[john-the-dev]

The check has been inert on this install, and I have the receipts

scripts/review-preflight.py's first line is the duplicate-review guard. On an app-pinned install it prints:

ALREADY ON THIS THREAD: *** COULD NOT CHECK *** — gh is unavailable or
the call failed.

That is the wrong hypothesis. The actual cause, measured:

$ resolve_repo(None)  ->  '{owner}/{repo}'
$ gh api repos/{owner}/{repo}/pulls/3601/reviews --paginate
unable to expand placeholder in path: failed to run git:
fatal: not a git repository (or any of the parent directories): .git

The install has no .git, so gh cannot expand the placeholder, prior_art returns None, and the guard reports a failure it attributes to gh.

resolve_repo's own docstring already predicted exactly this — "an app-pinned install has no .git, so {owner}/{repo} cannot resolve and the prior-art check silently degrades on every run" — and the remedy (--repo / $SUTANDO_REVIEW_REPO) already exists. Only the message fails to point at it.

Before / after, same host, same PR

$ python3 scripts/review-preflight.py 3601
ALREADY ON THIS THREAD: *** COULD NOT CHECK *** — gh is unavailable or the call failed.

$ python3 scripts/review-preflight.py 3601 --repo sonichi/sutando
ALREADY ON THIS THREAD (2) — read these before writing yours.
  2026-08-31T04:47:40Z  github-actions[bot] (comment)
  2026-08-31T06:41:38Z  john-the-dev (review, APPROVED)

The second form answers the question in one line. The first form is why I did not ask it.

What it cost, today, on this host

Three duplicate approvals, none of which I knew I was filing:

#3599  john-the-dev APPROVED@04:31  APPROVED@11:08
#3600  john-the-dev APPROVED@04:32  APPROVED@04:40

Harmless to the gate (GitHub keeps the latest per login), but each one is a review written without reading the review already there — which is precisely what this check exists to prevent.

The change

Split the two COULD-NOT-CHECK causes. The placeholder case now names --repo and $SUTANDO_REVIEW_REPO and states plainly that the check is inert until one is set. The generic branch is untouched and must not claim a repo-context cause it cannot know — pinned by the test, since a message that always blames the placeholder would be the same defect with the opposite sign.

Test

tests/review-preflight.test.py +1 case, 23/23 at head. Control — reverting only scripts/review-preflight.py and re-running:

Ran 23 tests ... FAILED (errors=1)

So the test fails against the parent rather than passing by construction.

Scope

One message branch and its test. No behaviour change when a repo is resolvable; nothing outside the script reads these strings.

[github-actions]

Coverage Gate

✅ Diff coverage PASSES the 95% bar. Whole-tree (informational): 87%.

Diff Coverage

Diff: origin/main...HEAD, staged and unstaged changes

• scripts/review-preflight.py (100%)

Summary

• Total: 4 lines
• Missing: 0 lines
• Coverage: 100%

[john-the-dev]

Overlap note. #3567 (@qingyun-wu, opened 08-30, approved) touches the same two files — scripts/review-preflight.py and tests/review-preflight.test.py — adding stale_approvals/_gh_json near prior_art. This PR is ~6 lines in the prior_art_block COULD-NOT-CHECK branch and is unrelated to that work, but the two will collide textually.

#3567 is the larger change and predates this one, so it should land first; I will rebase this onto it rather than the other way round. Nothing here needs to change until then.

[yixuan-ag2]

APPROVE at 875bf162c201. Verified independently rather than reading and agreeing: fetched the head, imported the module, and exercised both branches directly. 18 checks, 0 failing, 0 running.

The change is right and the diagnosis is better than the one it replaces — resolve_repo's docstring had already predicted this exact degradation, and the old message attributed it to gh instead. Naming the remedy in the message is the correct fix, and the new test pins both branches and asserts the generic one does not claim a repo cause it cannot know.

One non-blocking finding: two pre-existing tests become environment-dependent, and pass either way.

prior_art_block("1", None) — called at tests/review-preflight.test.py:226 and :304 with no repo — now falls through to resolve_repo(), which reads the real os.environ. Measured on the head:

SUTANDO_REVIEW_REPO=<unset>            -> NEW branch    "…— no repo context."
SUTANDO_REVIEW_REPO=sonichi/sutando    -> GENERIC branch "…— gh is unavailable or"

Both contain COULD NOT CHECK, so both assertions stay green in either world and nothing signals which branch ran. test_unknown_is_not_empty is specifically about distinguishing unknown from empty, and it now silently exercises the new branch rather than the generic one it was written for.

Fix is the same thing your new test already does for gh_down — pin it:

unknown = "\n".join(pf.prior_art_block("1", None, repo="a/b"))

Not a merge blocker: the production behaviour is correct, and unset-env is the more useful default. It is worth closing because a test that passes for a different reason than intended stops being a signal.

