spec-to-repo – Coding skill for AI agents

Spec to Repo

Turn a natural-language project specification into a complete, runnable starter repository. Not a template filler — a spec interpreter that generates real, working code for any stack.

When to Use

• User provides a text description of an app and wants code
• User has a PRD, requirements doc, or feature list and needs a codebase
• User says "build me an app that...", "scaffold this", "bootstrap a project"
• User wants a working starter repo, not just a file tree

Not this skill when the user wants a SaaS app with Stripe + Auth specifically — use product-team/saas-scaffolder instead.

Core Workflow

Phase 1 — Parse & Interpret

Read the spec. Extract these fields silently:

| Field | Source | Required |

|-------|--------|----------|

| App name | Explicit or infer from description | yes |

| Description | First sentence of spec | yes |

| Features | Bullet points or sentences describing behavior | yes |

| Tech stack | Explicit ("use FastAPI") or infer from context | yes |

| Auth | "login", "users", "accounts", "roles" | if mentioned |

| Database | "store", "save", "persist", "records", "schema" | if mentioned |

| API surface | "endpoint", "API", "REST", "GraphQL" | if mentioned |

| Deploy target | "Vercel", "Docker", "AWS", "Railway" | if mentioned |

Stack inference rules (when user doesn't specify):

| Signal | Inferred stack |

|--------|---------------|

| "web app", "dashboard", "SaaS" | Next.js + TypeScript |

| "API", "backend", "microservice" | FastAPI (Python) or Express (Node) |

| "mobile app" | Flutter or React Native |

| "CLI tool" | Go or Python |

| "data pipeline" | Python |

| "high performance", "systems" | Rust or Go |

After parsing, present a structured interpretation back to the user:

## Spec Interpretation

**App:** [name]
**Stack:** [framework + language]
**Features:**
1. [feature]
2. [feature]

**Database:** [yes/no — engine]
**Auth:** [yes/no — method]
**Deploy:** [target]

Does this match your intent? Any corrections before I generate?

Flag ambiguities. Ask at most 3 clarifying questions. If the user says "just build it", proceed with best-guess defaults.

Phase 2 — Architecture

Design the project before writing any files:

1. Select template — Match to a stack template from references/stack-templates.md

2. Define file tree — List every file that will be created

3. Map features to files — Each feature gets at minimum one file/component

4. Design database schema — If applicable, define tables/collections with fields and types

5. Identify dependencies — List every package with version constraints

6. Plan API routes — If applicable, list every endpoint with method, path, request/response shape

Present the file tree to the user before generating:

project-name/
├── README.md
├── .env.example
├── .gitignore
├── .github/workflows/ci.yml
├── package.json / requirements.txt / go.mod
├── src/
│   ├── ...
├── tests/
│   ├── ...
└── ...

Phase 3 — Generate

Write every file. Rules:

• Real code, not stubs. Every function has a real implementation. No // TODO: implement or pass placeholders.
• Syntactically valid. Every file must parse without errors in its language.
• Imports match dependencies. Every import must correspond to a package in the manifest (package.json, requirements.txt, go.mod, etc.).
• Types included. TypeScript projects use types. Python projects use type hints. Go projects use typed structs.
• Environment variables. Generate .env.example with every required variable, commented with purpose.
• README.md. Include: project description, prerequisites, setup steps (clone, install, configure env, run), and available scripts/commands.
• CI config. Generate .github/workflows/ci.yml with: install, lint (if linter in deps), test, build.
• .gitignore. Stack-appropriate ignores (node_modules, __pycache__, .env, build artifacts).

File generation order:

1. Manifest (package.json / requirements.txt / go.mod)

2. Config files (.env.example, .gitignore, CI)

3. Database schema / migrations

4. Core business logic

5. API routes / endpoints

6. UI components (if applicable)

7. Tests

8. README.md

Phase 4 — Validate

After generation, run through this checklist:

• [ ] Every imported package exists in the manifest
• [ ] Every file referenced by an import exists in the tree
• [ ] .env.example lists every env var used in code
• [ ] .gitignore covers build artifacts and secrets
• [ ] README has setup instructions that actually work
• [ ] No hardcoded secrets, API keys, or passwords
• [ ] At least one test file exists
• [ ] Build/start command is documented and would work

Run scripts/validate_project.py against the generated directory to catch common issues.

