Add Subfeature

Use this skill when an existing canonical feature needs a durable child planning folder instead of direct in-place edits to the parent feature plan.

Responsibilities

1. Resolve the parent feature planning folder under the repository planning layout.
2. Initialize the feature-local subfeatures/ registry when it does not exist yet.
3. Create one durable subfeature under docs/features/<feature>/subfeatures/<subfeature-id>/.
4. Maintain machine-readable subfeature metadata for parent-child and impact context.
5. Seed the subfeature as a real planning folder with its own .planning-meta.json.

Preferred Input

• a parent feature slug, folder name, or path
• a subfeature ID or short slug
• an optional subfeature type such as additive, narrowing, superseding, or replacement
• an optional summary of why the feature needs the child capability