| name | yagni-review |
| description | Review diffs for over-engineering only. Finds what to delete: reinvented standard library, unneeded dependencies, speculative abstractions, dead flexibility. One line per finding with tag and replacement. Use when the user says "review for over-engineering", "what can we delete", "is this over-engineered", "simplify review", "yagni review", or invokes /yagni-review. Complements correctness-focused /review — this one only hunts complexity.
|
YAGNI Review
Review the current branch's diff against main for unnecessary complexity.
One line per finding: location, what to cut, what replaces it. The diff's
best outcome is getting shorter.
Scope
Over-engineering and complexity only. Correctness bugs, security holes,
and performance are explicitly out of scope — route them to /review.
Step 1: Get the Diff
git diff main...HEAD
If main doesn't exist locally, try origin/main, then master.
Step 2: Classify Findings
For each finding, assign one tag:
| Tag | What to cut | Replacement |
|---|
delete: | Dead code, unused flexibility, speculative feature | Nothing — remove it |
stdlib: | Hand-rolled thing the standard library ships | Name the function/class |
native: | Dependency or code doing what the platform already does | Name the native feature |
yagni: | Abstraction with one implementation, config nobody sets, layer with one caller | Inline until a second use exists |
shrink: | Same logic, fewer lines | Show the shorter form |
Step 3: Format Output
One line per finding:
L<line>: <tag> <what>. <replacement>.
For multi-file diffs: <file>:L<line>: <tag> <what>. <replacement>.
Examples
L12-38: stdlib: 27-line email validator class. "@" check + confirmation email, 1 line.
L4: native: moment.js imported for one format call. Intl.DateTimeFormat, 0 deps.
repo.py:L88: yagni: AbstractRepository with one implementation. Inline it.
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.
Step 4: Score
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, performance are out of scope — route to
/review.
- A single smoke test or
assert-based self-check is the minimum, not bloat — never flag it.
- Does not apply the fixes, only lists them.
Optional: Persist Findings
If the user wants to track deferred findings, mark them with deferred: comments
in the code (format: # deferred: <ceiling>, <upgrade path>). Then run
/debt-ledger to harvest them into a ledger.
