fix(bin): handle dash-leading harness commands portably

[harsh9200]

Intent

Fix firstmate's recurring macOS Claude Stop-hook wake noise caused when BSD basename interprets a login-shell command such as -zsh as an option. Reproduce the stderr failure first, then make every process-command extraction in the session-lock and harness detection composition portable without adding GNU coreutils, using pure-shell suffix extraction. Sweep bin/ for the same basename or dirname GNU-flag portability class, including bin/fm-harness.sh detect_own, add or extend colocated regression coverage proving the Stop auto-arm stale-owner path and harness detection emit no stderr under BSD basename semantics, and keep touched shell scripts ShellCheck-clean. Limit the change to this portability fix and its focused tests.

What Changed

• Replace basename process-command parsing with portable shell suffix extraction in harness detection and session-lock ancestry/liveness checks, preventing BSD basename errors for commands such as -zsh.
• Add regression coverage proving dash-leading commands emit no stderr and the Claude Stop auto-arm stale-owner flow continues successfully.

Risk Assessment

✅ Low: Captain, the change is narrowly scoped, preserves command-name extraction semantics, removes BSD basename option parsing from all identified process-command paths, and adds focused regression coverage for both affected flows.

Testing

Reproduced the native and base-commit BSD stderr leak first, then verified the target harness emits no stderr and manually exercised stale-owner Stop auto-arm through lock reclamation to a clean persisted epoch. Both focused automated suites completed successfully, evidence transcripts were preserved, and the worktree remained clean. ShellCheck/static analysis was not run because this testing step explicitly prohibited it; no visual artifact applies to this silent shell-hook/CLI change.

Evidence: BSD failure reproduction

Native macOS basename -zsh exited 1 with the BSD illegal-option diagnostic.

Native macOS BSD basename reproduction
Command: basename -zsh
Exit: 1
Stderr:
basename: illegal option -- z
usage: basename string [suffix]
       basename [-a] [-s suffix] string [...]

Evidence: Base-to-target harness comparison

Base commit leaked 108 stderr bytes for comm=-zsh; the target returned unknown with zero stderr.

Base-commit harness detection with ps comm=-zsh
Command: base bin/fm-harness.sh at 99533c5d
Exit: 0
Stdout: unknown
Stderr bytes: 108
Stderr:
basename: illegal option -- z
usage: basename string [suffix]
       basename [-a] [-s suffix] string [...]

Evidence: Stale `-zsh` Stop-hook evidence

The manual Stop-hook flow exited silently, reclaimed the stale lock, executed auto-arm, and recorded a clean epoch.

Manual Claude Stop auto-arm stale-login-shell verification
Simulated stale owner command: -zsh
Hook exit: 0
Hook stdout bytes: 0
Hook stderr bytes: 0
Original stale owner pid: 13994
Reclaimed lock owner pid: 97982
Auto-arm executed pid: 14212
Epoch: epoch=2 owner_pid=13996 outcome=clean updated_at=1785355110

Evidence: Focused Stop auto-arm tests

Focused regression transcript covering BSD basename semantics and stale-owner Stop auto-arm behavior.

FM_TEST_BEGIN 2026-07-29T19:56:29Z tests/fm-claude-stop-autoarm.test.sh family=unclassified expected_gate_skip=none
ok - settings.json registers the asyncRewake auto-arm with timeout >= 28800 and a foreground arm
ok - auto-arm: inert in a linked child worktree even when in-flight
ok - auto-arm: inert with no session lock
ok - auto-arm: a demonstrably dead recorded session owner is reclaimed through fm-lock.sh before arming
ok - auto-arm: stale -zsh lock-owner composition is silent with BSD basename semantics
ok - auto-arm: inert without arm, rewake, or lock replacement when another live harness owns the home
ok - auto-arm: inert while AFK owns supervision
ok - auto-arm: stale-owner recovery leaves the AFK and supervision-need gates unchanged
ok - auto-arm: resolves the outermost pid of a nested contiguous claude ancestry (bg-spare chain)
ok - auto-arm: inert with nothing in flight and no X-mode need
ok - auto-arm: actionable close translates to exactly one exit-2 rewake with reason
ok - auto-arm: watcher: FAILED translates to an exit-2 alarm rewake
ok - auto-arm: clean close exits silently with a clean epoch
ok - auto-arm: X-mode poll need arms the cycle even with no tasks in flight
ok - auto-arm: concurrent firings admit one owner and one rewake translation
ok - auto-arm: need vanishing mid-cycle closes without a rewake
ok - auto-arm: mid-cycle AFK hands triage to the daemon with no rewake
ok - auto-arm: active in a marked secondmate home
ok - fm-lock: shared session-lock lib preserves the status path
FM_TEST_END 2026-07-29T19:57:39Z tests/fm-claude-stop-autoarm.test.sh exit=0 duration_ms=70236 gate_skip=false
FM_TEST_SUMMARY total=1 failed=0 skipped_gate=0 duration_ms=70408
FM_TEST_SUMMARY_FAMILY family=unclassified count=1 duration_ms=70236 failed=0
FM_TEST_SLOWEST rank=1 script=tests/fm-claude-stop-autoarm.test.sh duration_ms=70236

Evidence: Harness regression tests

Surrounding harness-resolution and launch compatibility regression transcript.

