Update app.py

app.py

@@ -38,9 +38,29 @@ app.config['MAX_CONTENT_LENGTH'] = 50 * 1024 * 1024  # 50MB limit
 FAISS_INDEX_DIR = os.path.join(APP_ROOT, "faiss_indices")
 EMBEDDING_DIM = 768  # all-mpnet-base-v2 embedding dimension
 
-# Ensure writable directories exist when running under gunicorn
-os.makedirs(app.config['UPLOAD_FOLDER'], exist_ok=True)
-os.makedirs(FAISS_INDEX_DIR, exist_ok=True)
+def _ensure_writable_directory(path: str) -> str:
+    try:
+        os.makedirs(path, exist_ok=True)
+        test_file = os.path.join(path, '.write_test')
+        with open(test_file, 'w') as f:
+            f.write('ok')
+        os.remove(test_file)
+        return path
+    except Exception:
+        fallback = os.path.join('/tmp', os.path.basename(path))
+        os.makedirs(fallback, exist_ok=True)
+        try:
+            test_file = os.path.join(fallback, '.write_test')
+            with open(test_file, 'w') as f:
+                f.write('ok')
+            os.remove(test_file)
+            return fallback
+        except Exception:
+            return path
+
+# Ensure writable directories exist when running under gunicorn, fallback to /tmp if needed
+app.config['UPLOAD_FOLDER'] = _ensure_writable_directory(app.config['UPLOAD_FOLDER'])
+FAISS_INDEX_DIR = _ensure_writable_directory(FAISS_INDEX_DIR)
 
 # Chunking Configuration
 CHUNK_SIZE = 1000