Creates specs before coding. Use when starting a new project, feature, or significant change and no specification exists yet. Use when drafting a PRD or requirements document with objectives and scope, or when requirements are unclear, ambiguous, or only exist as a vague idea. Use when a single requirement spans several independently testable capabilities and needs decomposing into a capability map of modules before specifying.
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# Spec-Driven Development
## Overview
Write a structured specification before writing any code. The spec is the shared source of truth between you and the human engineer — it defines what we're building, why, and how we'll know it's done. Code without a spec is guessing.
## When to Use
- Starting a new project or feature
- Requirements are ambiguous or incomplete
- The change touches multiple files or modules
- You're about to make an architectural decision
- The task would take more than 30 minutes to implement
**When NOT to use:** Single-line fixes, typo corrections, or changes where requirements are unambiguous and self-contained.
## The Gated Workflow
Spec-driven development has four phases, preceded by a scope check (Phase 0) that activates only when one request bundles several independently testable capabilities. Do not advance to the next phase until the current one is validated.
```
SPECIFY ──→ PLAN ──→ TASKS ──→ IMPLEMENT
│ │ │ │
▼ ▼ ▼ ▼
Human Human Human Human
reviews reviews reviews reviews
```
### Phase 0: Scope Check
…
The line at the top of this page pins the label git:20260916.3a6b22e, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
GET https://markdownregistry.com/api/v1/artifacts/art_bptrlkehd76h6wbe
GET https://markdownregistry.com/api/v1/resolve?ref=nota-america/forgecat-agent-profiles/spec-driven-development
GET https://markdownregistry.com/api/v1/blob/a204d46e33d2f62c83064040083cd2348a9617dcbe2f45f12a3a57895f7bcdc3
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
nota-america/forgecat-agent-profiles · profiles/addyosmani/agent-skills/for-claude/.claude/skills/api-and-interface-design/SKILL.md · Guides stable API and interface design. Use when designing APIs,
nota-america/forgecat-agent-profiles · profiles/addyosmani/agent-skills/for-claude/.claude/skills/browser-testing-with-devtools/SKILL.md · Tests in real browsers via Chrome DevTools MCP. Use when building
nota-america/forgecat-agent-profiles · profiles/addyosmani/agent-skills/for-claude/.claude/skills/ci-cd-and-automation/SKILL.md · Automates CI/CD pipeline setup. Use when setting up or modifying
nota-america/forgecat-agent-profiles · profiles/addyosmani/agent-skills/for-claude/.claude/skills/code-review-and-quality/SKILL.md · Conducts multi-axis code review. Use before merging any change. Use
nota-america/forgecat-agent-profiles · profiles/addyosmani/agent-skills/for-claude/.claude/skills/code-simplification/SKILL.md · Simplifies code for clarity. Use when refactoring code for clarity
nota-america/forgecat-agent-profiles · profiles/addyosmani/agent-skills/for-claude/.claude/skills/constraint-driven-development/SKILL.md · Establishes a project's quality bar as a written contract and stops
nota-america/forgecat-agent-profiles · profiles/addyosmani/agent-skills/for-claude/.claude/skills/context-engineering/SKILL.md · Optimizes agent context setup. Use when starting a new session,
nota-america/forgecat-agent-profiles · profiles/addyosmani/agent-skills/for-claude/.claude/skills/deprecation-and-migration/SKILL.md · Manages deprecation and migration. Use when removing old systems,
nota-america/forgecat-agent-profiles · profiles/addyosmani/agent-skills/for-claude/.claude/skills/documentation-and-adrs/SKILL.md · Records decisions and documentation. Use when you need to document
nota-america/forgecat-agent-profiles · profiles/addyosmani/agent-skills/for-claude/.claude/skills/doubt-driven-development/SKILL.md · Subjects every non-trivial decision to a fresh-context adversarial
addyosmani/agent-skills · skills/spec-driven-development/SKILL.md · Creates specs before coding. Use when starting a new project, feature, or significant change and no specification…
a5c-ai/babysitter · library/methodologies/pilot-shell/skills/spec-driven-development/SKILL.md · Specification creation and management for the Pilot Shell methodology. Covers semantic search, clarifying questions…
sandbaseai/sandbase-skills · marketing/spec-driven-development/SKILL.md · Plan, implement, or review spec driven development work in an existing codebase with compatibility, security, and…
shashankswe2020-ux/whoop-mcp · .github/skills/spec-driven-development/SKILL.md · Creates specs before coding. Use when starting a new project, feature, or significant change and no specification…
magnus919/agent-skills · spec-driven-development/SKILL.md · Design and run a Spec-Driven Development (SDD) pipeline for AI software factories — where structured specifications are…
nota-america/forgecat-agent-profiles · profiles/addyosmani/agent-skills/for-forgecat/platforms/cursor/.cursor/skills/spec-driven-development/SKILL.md · Creates specs before coding. Use when starting a new project, feature, or significant change and no specification…
nota-america/forgecat-agent-profiles · profiles/addyosmani/agent-skills/for-forgecat/skills/spec-driven-development/SKILL.md · Creates specs before coding. Use when starting a new project, feature, or significant change and no specification…
nota-america/forgecat-agent-profiles · profiles/addyosmani/agent-skills/for-forgecat/platforms/codex/.agents/skills/spec-driven-development/SKILL.md · Creates specs before coding. Use when starting a new project, feature, or significant change and no specification…