Examples

Example 1: Task Management API

Input spec:

> "Build me a task management API. Users can create, list, update, and delete tasks. Tasks have a title, description, status (todo/in-progress/done), and due date. Use FastAPI with SQLite. Add basic auth with API keys."

Output file tree:

task-api/
├── README.md
├── .env.example              # API_KEY, DATABASE_URL
├── .gitignore
├── .github/workflows/ci.yml
├── requirements.txt          # fastapi, uvicorn, sqlalchemy, pytest
├── main.py                   # FastAPI app, CORS, lifespan
├── models.py                 # SQLAlchemy Task model
├── schemas.py                # Pydantic request/response schemas
├── database.py               # SQLite engine + session
├── auth.py                   # API key middleware
├── routers/
│   └── tasks.py              # CRUD endpoints
└── tests/
    └── test_tasks.py         # Smoke tests for each endpoint

Example 2: Recipe Sharing Web App

Input spec:

> "I want a recipe sharing website. Users sign up, post recipes with ingredients and steps, browse other recipes, and save favorites. Use Next.js with Tailwind. Store data in PostgreSQL."

Output file tree:

recipe-share/
├── README.md
├── .env.example              # DATABASE_URL, NEXTAUTH_SECRET, NEXTAUTH_URL
├── .gitignore
├── .github/workflows/ci.yml
├── package.json              # next, react, tailwindcss, prisma, next-auth
├── tailwind.config.ts
├── tsconfig.json
├── next.config.ts
├── prisma/
│   └── schema.prisma         # User, Recipe, Ingredient, Favorite models
├── src/
│   ├── app/
│   │   ├── layout.tsx
│   │   ├── page.tsx          # Homepage — recipe feed
│   │   ├── recipes/
│   │   │   ├── page.tsx      # Browse recipes
│   │   │   ├── [id]/page.tsx # Recipe detail
│   │   │   └── new/page.tsx  # Create recipe form
│   │   └── api/
│   │       ├── auth/[...nextauth]/route.ts
│   │       └── recipes/route.ts
│   ├── components/
│   │   ├── RecipeCard.tsx
│   │   ├── RecipeForm.tsx
│   │   └── Navbar.tsx
│   └── lib/
│       ├── prisma.ts
│       └── auth.ts
└── tests/
    └── recipes.test.ts

Example 3: CLI Expense Tracker

Input spec:

> "Python CLI tool for tracking expenses. Commands: add, list, summary, export-csv. Store in a local SQLite file. No external API."

Output file tree:

expense-tracker/
├── README.md
├── .gitignore
├── .github/workflows/ci.yml
├── pyproject.toml
├── src/
│   └── expense_tracker/
│       ├── __init__.py
│       ├── cli.py            # argparse commands
│       ├── database.py       # SQLite operations
│       ├── models.py         # Expense dataclass
│       └── formatters.py     # Table + CSV output
└── tests/
    └── test_cli.py

Anti-Patterns

| Anti-pattern | Fix |

|---|---|

| Placeholder code — // TODO: implement, pass, empty function bodies | Every function has a real implementation. If complex, implement a working simplified version. |

| Stack override — picking Next.js when the user said Flask | Always honor explicit tech preferences. Only infer when the user doesn't specify. |

| Missing .gitignore — committing node_modules or .env | Generate stack-appropriate .gitignore as one of the first files. |

| Phantom imports — importing packages not in the manifest | Cross-check every import against package.json / requirements.txt before finishing. |

| Over-engineering MVP — adding Redis caching, rate limiting, WebSockets to a v1 | Build the minimum that works. The user can iterate. |

| Ignoring stated preferences — user says "PostgreSQL" and you generate MongoDB | Parse the spec carefully. Explicit preferences are non-negotiable. |

| Missing env vars — code reads process.env.X but .env.example doesn't list it | Every env var used in code must appear in .env.example with a comment. |

| No tests — shipping a repo with zero test files | At minimum: one smoke test per API endpoint or one test per core function. |

| Hallucinated APIs — generating code that calls library methods that don't exist | Stick to well-documented, stable APIs. When unsure, use the simplest approach. |

Validation Script

scripts/validate_project.py

Checks a genera

… (full content is in the download package)