/test-plan

Produce a test plan for $1 (default: the working diff against the repo's default branch).

Steps:

1. Scope the change: git diff $1 --stat for breadth, then read the changed code to understand behavior — inputs, outputs, side effects, and error paths.
2. Apply the test-design-heuristics skill to decide what deserves a test and at which level.
3. Output a plan with:
   • What to test — the behaviors and contracts that matter, as a checklist.
   • Level — for each, unit / integration / end-to-end, with a one-line why.
   • Edge cases — boundaries, empty/null, error paths, concurrency, idempotency — only the ones that actually apply here.
   • Skip — what is not worth testing (framework code, trivial getters), so the plan stays honest.

Keep it proportional: a small change gets a small plan. Don't pad. This produces a plan, not the tests — offer to write them as a follow-up if the author wants.