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Remove anyio.create_task_group() from receive_messages() to fix the RuntimeError "Attempted to exit cancel scope in a different task than it was entered in" when using the SDK with FastAPI's SSE streaming. The issue occurred because FastAPI can move async generators between different asyncio tasks during the streaming lifecycle, which conflicts with anyio's cancel scope tracking. Changes: - Remove task group usage from receive_messages() - Read stderr sequentially after stdout completes - Add test to ensure no task groups are used - Fix existing test expectation for buffer overflow This is a minimal fix that maintains compatibility while solving the core issue. The trade-off is that stderr is read after stdout instead of concurrently, but this is unlikely to cause issues in practice. 🤖 Generated with [Claude Code](https://claude.ai/code) Co-Authored-By: Claude <noreply@anthropic.com>
25 lines
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1,015 B
Python
25 lines
No EOL
1,015 B
Python
"""Test FastAPI streaming compatibility (issue #4 fix)."""
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import inspect
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from claude_code_sdk._internal.transport.subprocess_cli import SubprocessCLITransport
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def test_no_task_groups_in_receive_messages():
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"""Verify receive_messages doesn't use task groups (fixes FastAPI issue #4)."""
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# Get the source code of receive_messages
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source = inspect.getsource(SubprocessCLITransport.receive_messages)
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# The fix: ensure no task group or task creation
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assert "create_task_group" not in source, (
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"receive_messages must not use create_task_group to avoid "
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"RuntimeError with FastAPI streaming"
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)
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assert "asyncio.create_task" not in source, (
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"receive_messages must not create tasks to maintain "
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"compatibility with FastAPI's generator handling"
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)
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# Verify stderr is still being read (sequential approach)
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assert "_stderr_stream" in source, "Should still read stderr"
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assert "stderr_lines" in source, "Should collect stderr output" |