### Running the Kakera Example

Source: https://github.com/yusukebe/kakera/blob/main/AGENTS.md

Instructions for setting up and running the example application. This includes installing dependencies and starting the development server.

```sh
cd example
bun install
bun run dev          # wrangler dev (runs [build] automatically, watches routes/)
bun run deploy       # wrangler deploy
```

--------------------------------

### Example Project Setup

Source: https://github.com/yusukebe/kakera/blob/main/README.md

Commands to set up and run the example Kakera project locally.

```sh
cd example
bun install
bun run dev
```

--------------------------------

### Complete Project Setup for Kakera Worker

Source: https://context7.com/yusukebe/kakera/llms.txt

Step-by-step guide to setting up a new project with Kakera Worker, including dependency installation, creating the host worker, defining routes with Hono, and creating the build script. This covers the essential files and commands.

```sh
# 1. Create project
mkdir my-app && cd my-app
bun init -y

# 2. Install dependencies
bun add kakera-worker hono
bun add -d wrangler typescript @cloudflare/workers-types

# 3. Create host worker
mkdir src
echo 'export { app as default } from "kakera-worker"' > src/app.ts

# 4. Create routes
mkdir routes
cat > routes/index.ts << 'EOF'
import { Hono } from 'hono'
const app = new Hono()
app.get('/', (c) => c.text('Hello!'))
export default app
EOF

cat > routes/users.ts << 'EOF'
import { Hono } from 'hono'
const app = new Hono()
app.get('/',    (c) => c.json({ users: [] }))
app.get('/:id', (c) => c.json({ id: c.req.param('id') }))
export default app
EOF

# 5. Create build script
cat > build.ts << 'EOF'
import { Glob } from 'bun'
const entrypoints = [...new Glob('routes/*.{ts,tsx}').scanSync('.')]
const result = await Bun.build({ entrypoints, outdir: './dist', target: 'browser', format: 'esm' })
if (!result.success) { for (const log of result.logs) console.error(log); process.exit(1) }
EOF

# 6. wrangler.jsonc already shown above

# 7. Run locally — wrangler runs [build].command automatically
bun run dev
# → GET http://localhost:8787/          → "Hello!"
# → GET http://localhost:8787/users     → {"users":[]}
# → GET http://localhost:8787/users/42  → {"id":"42"}

```

--------------------------------

### Install Kakera Worker

Source: https://github.com/yusukebe/kakera/blob/main/README.md

Install the kakera-worker package using npm.

```sh
npm i kakera-worker
```

--------------------------------

### Define a Route with Hono

Source: https://github.com/yusukebe/kakera/blob/main/README.md

Example of a route file defining a Hono application for handling requests. This file would typically be placed in the 'routes/' directory.

```ts
// routes/users.ts
import { Hono } from 'hono'

const app = new Hono()
app.get('/', (c) => c.json({ users: [] }))
app.get('/:id', (c) => c.json({ id: c.req.param('id') }))

export default app
```

--------------------------------

### Index Route Handler with Hono Tiny

Source: https://context7.com/yusukebe/kakera/llms.txt

Example of an index route file (`routes/index.ts`) using Hono Tiny to handle the root path. This route handles requests to the base URL.

```typescript
// routes/index.ts — handles GET /
import { Hono } from 'hono/tiny'

const app = new Hono()
app.get('/', (c) => c.text('Hello from kakera!'))

export default app
```

--------------------------------

### User Route Handler with Hono

Source: https://context7.com/yusukebe/kakera/llms.txt

Example of a route file (`routes/users.ts`) using Hono to handle requests. The host worker strips the first path segment, so this route handles paths relative to `/users`.

```typescript
// routes/users.ts
import { Hono } from 'hono'

const app = new Hono()

// Receives GET /   (original request was GET /users)
app.get('/', (c) => {
  return c.json({
    users: [
      { id: 1, name: 'Alice' },
      { id: 2, name: 'Bob' }
    ]
  })
})

// Receives GET /42  (original request was GET /users/42)
app.get('/:id', (c) => {
  const id = c.req.param('id')
  return c.json({ id, name: `User ${id}` })
})

export default app
```

--------------------------------

### Example Route Module with Hono

Source: https://github.com/yusukebe/kakera/blob/main/AGENTS.md

Define a route module by default-exporting a fetch handler, typically an instance of a framework like Hono. The host worker strips the first path segment, so the route module receives requests relative to its own path.

```typescript
// routes/users.ts
import { Hono } from 'hono'
const app = new Hono()
app.get('/', (c) => c.json({ users: [] }))
app.get('/:id', (c) => c.json({ id: c.req.param('id') }))
export default app
```

--------------------------------

### Bun Build Script for Kakera Routes

Source: https://github.com/yusukebe/kakera/blob/main/AGENTS.md

Use a Bun script to bundle route files into individual ESM modules. This script uses `Bun.Glob` to find entrypoints and `Bun.build` to create the bundles, targeting the browser environment. It includes error handling for the build process.

```typescript
// build.ts
import { Glob } from 'bun'

const entrypoints = [...new Glob('routes/*.{ts,tsx}').scanSync('.')]
const result = await Bun.build({
  entrypoints,
  outdir: './dist',
  target: 'browser',
  format: 'esm'
})

if (!result.success) {
  for (const log of result.logs) console.error(log)
  process.exit(1)
}
```

