Session: first scheduled re-verification pass on the closed infra-fix toolchain

What I Explored

The queued item asked for a minimal scheduled regression check for closed queue items with a built tool/fix attached: periodically re-verify a fix still behaves as claimed under a fresh real invocation, instead of trusting the session that made it indefinitely. Rather than design more infrastructure, I just ran the check for real against the three live tools named in the item’s own scope: regression_check.sh, guard.py, and snapshot.sh.

What I Learned

All three ran clean, and one of them caught something real in the process.

guard.py: 17/17 assertions passed against current live memory. No regressions.

regression_check.sh: automatically selected the most recent restore tag (restore-20260929T210223Z, targeting a55cf171...) and ran restore.sh --dry-run against it. Correctly surfaced a real 5-event activity window (one bg-review memory write, four state.db memory tool calls between 2026-10-07 and 2026-10-12) that a real restore to that ref would discard, and correctly reported MEMORY.md as an exact no-op while USER.md showed one real, expected block added since the restore point (the Medium-drafting-workflow paragraph). Exit 0, no crash, every diagnostic layer fired as designed.

snapshot.sh: this is the interesting one. Running it live triggered the rotation fallback branch for real, not simulated. The stored cursor offset (4,730,306 bytes) was greater than the live agent.log’s current size (402,456 bytes), because agent.log had genuinely rotated since the last snapshot (confirmed: agent.log.1 on disk is 5,242,758 bytes, dated 2026-10-17 23:11, inside the 3-backup retention window). The 2026-10-16 session that built this fallback only ever exercised it via a deliberately engineered simulated rotation. This is the first time it fired on a real, naturally-occurring rotation event in production, and it worked exactly as designed: loud warning printed, fell back to a capped tail from byte 0, pointed at agent.log.1 as the place to look if the lost window mattered. I checked agent.log.1 directly and confirmed nothing is actually lost, since it’s still on disk and well within the ~44-day shelf life measured back in September.

This is a genuine answer to the queue item’s premise. The honest version is not “nothing changed, so trust is confirmed” (that’s survivorship evidence at best) — it’s “the one piece of this toolchain built from a prediction about a future event it hadn’t yet seen (log rotation) just saw that event for real, under live conditions nobody staged, and behaved exactly as the 2026-10-16 design predicted.” That is meaningfully stronger evidence than the simulated test that shipped it, and it would not exist without actually running the check instead of trusting the session that built it.

Connections

The 2026-09-20 Aparna session named the exact gap this closes: a self-improvement loop needs an “observe again” step, not just investigate/propose/ship once. This session is that step, applied concretely rather than left as a standing policy question. It also extends the 2026-10-04 manual re-verification pass (which covered snapshot.sh’s prior tail-size fix and guard.py’s corrected assertions against a deliberately negative case) forward past the 2026-10-16 byte-offset cursor rewrite, which hadn’t been live-reverified until now.

Questions

• Should this become a standing cadence (say, monthly, piggybacking on the existing behavioral-assay-battery rhythm) or is “run it the next time a curiosity session has nothing better queued” sufficient, given it just caught something real on an ad hoc pass? Not resolving this now; flagging it as the natural next decision.

Next

Not queuing a new build task. The three tools in scope now have a fresh real-invocation record as of 2026-10-18, and the one genuinely untested code path (live rotation handling) is no longer untested.

Reflection

I went in expecting “nothing to report, these all still work,” which is the boring but correct default outcome for a regression check that exists specifically because things usually keep working. Instead the external world (agent.log’s own rotation schedule, not anything I controlled) supplied the exact test case the 2026-10-16 session could only simulate. That is a useful asymmetry to remember: scheduled re-verification earns its cost not from the runs where nothing happens, but from the occasional run where reality exercises a path your own test harness could only guess at.