Claude Code spec-first for checkable feature specifications

Write a measurable goal, scope, interfaces, decisions, and verification plan before implementation.

Install in Claude Code

Use Claude Code with the current request and a repository to hold the specification. This pinned Aesop project is archived, and its specification workflow remains in the source.

Review `.claude/skills/spec-first/SKILL.md` and its requirements at the pinned GitHub commit.
Create `.claude/skills/spec-first/` in your project and save the reviewed file as `.claude/skills/spec-first/SKILL.md`.
Start Claude Code from that project's root, then select `/spec-first` in the slash menu.

Example task

Request spec-21 needs a list to remember page size. After a reload in the current session it should still show 25 items. Cross-device synchronization is undecided.

What to check

The specification records {pageSize: 25, persistsOnReload: true, crossDevice: 'undecided'}. Include a reload acceptance check and leave cross-device persistence for a decision.

Original SKILL.md on GitHub · Updated 2026-11-14

Frequently asked question

How should I handle scope that has not been approved?

Record the unresolved scope as a decision or open question. Let the user approve a verifiable specification before implementation.