babysit classifier: count_classified counts stale pipe-row classifications from non-thread review-summary comments

[kyle-sexton]

Found by the control tower's merge digest of PR #634 (shared babysit classifier, #534).

count_classified in plugins/source-control/skills/babysit-prs/scripts/babysit_classify.py counts self-authored classification pipe-rows in ANY comment, including PR-level review-summary comments that are never thread-resolved. A stale classification posted outside a review thread keeps counting after its finding is discounted by the thread-state guard, so classified can be inflated past a fresh open finding — a fail-open path for READINESS_OK.

Requires a specific posting pattern (classification rows in non-thread comments), so lower likelihood than the truncation defect fixed on #634, but same gate surface and same failure direction. Candidate fix: only count pipe-rows that live inside review-thread comments, or apply thread-state discounting to the comment container before counting.

Related: #534, PR #634 (digest thread), #465 (open-state discount).

[kyle-sexton]

This was generated by AI during triage.

Triage (umbrella-fold) — found during the digest of PR #634 (closes #534), same babysit-classifier gate surface and fail-open direction as the truncation defect #634 fixed. count_classified counting stale pipe-rows from non-thread review-summary comments is the same shared-classifier-correctness class #534 exists to fix. Folding rather than routing standalone per the umbrella-fold rule.

Blocked by #534's decision. Not routed to needs-human individually.

[kyle-sexton]

Priority escalation + gate-off blocker designation (control tower, deferral-discipline audit 2026-07-20). This is the single live fail-open on main from today's merges: count_classified can credit stale pipe-row classifications posted outside review threads, letting babysit-readiness-gate emit READINESS_OK past a live unclassified finding. It reached main because Codex missed it at review (coverage gap, #618 class) — the human GATE-ON merge is the only current backstop. Per the ratified backstop clause: this must be fixed before the #476 gate-off flip; the flip is now contingent on it. Labeled priority: high. [Class B decide-and-log, operator veto window]