Code Polish

A constraint-based protocol for normalizing code comments and performing safe, non-semantic cleanup. This skill exists because human-written code tends to carry casual, outdated, or missing comments, while the goal is professional-grade documentation without touching behavior.

This file is self-contained. Do not require any other skill file to execute this protocol.

Prime Directive

Comments and non-semantic cleanup are the job. Logic is never the job. If a change would alter what the code does — not just what it says or how it's arranged — it is out of scope, no matter how obviously "correct" the fix seems.

When to Use

Apply this skill when:

• The user asks to "clean up," "professionalize," or "polish" existing code
• Code is being prepped for code review, handoff, open-sourcing, or documentation
• A file has a mix of human and AI-written comments and needs one consistent, professional voice
• Comments are outdated, missing, redundant, or written casually (venting, placeholders, inside jokes)
• The user wants comments improved but explicitly does not want logic touched

Do not apply this skill when:

• The user wants a bug fixed or behavior changed (that's a different job — logic edits are out of scope here)
• The user wants a full rewrite or architectural restructuring
• The only ask is adding new features or functionality

Phase 0 — Full Read

Before editing anything, read the entire file (or the entire relevant module if the codebase is large — not just the function in question). Do not comment or clean incrementally while still reading. A comment written without full context is a guess, and guesses are how "professional" comments end up wrong.

Identify:

• The language and its idiomatic comment/docstring convention (JSDoc, Python docstrings, /// for Rust, XML doc comments, etc.)
• Any existing project comment style already in use elsewhere in the file — match it rather than importing a foreign convention
• Any comment that encodes real, non-obvious information (race conditions, workarounds for external bugs, "don't reorder this" warnings, business-rule justifications)

Phase 1 — Comment Audit

Classify every existing comment into one of these categories before touching it:

| Category | Example | Action | |---|---|---| | Junk / venting | // wtf is this, // idk why but it works | Remove tone, extract any real information underneath, rewrite professionally — or delete if it truly holds zero information | | Placeholder | // fix later, // TODO hack | Convert to a proper TODO: note with the actual concern stated plainly, or remove if stale/resolved | | Dead code comments | Blocks of commented-out code | Remove, unless the surrounding context makes clear it's intentionally preserved (e.g., a documented fallback) — flag these to the user rather than silently deleting | | Redundant | i++ // increment i | Delete — the code already says this | | Outdated / wrong | Comment describes behavior the code no longer has | Rewrite to match current behavior. Flag to the user that it was stale, don't just silently fix it | | Valuable but informal | // careful, this breaks if you call it twice, learned that the hard way | Preserve the information, rewrite the tone. Never delete real warnings just because the phrasing is casual | | Missing | Complex logic, non-obvious business rules, or public APIs with no docstring | Add one. Don't over-comment simple, self-explanatory lines |

Phase 2 — Non-Semantic Cleanup

Scope is strictly limited to changes that cannot alter behavior:

• Consistent indentation and whitespace
• Consistent brace/bracket style matching the surrounding file
• Removing truly dead code (unreachable blocks) — only when unambiguous, and flagged in the summary
• Splitting overly long lines for readability
• Local variable renaming for clarity is allowed only for private/local-scope names, and only when the improvement is unambiguous — never rename anything exported, public, or referenced across files without calling it out explicitly first

Anything beyond this — reordering logic, extracting functions, changing control flow, altering algorithms — is out of scope for this skill.

Phase 3 — Comment Rewrite / Addition

Apply these standards to every comment touched or added:

• Explain why, not what. The code already shows what it does; a comment earns its place by explaining intent, tradeoffs, or non-obvious constraints.
• Use the language's idiomatic doc format for functions, classes, and public APIs (JSDoc, docstrings, ///, etc.) — match the convention already used elsewhere in the file if one exists.
• Be concise. No padding, no restating the obvious, no filler sentences.
• No informal register. No jokes, no venting, no first-person asides ("I think this works because...").
• No AI-tell phrasing. Avoid generic filler like "This function is responsible for..." or "Note that..." padding, and avoid em-dashes. Write plainly and directly, the way a careful senior engineer would.
• Don't invent behavior. If you're not certain why something is done a certain way, say what the code does, not a fabricated justification for why.

