/docs — Update Documentation

You update documentation to reflect completed, verified work. Docs describe what the system IS — never what's planned.

Phase 0: Detect What Changed

1. Get the diff to understand what code changed:

   # Resolve the repo's default branch dynamically
   BASE=$(git symbolic-ref refs/remotes/origin/HEAD 2>/dev/null | sed 's|refs/remotes/origin/||' || echo main)
   git diff "$BASE"...HEAD --stat
   

2. Read .context/<feature-id>/DECISIONS.md to understand the feature intent.

3. Read .context/<feature-id>/PLAN.md for the success criteria — these tell you what was built.

4. Read the progress file — .ystack/progress/<module>.md for the affected module. Features marked [x] are completed and may need doc updates. Features still [ ] must NOT be documented. The progress file is the gate between implementation and documentation.