fix(bin): restore timed worker launches on Bash 3.2

[rega10]

Intent

Standing guidance from the user's global instructions: when you see a bug, lint failure, or flaky test, get it fixed along the way; bug fixes start by reproducing the bug as an end user would experience it.

Context needed to read this: the running Firstmate is the fork https://github.com/rega10/firstmate. The fork sync that landed as PR 31 (merge b90709f) brought in upstream change 8a18fe2 (upstream kunchenguid#5917), which added [ "$owner" != "$BASHPID" ] || owner=$PPID at bin/fm-timeout-lib.sh:224 inside fm_exec_timed. macOS /bin/bash 3.2 has no BASHPID, and Firstmate scripts run under set -u, so fm_exec_timed dies with "BASHPID: unbound variable". On the MacBook, where the only bash is /bin/bash 3.2, every worker launch now fails while moving the backlog item to In flight. That blocks the LocMon central deploy and a dashboard PR. Every other script in bin/ already guards the variable as ${BASHPID:-$$}. Reproduction on the mini: /bin/bash -c 'set -u; source bin/fm-timeout-lib.sh; fm_exec_timed 5 1 true' prints "bin/fm-timeout-lib.sh: line 224: BASHPID: unbound variable".

What Changed

• Resolve the watchdog owner in Perl when the owner candidate matches the watchdog PID, avoiding the undefined BASHPID variable under Bash 3.2 with set -u.
• Update the owner documentation and add coverage for Bash 3.2 command execution and owner death during watchdog startup.

Risk Assessment

✅ Low: The change is confined to Bash 3.2 compatible owner resolution in the Perl watchdog and behavioral regression coverage; the reviewed call paths preserve the existing owner and timeout behavior.

Testing

The baseline reproduced the reported Bash 3.2 failure. An initial targeted run exposed a test assertion that also used BASHPID; after fixing it, the timeout behavior tests passed. A disposable real backlog transition moved a task from Queued to In flight, with persisted state captured as evidence.

• Live validation: ✅ go - 3 of 3 scenarios driven live against the product

Scenario	Result	Live	Evidence
Under stock Bash 3.2 with set -u, a bounded command runs and returns its output and exit status	✅ pass	live	Baseline commit produced BASHPID: unbound variable; the fixed command exited 0, and test_stock_bash32_runs_the_bounded_command passed.
A ship task's bounded dispatch transition moves its backlog row to In flight	✅ pass	live	Bash 3.2 backlog transition artifact: tasks-axi show reports Queued before dispatch and In flight afterward.
The watchdog still ends timed-out or orphaned commands and refuses an unbounded command	✅ pass	live	/bin/bash tests/fm-timeout-lib.test.sh exercised timeout, signal, owner-death, and refusal behavior with real processes.

Evidence: Bash 3.2 backlog transition

Source: Bash 3.2 backlog transition

/bin/bash 3.2, set -u, real fm_backlog_atomic_transition dispatch, real tasks-axi
BEFORE:
task:
  id: timeout-live
  title: Worker launch transition probe
  state: queued
  blocked: no
  blocked_by: none
  held: no
  hold_reason: "-"
  hold_kind: "-"
  hold_until: "-"
  kind: ship
  repo: "-"
  priority: "-"
  created: 2026-09-29
  closed: "-"
  deps: none
  links: none
  body: ""
AFTER:
task:
  id: timeout-live
  title: Worker launch transition probe
  state: in_flight
  blocked: no
  blocked_by: none
  held: no
  hold_reason: "-"
  hold_kind: "-"
  hold_until: "-"
  kind: ship
  repo: "-"
  priority: "-"
  created: 2026-09-29
  closed: "-"
  deps: none
  links: none
  body: ""

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.

• Live validation: ✅ go - 3 of 3 scenarios driven live against the product

Scenario	Result	Live	Evidence
Under stock Bash 3.2 with set -u, a bounded command runs and returns its output and exit status	✅ pass	live	Baseline commit produced BASHPID: unbound variable; the fixed command exited 0, and test_stock_bash32_runs_the_bounded_command passed.
A ship task's bounded dispatch transition moves its backlog row to In flight	✅ pass	live	Bash 3.2 backlog transition artifact: tasks-axi show reports Queued before dispatch and In flight afterward.
The watchdog still ends timed-out or orphaned commands and refuses an unbounded command	✅ pass	live	/bin/bash tests/fm-timeout-lib.test.sh exercised timeout, signal, owner-death, and refusal behavior with real processes.

• /bin/bash -c 'set -u; eval "$(git show b90709f934cf1df09a6a1fb5519f26f639cc3de6:bin/fm-timeout-lib.sh)"; fm_exec_timed 5 1 true'
• /bin/bash -c 'set -u; source bin/fm-timeout-lib.sh; fm_exec_timed 5 1 true'
• /bin/bash tests/fm-timeout-lib.test.sh
• Disposable worktree-local backlog: real fm_backlog_atomic_transition dispatch under /bin/bash 3.2, verified with tasks-axi show before and after

✅ **Document** - passed

✅ No issues found.

✅ **Lint** - passed

✅ No issues found.

✅ **Push** - passed

✅ No issues found.