Phase 4 — Verification

Before presenting the result:

• Confirm the edited file's logic is behaviorally identical to the original — comments and whitespace are the only permitted diffs, plus whatever narrow Phase 2 cleanup was done.
• Re-read the diff end to end, not just the changed lines in isolation, to catch anything that accidentally shifted meaning.
• If a rewritten comment removes information that was present in the original (even informally stated), that's a failure — go back and preserve it.

Phase 5 — Report Back

Summarize for the user, don't just hand back a silent diff:

• How many comments were rewritten, added, or removed, and why
• Any comments flagged as "informal but contained a real warning" — confirm the information was preserved
• Any dead code or stale comments removed, listed explicitly
• Anything you were unsure about and left alone rather than guessing

Examples

Junk / venting → professional

js
// before
// ugh this took forever to figure out. api rate limits us super hard in prod so we have to do exponential backoff here. just leave it alone
function retryFetch(url, attempts) { ... }

// after
// Uses exponential backoff to handle aggressive API rate-limiting in production.
function retryFetch(url, attempts) { ... }

Redundant → removed

python
# before
count += 1  # increment count by 1

# after
count += 1

Valuable but informal → tone rewritten, information preserved

python
# before
# careful, this breaks if you call it twice, learned that the hard way

# after
# Not idempotent: calling this more than once per session corrupts the
# cache index. Callers must guard against duplicate invocation.

Missing → added

java
// before
public double calculate(double base, int tier) {
    return base * (tier > 2 ? 0.85 : 1.0);
}

// after
/**
 * Applies the loyalty discount. Tiers above 2 qualify for a 15% discount;
 * this threshold matches the current pricing policy, not a technical limit.
 */
public double calculate(double base, int tier) {
    return base * (tier > 2 ? 0.85 : 1.0);
}

Outdated / wrong → corrected and flagged

go
// before
// returns nil if user not found
func GetUser(id string) (*User, error) { ... } // now returns ErrNotFound instead

// after
// Returns ErrNotFound if the user does not exist.
func GetUser(id string) (*User, error) { ... }
// (flagged to user: original comment was stale — function used to return nil,
// now returns a named error)

Security & Safety Notes

This skill never:

• Changes program logic, control flow, or algorithmic behavior
• Restructures code (extracting/inlining functions, reordering execution, changing architecture)
• Renames anything public, exported, or cross-referenced without explicit confirmation
• Deletes a comment solely because its tone is casual, without checking whether it carries real information first
• Fabricates a rationale for a comment when the actual reason isn't knowable from context — state what's certain only

Limitations

• Cannot verify runtime behavior — Phase 4 is a read-through diff check, not a test run. For anything beyond trivial files, the user should still run the actual test suite after applying this skill.
• Judgment calls on ambiguous cases (e.g., "is this dead code intentional or forgotten?") default to flagging rather than guessing — this means some cleanup will need a quick human yes/no rather than happening silently.
• Not a substitute for a linter or formatter — Phase 2 cleanup is deliberately conservative and won't enforce a full style guide (e.g., max line length rules, import ordering) unless that's trivially inferable from the surrounding file.
• Comment quality is bounded by how well the code's actual intent can be inferred from context. If the "why" genuinely isn't recoverable from the file (no domain knowledge, no commit history, no ticket references available), the honest output is a comment describing what, not a confident but invented why.
• Large files or unfamiliar codebases increase the risk of Phase 0 missing context that would have changed a comment's wording — flag uncertainty in the Phase 5 report rather than presenting low-confidence rewrites as settled.