{
  "tool": "probe_stdio_lifecycle.py",
  "started_at": "2026-10-30T02:29:16.328645+00:00",
  "python": "3.12.3",
  "platform_note": "Linux/CPython; pipe buffer 64 KiB default",
  "catalog_sha256_source": "fixtures/",
  "versions": {
    "mcp": "2.2.0",
    "anyio": "4.15.1",
    "pydantic": "2.14.2"
  },
  "L1_control_drain": {
    "scenario": "L1",
    "arm": "drain_stdout_control",
    "blob_bytes": 262144,
    "started_at": "2026-10-30T02:29:16.331461+00:00",
    "alive_before_eof": "S",
    "seconds_waited_after_eof": 10.0,
    "state_at_wait_end": "Z",
    "exited_on_eof_within_10s": true,
    "exit_status": 0,
    "signal_needed": null,
    "stdout_bytes_read": 262190,
    "stderr_tail": [
      "FIXTURE_READY mode=big blob_bytes=262144",
      "FIXTURE_BIG_QUEUED",
      "FIXTURE_STDIN_EOF"
    ],
    "finished_at": "2026-10-30T02:29:18.536050+00:00"
  },
  "L1_unread": {
    "scenario": "L1",
    "arm": "leave_stdout_unread",
    "blob_bytes": 262144,
    "started_at": "2026-10-30T02:29:18.536842+00:00",
    "alive_before_eof": "S",
    "seconds_waited_after_eof": 10.0,
    "state_at_wait_end": "S",
    "exited_on_eof_within_10s": false,
    "state_after_sigterm": "Z",
    "signal_needed": "SIGTERM",
    "exit_status": -15,
    "stdout_bytes_read": 0,
    "stderr_tail": [
      "FIXTURE_READY mode=big blob_bytes=262144",
      "FIXTURE_BIG_QUEUED",
      "FIXTURE_STDIN_EOF"
    ],
    "finished_at": "2026-10-30T02:29:33.555990+00:00"
  },
  "L2": {
    "scenario": "L2",
    "started_at": "2026-10-30T02:29:33.556835+00:00",
    "stdout_bytes": 0,
    "stdout_nonempty_lines": [],
    "stderr": [
      "FIXTURE_READY mode=surrogate repr='bad-\\udcff-name'",
      "FIXTURE_BAD_QUEUED",
      "FIXTURE_TOP_LEVEL_EXIT ExceptionGroup: unhandled errors in a TaskGroup (1 sub-exception)",
      "+ Exception Group Traceback (most recent call last):",
      "|   File \"/home/ubuntu/blog-automation/workspaces/348a8b3b-2c35-4497-81c7-b0d56d61ba52/tree/research/evidence/mcp-stdio-transport-lifecycle-2026/probe-r1/fixtures/fixture_stdio_writer.py\", line 68, in <module>",
      "|     anyio.run(main)",
      "|   File \"/tmp/rockb-7b6bfda2-zbx_5rkh/venv/lib/python3.12/site-packages/anyio/_core/_eventloop.py\", line 83, in run",
      "|     return async_backend.run(func, args, {}, backend_options)",
      "|            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^",
      "|   File \"/tmp/rockb-7b6bfda2-zbx_5rkh/venv/lib/python3.12/site-packages/anyio/_backends/_asyncio.py\", line 2548, in run",
      "|     return runner.run(wrapper())",
      "|            ^^^^^^^^^^^^^^^^^^^^^",
      "|   File \"/usr/lib/python3.12/asyncio/runners.py\", line 118, in run",
      "|     return self._loop.run_until_complete(task)",
      "|            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^",
      "|   File \"/usr/lib/python3.12/asyncio/base_events.py\", line 687, in run_until_complete",
      "|     return future.result()",
      "|            ^^^^^^^^^^^^^^^",
      "|   File \"/tmp/rockb-7b6bfda2-zbx_5rkh/venv/lib/python3.12/site-packages/anyio/_backends/_asyncio.py\", line 2531, in wrapper",
      "|     return await func(*args)",
      "|            ^^^^^^^^^^^^^^^^^",
