fix(socket_mode): shut down current_session_runner in built-in close()

[WilliamBergamin]

Summary

The built-in SocketModeClient starts three IntervalRunner daemon threads in __init__

• current_session_runner
• current_app_monitor
• message_processor But close()only shut down two of them.current_session_runnersurvivedclose()`, so a long-lived process that opens and closes many client instances leaks one idle daemon thread per closed instance (issue SocketModeClient.close() leaks current_session_runner thread (built-in client) #1873).

For comparison, the sync sibling websocket_client's close() already shuts down current_session_runner, and the async backends cancel all their futures.

Why

Adding current_session_runner.shutdown() call alone deadlocks close() on any client that actually connected. That runner runs _run_current_session -> Connection.run_until_completion, whose loop exits only when the connection state is terminated. disconnect() nulls the socket but does not set terminated, and IntervalRunner.shutdown() joins the thread with no timeout, so join() blocks forever.

So close() sets current_session_state.terminated = True before disconnecting, mirroring what connect() already does when it retires an old session. The loop returns, the join completes, and all three runners are reaped. This is the same CI hang the earlier #1874 ran into; setting terminated is what resolves it.

Tests

Adds test_close_reaps_current_session_runner to tests/slack_sdk/socket_mode/test_interactions_builtin.py. It connects using the existing mock socket-mode server, calls close(), and asserts all three runner threads are no longer alive. Because it exercises the connected path, it hangs under pytest-timeout if terminated is not set. It guards both the leak and the deadlock. The existing test_interactions suite (connect/close over many buffer sizes) still passes.

Notes

• Credit to @animaartificialis for reporting SocketModeClient.close() leaks current_session_runner thread (built-in client) #1873 and diagnosing the leak in fix(socket_mode): shut down current_session_runner in close() #1874.
• No changes to the async or websocket_client clients; they already shut this runner down.

Closes #1873

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.13%. Comparing base (c30a05d) to head (6ee2433).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1962   +/-   ##
=======================================
  Coverage   84.13%   84.13%           
=======================================
  Files         118      118           
  Lines       13553    13556    +3     
=======================================
+ Hits        11403    11406    +3     
  Misses       2150     2150           

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[zimeg]

@WilliamBergamin 💌 Praises to these patches! Thanks for keeping code health in mind.