fix(spawn): clear stale psmux session registration before re-create#78
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A psmux (native-Windows) server that dies uncleanly leaves the session NAME
registered with no live server behind it. new-session then becomes a SILENT
no-op (rc=0, creates nothing) and the name can never come back — stranding a
peer's cell ("session got killed and won't return"; diagnosed on workstation-lc
2026-06-18). Real tmux on Linux/mac doesn't hit this.
_launch_via_tmux's create path now goes through _tmux_create_session, which:
1. kill-session first to clear any stale (server-less) registration
(harmless no-op when the name is truly absent),
2. creates, then VERIFIES via has-session and RETRIES — because psmux clears
the stale lock ASYNCHRONOUSLY (~1s) and the create's rc is 0 even on the
silent no-op, so the exit code can't be trusted.
Harmless no-op on real tmux (create takes first try, loop breaks immediately).
Tests: harness made stateful (a created session then exists) + time.sleep
no-op'd; dropped the obsolete CalledProcessError case (check=True removed);
added stale-clear + async-retry coverage. 28 + 61 adjacent tests green.
OPEN for Lab review:
- Confirm the branch base (cut off spawn-win-launch-fix @639fbda).
- Verify psmux honors the `=`exact-match target prefix used by
_tmux_has_session / the new kill-session; if not, BOTH need the bare-name
form (couldn't confirm locally — psmux non-interactive state was polluted).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CHWUyK8b64sauTAK1GGQSo
…ws CI fix) test_run_spawn_grok_assisted_memory_no_double_system_prompt asserts on the composed grok argv (no doubled --system-prompt-override) but only mocked os.execve. On Windows, grok launch() takes the subprocess.run branch (v0.12.1 pane-collapse fix), so the execve mock never fired, the real /bin/fake-grok exec failed (WinError 2), exec_args stayed empty → assert 0 == 1. Red on Windows CI. Pre-existing on main (verified on 98957f5 without the stale-session commit) — not caused by PR #78; the full-suite CI just surfaces it. Fix per the file's own convention (cf. test_claude_launch_posix_uses_execve): pin sys.platform to a POSIX value so launch() takes the mocked os.execve branch. The assertion is platform- independent (argv composition), so this preserves intent; the Windows-vs-POSIX launch split itself is already covered by test_grok_launch_win32_blocks_posix_execve. Full spawn suites green: 101 passed (PYTHONPATH=src). Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01CHWUyK8b64sauTAK1GGQSo
darw007d
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Jun 18, 2026
Version bump to ship the already-merged + CI-green stranding fix to PyPI:
_tmux_create_session clears a stale (server-less) psmux session registration
before re-create (kill → create → verify-via-has-session + retry), so a peer
cell whose multiplexer died uncleanly can respawn instead of being stranded
('session got killed and won't return'). No-op on real tmux. Also carries the
test fix that cleared the pre-existing #77 Windows-CI red. Code merged in #78
(0422c4b); this is version + publish only.
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
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Problem
A psmux (native-Windows multiplexer) server that dies uncleanly — operator closed the owning console,
kill, a crash — leaves the session name registered with no live server behind it.new-sessionthen becomes a silent no-op (rc=0, creates nothing), and the name can never come back. That is the exact failure that strands a peer's cell: "the session got killed and won't return." Diagnosed end-to-end on workstation-lc 2026-06-18 (psmux v3.3.5).Real tmux on Linux/mac does not hit this —
new-sessionis synchronous and a dead session leaves no blocking registration.Fix
_launch_via_tmux's create path now goes through a new_tmux_create_session(), which:kill-sessionfirst to clear any stale (server-less) registration — a harmless no-op when the name is truly absent;has-sessionand RETRIES (6× / 0.4s) — because psmux clears the stale lock asynchronously (~1s observed) andnew-session's exit code is0even on the silent no-op, so the rc cannot be trusted.On real tmux this is a harmless no-op: the create succeeds on the first attempt and the verify loop breaks immediately.
Tests
has-session-exists) andtime.sleepno-op'd.CalledProcessErrorfailure case (check=Trueremoved).tests/test_spawn_tmux_session.py28 passed; adjacenttest_spawn_command.py+test_claude_tmux_template.py61 passed (run withPYTHONPATH=src).Note for reviewers
_tmux_has_sessionand the newkill-sessionuse the tmux=nameexact-match prefix. Confirmed working on psmux empirically (normal spawns + has-session function on the Windows box today; the stranding bug is the stale-server case, orthogonal to=parsing). Flagging in case a future psmux build changes=handling.🤖 Generated with Claude Code