Skills

Determine runtime owner, first-fix layer, and canonical long-term module or package owner in layered codebases. Use when placing code across UI vs platform shell vs runtime orchestration vs domain or application vs shared core vs adapter or integration layers, debugging ownership issues, removing duplicate policy paths, or answering "where should this live?" architecture questions.

Decide exactly where bug-fix test coverage belongs. Use before adding, moving, or deleting tests after a bug fix or architectural change. Select one owning layer, reuse existing canonical suites, block redundant or weakly placed tests, and remove weaker duplicates.

Find duplicate ownership, hidden second sources of truth, and contract drift in layered codebases. Use when reviewing normalization, validation, defaulting, canonicalization, persistence mapping, runtime-vs-durable state, duplicated helpers, query or cache ownership, or any "who owns this rule?" architecture question. Especially useful for SSOT audits across frontend, backend, shared core, and adapter layers, and when the user explicitly asks for duplicate-ownership exploration with subagents.

Enforce a hard-cut cleanup policy: keep one canonical implementation and delete compatibility, migration, fallback, adapter, coercion, and dual-shape code. Use for pre-release or internal-draft refactors where the goal is one final shape, especially when changing schemas, contracts, persisted state, routing, configuration, feature flags, enum/value sets, or architecture.

Performs root-cause-first debugging and review by tracing expected behavior to the first unintended side effect before changing contracts, parsing, or types. Use when debugging protocol errors, deserialization failures, null payloads, missing fields, restore or hydration issues, state-ownership bugs, unexpected requests, background mutations, or reviewing junior-created code where the visible failure may be downstream noise.