fix message duplication on auto-save after resume

The PUT endpoint was re-merging old DB messages (which already included
previous merges) with disk messages on every turn, causing duplication.
Now the client passes resumedMessageCount so the server always slices
only the original pre-resume messages before concatenating.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/workspaces/officerdev/src/apps/Chat/ChatPanelWrapper.tsx

@@ -41,6 +41,7 @@ const ChatPanelInner = ({
   const savedIdRef = useRef(savedId);
   savedIdRef.current = savedId;
   const chatSessionRef = useRef<string | null>(null);
+  const resumedMessageCountRef = useRef(initialMessages?.length ?? 0);
 
   const handleTurnComplete = useCallback(
     (hadToolCalls: boolean) => {
@@ -48,7 +49,8 @@ const ChatPanelInner = ({
       const id = savedIdRef.current;
       const sid = chatSessionRef.current;
       if (id != null && sid) {
-        updateSessionMessages(id, sid).catch(() => {});
+        const count = resumedMessageCountRef.current;
+        updateSessionMessages(id, sid, count > 0 ? count : undefined).catch(() => {});
       }
     },
     [onTurnComplete, updateSessionMessages],

src/workspaces/officerdev/src/apps/ChatHistory/ChatDetailPanel.tsx

@@ -95,12 +95,14 @@ function NewChat({ resumeSummary, initialMessages, savedId: initialSavedId }: Ne
   const savedIdRef = useRef(savedId);
   savedIdRef.current = savedId;
   const chatSessionRef = useRef<string | null>(null);
+  const resumedMessageCountRef = useRef(initialMessages?.length ?? 0);
 
   const onTurnComplete = useCallback(() => {
     const id = savedIdRef.current;
     const sid = chatSessionRef.current;
     if (id != null && sid) {
-      updateSessionMessages(id, sid).catch(() => {});
+      const count = resumedMessageCountRef.current;
+      updateSessionMessages(id, sid, count > 0 ? count : undefined).catch(() => {});
     }
   }, [updateSessionMessages]);
 

src/workspaces/state/src/useSavedSessions.ts

@@ -88,8 +88,8 @@ export function useSavedSessions() {
     return client.post<ResumeResult>(`/saved-sessions/${id}/resume`);
   }
 
-  async function updateSessionMessages(savedId: number, sessionId: string) {
-    await client.put(`/saved-sessions/${savedId}`, { sessionId });
+  async function updateSessionMessages(savedId: number, sessionId: string, resumedMessageCount?: number) {
+    await client.put(`/saved-sessions/${savedId}`, { sessionId, resumedMessageCount });
   }
 
   return {