[finding] check:objectui-changeset --self-test cannot run on macOS: bump-objectui.sh uses the bash-4 `mapfile` builtin

[os-zhuang]

Found while running the derived gate families for #11770 (PR #12070). Out of that card's scope, filed rather than fixed.

pnpm check:objectui-changeset cannot run on macOS. Its --self-test shells out to scripts/bump-objectui.sh, which uses mapfile at lines 324 and 327:

 mapfile -t local_refs < <(
 mapfile -t remote_refs < <(

mapfile is a bash 4 builtin. macOS ships GNU bash, version 3.2.57(1)-release as /bin/bash (Apple has not shipped bash 4+ for licensing reasons), so every self-test case that reaches that code path dies with:

scripts/bump-objectui.sh: line 324: mapfile: command not found

and the gate ends ⛔ objectui-changeset-digest --self-test: 7 failure(s), exit 1 — with status=127 (command-not-found) on two of them, i.e. the script never ran the logic those cases exist to pin.

Measured on a clean checkout of origin/main + a diff touching neither scripts/bump-objectui.sh nor .objectui-sha, so it is not a regression from any card: it is a host-portability gap. CI runs on Linux, where bash 5 provides mapfile, so the gate is green there and this is invisible to every PR.

Why it is worth recording rather than shrugging at: the pin-bump procedure in docs/releases-maintenance.md is run by hand, locally, and bump-objectui.sh is the script that runs it. On a macOS seat the branch-reachability warnings that #10495 added — "the pin you are writing is not on main", "this commit was never pushed" — are exactly the code that cannot execute. The self-test failing is the visible symptom; the operator-facing consequence is that the guard those cases pin does not fire for a maintainer bumping the pin from a Mac. The failure is loud in the self-test but the real path degrades at line 324 the same way.

Two candidate remedies (implementer judges, and the second may be enough on its own):

1. Replace mapfile -t x < <(cmd) with a bash-3.2-compatible read loop (while IFS= read -r line; do x+=("$line"); done < <(cmd)), which is what the rest of the script's idiom already allows.
2. Or make the incompatibility loud rather than silent: have bump-objectui.sh refuse up front on BASH_VERSINFO[0] -lt 4 with the remedy in the message, so a macOS operator is told to use /opt/homebrew/bin/bash instead of getting a mid-run command not found and a partially-applied pin.

No other gate in the derived set for #11770 failed; the remaining 18 were exit 0 on the same host.

[yinlianghui-tw]

Triage: finding → pm:queue + domain:devx, Task, S — lands in scripts/bump-objectui.sh (pin toolchain, devx per the lane table). The operator-facing half is what makes this queue-worthy rather than shrug-worthy: the pin-bump procedure is run by hand locally, and on a macOS host the #10495 reachability guards are exactly the code that cannot execute — a maintainer can apply a partially-guarded pin today. Do both remedies from the card: the bash-3.2-compatible read loop for the two mapfile sites, plus the loud BASH_VERSINFO[0] -lt 4 up-front refusal is then unnecessary — if the rewrite removes the last bash-4 dependency, prefer the rewrite alone and prove it by running the self-test under /bin/bash 3.2 semantics (or document why the guard is still wanted). Acceptance: pnpm check:objectui-changeset --self-test green on a bash-3.2 host (or an equivalent demonstration), unchanged on Linux.

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[yinlianghui]

Claim: PM seat domain:devx (objectstack), session af22b339-91b5-5814-8b9b-2453fc5b3f68.

• Branch: claude/issue-12071-bump-objectui-bash3-portability
• Worktree: dedicated per-task worktree off a fetched origin/main (Prime Directive Migrate documentation site to Fumadocs with monorepo structure and shared content #11)
• Domain: domain:devx
• Declared file surface: scripts/bump-objectui.sh, and scripts/objectui-changeset-digest.mjs only if the self-test needs a new case. Nothing else.
• Model tier: opus. Derived: node scripts/pm/dispatch-gates.mjs --tier scripts/bump-objectui.sh … → "no path-derived mandate … the tier stays the PM's per-card judgment call".
• Clause ② (contract review): no. A local operator script's shell portability. No shipped surface moves.
• Serial constraints: none. No open PR claims scripts/bump-objectui.sh; last touch on origin/main is e47d5ef61.

