Feature Specification Skill

Purpose

Transform vague or incomplete requests into comprehensive, validated specifications through iterative dialogue. This skill produces a CDC (Cahier Des Charges) document in French that serves as the foundation for all subsequent phases.

Key difference from feature-research:

• feature-specification

  = WHAT to do (define precisely)

• feature-research

  = HOW to do it (technical research)

IMPORTANT: User Interaction

ALWAYS use the

AskUserQuestion

tool to ask questions to the user.

This tool allows structured questioning with multiple choice options:

• Ask 1-4 questions at a time
• Provide 2-4 options per question with descriptions
• User can select options or provide custom "Other" response
• Use

  multiSelect: true

  when multiple answers are valid

Example usage:

AskUserQuestion:
  questions:
    - question: "Who are the primary users of this feature?"
      header: "Users"
      options:
        - label: "Internal employees"
          description: "Staff members using internal tools"
        - label: "External customers"
          description: "End users of the product"
        - label: "Administrators"
          description: "Users with elevated privileges"
      multiSelect: true

Why this matters:

• Structured questions are clearer for users
• Options help users think through possibilities
• Responses are unambiguous
• Conversation stays focused

Specification Workflow

Phase 1: Initial Context Analysis

1. Read the user request - Understand the initial ask
2. Analyze project context - Use Glob/Grep to discover:
   • Project structure and technologies
   • Existing similar features
   • Conventions and patterns in use
3. Identify domain - Understand the business context
4. Ask initial framing questions - Start the dialogue

Example initial analysis:
- Found: package.json → Node.js/React project
- Found: src/modules/auth/ → Authentication module exists
- Found: PostgreSQL migrations → Database with existing schema

Phase 2: Deep Iterative Questioning

Ask questions across these categories. See

references/questioning-guide.md

for complete guide.

2.1 Motivation & Objectives

• What problem does this solve?
• What are the business goals?
• How will success be measured?

2.2 Users & Personas

• Who will use this?
• What is their technical level?
• What are their current workflows?

2.3 Detailed Functionality

• What exactly should happen?
• What actions must be possible?
• What are expected inputs/outputs?

2.4 Constraints & Limits

• Technical constraints (performance, security)?
• Business constraints (regulations, processes)?
• Time or budget constraints?

2.5 Integration & Dependencies

• What existing systems to integrate with?
• What prerequisites must be in place?
• Impact on existing functionality?

2.6 Edge Cases & Exceptions

• What if X fails?
• How to handle edge cases?
• What error scenarios to anticipate?

Questioning principles:

• Ask 2-4 questions at a time, not overwhelming lists
• Build on previous answers
• Validate understanding before moving on
• Be specific based on project context discovered

Phase 3: Contextual Codebase Research

Explore the codebase to inform specifications:

1. Find similar implementations

   Glob: **/*Service.ts, **/*Controller.cs
   Grep: "similar-feature-name"
   

2. Understand existing patterns

   • How are similar features structured?
   • What conventions are followed?
   • What dependencies are used?

3. Identify integration points

   • Which components will be affected?
   • What interfaces exist?
   • What data models are relevant?

Phase 4: Proactive Proposals

Be a force of proposal, not just passive. See

references/proposal-techniques.md

.

Propose simplifications:

"Rather than a complete notification system, I suggest starting with
emails only. This validates the concept before adding push/SMS."

Suggest alternatives:

"I noticed you don't have a queue system. For emails, I suggest using
Hangfire which is already configured in the project."

Identify quick wins:

"We could reuse the existing EmailTemplate component from the
password-reset feature."

Anticipate problems:

"If we store files locally, this won't work with multiple server
instances. Consider using Azure Blob Storage instead."

Phase 5: CDC Documentation

Compile all gathered information into a CDC document.

1. Create

   CDC.md

   using template from

   references/cdc-template.md

2. Review completeness - Ensure all sections are filled appropriately
3. Present for user approval

Context-Aware Questions

Adapt questions based on discovered project context:

If PostgreSQL detected:

"This feature will need new database tables. Have you thought about the data model?"

If React + TypeScript detected:

"Should we include E2E tests with Playwright for this feature?"

If similar feature found:

"I found a similar feature in

src/modules/orders

. Should we follow the same pattern?"

If authentication exists:

"Should this feature be restricted to authenticated users? Specific roles?"

Output

The skill produces

CDC.md

containing:

• Clear problem statement and context
• Validated objectives with success criteria
• Explicit scope (in/out)
• Functional requirements with acceptance criteria
• Non-functional requirements (performance, security, accessibility)
• Constraints and prerequisites
• User personas and usage scenarios
• Identified risks with mitigations
• Documented decisions
• User approval

See

references/cdc-template.md

for the complete template.

Tips for Effective Specification

1. Ask before assuming - Clarify ambiguities early
2. Be context-aware - Use project analysis to ask relevant questions
3. Propose, don't just ask - Offer options based on your analysis
4. Document as you go - Capture decisions in real-time
5. Validate incrementally - Confirm understanding before moving on
6. Think integration - Consider how this fits the existing system
7. Anticipate problems - Surface issues early
8. Keep scope focused - Help user avoid scope creep

Integration with Workflow

Phase 0: Specification (this skill)
   ↓ CDC.md
Phase 1: Research (feature-research)
   ↓ findings.md
Phase 2: Planning (implementation-planner)
   ...

The CDC becomes input for

feature-research

, providing clear requirements for technical research.

Bundled Resources

• references/cdc-template.md

  - Complete CDC template in French

• references/questioning-guide.md

  - Detailed questioning strategies by category

• references/proposal-techniques.md

  - Techniques for being proactive