fix: Update Google OAuth token and refresh token handling; add error handling for token refresh and improve transcript fetching with fallback mechanisms

Google_oauth_token.json

@@ -1 +1 @@
-{"token": "ya29.a0AQvPyIO26RTYjrTK11YqxleX0yEhb_vlrw0TChQxwxTP2GWBonDMQonUUdknaad1vpWBNMhMOrD0Mbw9pNon3W20odwEFIyiPcXX0DRC07hrmbPIiUN4R9hlbl5H_gZdBMfa6oHoBIAb358uMxWCtVoawWEuKAm_XZrZhIsEG8xlXSLY5e_Mi50nu77y09IYASOHe2QaCgYKAacSARcSFQHGX2MiZB9Z5G4jtAvKppNhrfPtKA0206", "refresh_token": "1//0gyGUH_G9f9CbCgYIARAAGBASNwF-L9Irnwc3yS0FAs7ocMc8Vtmxu-C3GbrkS_deBoCRToBbEBl0vkRHEjVWmIHw2EZ6RpjFGX8", "token_uri": "https://oauth2.googleapis.com/token", "client_id": "769133159215-9gbq0l5v49kmclfcq7vbq7tutck0aphd.apps.googleusercontent.com", "client_secret": "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", "scopes": ["https://www.googleapis.com/auth/spreadsheets", "https://www.googleapis.com/auth/gmail.send", "https://www.googleapis.com/auth/drive.file"], "universe_domain": "googleapis.com", "account": "", "expiry": "2026-05-31T12:33:45Z"}
+{"token": "ya29.a0AQvPyINisnTmbbUbKvU_Oon2bsyEI0RplGRg35lszdgHJSGyHGEgIIJ9egNQxH2WYTL620YwTJxDsK7sZv2nbfSw5kUQc76A8mklMLSxn762j0NYpdeXt5RbOQg8KJf6prPxH8CsPuwz7ks1bK0BFz4vy04QkPBMlNSRtMkba_OA_TL_ly7_03bGAaCK29Q_z2RWGCkaCgYKAS4SARcSFQHGX2MiWhTmNjFUY-_7XXKWJbeV9w0206", "refresh_token": "1//0gSFNaVNizGvECgYIARAAGBASNwF-L9Ir0TRSCojKNffp98YYGDMRNlnndT_iKz3QfIcYtWShLJRGy_S2QDCzQhPPwcrAJlH12lo", "token_uri": "https://oauth2.googleapis.com/token", "client_id": "769133159215-9gbq0l5v49kmclfcq7vbq7tutck0aphd.apps.googleusercontent.com", "client_secret": "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", "scopes": ["https://www.googleapis.com/auth/spreadsheets", "https://www.googleapis.com/auth/gmail.send", "https://www.googleapis.com/auth/drive.file", "https://www.googleapis.com/auth/youtube.force-ssl"], "universe_domain": "googleapis.com", "account": "", "expiry": "2026-05-31T16:17:24Z"}

app.py

@@ -183,8 +183,14 @@ def load_credentials() -> Credentials | None:
     creds = Credentials.from_authorized_user_file(TOKEN_PATH, SCOPES)
     if not creds.valid:
         if creds.expired and creds.refresh_token:
-            creds.refresh(GoogleRequest())
-            Path(TOKEN_PATH).write_text(creds.to_json(), encoding="utf-8")
+            try:
+                creds.refresh(GoogleRequest())
+                Path(TOKEN_PATH).write_text(creds.to_json(), encoding="utf-8")
+            except Exception as e:
+                print(f"[WARN] Failed to refresh token: {e}. Forcing re-auth.")
+                if os.path.exists(TOKEN_PATH):
+                    os.remove(TOKEN_PATH)
+                return None
         else:
             return None
     return creds
@@ -1118,4 +1124,4 @@ def generate(payload: GenerateRequest):
 
 if __name__ == "__main__":
     import uvicorn
-    uvicorn.run("fastapi_app:app", host="0.0.0.0", port=8000, reload=True)
+    uvicorn.run("app:app", host="0.0.0.0", port=8000, reload=True)

gemini_transcript.py

@@ -261,7 +261,15 @@ class YouTubeTranscriptFetcher:
         raise ValueError(f"Unsupported YouTube URL: {url}")
 
     def _fetch_once(self) -> str:
-        transcript = self.api.fetch(self.video_id, languages=self.languages)
+        try:
+            transcript = self.api.fetch(self.video_id, languages=self.languages)
+        except NoTranscriptFound:
+            logger.info("[Tier 1] Requested languages %s not found. Finding first available transcript...", self.languages)
+            transcript_list = self.api.list_transcripts(self.video_id)
+            first_transcript = next(iter(transcript_list))
+            logger.info("[Tier 1] Falling back to language: %s", first_transcript.language_code)
+            transcript = first_transcript.fetch()
+            
         return " ".join(item.text for item in transcript)
 
     def _try_all_tiers(self) -> tuple[str, str]:
@@ -399,8 +407,10 @@ class YtDlpTranscriptFetcher:
         """
         Search manual subtitles first, then auto-generated, for a
         matching language + preferred format.
+        If requested languages are not available, fallback to any available language.
         Returns (url, format_ext).
         """
+        # 1. Try preferred languages
         for subs_dict in (manual_subs, auto_subs):
             if not subs_dict:
                 continue
@@ -420,9 +430,31 @@ class YtDlpTranscriptFetcher:
                     if track.get("url"):
                         return track["url"], track.get("ext", "vtt")
 
+        # 2. Fallback to ANY available language
+        logger.info("[yt-dlp] Preferred languages %s not found. Falling back to any available language.", self.languages)
+        for subs_dict in (manual_subs, auto_subs):
+            if not subs_dict:
+                continue
+            # Try preferred formats across all languages
+            for fmt in self.PREFERRED_FORMATS:
+                for lang, tracks in subs_dict.items():
+                    if not tracks:
+                        continue
+                    for track in tracks:
+                        if track.get("ext") == fmt and track.get("url"):
+                            logger.info("[yt-dlp] Falling back to language: %s", lang)
+                            return track["url"], fmt
+            # No preferred format matched — use first available with URL across all languages
+            for lang, tracks in subs_dict.items():
+                if not tracks:
+                    continue
+                for track in tracks:
+                    if track.get("url"):
+                        logger.info("[yt-dlp] Falling back to language: %s", lang)
+                        return track["url"], track.get("ext", "vtt")
+
         raise RuntimeError(
-            f"No subtitles found in yt-dlp metadata for "
-            f"languages {self.languages} (video: {self.video_id})"
+            f"No subtitles found in yt-dlp metadata for video: {self.video_id}"
         )
 
     def fetch(self) -> str:
@@ -580,10 +612,15 @@ class YouTubeApiTranscriptFetcher:
 
             if not caption_id:
                 available = [i["snippet"]["language"] for i in items]
-                raise RuntimeError(
-                    f"No caption track matches languages {self.languages}. "
-                    f"Available: {available}"
-                )
+                if available:
+                    logger.info("[YT-API] Preferred languages %s not found. Falling back to any available language.", self.languages)
+                    caption_id = items[0]["id"]
+                    lang = items[0]["snippet"]["language"]
+                    logger.info("[YT-API] Falling back to language: %s, id=%s", lang, caption_id)
+                else:
+                    raise RuntimeError(
+                        f"No caption tracks found for video {self.video_id}"
+                    )
 
             # Step 3: Download caption content as SRT
             caption_content = youtube.captions().download(