Introduction: The Human-AI Partnership in SDD

Welcome to Unit 5! You've learned to evaluate specifications in Units 1-4. Now you'll learn the actual Spec-Driven Development workflow: collaborating with AI to generate specifications.

The Traditional Mistake:

Many developers think SDD means "write detailed specifications by hand before coding." That's the old way - and it's why specification-driven approaches failed historically. They were too time-consuming.

The SDD Reality with AI:

In modern SDD with Claude Code:

  • Humans provide requirements and intent (structured prompts)
  • AI generates formal specifications using templates
  • Humans review for quality and business correctness
  • AI refines based on feedback
  • Humans approve when spec meets quality threshold

Your Role in the Partnership:

You are NOT a specification writer. You are a specification architect:

  • Define WHAT you want (business intent)
  • Review AI-generated specs critically
  • Catch domain knowledge AI doesn't have
  • Guide refinement through targeted feedback
  • Approve when quality threshold met (≥75/100)

AI's Role:

Claude Code is your specification generator:

  • Systematically covers all template sections
  • Considers edge cases you might forget
  • Maintains consistent format
  • Generates complete technical plans
  • But needs your domain expertise to validate
Core Principle: Division of Labor

Humans define WHAT and WHY. AI generates HOW.

This division leverages each party's strengths:

  • Humans excel at understanding business needs, domain constraints, and user value
  • AI excels at systematic documentation, comprehensive coverage, and consistent formatting

With AI assistance, specification creation becomes faster than jumping straight to code while producing better outcomes.

The AI-Accelerated SDD Workflow

Here's the typical workflow when building features with AI assistance:

  1. Human provides structured requirements - Context, requirements, user perspective, constraints
  2. AI generates comprehensive specification - Follows template, covers all sections
  3. Human reviews critically - Validates business logic, checks domain accuracy, scores on 5 dimensions
  4. AI refines based on feedback - Addresses specific issues, adds missing details
  5. Human approves final spec - Confirms ≥75/100 score, verifies readiness
  6. AI generates tests and implementation - Creates tests and code matching specification
  7. Human validates against business needs - Runs tests, checks behavior

This workflow transforms specification from a bottleneck into an accelerator.

The Specification Generation Prompt Pattern

When you want to add a feature to TaskMaster, you start by giving Claude Code requirements in a structured prompt.

Essential Prompt Structure:

Three critical sections for quality:

  • ANALYZE EXISTING CODE - AI extracts patterns from your codebase
  • EXAMPLE REFERENCE - AI matches your existing spec quality/style
  • CONSTRAINTS - Guards against implementation details and vague language

Impact on iterations:

ApproachIterationsInitial Score
Informal ("I need auth...")3-465/100
Enhanced (all sections)1-278-85/100
The 5 Dimensions of Specification Quality

Score specifications out of 100 across five dimensions:

1. Clarity (0-25) - Terms defined, no ambiguity (❌ "Valid format" → ✅ "Regex: ^[a-z0-9-]{1,30}$")
2. Completeness (0-25) - All template sections present, no [TBD] markers
3. Testability (0-20) - Given/When/Then format, concrete examples with real data
4. Consistency (0-20) - Follows CLAUDE.md, matches existing API patterns
5. Appropriate Abstraction (0-10) - WHAT not HOW, no database/code details

Calibrating Your Scores:

Use these ranges to score consistently:

Clarity (0-25):

  • 20-25: All terms defined precisely with formats/patterns. Zero ambiguous language.
  • 15-19: Most terms defined, 1-2 need precision (e.g., "reasonable limit" vs "10 max")
  • 10-14: Multiple vague terms, but core concepts understandable
  • 0-9: Ambiguity prevents understanding requirements

Completeness (0-25):

  • 20-25: All template sections present with substance. No [TBD] or "will be determined"
  • 15-19: All sections present, but 1-2 are thin (single sentence where paragraph needed)
  • 10-14: Missing 1 section OR multiple sections are stubs
  • 0-9: Multiple sections missing or mostly empty

Testability (0-20):

  • 16-20: All scenarios in Given/When/Then. Examples use real formats (UUID4, ISO-8601)
  • 12-15: Structured scenarios but some examples use placeholders ("some-id", "timestamp")
  • 8-11: Scenarios present but lack concrete structure or realistic data
  • 0-7: No structured scenarios, or only narrative descriptions

Consistency (0-20):

  • 16-20: Matches all CLAUDE.md conventions (naming, error formats, response structure)
  • 12-15: Follows most conventions, 1-2 minor deviations
  • 8-11: Multiple inconsistencies with existing API patterns
Efficient Review Workflow

10-Minute Triage: All sections present? Obvious vague terms? Matches conventions? Examples realistic?

30-Minute Deep Review: Score each dimension, identify specific issues

5-Minute Revision Check: Feedback addressed? Score ≥75?

Give specific feedback:

  • ✅ "Line 42: Replace 'valid format' with regex: ^[a-z0-9-]{1,30}$"
  • ❌ "Make it clearer"
Summary: Your Workflow
  1. Prepare prompt (5 min): Identify related code/specs, gather requirements
  2. Generate (2 min): Provide enhanced prompt to Claude
  3. Review and score (10-30 min): Evaluate on 5 dimensions
  4. Refine (5-10 min/iteration): Specific feedback, re-score
  5. Approve (≥75 score): Proceed to implementation

Result: 10-15 minutes to approved spec vs. 20-25 minutes with informal prompts.

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