engineering

Build software that fits the system and delivers the requirement, across application code, infrastructure, and the tests that prove it. Judge the design before writing code. Build test-first, and ship behind the gates. Most of the difficulty lives in choosing the right seam and guarding the blast radius, and then in proving the change does what was asked.

Keep the project legible as you work: maintain its AGENTS.md/CLAUDE.md and task list via project-context.

Steps

1. State the requirement. Write what the change must deliver and the acceptance criteria that decide done. Code measured against nothing cannot be reviewed.

2. Design the seam. Name the boundary the change lives behind: the interface and the data shape it commits to, and the direction its dependencies point. Check the seam against engineering practices before writing code; a wrong seam is expensive to move later.

3. Build test-first. Follow tdd: a failing test per stated behavior, then the minimum code that passes. Layer the tests by the test strategy, unit for logic, integration for boundaries, end-to-end for the critical path. Write the code with zero inline comments; a comment appears only for a complex algorithmic edge case or an invariant the code cannot express, stated in Simplified Technical English.

4. Validate at the boundary. Reject malformed or unauthorized input before any work runs. Untrusted data gets checked at the edge, before it travels down the call stack.

5. Change infrastructure behind a plan. For an infrastructure change, follow infra safety: validate, scan, read the plan, and name the blast radius before any mutation. A teardown runs only against a named, non-production target with recorded approval.

6. Finish the user-facing edges. For a UI change, cover the loading, empty, and error states and the accessibility checklist. An API change covers the error contract, pagination, and idempotency.

7. Gate and verify. Pass the appsec gate (every code change, app or infra, runs skill-gate --strict through that skill's fixed order), then confirm each acceptance criterion against the running change. The work is done when every criterion passes and the appsec gate is green.