Hat	Stage	Upstream gate	Output	Unblocks
Eng	Engineering	PRD approved	engineering/outputs/specs/SPEC-NNN-<slug>.md	/tdd, /erd, /adr, /ralph-workspace-plan

When to Use

User has an approved PRD and wants to draft the engineering spec.

Prerequisites

• PRD status: approved AND in .workbench-state/approved.json.
• project.conf REPOS populated.

Protocol

1. Read PRD (frontmatter + all sections). Identify outcomes and constraints.
2. Read engineering context — engineering/context-library/ stack notes; approved ADRs only from engineering/outputs/adrs/.
3. Pick SPEC number — scan engineering/outputs/specs/SPEC-*.md, max + 1, three-digit pad. Slug matches PRD slug.
4. Decide per repo: modified? yes/no with one-liner.
5. Write engineering/outputs/specs/SPEC-{NNN}-{slug}.md with 11 sections: Scope, Target repos, Architecture impact, API+contracts, Data model, Rollout, Observability, Failure modes, Rollback, Risks+opens, Dependencies (ADRs / other SPECs / external teams).
6. Update EPIC-PIPELINE.md — set PRD row’s Spec column.

Output Frontmatter

id: SPEC-{NNN}
title: {title}
status: draft
created: {today}
owner: {gh-user}
epic: {EPIC_ID}
prd: PRD-{NNN}
target_repos:
  - {repo-1}

Do Not

• Include class-level pseudocode — that’s /tdd.
• Produce a spec without an approved PRD.

Source

skills/eng-spec/SKILL.md