Addlightness review

/addlightness-review -- read-only weight report

Measure code weight and surface removable "fat" candidates. This is the diagnostic half of addlightness: it reports, it never edits. For actual trimming use /addlightness; for performance numbers use /addlightness-bench.

Scope -- READ-ONLY

This skill NEVER modifies files. It reads, measures, and reports. Period.

• No Edit, no Write, no in-place fixes, no "I went ahead and removed it".
• Output is a report the human reads and decides on.
• If the user wants the trims applied, tell them to run /addlightness <file...> (which spawns the edit-capable code-trimmer agent behind an equivalence gate).
• When in doubt, do less: describe the candidate, do not touch the code.

Repeat this contract back to the user if they ask you to "just fix it" here -- review reports, /addlightness edits.

How to run

For each target file, get its weight metrics from the zero-dependency engine. Two equivalent paths -- prefer the agent for multi-file work, the direct call for a single quick read:

1. Via the agent (preferred for >1 file or a fat-candidate narrative): spawn the weight-analyst agent. It is read-only by contract (its prompt forbids mutating Bash commands; it has no Edit/Write) and returns the metrics table plus a ranked fat list and a KEEP list. The agent analyzes one file per invocation — spawn one weight-analyst invocation per file and aggregate the JSON yourself.

2. Direct (single file, fastest):

   node "${CLAUDE_PLUGIN_ROOT}/lib/weigh.js" path/to/file.js --json
   

   The engine emits one JSON object per file with the scalar weight plus the raw components (loc, cyclomatic, imports, functions, nesting, tokens), an approx boolean (true = JS/TS regex approximation, false = Python ast-accurate), and the weight_formula string. Parse the JSON line; do not screen-scrape prose. The approx flag is the authoritative accuracy signal — read it rather than guessing from the language.

   weight = 1.0*loc + 2.0*cyclomatic + 1.5*imports + 1.0*functions + 3.0*nesting
   

   JS/TS metrics are regex-on-stripped-source approximations (comments, strings, and templates are stripped first). Python metrics come from the stdlib ast module and are accurate. Say which is which when you report.

Aggregate across all targets into one report. Glob the user's pattern (e.g. src/**/*.js) yourself, then weigh each match.

Fat categories to flag

For every candidate, report a row -- never an edit:

field	meaning
category	one of the categories below
location	file:line (or file:start-end)
current	the exact code as it stands
proposed	what a trim would look like (for the human, not applied)
why-safe	the specific reason removing it preserves behavior
risk	low / medium / high -- residual doubt after why-safe

Categories:

• single-use-wrapper -- a function/helper called from exactly one site that adds no abstraction value; inlining removes a hop. Confirm the single call site with Grep before flagging.
• impossible-defensive-check -- a guard that the local control flow or the type system already proves can never fire. Only flag when you can show the proof (the value is produced two lines up, the type is non-null by construction, etc.). If the value crosses a trust boundary, it goes on the KEEP list instead -- see below.
• redundant-destructure -- destructuring then immediately re-wrapping, or pulling fields never used.
• redundant-coercion -- Boolean(x) in a boolean context, String(x) in a template, !!x where truthiness already suffices, +x on a known number.
• dead-branch / unreachable -- a branch no input can reach, an if (false), a return followed by code, an arm shadowed by an earlier one.
• useless-async -- async on a function that never awaits and whose caller does not rely on the Promise wrapping. (Flag cautiously -- check call sites; removing async changes the return type and turns sync throws into thrown errors instead of rejected Promises.)
• restate-comment -- a comment that restates the next line (// increment i above i++). Why-comments are NOT fat -- never flag those.
• verbose-identifier -- an over-long name in a narrow/private scope where a shorter one is clearer. Never flag public/exported names.
• unused-import -- an import/require with no remaining reference. Confirm with Grep across the file (and re-exports) before flagging.

Output

Produce three sections, in this order:

1. Metrics table -- one row per file: weight | loc | cyclomatic | imports | functions | nesting | tokens, with a total/average row. Note JS=approx, Python=ast-accurate.
2. Ranked fat-candidate list -- the rows above, sorted by value-to-risk (high-confidence, high-payoff first). Group by file.
3. KEEP list -- co-equal in importance to the removals. Every defensive check, validation, guard, or coercion that looks like fat but must stay, with the reason it stays. The headline reason is the trust boundary: any value that is externally controlled -- public API parameters, file/socket IO, parsed/network/env/user/CLI data -- keeps its validation even if current tests pass without it. A passing test suite with well-formed inputs is NOT proof the check is dead; it is the #1 way validation gets wrongly stripped.

A review with an empty KEEP list on real code is suspect -- you probably mislabeled a boundary check as fat.

Weight interpretation

The scalar is a relative before/after metric, not an industry standard. Lower = lighter. Read the ratios, not raw size:

• comment/LOC > ~0.25 -- comment-heavy; check whether comments restate code (fat) or explain why (keep).
• high tokens/LOC -- dense long lines / verbose identifiers / long literals; candidate for naming or extraction (report, don't apply).
• low cyclomatic-per-LOC -- lots of straight-line filler relative to actual decisions; suggests padding, boilerplate, or copy-paste.
• high LOC/function with low complexity -- long but simple functions = ceremony/padding rather than essential logic.
• high nesting -- the heaviest-weighted dimension (3.0); deep nesting is the strongest structural-fat signal (early returns / guard clauses often flatten it).

Raw LOC alone is a weak signal -- a 200-line file of essential branching can be leaner than a 60-line file of wrappers. Always pair LOC with the complexity and nesting ratios.

What NOT to do

• Never modify a file. Not even "a tiny obvious one". Report it.
• Never claim AST precision for JS/TS. Those numbers are regex approximations on stripped source; say "approximate". Python via ast may be called accurate.
• Never flag externally-controlled validation as fat. Trust-boundary checks go on the KEEP list, with the boundary named.
• Never delete why-comments from the recommendation -- only restate-comments are candidates.
• Don't flag a single-use-wrapper or unused-import without confirming call sites / references via Grep first.
• Don't present static metrics as a behavioral guarantee -- they are change-magnitude and structural signals. The user's own test suite is the only true equivalence proof, and that proof belongs to /addlightness, not here.