spec-writer

name	spec-writer
description	Write feature specifications that capture requirements and acceptance criteria. Use when (1) writing a new feature spec, (2) documenting functional requirements, (3) defining acceptance criteria for a feature, (4) capturing design goals and constraints for planned work, or (5) structuring a product idea into a formal specification.
argument-hint	[feature name or description]

Spec Writing

Capture WHAT and WHY. Never prescribe HOW.

When invoked with arguments, write a spec for: $ARGUMENTS

Workflow

1. Gather context: Collect feature description, target users, problem statement, and constraints from user input or $ARGUMENTS. Ask clarifying questions for missing information.
2. Create directory: specs/feature-name/
3. Copy assets/spec.md to specs/feature-name/README.md
4. Complete every section from the Required Sections table below
5. Validate against the checklist before completing

Required Sections

Section	Content
Feature Overview	2-3 paragraphs: what, who, problem solved
Success Criteria	Measurable outcomes defining "done"
Design Goals	Primary (must) and secondary (nice to have)
User Experience	1-2 paragraphs: interaction, journey
Design Rationale	1-2 paragraphs: why this approach, trade-offs
Constraints/Assumptions	Technical constraints, business assumptions
Functional Requirements	FR-N format, max 6-8, with acceptance criteria
Edge Cases	Unusual inputs, failure scenarios

Acceptance Criteria

- [ ] Given [context], when [action], then [expected result]

Include 2-4 criteria per requirement: happy path + key failure cases.

Scope Check

More than 6-8 requirements = feature too large. Split: identify 3-4 core requirements, flag rest for separate spec in "Scope Notes" section.

Validation Checklist

• Single MVP focus (one deliverable)
• All requirements have testable criteria
• No TODO/TBD placeholders
• Edge cases documented

Exclusions

A spec defines WHAT to build, not HOW to build it. Exclude:

• Implementation approach or technical strategy
• Architecture diagrams
• Code examples
• Database schemas
• API signatures
• Technology or framework choices
• Development estimates, timelines, or phase sections

Supporting Files

• assets/spec.md - Spec template
• references/spec-guide.md - Extended guidance on ADRs and archival