module-ownership

name	module-ownership
description	Assign module ownership, define cross-module boundaries, and review ownership drift in modular codebases. Use when adding a module, moving behavior out of a root shell or app entrypoint, changing shared state or contracts, or reviewing a PR for ambiguous responsibility.

Module Ownership

Use this skill to decide where behavior belongs in a modular codebase and how to keep cross-module boundaries honest.

Use When

• Adding a new feature or module and you need a clear owner.
• Moving behavior out of an app shell, root component, or entrypoint.
• Changing shared state, shared contracts, or cross-module imports.
• Touching privileged boundaries such as host services, IPC, filesystem, network, auth, or process control.
• Reviewing a PR for ownership drift, mixed concerns, or a too-wide blast radius.

Working Rules

• Give every behavior one primary owner.
• Keep composition layers thin: route, mount, wire, and pass callbacks.
• Let feature modules own their UI, local controllers, selectors, and domain mutation orchestration.
• Put shared contracts, data shapes, and pure helpers in a shared or core layer.
• Keep privileged operations behind a named service, client, or host boundary.
• Prefer the smallest truthful change that preserves the current architecture.
• If docs and code disagree, trust the live code path and note the drift.

Process

1. Identify the user-visible behavior.
2. Find the source of truth for the state involved.
3. Assign the primary owner module.
4. Separate reads from writes.
5. Check whether the change crosses a trust or privilege boundary.
6. Move shared contracts to a shared layer if more than one module needs them.
7. Update the repo's module map or ownership doc when ownership changes.

Output

When you answer with an ownership decision, keep it concise and explicit:

• Owner
• Why it owns the behavior
• What stays out of scope
• Files or modules to touch
• Boundary notes
• Follow-up doc or ADR, if one is warranted

Reference

For a reusable ownership matrix and checklist, see references/ownership-matrix-template.md.