# Sdd Workflow

> Use this skill when the user asks to build a new feature, implement code, or start development work. Enforces the Spec-Driven Development (SDD) 4-phase workflow before any code is written. Invoke when the user says "build", "implement", "create a feature", "write code for", or "add support for".

- Skill: `theinterneti/sdd-workflow-2` (Agent Skill)
- Install (CLI): `npx skillmds@latest add theinterneti/sdd-workflow-2`
- Raw SKILL.md: https://api.skillmd.com/api/skills/theinterneti/sdd-workflow-2/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Productivity
- Author: theinterneti (https://skillmd.com/u/theinterneti)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/theinterneti/sdd-workflow-2

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### Spec-Driven Development Workflow (TTA.dev)

**No implementation code may be written before completing the SDD phases.**

#### The 4 Phases

Execute these phases **sequentially**. No phase may be skipped.

1. **`/specify`** — Functional Specification (The "What")
   - User journeys, edge cases, success criteria, out-of-scope
   - Output: Markdown document for user review and approval

2. **`/plan`** — Technical Plan (The "How")
   - Which packages are affected (`tta-dev-primitives`, `tta-observability-integration`, etc.)
   - New modules, classes, functions to create
   - How the feature composes with existing primitives (`>>`, `|`)
   - External dependencies with justification
   - Observability strategy (traces, metrics, logs)

3. **`/tasks`** — Task Breakdown
   - Isolated, testable work units
   - Each task includes acceptance test description
   - Numbered by dependency (topological sort)
   - Format: Markdown checklist

4. **`/implement`** — Test-Driven Implementation
   - **Red**: Write failing test encoding acceptance criteria
   - **Green**: Minimal implementation to pass the test
   - **Refactor**: Clean up while tests stay green
   - Run quality gate before marking task complete

#### Exceptions

- **`/spike`**: User explicitly requests prototype code. Spike code must never be merged without going through the full SDD workflow afterward.

#### Enforcement

- If the user asks for code without a spec, initiate `/specify` first and explain the SDD process.
- Reference this process by phase (e.g., "Per Phase 1, I need to generate a spec first.").

#### Deep Reference

For the complete SDD Constitution with all tables and detailed guidance, see [`docs/agent-guides/sdd-constitution.md`](../../docs/agent-guides/sdd-constitution.md).