Spec Writer Skill

Goal

Transform a user goal or feature request into a structured PRD using EARS syntax. Before generating requirements, invoke the ambiguity layer to clarify unclear aspects. Human approval required before proceeding to implementation.

Steps

1. Receive and understand the goal

   • First, check for Step 0 strategic context in docs/strategic/ (e.g., BUSINESS_CASE.md, EMPATHY_MAP.md, PROBLEM_STATEMENT.md). If present, read them.
   • Ask the user: "Describe what you want to build in plain language"
   • Identify: Who is the user? What problem does it solve? What does success look like? (using the strategic docs if available)

2. Ambiguity Layer — ask clarifying questions Identify and ask about ALL ambiguous aspects before writing requirements:

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   Questions to ask (examples):
   - "Who are the users of this feature? (roles, permissions, guest vs authenticated)"
   - "What happens if [edge case] occurs?"
   - "What are the performance expectations? (response time, concurrent users)"
   - "Is there an existing system this integrates with? What are its constraints?"
   - "What is explicitly out of scope for this version?"
   - "Are there any regulatory requirements? (GDPR, HIPAA, PCI-DSS)"
   - "What devices/browsers must be supported?"
   

   Wait for answers before proceeding.

3. Generate the PRD using templates/product/PRD_TEMPLATE.md

4. Write EARS requirements — use all 5 patterns as appropriate:

   Ubiquitous (always applies):

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   THE SYSTEM SHALL encrypt all data in transit using TLS 1.3 or higher.
   

   Event-Driven (triggered by an event):

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   WHEN a user submits a login form with incorrect credentials 3 consecutive times
   THE SYSTEM SHALL lock the account for 15 minutes and send an email notification.
   

   State-Driven (while in a state):

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   WHILE the payment processing service is unavailable
   THE SYSTEM SHALL queue requests and retry with exponential backoff up to 3 times.
   

   Optional Feature (feature flag / conditional):

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   WHERE two-factor authentication is enabled for the account
   THE SYSTEM SHALL require a TOTP code on each login attempt.
   

   Unwanted Behavior (negative requirements):

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   THE SYSTEM SHALL NOT store plaintext passwords in any medium.
   THE SYSTEM SHALL NOT expose internal stack traces in HTTP responses.
   

5. Write acceptance criteria Each requirement needs 1+ verifiable acceptance criteria:

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   Given [precondition]
   When [action]
   Then [expected outcome with measurable result]
   

6. Non-functional requirements Always include:

   • Performance: expected response time, throughput
   • Security: data classification, access control requirements
   • Accessibility: WCAG level (if UI feature)
   • Scalability: expected load, growth projections

7. Out of scope section Explicitly list what this feature does NOT include. This prevents scope creep.

8. Present PRD to human for approval Say: "Here is the PRD. Please review and approve before I proceed to architecture/planning."

9. After approval: create SDLC checkpoint S01

   • Invoke sdlc-checkpoint.skill → creates SESSION_SNAPSHOT/S01_requirements.md
   • Updates PROJECT_STATE.md → current phase: S02_DESIGN

Constraints

• NEVER skip the ambiguity layer — unresolved ambiguity is the #1 cause of rework
• NEVER start planning or implementation without human approval of the PRD
• All requirements must be EARS-formatted and verifiable (not vague like "fast" or "user-friendly")
• Use the PRD template in templates/product/PRD_TEMPLATE.md

Output Format

Completed PRD.md file at project root (or docs/) using templates/product/PRD_TEMPLATE.md structure.