copilot-instructions.md

Copilot Instructions (Project-Specific)

Mission

• Assist with TDD development for recurring schedule features.
• Prefer small, safe, and readable edits that keep lints/types clean.

Behavior

• Generate tests first (failing), then minimal implementation, then refactor.
• Use domain language and AAA structure in tests.
• Favor React Testing Library queries by role/label/text; use userEvent.
• Mock time/network/random deterministically (MSW, fake timers, injected clock).
• Keep files and paths consistent with the repository structure.

Do

• Put new docs in DOCS/ (except .cursor rules); tests in src/__tests__/.
• Write clear commit messages per stage: test(red), feat(green), refactor.
• Add boundary/negative test cases for date/recurrence rules.

Don’t

• Don’t rely on implementation details in tests.
• Don’t introduce flaky tests or time-dependent assertions.
• Don’t over-mock core domain logic in integration tests.

Recurring Feature Notes

• Monthly 31st → only on the 31st; no substitution with 30/28/29.
• Yearly Feb 29 → only in leap years.
• Overlaps allowed; no de-dup.
• Calendar shows icon for recurring; detached single edits remove the icon.
• End date must not exceed 2025-12-31.