# Drill

> Lock one change from language through obligation, place, and slice before writing. ALWAYS use when those levels mix, implementation starts before place is locked, or a lower question fires while a higher lock is open. Do not use for a checked staged transformation.

- Skill: `jcosta33/drill` (Agent Skill)
- Install (CLI): `npx skillmds@latest add jcosta33/drill`
- Raw SKILL.md: https://api.skillmd.com/api/skills/jcosta33/drill/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: jcosta33 (https://skillmd.com/u/jcosta33)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/jcosta33/drill

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# Drill

Lock the next seam. Write only that seam.

## Method

Work one level at a time. A higher lock that moves drops the in-flight slice.

1. **Language.** Name the thing in the project's words. Stop until the name is shared.
2. **Obligation.** Name what the slice guarantees: the behavior a caller can now rely on, and what
   must stay true that already was. Then verify-with and rollback for each. Machinery is not
   implied by the guarantee. Do not open a staged transformation artifact.
3. **Place.** Name the files, symbols, and runtime boundary. When coupling is unproven, trace the
   path to closure first.
4. **Slice.** Name the smallest write that keeps the obligation. Reuse first: search for the
   existing rule and call it. Duplicate only with a named reason, and proximity is not a reason.
   Do not extract a wrapper that restates an existing operation. Then write it.

Prove discoverable technical questions from evidence. Structure remaining human-owned locks as
explicit choices. Do not ask a lower question while a higher lock is open.

Escalate when ordered waves plus rollback must outlive the session.

Native notes only. No `CONTEXT.md`. No Suspec artifact.

## Output

Return the four locks, the write, and the verify evidence as rendered Markdown. Keep evidence to the
smallest untouched decisive excerpt.