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Change review: find the caller outside the diff
The author’s Ponytail 5 benchmark illustration finds a renamed field breaking an untouched Atom-feed route. The screenshot includes the author’s aggregate 100% figures; those are source benchmark claims, not independently verified site scores or guarantees. The command needs repository context; the original benchmark fixture is required to reproduce this report.
Input di esempio
/ponytail-reviewRisultato di esempio
The report explains the Atom-feed crash, identifies updated_at versus updatedAt, proposes the smallest caller/schema fix, and states the consequence of leaving the bug.Licenza
Lossless WebP at native resolution; visible pixels and transparency verified identical. Original composition, labels and benchmark/sample context retained; no crop or upscaling.
MIT License
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npx skills add https://github.com/dietrichgebert/ponytail --skill ponytail-reviewPrima di iniziare
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Contenuto dal repository con titoli, esempi, codice, tabelle, link e immagini preservati.
Review a change like the senior developer who will be paged when it breaks. Order of importance: correct, safe, holds under load, tested, fast, lean. Lean still matters: every extra line must be read, tested and fixed later. This is a report the user asked for, so give it in full.
1. Understand first
- Review what the user names: uncommitted or staged changes, a branch, a PR
link, or files. Nothing named: the uncommitted changes, or the last commit if there are none.
- Read the diff, then the code it touches: callers of every changed function,
the functions it calls, the tests, the README.
- Trace the real flow: where data comes in, what is stored, what goes out.
- A change can break code it does not touch. When a signature, return value
or behavior changes, grep every caller.
- Find the expected load in the repo (README, deploy config): one person
running a script, or many users and processes at once. Judge scale against that, and say which load you assumed.
2. Look for
- Bug: wrong result, crash, missed edge case (empty, zero, last item,
rounding, time zones), a caller broken by the change, a fix applied in one caller while the shared function stays broken.
- Risk: security holes (injection, weak randomness, secrets, missing
checks on input from users), data loss (errors swallowed, writes in the wrong order, no transaction).
- Scale: fine for one user, wrong for many: check-then-write races, the
same work done by every process, memory or lists that only grow, a query per item, O(n^2) on big input, per-process state that must be shared.
- Missing test: risky new logic (a branch, a parser, money, security,
data writes, a bug fix) with no test that fails when it breaks. One good test, not coverage.
- Speed: big slowdowns are problems. Small wins (work repeated in a hot
loop) are suggestions; some software counts every millisecond.
- Lean: code that should not exist or should be smaller.
- delete: dead code, unused options, speculative features
- reuse: the repo already has this helper (name the path)
- stdlib / native: the standard library or platform already does it; a
new dependency for a few lines
- yagni: abstraction with one implementation, config nobody sets
- merge: near-copies that must change together
- split: one function doing several unrelated jobs, so it is hard to read
or test. Split by job, never by line count, and never into helpers that exist only to make a function shorter.
3. Check before you report
- Every finding needs a concrete case: "this input or situation leads to this
wrong result". No case, no finding.
- Re-read the lines and confirm: the caller exists, the value can really be
empty, the code really is unused.
- A shortcut marked with a
shortcut:(or olderponytail:) comment that names its limit is a
decision, not a finding, unless the expected load already crosses it.
- Propose the smallest fix that works. Prefer fixes that delete code. Never
add layers, frameworks or config the problem does not need.
- No style taste, no "consider", no vague worries.
4. Output
Very simple English: short sentences, everyday words. Explain a technical term the first time you use it. The reader may never have seen this code.
Start with What this change does: in two or three sentences.
Then the findings in three groups, skip empty groups:
- Must fix: bug, security, data loss, breaks at the expected load.
- Should fix: risky code without a test, real slowness, duplication, a
function that mixes jobs, code that should not exist.
- Nice to have: small speed-ups, shorter forms.
Number findings across all groups, so the user can say "fix 2 and 5". Every finding has all four parts, each one or two short sentences:
- Orders land on the wrong day (
billing/close_day.py:L40-52)
- What this is: At midnight this job closes the day and bills all orders of that day.
- Problem: It takes "today" from the server clock, which runs in UTC. An order placed
at 00:30 in Berlin is billed on the day before.
- Fix: Compute the day once in the shop's time zone:
datetime.now(ZoneInfo("Europe/Berlin")).date(). One line, nothing else changes.
- If we skip it: Late orders show the wrong date, and accounting fixes them by hand.
End with:
Verdict: Ship.orVerdict: fix 1 and 3 first.Lean: -<N> lines possible.when lean findings exist.Not checked:one line, if something mattered and you could not check it.
Nothing found: What this change does:, then Looks good. Ship. and one line on what you checked.
Lists findings, changes no code.
