending_prompt,
         )
         with self._lock:
             self._runs[record.run_id] = record
@@ -442,6 +444,7 @@ class RunManager:
                 'current_stage': record.current_stage,
                 'started_at': record.started_at,
                 'updated_at': record.updated_at,
+                'pending_prompt': record.pending_prompt,
                 'error': record.error,
                 'events': [dict(event) for event in record.events],
             }
@@ -1303,7 +1306,8 @@ def create_app(state: AgentState) -> FastAPI:
             request.resume_session_id or request.session_id
         ) or uuid4().hex
         account_key = state._account_key(request.account_id)
-        run_record = state.run_manager.start(account_key, requested_session_id)
+        prompt = request.prompt.strip()
+        run_record = state.run_manager.start(account_key, requested_session_id, prompt)
         run_lock = state.run_lock_for(request.account_id, requested_session_id)
         agent = state.agent_for(request.account_id, requested_session_id)
         config = state.config_for(request.account_id)
@@ -1326,7 +1330,7 @@ def create_app(state: AgentState) -> FastAPI:
                 directory=session_directory,
                 agent=agent,
                 session_id=requested_session_id,
-                prompt=request.prompt.strip(),
+                prompt=prompt,
             )
         if run_lock.locked():
             queued_event = {
@@ -1384,14 +1388,14 @@ def create_app(state: AgentState) -> FastAPI:
                             )
                         stored = _sanitize_stored_session_for_resume(stored)
                         result = agent.resume(
-                            request.prompt.strip(),
+                            prompt,
                             stored,
                             runtime_context=request.runtime_context,
                             event_sink=emit_agent_event,
                         )
                     else:
                         result = agent.run(
-                            request.prompt.strip(),
+                            prompt,
                             session_id=requested_session_id,
                             runtime_context=request.runtime_context,
                             event_sink=emit_agent_event,