retry a turn the agent restart cut off

the cut-off notice is its own event now rather than an error: nothing is broken
and nothing is lost but the turn, so the row says what happened and offers the
one action that fixes it. the conversation is already durable — the claude
session id is written through to disk and passed back as resume: — so retry
just resends the prompt on a session the fresh agent picks up with full
context. read back out of the transcript, so a second window on the same
session can offer it too.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/servers/api/chat/types.ts

@@ -156,6 +156,12 @@ export type ServerMessage =
   | {
       type: 'stopped';
     }
+  | {
+      // The agent process went away mid-turn (almost always `pm2 restart officer-agent`). Its own type
+      // rather than an `error` because it is recoverable and the recovery is one click: the conversation
+      // is on disk and the next turn resumes it, so the UI offers to send the same prompt again.
+      type: 'cut-off';
+    }
   | {
       // Ack for a client 'disconnect': the session was torn down server-side.
       type: 'disconnected';

src/servers/api/chat/websocket.ts

@@ -622,10 +622,7 @@ async function endTurnIfAgentIsGone(
   const session = sessionManager.getSession(sessionId);
   if (session) session.isGenerating = false;
 
-  const event: ServerMessage = {
-    type: 'error',
-    message: 'The agent restarted while this turn was running, so it was cut off. The conversation is intact.',
-  };
+  const event: ServerMessage = { type: 'cut-off' };
   try {
     const seq = await appendChatEvent(sessionId, event);
     sendToClient(ws, event, seq);