Agent Skills: Knip Code Cleanup

Knip Code Cleanup

Run knip to find and remove unused files, dependencies, and exports from this codebase.

Setup

1. Check if knip is available:

   • Run npx knip --version to test
   • If it fails or is very slow, check if knip is in package.json devDependencies
   • If not installed locally, install with npm install -D knip (or pnpm/yarn/bun equivalent based on lockfile present)

2. Knip does NOT remove unused imports/variables inside files — that's a linter's job. Knip finds unused files, dependencies, and exports across the project.

Workflow

Always follow this configuration-first workflow. Even for simple "run knip" or "clean up codebase" prompts, configure knip properly before acting on reported issues.

Step 1: Understand the project

• Check what frameworks and tools the project uses (look at package.json)
• Check if a knip config exists (knip.json, knip.jsonc, or knip key in package.json)
• If a config exists, review it for improvements (see Configuration Best Practices below)

Step 2: Run knip and read configuration hints first

npx knip

Focus on configuration hints before anything else. These appear at the top of the output and suggest config adjustments to reduce false positives.

Step 3: Address hints by adjusting knip.json

Fix configuration hints before addressing reported issues. Common adjustments:

• Enable/disable plugins for detected frameworks
• Add entry patterns for non-standard entry points
• Configure workspace settings for monorepos

Step 4: Repeat steps 2-3

Re-run knip after each config change. Repeat until configuration hints are resolved and false positives are minimized.

Step 5: Address actual issues

Once the configuration is settled, work through reported issues. Prioritize in this order:

1. Unused files — address these first ("inbox zero" approach removes the most noise)
2. Unused dependencies — remove from package.json
3. Unused devDependencies — remove from package.json
4. Unused exports — remove or mark as internal
5. Unused types — remove, or configure ignoreExportsUsedInFile (see below)

Step 6: Re-run and repeat

Re-run knip after each batch of fixes. Removing unused files often exposes newly-unused exports and dependencies.

Configuration Best Practices

When reviewing or creating a knip config, follow these rules:

• Never use ignore patterns — ignore hides real issues and should almost never be used. Always prefer specific solutions. Other ignore* options (like ignoreDependencies, ignoreExportsUsedInFile) are fine because they target specific issue types.
• Many unused exported types? Add ignoreExportsUsedInFile: { interface: true, type: true } — this handles the common case of types only used in the same file. Prefer this over broader ignore options.
• Remove redundant patterns — Knip already respects .gitignore, so ignoring node_modules, dist, build, .git is redundant.
• Remove entry patterns covered by defaults — Auto-detected plugins already add standard entry points. Don't duplicate them.
• Config files showing as unused (e.g. vite.config.ts) — Enable or disable the corresponding plugin explicitly rather than ignoring the file.
• Dependencies matching Node.js builtins (e.g. buffer, process) — Add to ignoreDependencies.
• Unresolved imports from path aliases — Add paths to knip config (uses tsconfig.json semantics).

Production Mode

Use --production to focus on production code only:

npx knip --production

This excludes test files, config files, and other non-production entry points. Do NOT use project or ignore patterns to exclude test files — use --production instead.

Cleanup Confidence Levels

Auto-delete (high confidence):

• Unused exports that are clearly internal (not part of public API)
• Unused type exports
• Unused dependencies (remove from package.json)
• Unused files that are clearly orphaned (not entry points, not config files)

Ask first (needs clarification):

• Files that might be entry points or dynamically imported
• Exports that might be part of a public API (index.ts, lib exports)
• Dependencies that might be used via CLI or peer dependencies
• Anything in paths like src/index, lib/, or files with "public" or "api" in the name

Use the AskUserQuestion tool to clarify before deleting these.

Auto-fix

Once configuration is settled and you're confident in the results:

# Auto-fix safe changes (removes unused exports and dependencies)
npx knip --fix

# Auto-fix including file deletion
npx knip --fix --allow-remove-files

Only use --fix after the configuration-first workflow is complete.

Error Handling

If knip exits with code 2 (unexpected error like "error loading file"):

• Check if a config file exists — if not, create knip.json in the project root
• Check for known issues at knip.dev
• Review the configuration reference for syntax/option errors
• Run knip again after fixes

Common Commands

# Basic run
npx knip

# Production only (excludes test/config entry points)
npx knip --production

# Auto-fix what's safe
npx knip --fix

# Auto-fix including file deletion
npx knip --fix --allow-remove-files

# JSON output for parsing
npx knip --reporter json

Notes

• Watch for monorepo setups — may need --workspace flag
• Some frameworks need plugins enabled in config
• Knip does not handle unused imports/variables inside files — use ESLint or Biome for that