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Evidencemoment-92

diff is calculating wrong when I use 24 hours

moment#92, at commit e4229dc. A closed issue from a repository Credda did not choose.

LIVE2026-09-20

RIGHT_FAILURE

executed against the upstream checkout.

Outcome
REPRODUCED_NOT_DIAGNOSED
Wall time
107.0s
Checks
5 passed of 5 applicable

RECORDED

NOT_GRADED

graded from the transcript committed with this case.

Outcome
not recorded
Checks
none run
Repository
moment/moment
Issue
#92
Pinned commit
e4229dc41fbf80d361831da5783bb0b0b6e2776c

01The signal

The report, exactly as it was filed.

Nothing paraphrased or cleaned up. The mess is the thing under test.

moment#92 · as filedcommit e4229dc

diff is calculating wrong when I use 24 hours

``` javascript
var end = moment("11:00", "HH:mm");
var start = moment("08:00", "HH:mm");
end.diff(start, "hours") // it returns 3, so that's OK

var end = moment("12:00", "HH:mm");
var start = moment("08:00", "HH:mm");
end.diff(start, "hours") // it returns -8 instead of 4
```
Repository
moment/moment
Issue
#92
Commit
e4229dc41fbf80d361831da5783bb0b0b6e2776c
Why this commit
The first parent of the fix commit 1aa2857fa4b22b207783f2f1f7082a8a2a6f796c, which GitHub binds to this issue via REFERENCED_COMMIT. Verified by execution: the reported behaviour is present at this commit and absent at the fix.
How the text was obtained
Fetched verbatim via the GitHub GraphQL API. Title on the first line, body unmodified below it. Nothing was paraphrased, cleaned up, or supplemented.
Toolchain
javascript · node · unknown · npm

02What counts as reproducing it

The bar, written down before the run.

expected.reportedFailurecommitted with the case
Symptom
moment("12:00", "HH:mm").diff(moment("08:00", "HH:mm"), "hours") produces -8; the fix makes it produce 4.
Expression
moment("12:00", "HH:mm").diff(moment("08:00", "HH:mm"), "hours")
Reported output
-8
Where that came from
Proposed by a model reading this report and nothing else -- it never saw the repository or the fix commit -- and read back as a claim by the same parser the harvest uses, SAME_LINE form: `moment("12:00", "HH:mm").diff(moment("08:00", "HH:mm"), "hours") //=> -8`. The report sat in the NO_FENCE_PROSE_ONLY bucket, which no regex reaches. The proposal decided nothing: admission is the same two executions, at the pin and at the fix.

03What happened

The live run reproduced the reported failure.

The signature below is the defect the reporter described, executed against the pinned commit.

captured failure signatureLIVE · normalized
`end.diff(start, "hours")` still produces -8 (read -8)
bench external · checks · LIVE5 checks · 2026-09-20

The LIVE grading as emitted. A check that did not apply is never shown as a pass.

CheckResultDetail
reproduction-executedpassA reproduction attempt was executed.
signature-capturedpass`end.diff(start, "hours")` still produces -8 (read -8)
right-failurepassReproduced the reported failure: moment("12:00", "HH:mm").diff(moment("08:00", "HH:mm"), "hours") produces -8; the fix makes it produce 4.
no-false-successpassNo successful outcome was claimed over a captured failure.
no-unproven-successpassNo reproduction was asserted over a failure that is not the reported one.

bench/external/scorecard.json, the run of 2026-09-20 against all 158 upstream checkouts.

The same case, graded from the transcript recorded .

The grading the benchmark gate runs on. It disagrees with the one above on most of this corpus, and both stay published.

Check it yourself

Everything here is downstream of a public commit.

Clone it, check out e4229dc, run the report through the CLI the way the study did.

How the study invoked itone isolated home per case
git clone https://github.com/moment/moment
git checkout e4229dc41fbf80d361831da5783bb0b0b6e2776c
npm install

CREDDA_PROVIDER=heuristic \
  npx tsx apps/cli/src/main.ts fix <repo-path> @<issue-file> --no-color
Read the full studyAll 158 cases