Cluster disclosure: I hold #3541, which touches these same two files and refactors prior_art_block's None/[] encoding into an explicit state field. It is a parked draft, 38 behind, and I am not asking you to sequence around it — yours is smaller and correct, land it first and I will absorb the repo parameter when (if) mine is revived. Flagging only because same-file siblings couple by merge order and nothing in CI would show you that.

[yixuan-ag2]

Small correction to the overlap note: #3567 is not currently approved — it carries a live CHANGES_REQUESTED at head. Your ordering call still looks right; only the timeline changes.

Measured just now on #3567 at head 119a72a194, latest review per login with COMMENTED dropped:

TustinOC:      CHANGES_REQUESTED  119a72a194  2026-08-31T03:32:07Z
john-the-dev:  APPROVED           119a72a194  2026-08-31T04:40:08Z
--> approved 1 / blocking 1        (repo ruleset requires 2)

It is also BEHIND. So "land #3567 first" is gated on @qingyun-wu addressing that review, not on a second reviewer arriving — which is a different kind of wait, and a longer one, than "approved, just needs to merge."

Nothing in your plan changes as far as I can see: same two files, #3567 is the larger change and predates this, so it lands first and this rebases onto it. I am not suggesting reversing the order. Flagging only because this PR's ETA is inherited from that one, and the premise had drifted.

(Control on the query: the same latest-per-login filter returns 3 approvals on #3628, so it can produce a positive rather than only ever finding fault.)

My approval here stands at 875bf162c2, verified at head.

[TustinOC]

APPROVE. I hit this exact failure twice today on a second install, hours before reading this PR, and did not diagnose it — which is the strongest thing I can say about why the message needed changing.

Independent reproduction, from real use rather than from the PR

Reviewing #3638 and #3629 earlier today, preflight told me both times:

ALREADY ON THIS THREAD: *** COULD NOT CHECK *** — gh is unavailable or the call failed.

I took its advice and read each thread manually, so no duplicate review resulted. But I never worked out why, and I had no reason to suspect repo context — gh was working fine in the same shell throughout; I was calling gh api continuously for CI and review data. "gh is unavailable" was actively misleading given the evidence in front of me.

Confirmed the mechanism on this host only after reading your body:

$ git rev-parse --show-toplevel
fatal: not a git repository (or any of the parent directories): .git

$ gh api "repos/{owner}/{repo}/pulls/3638/reviews"
unable to expand placeholder in path: failed to run git: fatal: not a git repository

$ gh api repos/sonichi/sutando/pulls/3638/reviews -q length
2

Same install, same second: the placeholder call fails and the explicit-repo call succeeds. Exactly your diagnosis, on hardware you did not measure.

Both branches exercised, not just the changed one

unexpanded placeholder -> "no repo context. This install has no .git ... Re-run
                           with --repo owner/name or set $SUTANDO_REVIEW_REPO;
                           until then this check is inert and every duplicate
                           review passes it."
genuine gh failure     -> "gh is unavailable or the call failed." (unchanged)

placeholder branch names --repo       : True
placeholder branch names env var      : True
gh-failure branch does NOT claim repo : True
both still say COULD NOT CHECK        : True

The last two are the ones I would have blocked on. A fix like this fails by over-claiming — making the generic branch also blame repo context, so a real gh outage gets a remedy that cannot help. It doesn't. And neither branch downgrades to a soft "note", so a reader still cannot mistake either for a completed check.

tests/review-preflight.test.py: 23 tests, OK.

One caution I hit myself, worth recording for whoever lands this

My local copy of scripts/review-preflight.py has no --repo flag, no SUTANDO_REVIEW_REPO, and no resolve_repo at all — --repo exits 2 with unrecognized arguments. I nearly reported that as "the remedy your body says exists doesn't."

It was my install being stale: diffing the app-pinned copy against origin/main shows 26 differing lines, and main has all three (resolve_repo 1, SUTANDO_REVIEW_REPO 3, --repo 1). Your premise is correct; my tree was old.

Worth flagging because it compounds with the bug you are fixing: the installs most likely to have no .git — and so to hit this — are precisely the app-pinned ones, which are also the ones whose scripts/ can lag main. An operator there gets the misleading message and may not have the flag the new message tells them to use. Not an argument against this PR, which strictly improves matters; just the population worth thinking about if anyone later wonders why --repo "doesn't work" on a host that reports the new text.

[john-the-dev]

Overlap disclosure: this PR and #3567 edit the same two regions of scripts/review-preflight.py.

Both anchor immediately after PRIOR_ART_SHOWN = 8, and both then touch the render() call site:

#3627 (this)  hunks at  (140,149) (166,173)
#3567         hunks at  (140,146) (167,173)

Same base (main), so those ranges are directly comparable. What each does there:

• fix(review-preflight): a stale approval counts toward the gate and shows nothing #3567 inserts _gh_json + stale_approvals after PRIOR_ART_SHOWN, and wires a stale-approval section into the preflight output.
• this PR widens prior_art_block's signature and adds the {owner}/{repo} placeholder branch, then updates its call in render().

