build— agent skill

Implement the approved plan incrementally: $ARGUMENTS

Follow these disciplines:

Before Starting

why-not-mechanizable: skill workflow guidance; each step requires understanding the surrounding context (repo, task shape, prior state).

• Verify an approved plan exists (in .claude/state/plans/ or the current conversation) (review-time: see section note)
• If no plan exists, stop and ask the user to run /plan first (review-time: see section note)
• Read the plan and identify the task list (review-time: see section note)
• Load relevant expert agents based on the plan's domain (see rules/agent-routing.md) - their guardrails apply to every increment (review-time: see section note)

Increment Rules

For each task in the plan:

1. Ask: "What is the simplest thing that could work?" (review-time: see section note)
2. Scope: touch only what the task requires - no drive-by refactors, no "while I'm here" changes (review-time: see section note)
3. Follow `rules/engineering-principles.md`: vertical slicing, change sizing (~100 lines per commit, max 300, split at 1000+), and anti-rationalization rules all apply (review-time: see section note)
4. Compile continuously: the project must build after every increment. Run typecheck after each file change. (review-time: see section note)
5. Test alongside: write tests as part of the increment, not as a separate step afterward (review-time: see section note)
6. Checkpoint: after completing each task: (review-time: see section note)

• Run /verify-done (typecheck + lint + tests + build) - do not rely on post-edit hooks alone (review-time: see section note)
• If all pass, commit with a conventional commit message (review-time: see section note)
• If any fail, fix before moving to the next task - never accumulate errors across tasks (review-time: see section note)

Feature Flags

If the feature is large and will take multiple sessions:

• Use a feature flag to keep incomplete work behind a toggle (review-time: see section note)
• Each increment should be independently mergeable (behind the flag) (review-time: see section note)
• The flag is removed only when the full feature is complete and tested (review-time: see section note)

Completion

After all tasks are done:

• Run /verify-done one final time (review-time: see section note)
• Summarize what was built and what changed (review-time: see section note)
• Flag any deferred items or follow-up work as issues (review-time: see section note)