Scaffold: .NET 9 + React 19 Project

Creates a complete greenfield project structure ready for development.

Tech stack: .NET 9, ASP.NET Core, React 19, Vite, TypeScript, Tailwind CSS v4, Zustand, SQLite.

Input

$ARGUMENTS contains one or two arguments:

1. $1 (required) — absolute or relative path to the project root directory (e.g., ~/repos/playground/my-app).
2. $2 (optional) — an MVP spec, either as:
   • A file path to a spec/outline document (e.g., ~/docs/mvp-outline.md)
   • Inline text describing the MVP (e.g., "A marketplace where freelancers sell AI skills")

Parsing rules: Split $ARGUMENTS on the first whitespace to get $1. Everything after that first whitespace is $2. If $2 is quoted, strip the surrounding quotes.

Validation: If $1 is empty or missing, STOP with error: "Usage: /scaffold [spec-file-or-text]".

Expand ~ to the user's home directory. Resolve relative paths against the current working directory.

If the target directory already exists AND contains a CLAUDE.md file, STOP: "Project already exists at {path}."

Detecting spec type (when $2 is present)

1. Expand ~ in $2 and resolve relative paths.
2. Check if the resolved path exists as a file on disk (use test -f).
   • If file exists: treat $2 as a spec file path. Read its full contents.
   • If file does not exist: treat $2 as inline text.

Steps

1. Create directory structure

mkdir -p {path}/backend {path}/frontend {path}/_docs

Result:

{path}/
├── backend/
├── frontend/
└── _docs/

2. Process spec (only when $2 is provided)

Skip this step entirely if $2 was not provided.

2a. Store the full spec

• If $2 is a file path: Read the file contents and write them VERBATIM to {path}/_docs/spec.md.
• If $2 is inline text: Write the text as-is to {path}/_docs/spec.md.

The file _docs/spec.md must contain the FULL original input, unmodified.

2b. Extract the project mission

Read the spec content (whether from file or inline text) and distill a 1-3 sentence project mission that captures the core concept. This is a brief description of WHAT the project is, not HOW to build it.

Store the result as {mission} — it will be used in step 4 (CLAUDE.md).

Guidelines for extraction:

• Focus on the core product/service concept
• Strip implementation details, phases, and technical plans
• If the input is already short (1-3 sentences), use it directly as the mission
• If the input is long (a brainstorm doc, full spec, etc.), synthesize the essence

3. Create .gitignore

Write this EXACT content to {path}/.gitignore:

# .NET
bin/
obj/
*.user
.vs/

# Node
node_modules/
dist/
.vite/

# IDE
.idea/

# OS
.DS_Store

# Environment
.env
.env.local

# SQLite
*.db
*.db-journal

4. Create CLAUDE.md

Derive {project_name} from the directory name (e.g., /tmp/my-app → my-app).

Write this EXACT template to {path}/CLAUDE.md:

# CLAUDE.md — {project_name}

## Project
{project_description}

## Tech Stack
- Backend: .NET 9, ASP.NET Core, EF Core 9, SQLite
- Frontend: React 19, Vite, TypeScript, Tailwind CSS v4, Zustand

## Implementation Status
<!-- Updated after each feature completion -->

*No features implemented yet.*

## Commands

### Backend
```bash
cd backend && dotnet restore && dotnet build && dotnet run
```

### Frontend
```bash
cd frontend && npm install && npm run dev
```

### Tests
```bash
cd backend && dotnet test
cd frontend && npm test
```

Substitution for {project_description}:

• If $2 was NOT provided: use {to be populated}
• If $2 WAS provided: use {mission} from step 2b (1-3 sentences, NOT the full spec — the full spec lives in _docs/spec.md)

5. Create minimal backend with health endpoint

Run from within the project directory:

cd {path}/backend && dotnet new web -n Api

Then overwrite {path}/backend/Api/Program.cs with this EXACT content:

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddCors(options =>
{
    options.AddDefaultPolicy(policy =>
        policy.AllowAnyOrigin()
              .AllowAnyHeader()
              .AllowAnyMethod());
});

var app = builder.Build();
app.UseCors();

app.MapGet("/health", () => Results.Ok(new { status = "healthy" }));

app.Run();

This provides:

• /health endpoint for E2E test startup detection
• Permissive CORS for local dev
• Minimal foundation for backend implementation

6. Git init + initial commit

cd {path} && git init && git add . && git commit -m "chore: initial scaffold"

Self-Verify Gate Checklist

After completing all steps, verify EVERY item. If ANY item fails, fix it before reporting success.

Always verify (8 items):

• Directory backend/ exists
• Directory frontend/ exists
• Directory _docs/ exists
• File CLAUDE.md exists at project root
• File .gitignore exists at project root
• File backend/Api/Program.cs exists AND contains /health endpoint
• .git/ exists (git repo initialized)
• At least one commit exists (git log --oneline -1 succeeds)

Additionally verify when spec was provided (+3 items):

• File _docs/spec.md exists
• _docs/spec.md contains the full original spec content (not truncated)
• CLAUDE.md ## Project section contains a brief mission (NOT the placeholder {to be populated after Phase 0})

Verification commands:

cd {path}
test -d backend && echo "PASS: backend/" || echo "FAIL: backend/"
test -d frontend && echo "PASS: frontend/" || echo "FAIL: frontend/"
test -d _docs && echo "PASS: _docs/" || echo "FAIL: _docs/"
test -f CLAUDE.md && echo "PASS: CLAUDE.md" || echo "FAIL: CLAUDE.md"
test -f .gitignore && echo "PASS: .gitignore" || echo "FAIL: .gitignore"
grep -q "/health" backend/Api/Program.cs && echo "PASS: /health endpoint" || echo "FAIL: /health endpoint"
test -d .git && echo "PASS: .git/" || echo "FAIL: .git/"
git log --oneline -1 && echo "PASS: commit exists" || echo "FAIL: no commits"

Additional verification when spec was provided:

test -f _docs/spec.md && echo "PASS: _docs/spec.md" || echo "FAIL: _docs/spec.md"
grep -q "to be populated" CLAUDE.md && echo "FAIL: CLAUDE.md still has placeholder" || echo "PASS: CLAUDE.md has mission"

Report without spec: "Scaffold complete at {path}. All 8 gate items verified." Report with spec: "Scaffold complete at {path}. All 11 gate items verified (spec seeded)."