Find Dead Code

Dead code is the silent tax — slow tests, larger bundles, mental load, security surface. But "delete it" is risky: code that looks dead can be reflected, dynamically imported, called via DI, or referenced from JSON config. This skill is the methodology for high-confidence deletion.

When to use

• Periodic cleanup (quarterly).
• Before a major refactor — know what you can safely remove.
• Onboarding a new engineer — show them what's still alive.
• Bundle size investigation — find what's shipping that nobody uses.
• Security audit — fewer code paths is fewer attack surfaces.

When NOT to use

• During active feature development — defer until things stabilize.
• In test code — dead tests are a different audit (see audit-tautological-tests).
• Highly dynamic codebases (heavy plugin systems, Ruby on Rails magic) — false positives dominate; manual review only.

Three confidence tiers