Atlas: opening message, isInit flag, strip trigger from history

- Add opening message instruction to atlas prompt
- Handle isInit flag in atlasChat() to not store the greeting trigger
  as a user turn in conversation history
- Update server.ts to pass is_init through to atlasChat()

Made-with: Cursor

src/server.ts

@@ -225,11 +225,13 @@ app.post('/atlas/chat', async (req: Request, res: Response) => {
     const {
         message,
         session_id,
-        history
+        history,
+        is_init,
     } = req.body as {
         message?: string;
         session_id?: string;
         history?: LLMMessage[];
+        is_init?: boolean;
     };
 
     if (!message) { res.status(400).json({ error: '"message" is required' }); return; }
@@ -238,7 +240,10 @@ app.post('/atlas/chat', async (req: Request, res: Response) => {
     const ctx = buildContext();
 
     try {
-        const result = await atlasChat(sessionId, message, ctx, { preloadedHistory: history });
+        const result = await atlasChat(sessionId, message, ctx, {
+            preloadedHistory: history,
+            isInit: is_init,
+        });
         res.json(result);
     } catch (err) {
         res.status(500).json({ error: err instanceof Error ? err.message : String(err) });