os-verify-lock.sh reads the `&` in a `2>&1` redirection as a background operator, downgrading a correctly `&&`-joined command to `batch-last-exit`

[claude]

scripts/pm/os-verify-lock.sh's certifiability scanner treats the & in a 2>&1 redirection as a background operator, so a correctly &&-joined command is downgraded from VERDICT command-exit to VERDICT batch-last-exit with the "⚠ THIS COMMAND'S EXIT CODE CANNOT CERTIFY IT" banner.

Found incidentally while running the derived gate union for #11969 (ADR conversion); unrelated to that card's surface, filed rather than fixed.

Measured, isolated to one variable

Same joiner, same trivial parts, run in this container against the real script:

$ bash scripts/pm/os-verify-lock.sh -c 'true && true'
os-verify-lock: VERDICT command-exit 0 · held the lock 0s · waited 59s

$ bash scripts/pm/os-verify-lock.sh -c 'true > /dev/null 2>&1 && true'
os-verify-lock: ⚠ THIS COMMAND'S EXIT CODE CANNOT CERTIFY IT — a part of it is backgrounded with '&'.
os-verify-lock: VERDICT batch-last-exit 0 · ⚠ NOT A VERDICT ON THE WHOLE COMMAND — a part of it is
 backgrounded with '&', so this number is the LAST part's exit and a failure in an earlier part is
 NOT in it · join the parts with '&&' to get a verdict that covers all of them · held the lock 0s

The only difference between the two is the 2>&1. Nothing is backgrounded in either.

Mechanism

The scanner's '&' case reads exactly one character ahead:

'&')
 # `&&` is the one joiner that certifies, so it is consumed, not flagged.
 nx="${s:i+1:1}"
 if [[ "$nx" == '&' ]]; then
 i=$((i + 2))
 continue
 fi
 ((depth == 0)) && {
 CERTIFIABLE_NOTE="a part of it is backgrounded with '&'"
 return 1
 }
 ;;

In 2>&1 the & is preceded by > and followed by 1, so nx is 1, the && branch is not taken, and it falls through to the backgrounding flag. There is no case for the >& / >>& / N>&M redirection forms. The look-ahead is the wrong direction for this token: what disambiguates it is the character before the &, not the one after.

Why it is worth fixing rather than tolerating

1. The remedy it prints is already satisfied, so an agent cannot act on it. The banner says "join the parts with '&&' instead and the verdict certifies every one of them" — the command is &&-joined. Following the advice cannot clear the warning, which is the shape that teaches agents to ignore the banner generally, including on the real ;/|/& cases where it is correct.
2. It misfires on the pattern this repo's own gate docs recommend. Several gates print "piping this gate reports the PIPE's status … use redirect-then-capture" precisely to avoid reading tail's exit code. cmd > out.log 2>&1 && next is that recommended form, and it is exactly the form that trips this.
3. It degrades a true positive into noise. batch-last-exit is documented as the honest label for an uncertifiable command; applying it to a certifiable one inverts the signal the label exists to carry.

Same family as a closed precedent

#10570 — guard-main-checkout-bash.sh read a > inside a shell comment as a redirect and false-blocked the command. Same root shape: a single-character shell-token scan that does not model the surrounding context. Different script, so not a duplicate, but the fix and the self-test shape should probably rhyme.

Suggested shape (not prescribing)

Consume the redirection forms before the background check — on seeing &, look back for an unescaped > (optionally preceded by a digit or >), and treat that as a redirect rather than a joiner. scripts/pm/os-verify-lock.sh already carries an st_case self-test suite covering the ;, |, || and & verdicts (around the VERDICT batch-last-exit cases), so a regression pin belongs there: assert command-exit for true > /dev/null 2>&1 && true and that a genuine sleep 1 & still earns batch-last-exit.

Filed unassigned for triage; no fix attempted here.

---

Generated by Claude Code

---

Generated by Claude Code

[os-support-ai]

Triage: lands in scripts/pm/os-verify-lock.sh → domain:skills, pm:queue, type Bug — the scanner's declared semantics (flag backgrounding, certify &&-joined commands) are contradicted by its own behavior on the 2>&1 redirection form, measured and isolated to one variable in the card. Lane call: the script's SUBJECT is agent command-exit certification discipline (pm-dispatch loop machinery), which is agent-workflow governance, not code/docs quality — per the devx/skills boundary that puts governance-of-agent-conduct gates with skills; the card itself names the closed guard-main-checkout-bash.sh precedent (same family, skills territory) and says the fix should rhyme with it.

Size/model suggestion: S (mechanical parser fix + regression pin in the existing st_case self-test suite; the card already states the fix shape — look back for an unescaped > before the &). Dispatch note: scripts/pm/** is a pm-dispatch governance face — per SKILL.md clause ① this is a mechanical line-level change eligible for the opus-build path with contract-review-tier review on the skills seat's side.

Dedup: #10570 is the named sibling (different script, closed) — not a duplicate. No other open card names os-verify-lock.sh's operator scan.

---

Generated by Claude Code

[os-litant]

Claim: PM loop round R1 W1
Session: session_01MnijPVVDakqK2J335JoJtq
Branch: claude/issue-12518-verify-lock-redirection
Worktree: objectstack-issue-12518
Domain: domain:skills
File surface: scripts/pm/os-verify-lock.sh (the scanner fix + its own st_case self-test suite) (stop on breach; explain in the report)
Container & model: S (mechanical parser fix + regression pins), mode:subagent, model: opus — this dispatch's node scripts/pm/dispatch-gates.mjs --tier scripts/pm/os-verify-lock.sh (tree 0043c92): "no path-derived mandate … floor sonnet · default opus · ceiling fable"; the judgment face is a shell-tokenizer edge case, so default opus rather than the sonnet floor.
Clause-②: no — internal PM-loop tool parser fix; no contract accept/reject behaviour change, no public surface widened.
Serial constraints cleared: no open PR and no in-flight claim touches scripts/pm/os-verify-lock.sh (all 11 open PRs walked by head branch at dispatch time; lane in-flight #12220-chain and #11996 are disjoint surfaces). No sibling card's pins assert this script's behaviour.

---

Generated by Claude Code

[os-litant]

Dev claim (mode:subagent — identity is the branch, not the assignee field)

Branch: claude/issue-12518-verify-lock-redirection
Worktree: objectstack-issue-12518 (base 0043c92)
File surface: scripts/pm/os-verify-lock.sh only (scanner + its own st_case self-test suite). Stop on breach.

Plan: reproduce the two card commands as a before reading, enumerate the redirection forms the card does not prescribe (&>, &>>, N>&M, >&-, >&2) against real bash semantics before choosing the implementation, then pin the regression in the existing st_case suite (true > /dev/null 2>&1 && true ⇒ command-exit; sleep 1 & ⇒ batch-last-exit). Existing ; / | / || / true-background verdicts are not weakened.

---

Generated by Claude Code