FM_TEST_BEGIN 2026-07-29T19:59:56Z tests/fm-secondmate-harness.test.sh family=secondmate expected_gate_skip=none
ok - A1 fm-harness.sh secondmate resolves the fallback chain; crew mode unchanged
ok - C1 fm-harness.sh secondmate-model/secondmate-effort resolve the optional tokens; bare harness stays empty (backward-compat)
ok - pi-signed identity: authoritative launch selection distinguishes shared wrapper ancestry
ok - B1 propagate_inheritable_config: copy, idempotence, convergence, absence-mirror, exclusion, no-op, skip diagnostics
ok - B2 spawn: secondmate runs the secondmate harness; its home inherits declared config
ok - B3 spawn: an absent secondmate-harness falls back to the crew harness (backward-compat)
ok - B4 spawn: no config at all -> own harness and no propagation side effects
ok - B5 spawn: an explicit per-spawn harness arg overrides config/secondmate-harness
ok - B6 spawn: an unverified resolved secondmate harness is refused (guard intact)
ok - B5b spawn: FM_BACKEND wins over inherited config/backend
ok - B5c spawn: explicit --backend wins over FM_BACKEND and inherited config/backend
ok - C2 spawn: a bare harness-only secondmate-harness file launches with no model/effort flag (backward-compat)
ok - C3 spawn: config/secondmate-harness's model token threads --model into the launch and meta
ok - C4 spawn: config/secondmate-harness's model+effort tokens thread into the launch and meta
ok - C5 spawn: an explicit --model overrides config/secondmate-harness's model token; the file's effort token still applies
ok - C6 spawn: an explicit --effort overrides config/secondmate-harness's effort token; the file's model token still applies
ok - C7 spawn: an explicit --harness starts with clean model/effort defaults
ok - C8 spawn: an explicit --harness still honors explicit model/effort flags
ok - C9 spawn: the harness fallback chain still resolves with no tokens; crew/scout launches are unaffected by this feature
ok - B7 bootstrap sweep pushes, re-converges, and mirrors absence; never inherits secondmate-harness
ok - B8 bootstrap sweep propagates config even when the home's tracked files are already current
ok - B9 bootstrap sweep defers new inherited config until the home ignores it
ok - B10 bootstrap sweep with no inherited config is a config no-op and still fast-forwards
ok - B12b backend inheritance: present values and primary absence converge exactly
ok - B11 bootstrap sweep surfaces config propagation failures
ok - B11 bootstrap rereads completed config writes after partial propagation
ok - B12 config-push propagates via shared live discovery, reports items, rereads on change only, and does not fast-forward
ok - B13 config-push reports dirty, non-allowing, and invalid homes without failing warnings-only runs
ok - B14 config-push exits nonzero on real propagation errors
ok - B14 config-push rereads completed config writes after partial propagation
ok - B15 config reread is per-home, exact-byte, ordered, and pointer-only
ok - B16 config reread isolation, ABSENT, generation safety, send failure, and retry
ok - B20 config reread publication failures retain exact generations for retry
ok - B21 config reread instruction-write failures retain exact retry generations
ok - B21 config reread preserves exact bytes when temporary adoption also fails
ok - B21 config reread serializes concurrent propagation and delivery
ok - B22 full config reread retry queues drain before new publication
ok - B23 mixed config reread delivery failures still bound sent history
ok - B26 config reread delivery stops after the oldest failed generation
ok - B17 config reread skips unchanged homes and reads destination post-write bytes
ok - B18 bootstrap config reread path works; spawn flexibility remains defaults-only
ok - B19 bootstrap respawns before inherited-config reread
ok - B25 spawn quarantines stale rereads without blocking relaunch
ok - B24 bootstrap detect-only mode remains filesystem read-only
# all fm-secondmate-harness tests passed
FM_TEST_END 2026-07-29T20:03:26Z tests/fm-secondmate-harness.test.sh exit=0 duration_ms=210132 gate_skip=false
FM_TEST_SUMMARY total=1 failed=0 skipped_gate=0 duration_ms=210240
FM_TEST_SUMMARY_FAMILY family=secondmate count=1 duration_ms=210132 failed=0
FM_TEST_SLOWEST rank=1 script=tests/fm-secondmate-harness.test.sh duration_ms=210132

Pipeline

Updates from git push no-mistakes

✅ **intent** - passed

✅ No issues found.

✅ **Rebase** - passed

✅ No issues found.

✅ **Review** - passed

✅ No issues found.

✅ **Test** - passed

✅ No issues found.

• basename -zsh using native macOS BSD basename
• Base-commit bin/fm-harness.sh from 99533c5d with an exported ps probe returning comm=-zsh
• Target bin/fm-harness.sh with the same comm=-zsh probe
• bin/fm-test-run.sh tests/fm-claude-stop-autoarm.test.sh
• Manual Claude Stop-hook stale-owner flow using comm=-zsh, a BSD-failing basename shim, and persisted lock/arm/epoch inspection
• bin/fm-test-run.sh tests/fm-secondmate-harness.test.sh
• rg sweep of bin/**/*.sh for GNU-style basename/dirname options and process-command extraction sites
• git status --short --untracked-files=all

✅ **Document** - passed

✅ No issues found.

✅ **Lint** - passed

✅ No issues found.

✅ **Push** - passed

✅ No issues found.