Review Library Use

Review Library Use

Audit code against the documented, version-specific conventions of the libraries it uses — the correct-usage rules, API contracts, and footguns captured in the repo's library-use reference. This is the review counterpart to the library-docs generator: library-docs distills "how to use this version correctly"; this skill checks the code actually does.

Relationship to the other reviewers (read first)

Deliberately non-overlapping:

• General/code-review agents judge logic, architecture, security, clean code — library-agnostic. This skill only flags things that are wrong relative to a specific library's docs/version.
• review-typescript judges type design. This skill judges library API usage.
• If a finding isn't tied to a convention in library-use (or, absent the file, to the library's official docs), it belongs to another reviewer — don't report it here.

Report only misuse a reader of that library's docs would recognize as wrong: calling a removed/renamed API, a pattern the docs deprecate, missing required setup/config, using a JS-SDK method that doesn't exist in the Java SDK, etc.

Usage

/review-library-use                  # Review context-related code
/review-library-use --staged         # Review staged changes
/review-library-use --unpushed       # Files changed across all unpushed commits
/review-library-use --changed        # Unstaged changes
/review-library-use --all            # Whole-repo audit (parallel agents)
/review-library-use --multi          # Also get external advisor opinions

Scope

--unpushed derives its range from git rev-list HEAD --not --remotes (oldest unpushed commit's parent → HEAD). If nothing is unpushed, or there's no remote/upstream (or the range walks back to the root commit), stop and ask the user to pick another scope.

Workflow

Step 1: Load the convention source

• Read .claude/skills/library-use/SKILL.md (or .agents/skills/library-use/SKILL.md if only that exists) — the per-repo reference. Parse each ## <library> \`` block: its version, docs/changelog links, and Conventions bullets. These are the rules to check.
• If it's missing: say so once and offer to generate it — No library-use reference found. Run \library-docs` to create one.` Then either (a) proceed in degraded mode against the top few libraries' official docs read on the fly, or (b) stop, per the user. Note in the output that coverage was degraded.
• Staleness check: if any documented version no longer matches the current lockfile, warn once (library-use is stale for <lib> (<recorded>→<lockfile>) — run library-docs) and review against the newer version's docs where it matters.

Step 2: Resolve scope and filter

Resolve the scope (see table). Reduce to files that actually import/use a documented library — grep the scoped files for each documented library's import name; skip files that touch none.

Step 3: Check usage against conventions

For each scoped file that uses a documented library, check its usage against that library's Conventions bullets (and the linked docs when a bullet needs confirmation):

• Removed/renamed/relocated APIs still called the old way (the classic stale-training-data bug).
• Deprecated patterns the docs steer away from.
• Missing required initialization/config, wrong option shapes, wrong call order.
• Cross-SDK confusion (method exists in another language's SDK, not this one).

Parallelize if scope > 5 files: one sub-agent per library (or per file group), each given that library's block; merge and dedupe.

Step 4: External opinions (if --multi)

Invoke second-opinion --quick with a prompt naming the libraries + versions and asking whether the scoped code uses them per current docs. Wait for all results before continuing.

Step 5: Classify and report

Group by severity. Every finding must cite the convention or doc it violates — otherwise drop it.

Severity

• Critical: doc-violating misuse that will fail at runtime for real inputs — calling a removed API, missing required init that crashes, wrong auth/security config from the library's guide.
• High: deprecated-but-working usage that breaks on the next upgrade, or a documented footgun that will bite (wrong option shape silently ignored, incorrect call order).
• Medium: using an older correct pattern when the pinned version documents a better/required one; non-idiomatic usage the docs warn against.
• Suggestion: minor doc-recommended improvements.

Output Format

## Library-Use Review: {scope}

### Reference
{library-use present? which libraries/versions were in scope. Note staleness or degraded mode.}

### Critical (doc-violating, will fail at runtime)
- {file}:{line} — {library} `{version}`: {what's wrong}
  **Convention:** {the bullet/doc rule it violates}  ·  **Docs:** {url}
  **Fix:** {concrete correct usage — with code}

### High (breaks on upgrade / documented footgun)
- {file}:{line} — {library}: {issue} — {fix}

### Medium (older pattern / non-idiomatic per pinned version)
- {file}:{line} — {library}: {issue} — {fix}

### Suggestions
- {doc-recommended improvements}

If --multi was used, append one subsection per advisor, then a Cross-Model Agreement subsection.

Examples

Stale API after a bump:

/review-library-use --staged

library-use records better-auth 2.0; the staged code calls emailAndPassword({ requireVerification }) — renamed to requireEmailVerification in 2.0. Reports Critical with the doc link and the corrected call. A general reviewer wouldn't know the rename.

Cross-SDK confusion:

/review-library-use --changed

Java code calls a firebase-admin method that only exists in the JavaScript SDK. Reports Critical, citing the Java SDK docs from the library-use block.

No reference yet:

/review-library-use

No library-use file. Reports that, offers library-docs, and (if asked) runs a degraded pass against the top 3 libraries' live docs — flagged as degraded coverage.

Troubleshooting

No library-use reference in the repo

Cause: library-docs hasn't been run here. Solution: Recommend running library-docs first. Optionally do a degraded on-the-fly pass against the most-used libraries' official docs, and label coverage as degraded.

Findings overlap with general code review

Cause: Flagging logic/quality issues not tied to a library convention. Solution: Drop them — those belong to the code-review agents. Keep only doc/version-specific misuse.

Reference version doesn't match the lockfile

Cause: Deps were upgraded after the reference was generated. Solution: Warn once, review against the current version's docs for the affected libraries, and recommend library-docs --refresh.

Notes

• Pair: library-docs (generates the reference) → library-use (the reference) → review-library-use (this).
• The reference is the source of truth for what to check; the official docs are the tiebreaker when a bullet is ambiguous.
• Respect CLAUDE.md: a repo may deliberately pin an older pattern — don't flag a documented, intentional choice.