Contributing

Prerequisites

Tool	Version
Node.js	≥ 20
pnpm	≥ 9

Install pnpm if you don't have it:

npm install -g pnpm

Repository structure

workflow/
├── flowyd/   # Core TypeScript library (this repo)
│   ├── src/          # Source code
│   ├── tests/        # Integration and e2e tests (Vitest)
│   ├── examples/     # Runnable usage examples
│   └── docs/         # VitePress documentation site
└── web-runner/       # React SPA demo (Vite + React Flow)

Setup

cd flowyd
pnpm install
pnpm build

To run the web runner after building the library:

cd ../web-runner
pnpm install
pnpm dev   # → http://localhost:5173

Development commands

pnpm dev            # watch mode — rebuilds on save
pnpm format         # Prettier — format all files
pnpm format:check   # Prettier — check without writing
pnpm typecheck      # tsc --noEmit
pnpm lint           # ESLint
pnpm lint:fix       # ESLint with auto-fix
pnpm test           # Vitest (all three projects: unit, integration, e2e)
pnpm test:unit
pnpm test:integration
pnpm test:e2e
pnpm test:watch     # Vitest watch mode
pnpm build          # production build → dist/
pnpm docs:dev       # VitePress dev server
pnpm docs:build     # VitePress production build

Before opening a PR

Run the full gate — all four must exit clean:

pnpm format:check && pnpm lint && pnpm typecheck && pnpm test && pnpm build

Code style

Formatting

Prettier with printWidth: 100, singleQuote: true, trailingComma: 'all'. Run pnpm format before committing.

TypeScript

• No any. Use unknown and narrow explicitly.
• No non-null assertions (!) without a comment proving the value is non-null.
• No as casts except at layer boundaries after a kind discriminant check — every cast needs a comment.
• Use state.kind === StateKind.Fork to narrow AnyState, not state as IForkState.

Zod

Every payload type is z.infer<typeof MySchema>. Never write a parallel interface alongside a Zod schema.

Conditionals

• Use curly braces on all if/else bodies — no exceptions. ("curly": "error" in ESLint config.)
• Prefer early returns over nested if-else chains.
• Use switch over long if-else chains on a discriminated value.

Error handling

Functions that can fail throw a typed error. No silent catch blocks:

// Correct
try {
  result = await doWork();
} catch (err) {
  throw new WorkflowExecutionError('failed', { cause: err });
}

// Never
try {
  result = await doWork();
} catch {
  result = defaultValue;
}

Comments

Write a comment only when the why would surprise an informed reader. Never explain what the code does — rename the identifier instead.

TSDoc

Every exported symbol needs a TSDoc block with a one-sentence description, @param, @returns, and @throws.

Test structure

Project	Glob	Purpose
unit	src/**/*.test.ts	Co-located unit tests
integration	tests/integration/**/*.test.ts	Multi-component flows
e2e	tests/e2e/**/*.test.ts	Full workflow invariants

tests/helpers.ts — shared makeCtx fixture used by guard unit tests.

Layer rules

Imports flow downward only:

visualization/
    ↓
core/
    ↓
states/   guards/
    ↓
types/

core/ must not import from visualization/. states/ must not import from core/. types/ must not import from any other layer. Treat a violation as a build error even when the compiler does not catch it.

After every code change

Run pnpm lint && pnpm typecheck && pnpm test && pnpm build. Append a version entry to Section 4 of CLAUDE.md and update README.md.