Scope note — this card is this seat's, and here is why

The title says objectui, but the fix lands in this repo's scripts/. The operative test is the landing repo, not the subject. You may read the objectui tree if you need to; you may not change anything in it. If your work starts wanting an edit over there, stop and report — that is a different seat's card.

Premise, re-verified on origin/main at the seat (re-measure in your worktree; do not inherit)

$ git show origin/main:scripts/bump-objectui.sh | grep -n 'mapfile'
324: mapfile -t local_refs < <(
327: mapfile -t remote_refs < <(

One correction to carry forward: the card names the gate as check:objectui-changeset, and the wiring is

"check:objectui-changeset": "node scripts/objectui-changeset-digest.mjs --self-test && node scripts/objectui-range.mjs --self-test"

There is no scripts/check-objectui-changeset.mjs — I looked for it and it does not exist. The half that shells out to bump-objectui.sh is objectui-changeset-digest.mjs (it copies the script into a fixture tree around line 1513 and invokes it at 1518). That is the file to read to understand how the self-test reaches line 324.

Zone 1 — rulings, not renegotiable

1. A fix you cannot demonstrate on Linux is not a fix. This is the crux of the card and the reason it is opus. CI runs bash 5, where mapfile exists, so the defect is invisible to every PR and so is your repair. A green CI run proves nothing here in either direction. You must produce evidence that survives that: run the affected path under a shell that actually lacks mapfile (a bash --posix-style constraint, a container with bash 3.2, or a harness that shadows the builtin), or add a static assertion that the script names no bash-4-only builtin. Say in the PR exactly which one you did and what it would have caught.
2. ⛔ Do not weaken the gate to make it pass. Deleting the self-test cases that reach line 324, or narrowing them to skip the shell-out, is the forbidden direction — it buys green by removing the instrument. The lane rule is that a gate whose self-description is false is worse than no gate.
3. The remedy is yours to choose from the card's two, or a third if you can defend it. But whichever you pick, the operator consequence the card names is the thing being fixed: a maintainer bumping the pin from a Mac currently loses the bump-objectui.sh writes the pin from local HEAD without asking whether that commit is on objectui main #10495 branch-reachability warnings silently, at line 324, mid-run. A fix that repairs the self-test but leaves the operator path degrading silently has fixed the symptom and not the defect.

Zone 2 — my assumptions. Falsify them; do not build on them

• I assume remedy (1) and remedy (2) are not exclusive, and that the honest answer may be both: the read-loop so the script works, and the up-front version refusal so a future bash-4-ism cannot reintroduce this silently. I have not costed either. Measure and decide; if you pick one, say why the other is unnecessary rather than just not mentioning it.
• I assume lines 324 and 327 are the only bash-4-isms in the script. I did not check. mapfile is the one the card found because it is the one that fired; readarray, declare -A, ${var^^}/${var,,}, and &>> are the usual companions. Sweep the whole script before you decide the population is two lines — and sweep the other shell scripts the same self-test reaches, because if this shape is repo-wide, that changes the card's size and I want to hear it before you fix it.
• I assume macOS /bin/bash 3.2 is the binding constraint and the card's measurement of it is right. I could not reproduce it — this seat is Linux. That is exactly why the ablation in Zone 1 ruling 1 matters: it is the only way either of us learns whether the fix works.
• I did not read bump-objectui.sh. If the source contradicts anything above, the source wins — report it and the card gets corrected.

Zone 3 — suggested route, take it or leave it

Read objectui-changeset-digest.mjs's self-test first to see how it invokes the script, then repair, then re-run pnpm check:objectui-changeset and quote its verdict line. The bash-3.2 read-loop the card sketches is idiomatic to the rest of the file, so it is likely the smaller half of the work; the demonstrable-on-Linux evidence is likely the larger half. Budget accordingly.

Report per the os-dev contract. Out-of-scope findings get filed, not fixed.

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