Add exponential backoff

app/services/note_client.py

@@ -1,37 +1,55 @@
 import logging
+import asyncio
 import httpx
 from app.config.settings import NOTE_SERVICE_URL
 
 
 class NoteServiceClient:
+    MAX_RETRIES = 3
+    RETRY_DELAYS = [1, 2, 4]  # exponential backoff in seconds
+
     async def create_audio_note(self, payload: dict):
         """Call the Note Service to create an audio note.
 
         This method catches HTTP errors and logs them instead of raising,
         to avoid making transcription endpoints return 500 when the
         Note Service is unavailable or returns 4xx/5xx.
+        Retries on 429 (rate limit) with exponential backoff.
         Returns parsed JSON on success or None on failure.
         """
-        try:
-            async with httpx.AsyncClient(timeout=30) as client:
-                r = await client.post(
-                    f"{NOTE_SERVICE_URL}/internal/notes/audio",
-                    json=payload,
+        url = f"{NOTE_SERVICE_URL}/internal/notes/audio"
+        
+        for attempt in range(self.MAX_RETRIES):
+            try:
+                async with httpx.AsyncClient(timeout=30) as client:
+                    r = await client.post(url, json=payload)
+                    r.raise_for_status()
+                    return r.json()
+            except httpx.HTTPStatusError as exc:
+                status = getattr(exc.response, "status_code", None)
+                
+                # Retry on 429 Too Many Requests
+                if status == 429 and attempt < self.MAX_RETRIES - 1:
+                    delay = self.RETRY_DELAYS[attempt]
+                    logging.warning(
+                        "NoteService rate limited (429), retrying in %ds (attempt %d/%d)",
+                        delay, attempt + 1, self.MAX_RETRIES
+                    )
+                    await asyncio.sleep(delay)
+                    continue
+                
+                logging.warning(
+                    "NoteService returned HTTP %s for %s: %s",
+                    status,
+                    url,
+                    exc,
                 )
-                r.raise_for_status()
-                return r.json()
-        except httpx.HTTPStatusError as exc:
-            status = getattr(exc.response, "status_code", "?")
-            logging.warning(
-                "NoteService returned HTTP %s for %s: %s",
-                status,
-                f"{NOTE_SERVICE_URL}/internal/notes/audio",
-                exc,
-            )
-            return None
-        except Exception as exc:  # network errors, timeouts, etc.
-            logging.exception("Failed to call NoteService: %s", exc)
-            return None
+                return None
+            except Exception as exc:  # network errors, timeouts, etc.
+                logging.exception("Failed to call NoteService: %s", exc)
+                return None
+        
+        return None
 
     async def save_transcript(self, payload: dict):
         # alias used elsewhere in the codebase