fix: override end_turn stop reason when streaming response contains toolUse blocks

src/strands/event_loop/streaming.py

@@ -411,6 +411,16 @@ async def process_stream(
             state = handle_content_block_stop(state)
         elif "messageStop" in chunk:
             stop_reason = handle_message_stop(chunk["messageStop"])
+            # Some models return "end_turn" even when tool calls are present,
+            # which prevents the event loop from processing those tool calls.
+            # Override to "tool_use" so tool execution proceeds correctly.
+            if stop_reason == "end_turn":
+                content = state["message"].get("content", [])
+                if any("toolUse" in item for item in content):
+                    logger.warning(
+                        "stop_reason override: end_turn -> tool_use (response contains toolUse blocks)"
+                    )
+                    stop_reason = "tool_use"
         elif "metadata" in chunk:
             time_to_first_byte_ms = (
                 int(1000 * (first_byte_time - start_time)) if (start_time and first_byte_time) else None

src/strands/models/bedrock.py

@@ -823,8 +823,6 @@ def _stream(
             logger.debug("got response from model")
             if streaming:
                 response = self.client.converse_stream(**request)
-                # Track tool use events to fix stopReason for streaming responses
-                has_tool_use = False
                 for chunk in response["stream"]:
                     if (
                         "metadata" in chunk
@@ -836,24 +834,10 @@ def _stream(
                             for event in self._generate_redaction_events():
                                 callback(event)
 
-                    # Track if we see tool use events
-                    if "contentBlockStart" in chunk and chunk["contentBlockStart"].get("start", {}).get("toolUse"):
-                        has_tool_use = True
-
-                    # Fix stopReason for streaming responses that contain tool use
-                    if (
-                        has_tool_use
-                        and "messageStop" in chunk
-                        and (message_stop := chunk["messageStop"]).get("stopReason") == "end_turn"
-                    ):
-                        # Create corrected chunk with tool_use stopReason
-                        modified_chunk = chunk.copy()
-                        modified_chunk["messageStop"] = message_stop.copy()
-                        modified_chunk["messageStop"]["stopReason"] = "tool_use"
-                        logger.warning("Override stop reason from end_turn to tool_use")
-                        callback(modified_chunk)
-                    else:
-                        callback(chunk)
+                    # The stop_reason override for end_turn -> tool_use is now
+                    # handled centrally in streaming.py so no model-specific
+                    # fixup is needed here.
+                    callback(chunk)
 
             else:
                 response = self.client.converse(**request)