diff --git a/backend/apps/agents/manager/session/SessionPersistence.py b/backend/apps/agents/manager/session/SessionPersistence.py
index f21ca50d..ad6f7373 100644
--- a/backend/apps/agents/manager/session/SessionPersistence.py
+++ b/backend/apps/agents/manager/session/SessionPersistence.py
@@ -10,7 +10,7 @@ from typing import Optional
 
 from typeguard import typechecked
 
-from backend.apps.agents.core.models import AgentSession
+from backend.apps.agents.core.models import AgentSession, Message
 from backend.apps.agents.core.ws_manager import ws_manager
 from backend.apps.agents.manager.session.session_store import (
     load_all_session_data,
@@ -49,6 +49,12 @@ def running_under_test() -> bool:
 from backend.apps.agents.manager.AgentManagerProtocol import AgentManagerProtocol
 
 
+SHUTDOWN_STOP_NOTE = (
+    "This chat was still running when OpenSwarm's engine shut down, so it stopped here; that was not "
+    "your Stop. Send a message to continue from where it left off."
+)
+
+
 class SessionPersistence(AgentManagerProtocol):
     @typechecked
     async def reconcile_on_startup(self) -> None:
@@ -134,6 +140,10 @@ class SessionPersistence(AgentManagerProtocol):
         for session_id, session in list(self.sessions.items()):
             if session.status in ("running", "waiting_approval"):
                 session.status = "stopped"
+                # Say who stopped it. A chat flushed as plain "stopped" reads exactly like the user's own
+                # Stop, and when something else killed the backend (an agent's pkill, 2026-09-01) the
+                # user's running work vanished with nothing saying why: silent loss, row 1.
+                session.messages.append(Message(role="system", content=SHUTDOWN_STOP_NOTE, branch_id=session.active_branch_id))
             session.closed_at = None
             for req in list(session.pending_approvals):
                 ws_manager.resolve_approval(req.id, {"behavior": "deny", "message": "Server shutting down"})
diff --git a/backend/tests/test_shutdown_stop_note.py b/backend/tests/test_shutdown_stop_note.py
new file mode 100644
index 00000000..af542800
--- /dev/null
+++ b/backend/tests/test_shutdown_stop_note.py
@@ -0,0 +1,38 @@
+"""A chat that was running when the backend shut down must say so, or the flush reads as the user's Stop.
+
+2026-09-01: an agent's `pkill -f uvicorn` SIGTERMed Eric's production backend twice; every running chat
+was persisted as plain "stopped" and nothing in the transcript said why (row 1, silent work loss)."""
+import asyncio
+from backend.apps.agents.agent_manager import agent_manager
+from backend.apps.agents.core.models import AgentSession, Message
+from backend.apps.agents.manager.session import SessionPersistence as sp
+
+
+def p_session(status: str) -> AgentSession:
+    s = AgentSession(name="t", model="sonnet", status=status)
+    s.messages.append(Message(role="user", content="build the thing", branch_id="main"))
+    return s
+
+
+def test_a_running_chat_gets_the_shutdown_note_and_stops(monkeypatch, tmp_path) -> None:
+    saved: dict = {}
+    monkeypatch.setattr(sp, "save_session", lambda sid, doc: saved.__setitem__(sid, doc))
+    s = p_session("running")
+    agent_manager.sessions.clear(); agent_manager.sessions[s.id] = s
+    asyncio.run(agent_manager.persist_all_sessions())
+    doc = saved[s.id]
+    assert doc["status"] == "stopped"
+    last = doc["messages"][-1]
+    assert last["role"] == "system", "the note is the platform speaking, never the model"
+    assert "not your Stop" in last["content"] and "Send a message to continue" in last["content"]
+
+
+def test_a_settled_chat_is_flushed_untouched(monkeypatch) -> None:
+    saved: dict = {}
+    monkeypatch.setattr(sp, "save_session", lambda sid, doc: saved.__setitem__(sid, doc))
+    s = p_session("completed")
+    agent_manager.sessions.clear(); agent_manager.sessions[s.id] = s
+    asyncio.run(agent_manager.persist_all_sessions())
+    doc = saved[s.id]
+    assert doc["status"] == "completed"
+    assert doc["messages"][-1]["role"] == "user", "no note on a chat that was not running"