Fix CORS for Custom GPT access

fastapi_app.py

@@ -21,13 +21,14 @@ app = FastAPI(
     version="1.0.0"
 )
 
-# Add CORS middleware
+# Add CORS middleware - Allow requests from OpenAI and all origins
 app.add_middleware(
     CORSMiddleware,
-    allow_origins=["*"],
-    allow_credentials=True,
-    allow_methods=["*"],
+    allow_origin_regex=r"https://.*\.openai\.com|https://chat\.openai\.com|https://.*",
+    allow_credentials=False,  # Changed to False for wildcard origins
+    allow_methods=["GET", "POST", "OPTIONS"],
     allow_headers=["*"],
+    expose_headers=["*"],
 )
 
 # Request/Response models