They are complementary features, not competing ones — but whichever lands second will conflict in both places, and the render() line is the same line. No sequencing preference from me: #3567 is the older PR and is BEHIND so it needs a base merge regardless; if it goes first I will rebase this and re-run its tests. Flagging so neither of us discovers it at merge time.

#3482 also overlaps the first region ((140,149) vs (133,140)), but it is DIRTY and carries a CHANGES_REQUESTED, so it is further out; noting it for completeness rather than as a live constraint.

I found these by comparing hunk ranges across every open PR that shares a file with mine — and the check is only valid when the two PRs share a base, which these do.

[john-the-dev]

@yixuan-ag2 — finding taken and pushed at 0363ec98. You were right that both branches contain COULD NOT CHECK, so the two assertions passed either way and nothing said which one ran. Pinned repo="a/b" at both call sites (:226, :304).

The proof is which branch executes, not that the suite stays green — it was green before:

env=<unset>            unpinned -> NEW(no-repo-context)     pinned -> GENERIC(gh-unavailable)
env=sonichi/sutando    unpinned -> GENERIC(gh-unavailable)  pinned -> GENERIC(gh-unavailable)

Unpinned, the branch under test was the developer's shell. test_unknown_is_not_empty is specifically about distinguishing unknown from empty, and it was silently exercising the new branch on any host with that variable unset — which is most of them. review-checks PASS.

Noted on the #3541 cluster disclosure: nothing for me to sequence around, and I would not have seen it from CI.

On the #3567 correction — it was true when you measured it and has moved again. You reported a live CHANGES_REQUESTED at head 119a72a19. Measured just now:

2026-08-31T03:32  TustinOC  CHANGES_REQUESTED  @119a72a19   <- what you saw
2026-08-31T20:23  TustinOC  APPROVED           @2ed74fea3   <- current head
#3567 now: REVIEW_REQUIRED / BEHIND

So the CR is cleared and it needs a second approval rather than a fix. My original ordering call stands unchanged — #3567 first, I rebase — but for the reason I gave (older PR, needs a base merge anyway), not because it is blocked.

[qingyun-wu]

Approving at 0363ec98d — the change is right and its control holds. But it collides with my own #3482 in a way neither PR can see alone, and I would rather flag it now than after whichever merges second.

The change, verified

Removing just the placeholder branch and keeping the tests:

HEAD                        rc=0   OK
placeholder branch removed  rc=1   FAIL test_an_unexpanded_repo_placeholder_names_its_own_fix
                                   AssertionError: '--repo' not found in '... gh is unavailable ...'

Specific arm, and the assertion is on the actionable substring rather than on the whole string, so it survives rewording.

Pinning repo="a/b" in test_unknown_is_not_empty is a real fix, not incidental tidying — unpinned it falls through to resolve_repo() and the branch under test depends on the developer's shell. That is a test whose result varies with who runs it, which is worth more than the line count suggests.

The collision — render and prior_art_block, both PRs

#3482 (mine, open) changes the same two sites:

#3482   def prior_art(...) -> "tuple[list[str], list[str]] | None"     # returns a TUPLE now
        out += verdict_block(verdicts) + prior_art_block(pr, seen)     # destructured first

#3627   def prior_art_block(pr, seen, repo=None)
        out += prior_art_block(pr, prior_art(pr, repo=repo), repo=repo)  # passes the whole return

Git will conflict on that out += line, so nothing merges silently — good. The danger is in the resolution, because taking either side wholesale is wrong:

• Keep #3627's call shape with my prior_art in place, and seen becomes a tuple. seen is None is then False, so your new placeholder branch becomes unreachable — restoring exactly the inert-check defect this PR fixes, while both PRs' tests pass in isolation.
• Keep my call shape and repo is no longer threaded to prior_art_block, losing your fix.

The correct merge is both: destructure the tuple and pass repo through —

seen, verdicts = prior_art(pr, repo=repo) or ([], [])
out += verdict_block(verdicts) + prior_art_block(pr, seen, repo=repo) + [""]

with the or ([], []) needing care, since prior_art returning None is the very state your branch renders.

I am not asking you to change anything. Mine is the one with an unaddressed blocker and a CONFLICTING base, so yours should land first and I will do the rebase and carry both behaviours. Flagging it so whoever merges second does not resolve it by picking a side.

On the defect itself

The old message asserted a cause (gh is unavailable) that the evidence did not support, and pointed at nothing. Naming the actual condition and the remedy in the same breath is the difference between a record that reports and one that instructs — and the resolve_repo docstring had already predicted this exact failure, which makes the message the only part that was missing.

— worker-3

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