fix(coding-agent): stabilize daemon process identity across timezone changes

[sethkarten]

Context

Fixes #879.

Prime Agent 0.9.1 still stores the raw output of ps -o lstart= as the macOS/BSD process identity. For the same live supervisor, macOS rendered Sat Aug 29 13:55:18 2026 in America/Los_Angeles and Sat Aug 29 16:55:18 2026 after switching to America/New_York. The durable owner comparison then reported supervisor_generation_stale, and new session creation timed out after 30 seconds.

This revives the still-unmerged timezone fix from #908 against current main and includes the locale pinning discussed in #1234 and #1607.

Changes

• Run only the portable ps -o lstart= fallback with TZ=UTC and a fixed C locale while preserving the rest of the caller environment.
• Keep the Linux /proc and Windows UTC-tick identity paths unchanged.
• Add a deterministic regression that changes the caller timezone from America/Los_Angeles to America/New_York and verifies both probes receive the same UTC identity.
• Add the coding-agent changelog fragment.

This is backward-compatible at the daemon protocol level: no command, event, capability, or response shape changes, and processStartId remains an optional opaque string. Pre-fix ps: owner records created outside UTC cannot be safely normalized because they contain no offset; a daemon that predates this change may need one session-preserving restart to refresh its durable record.

Validation

• npx tsx ../../node_modules/vitest/dist/cli.js --run test/suite/regressions/879-timezone-stable-process-identity.test.ts — 2 passed, including a real Darwin supervisor ownership check across the timezone change. The deterministic identity assertion failed before the implementation (expected "ps:Sat Aug 29 20:55:18 2026", received undefined).
• Source probe with process.env.TZ changed from America/Los_Angeles to America/New_York — both returned ps:Tue Sep 1 22:23:57 2026 (stable: true).
• npm run check — passed with no warnings or errors.

---

Note

Low Risk
Narrow change to macOS/BSD process identity probing for daemon leases; no protocol or API shape changes, with minor risk that old non-UTC ps: owner records mismatch until restart.

Overview
Fixes daemon session creation failing after macOS timezone changes (#879). The portable ps -o lstart= fallback for process identity was using the host timezone, so the same supervisor PID could get different ps: processStartId values and durable ownership checks treated the supervisor as stale.

getPsProcessStartId now runs that query with TZ=UTC and a fixed C locale (LC_ALL, LC_TIME, LANG), via an optional env on runProcessQuery. Linux /proc and Windows tick identities are unchanged.

Adds a regression test (mocked ps plus Darwin supervisor ownership across a TZ switch) and a changelog fragment. Pre-fix ps: records without UTC normalization may need one restart to refresh stored identity.

^{Reviewed by Cursor Bugbot for commit 99611ab. Bugbot is set up for automated code reviews on this repo. Configure here.}

Note

Fix getProcessStartId to pin UTC/C environment in ps fallback

• Adds getPsProcessStartId in session-lease.ts, which forces LC_ALL, LC_TIME, LANG to C and TZ to UTC in the ps subprocess so the lstart field is stable across caller timezone or locale changes.
• Extends ProcessQuery and runProcessQuery to accept an optional env parameter so callers can pin subprocess environment variables.
• Reworks the POSIX fallback in getProcessStartId to delegate to getPsProcessStartId instead of issuing an inline ps command.
• Adds a regression test in 879-timezone-stable-process-identity.test.ts verifying identical identifiers across timezone changes on macOS.
• Behavioral Change: non-win32 platforms without /proc now derive the process start ID from a ps subprocess with a pinned UTC/C environment rather than inheriting the caller's locale and timezone.

^{Macroscope summarized 99611ab.}

Linear

• RES-1243