      "|   File \"/home/ubuntu/blog-automation/workspaces/348a8b3b-2c35-4497-81c7-b0d56d61ba52/tree/research/evidence/mcp-stdio-transport-lifecycle-2026/probe-r1/fixtures/fixture_stdio_writer.py\", line 34, in main",
      "|     async with stdio_server() as (read_stream, write_stream):",
      "|   File \"/usr/lib/python3.12/contextlib.py\", line 231, in __aexit__",
      "|     await self.gen.athrow(value)",
      "|   File \"/tmp/rockb-7b6bfda2-zbx_5rkh/venv/lib/python3.12/site-packages/mcp/server/stdio.py\", line 209, in stdio_server",
      "|     async with anyio.create_task_group() as tg:",
      "|   File \"/tmp/rockb-7b6bfda2-zbx_5rkh/venv/lib/python3.12/site-packages/anyio/_backends/_asyncio.py\", line 847, in __aexit__",
      "|     raise BaseExceptionGroup(",
      "| ExceptionGroup: unhandled errors in a TaskGroup (1 sub-exception)",
      "+-+---------------- 1 ----------------",
      "| Traceback (most recent call last):",
      "|   File \"/tmp/rockb-7b6bfda2-zbx_5rkh/venv/lib/python3.12/site-packages/anyio/_core/_tasks.py\", line 327, in _run_coro",
      "|     retval = await self._coro",
      "|              ^^^^^^^^^^^^^^^^",
      "|   File \"/tmp/rockb-7b6bfda2-zbx_5rkh/venv/lib/python3.12/site-packages/mcp/server/stdio.py\", line 203, in stdout_writer",
      "|     json = session_message.message.model_dump_json(by_alias=True, exclude_unset=True)",
      "|            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^",
      "|   File \"/tmp/rockb-7b6bfda2-zbx_5rkh/venv/lib/python3.12/site-packages/pydantic/main.py\", line 587, in model_dump_json",
      "|     return self.__pydantic_serializer__.to_json(",
      "|            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^",
      "| pydantic_core._pydantic_core.PydanticSerializationError: Error serializing to JSON: UnicodeEncodeError: 'utf-8' codec can't encode character '\\udcff' in position 4: surrogates not allowed",
      "+------------------------------------"
    ],
    "serialization_error_class": null,
    "process_state_after": "S",
    "process_alive_after": true,
    "exits_on_stdin_eof": true,
    "signal_needed": null,
    "finished_at": "2026-10-30T02:29:41.058971+00:00"
  },
  "L3": {
    "scenario": "L3",
    "started_at": "2026-10-30T02:29:56.432394+00:00",
    "after_first_connect": {
      "sessions": 1,
      "tools": [
        "echo"
      ],
      "children": 1
    },
    "second_connect": "MCPError: {'echo'} already exist in group tools.",
    "after_rejected_connect": {
      "sessions": 1,
      "tools": [
        "echo"
      ],
      "children": 2,
      "children_detail": [
        {
          "pid": 4074800,
          "state": "S"
        },
        {
          "pid": 4074805,
          "state": "S"
        }
      ]
    },
    "after_group_close": {
      "children": 0
    },
    "finished_at": "2026-10-30T02:29:59.192526+00:00"
  },
  "L4": {
    "scenario": "L4",
    "started_at": "2026-10-30T02:29:59.193276+00:00",
    "first_registration_tools": [
      "old"
    ],
    "second_registration_tools": [
      "new",
      "old"
    ],
    "after_disconnect": {
      "sessions": 0,
      "tools": [
        "old"
      ]
    },
    "stale_tools_remaining": [
      "old"
    ],
    "finished_at": "2026-10-30T02:30:00.439536+00:00"
  },
  "finished_at": "2026-10-30T02:30:00.440646+00:00"
}