From 6ce91c3eec813fc81171894b8498a8ab853a7f19 Mon Sep 17 00:00:00 2001
From: Eliot Joslin <eliot.joslin@gmail.com>
Date: Sun, 28 Jun 2026 21:25:25 -0500
Subject: [PATCH] fix(cli): resolve uncaught RuntimeError during generator
 exhaustion in stream_query

---
 src/google/adk/cli/fast_api.py | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/src/google/adk/cli/fast_api.py b/src/google/adk/cli/fast_api.py
index a6e7d9f62c..00d6d42f39 100644
--- a/src/google/adk/cli/fast_api.py
+++ b/src/google/adk/cli/fast_api.py
@@ -835,6 +835,11 @@ async def _invoke_callable_or_raise(
           "OpenTelemetry tracing is not enabled. Please set the"
           " `OTEL_PYTHON_TRACER_PROVIDER` environment variable to enable"
           " tracing."
+      )
+
+          " tracing."
+      )
+
       )
 
     @app.middleware("http")
@@ -923,14 +928,16 @@ async def stream_query(request: Request):
       output = await _invoke_callable_or_raise(method, parsed.input or {})
 
       if inspect.isgenerator(output):
+        _sentinel = object()
 
         async def _aiter_from_iter(iterator):
           while True:
-            try:
-              chunk = await run_in_threadpool(next, iterator)
-              yield chunk
-            except StopIteration:
+            # next(iterator, _sentinel) returns the sentinel object when exhausted,
+            # avoiding a StopIteration traceback and its PEP 479 RuntimeError conversion.
+            chunk = await run_in_threadpool(next, iterator, _sentinel)
+            if chunk is _sentinel:
               break
+            yield chunk
 
         content_iter = _aiter_from_iter(output)
       else:
@@ -941,4 +948,4 @@ async def _aiter_from_iter(iterator):
           media_type="application/json",
       )
 
-  return app
+  return app
\ No newline at end of file