quality-control

Review the diff between HEAD and a fixed point against the smell baseline below. This skill covers design smells only — bug hunting and documented-standards compliance belong to /code-review; spec conformance belongs to /validate_plan.

Process

1. Pin the fixed point

Whatever the user (or calling command) supplies — a commit SHA, branch name, tag, main, HEAD~5, etc. If unspecified, ask.

Capture: git diff <fixed-point>...HEAD (three-dot, merge-base comparison) and git log <fixed-point>..HEAD --oneline. Confirm the ref resolves (git rev-parse) and the diff is non-empty before spawning the sub-agent.

2. The smell baseline

A fixed set of Fowler code smells (Refactoring, ch.3). Two rules bind it:

• The repo overrides. A documented repo standard always wins; where it endorses something the baseline would flag, suppress the smell.
• Always a judgement call. Each smell is a labelled heuristic ("possible Feature Envy"), never a hard violation — and skip anything tooling already enforces.

Each smell reads what it is → how to fix; match it against the diff:

• Mysterious Name — a function, variable, or type whose name doesn't reveal what it does or holds. → rename it; if no honest name comes, the design's murky.
• Duplicated Code — the same logic shape appears in more than one hunk or file in the change. → extract the shared shape, call it from both.
• Feature Envy — a method that reaches into another object's data more than its own. → move the method onto the data it envies.
• Data Clumps — the same few fields or params keep travelling together (a type wanting to be born). → bundle them into one type, pass that.
• Primitive Obsession — a primitive or string standing in for a domain concept that deserves its own type. → give the concept its own small type.
• Repeated Switches — the same switch/if-cascade on the same type recurs across the change. → replace with polymorphism, or one map both sites share.
• Shotgun Surgery — one logical change forces scattered edits across many files in the diff. → gather what changes together into one module.
• Divergent Change — one file or module is edited for several unrelated reasons. → split so each module changes for one reason.
• Speculative Generality — abstraction, parameters, or hooks added for needs the work doesn't have. → delete it; inline back until a real need shows.
• Message Chains — long a.b().c().d() navigation the caller shouldn't depend on. → hide the walk behind one method on the first object.
• Middle Man — a class or function that mostly just delegates onward. → cut it, call the real target direct.
• Refused Bequest — a subclass or implementer that ignores or overrides most of what it inherits. → drop the inheritance, use composition.

3. Spawn the review sub-agent

One general-purpose Agent call. Include in the prompt:

• The diff command and commit list.
• The smell baseline from step 2 pasted in full — the sub-agent has no other access to it.
• The brief: "Report any baseline smell you spot in the diff — per file/hunk where relevant: name the smell and quote the hunk. Every finding is a judgement call; a documented repo standard overrides the baseline. Skip anything tooling enforces, and skip bug/spec findings — other reviews own those. Under 400 words."

4. Report

Present the sub-agent's findings under ## Design smells (judgement calls), verbatim or lightly cleaned. End with a one-line count and the worst finding (if any).