fix(async): preserve typed errors in research stream mode

tavily/async_tavily.py

@@ -723,8 +723,11 @@ async def stream_generator() -> AsyncGenerator[bytes, None]:
                                 yield chunk
                 except httpx.TimeoutException:
                     raise TimeoutError(timeout)
+                except (UsageLimitExceededError, ForbiddenError, InvalidAPIKeyError, BadRequestError, TimeoutError):
+                    # Preserve Tavily-specific error types for callers in streaming mode.
+                    raise
                 except Exception as e:
-                    raise Exception(f"Error during research stream: {str(e)}")
+                    raise Exception(f"Error during research stream: {str(e)}") from e
 
             return stream_generator()
         else:

tests/test_research.py

@@ -1,5 +1,9 @@
 import asyncio
 
+import pytest
+
+from tavily.errors import UsageLimitExceededError
+
 BASE_URL = "https://api.tavily.com"
 
 dummy_queued_response = {
@@ -147,3 +151,19 @@ def test_async_get_research(async_interceptor, async_client):
     request = async_interceptor.get_request()
     validate_get_research(request, response)
 
+
+def test_async_research_stream_preserves_usage_limit_error(async_interceptor, async_client):
+    async_interceptor.set_response(429, json={"detail": {"error": "quota exceeded"}})
+
+    async def run_test():
+        stream = await async_client.research(
+            input="Research the latest developments in AI",
+            stream=True,
+        )
+
+        with pytest.raises(UsageLimitExceededError, match="quota exceeded"):
+            async for _ in stream:
+                pass
+
+    asyncio.run(run_test())
+