Fix the typing issue and clean up the FastAPI Vite example

Author: anbuzin

examples/fastapi-vite/backend/routes/chat.py

@@ -2,8 +2,6 @@
 
 from __future__ import annotations
 
-from collections.abc import AsyncGenerator
-
 from fastapi import APIRouter
 from fastapi.responses import StreamingResponse
 from pydantic import BaseModel
@@ -30,14 +28,6 @@ class ChatRequest(BaseModel):
     session_id: str | None = None
 
 
-async def _iter_result(
-    result: ai.RunResult,
-) -> AsyncGenerator[ai.Message, None]:
-    """Unwrap RunResult into an AsyncGenerator for to_sse_stream."""
-    async for msg in result:
-        yield msg
-
-
 @router.post("/chat")
 async def chat(request: ChatRequest):
     """Handle chat requests and stream responses."""
@@ -57,7 +47,7 @@ async def chat(request: ChatRequest):
     result = ai.run(graph, llm, messages, TOOLS, checkpoint=checkpoint)
 
     async def stream_response():
-        async for chunk in to_sse_stream(_iter_result(result)):
+        async for chunk in to_sse_stream(result):
             yield chunk
 
         # If the run completed (no pending hooks), clear the checkpoint

examples/fastapi-vite/backend/uv.lock

@@ -7,7 +7,7 @@
 import dataclasses
 import json
 import uuid
-from collections.abc import AsyncGenerator
+from collections.abc import AsyncGenerator, AsyncIterable
 from typing import Any, Literal
 
 from .. import core
@@ -127,7 +127,7 @@ def begin_message(
 
 
 async def to_ui_message_stream(
-    messages: AsyncGenerator[core.messages.Message, None],
+    messages: AsyncIterable[core.messages.Message],
 ) -> AsyncGenerator[protocol.UIMessageStreamPart, None]:
     """
     Convert a proto_sdk message stream into AI SDK UI message stream parts.
@@ -257,7 +257,7 @@ async def to_ui_message_stream(
 
 
 async def filter_by_label(
-    messages: AsyncGenerator[core.messages.Message, None],
+    messages: AsyncIterable[core.messages.Message],
     label: str | None = None,
 ) -> AsyncGenerator[core.messages.Message, None]:
     """Filter a message stream to a single agent label.
@@ -273,7 +273,7 @@ async def filter_by_label(
 
 
 async def to_sse_stream(
-    messages: AsyncGenerator[core.messages.Message, None],
+    messages: AsyncIterable[core.messages.Message],
 ) -> AsyncGenerator[str, None]:
     """Convert a proto_sdk message stream directly into SSE-formatted strings."""
     async for part in to_ui_message_stream(messages):