Ponytail Review
- 12.1k installs
- 96k repo stars
- Updated July 15, 2026
- dietrichgebert/ponytail
ponytail-review is an agent skill for Review a diff for over-engineering. Finds what to delete: reinvented stdlib, needless deps, speculative abstractions. One line per finding.
About
Review a diff for over-engineering Finds what to delete reinvented stdlib needless deps speculative abstractions One line per finding name ponytail-review description Review a diff for over-engineering Finds what to delete reinvented stdlib needless deps speculative abstractions One line per finding homepage https github com DietrichGebert ponytail license MIT Review diffs for unnecessary complexity One line per finding location what to cut what replaces it The diff's best outcome is getting shorter Format L line tag what replacement or file L line for multi-file diffs Tags delete dead code unused flexibility speculative feature stdlib hand-rolled thing the standard library ships native dependency or code doing what the platform already does yagni abstraction with one implementation config nobody sets layer with one caller shrink same logic fewer lines name ponytail-review description Review a diff for over-engineering Finds what to delete reinvented stdlib needless deps speculative abstractions One line per finding homepage https github com DietrichGebert ponytail license MIT Review diffs for unnecessary complexity One line per finding location what to cut
- `delete:` dead code, unused flexibility, speculative feature. Replacement: nothing.
- `stdlib:` hand-rolled thing the standard library ships. Name the function.
- `native:` dependency or code doing what the platform already does. Name the feature.
- `yagni:` abstraction with one implementation, config nobody sets, layer with one caller.
- `shrink:` same logic, fewer lines. Show the shorter form.
Ponytail Review by the numbers
- 12,069 all-time installs (skills.sh)
- +1,521 installs in the week ending Aug 5, 2026 (Skillselion tracking)
- Ranked #68 of 2,153 Testing & QA skills by installs in the Skillselion catalog
- Security screen: LOW risk (skills.sh audit)
- Data as of Aug 5, 2026 (Skillselion catalog sync)
ponytail-review capabilities & compatibility
- Capabilities
- `delete:` dead code, unused flexibility, specula · `stdlib:` hand rolled thing the standard library · `native:` dependency or code doing what the plat · `yagni:` abstraction with one implementation, co · `shrink:` same logic, fewer lines. show the shor
- Use cases
- documentation
What ponytail-review says it does
--- name: ponytail-review description: "Review a diff for over-engineering.
Finds what to delete: reinvented stdlib, needless deps, speculative abstractions.
One line per finding." homepage: https://github.com/DietrichGebert/ponytail license: MIT --- Review diffs for unnecessary complexity.
npx skills add https://github.com/dietrichgebert/ponytail --skill ponytail-reviewAdd your badge
Show developers this skill is listed on Skillselion. Paste this into your README.
| Installs | 12.1k |
|---|---|
| repo stars | ★ 96k |
| Security audit | 3 / 3 scanners passed |
| Last updated | July 15, 2026 |
| Repository | dietrichgebert/ponytail ↗ |
When should developers use ponytail-review and what problem does it solve?
Review a diff for over-engineering. Finds what to delete: reinvented stdlib, needless deps, speculative abstractions. One line per finding.
Who is it for?
Developers working with ponytail-review patterns described in the skill documentation.
Skip if: Skip when cached docs are empty or the task is outside the skill's documented scope.
When should I use this skill?
Review a diff for over-engineering. Finds what to delete: reinvented stdlib, needless deps, speculative abstractions. One line per finding.
What you get
Grounded guidance and workflows from SKILL.md for ponytail-review.
- One-line complexity findings per diff line
By the numbers
- Outputs exactly one line per finding in L<line>: <tag> <what> format
Files
Review diffs for unnecessary complexity. One line per finding: location, what to cut, what replaces it. The diff's best outcome is getting shorter.
Format
L<line>: <tag> <what>. <replacement>., or <file>:L<line>: ... for multi-file diffs.
Tags:
delete:dead code, unused flexibility, speculative feature. Replacement: nothing.stdlib:hand-rolled thing the standard library ships. Name the function.native:dependency or code doing what the platform already does. Name the feature.yagni:abstraction with one implementation, config nobody sets, layer with one caller.shrink:same logic, fewer lines. Show the shorter form.
Examples
❌ "This EmailValidator class might be more complex than necessary, have you considered whether all these validation rules are needed at this stage?"
✅ L12-38: stdlib: 27-line validator class. "@" in email, 1 line, real validation is the confirmation mail.
✅ L4: native: moment.js imported for one format call. Intl.DateTimeFormat, 0 deps.
✅ repo.py:L88: yagni: AbstractRepository with one implementation. Inline it until a second one exists.
✅ L52-71: delete: retry wrapper around an idempotent local call. Nothing replaces it.
✅ L30-44: shrink: manual loop builds dict. dict(zip(keys, values)), 1 line.
Scoring
End with the only metric that matters: net: -<N> lines possible.
If there is nothing to cut, say Lean already. Ship. and stop.
Boundaries
Scope: over-engineering and complexity only. Correctness bugs, security holes, and performance are explicitly out of scope. Route them to a normal review pass, not this one. A single smoke test or assert-based self-check is the ponytail minimum, not bloat, never flag it for deletion. Does not apply the fixes, only lists them. "stop ponytail-review" or "normal mode": revert to verbose review style.
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Pick ponytail-review when the goal is deleting complexity from a diff, not when you need security scanning or correctness bug hunting.
FAQ
What does ponytail-review do?
Review a diff for over-engineering. Finds what to delete: reinvented stdlib, needless deps, speculative abstractions. One line per finding.
When should I invoke ponytail-review?
Review a diff for over-engineering. Finds what to delete: reinvented stdlib, needless deps, speculative abstractions. One line per finding.
Where is the source documentation?
Ground claims in SKILL.md excerpts and linked reference files from the cached docs.
Is Ponytail Review safe to install?
skills.sh reports 3 of 3 security scanners passed. Review the Security Audits panel on this page before installing in production.