--------------------------------

### Per-Route Bundling Script (`build.ts`)

Source: https://context7.com/yusukebe/kakera/llms.txt

This script uses Bun.Glob to find route files and Bun.build to compile each into an ESM bundle. Dependencies are inlined, suitable for a Worker Loader that receives one module per route. Ensure `target` is 'browser' for Workerd.

```typescript
// build.ts
import { Glob } from 'bun'

const entrypoints = [...new Glob('routes/*.{ts,tsx}').scanSync('.')]

const result = await Bun.build({
  entrypoints,
  outdir: './dist',
  target: 'browser', // correct for workerd (V8, no Node built-ins)
  format: 'esm'
})

if (!result.success) {
  for (const log of result.logs) console.error(log)
  process.exit(1)
}
// Output: dist/index.js, dist/users.js, dist/posts.js ...
```

```json
{
  "scripts": {
    "dev":    "wrangler dev",
    "build":  "bun run build.ts",
    "deploy": "wrangler deploy"
  }
}
```

--------------------------------

### Configure Route File Extensions

Source: https://github.com/yusukebe/kakera/blob/main/README.md

Customize the file extensions that Kakera should consider as route entry points using the 'extensions' option.

```ts
kakera({ extensions: ['js', 'mjs'] })
```

--------------------------------

### NPM Scripts for Development and Deployment

Source: https://github.com/yusukebe/kakera/blob/main/README.md

Defines NPM scripts for common development tasks: 'dev' to run the development server, 'build' to bundle routes, and 'deploy' to deploy to Cloudflare.

```json
{
  "scripts": {
    "dev": "wrangler dev",
    "build": "bun run build.ts",
    "deploy": "wrangler deploy"
  }
}
```

--------------------------------

### Kakera Public API Imports

Source: https://github.com/yusukebe/kakera/blob/main/AGENTS.md

Import core Kakera components like the default app instance, the kakera factory function, and type definitions for bindings and options. Use the zero-config path by exporting `app` directly.

```typescript
import { app, kakera, type KakeraBindings, type KakeraOptions } from 'kakera-worker'
```

--------------------------------

### Bun Build Script for Routes

Source: https://github.com/yusukebe/kakera/blob/main/README.md

A build script using Bun's Glob API to find and bundle all TypeScript and TSX route files in the 'routes/' directory into the 'dist/' directory.

```ts
// build.ts
import { Glob } from 'bun'

const entrypoints = [...new Glob('routes/*.{ts,tsx}').scanSync('.')]

const result = await Bun.build({
  entrypoints,
  outdir: './dist',
  target: 'browser',
  format: 'esm'
})

if (!result.success) {
  for (const log of result.logs) console.error(log)
  process.exit(1)
}
```

--------------------------------

### Wrangler Configuration for Kakera

Source: https://github.com/yusukebe/kakera/blob/main/README.md

Wrangler configuration file specifying the main entry point, build command, asset directory, and worker loader binding for a Kakera application.

```jsonc
// wrangler.jsonc
{
  "name": "my-app",
  "main": "src/app.ts",
  "build": {
    "command": "bun run build",
    "watch_dir": "routes"
  },
  "assets": { "directory": "dist", "binding": "ASSETS" },
  "worker_loaders": [{ "binding": "LOADER" }],
  "compatibility_date": "2026-03-17"
}
```

--------------------------------

### Host Worker Entry Point

Source: https://github.com/yusukebe/kakera/blob/main/README.md

The default host worker entry point, re-exporting the app from 'kakera-worker'.

```ts
// src/app.ts
export { app as default } from 'kakera-worker'
```

--------------------------------

### Host Worker with Options

Source: https://github.com/yusukebe/kakera/blob/main/README.md

Configure the kakera worker with options, such as specifying a different directory for route fetching.

```ts
import { kakera } from 'kakera-worker'
export default kakera({ dir: 'subdir' }) // fetches subdir/<name>.js via ASSETS
```

--------------------------------

### Wrangler Configuration for Kakera

Source: https://github.com/yusukebe/kakera/blob/main/AGENTS.md

Configure Wrangler to use Kakera by specifying the main entry point, build command, asset directory for bundles, and worker loader bindings. Ensure the compatibility date is set appropriately.

```json
{
  "main": "src/app.ts",
  "build": {
    "command": "bun run build",
    "watch_dir": "routes"
  },
  "assets": { "directory": "dist", "binding": "ASSETS" },
  "worker_loaders": [{ "binding": "LOADER" }],
  "compatibility_date": "2026-03-17"
}
```

--------------------------------

### KakeraOptions Configuration Shape

Source: https://context7.com/yusukebe/kakera/llms.txt

Define `KakeraOptions` to configure the `dir` (asset path prefix) and `extensions` (probed file extensions) for the `kakera()` factory.

```typescript
import { kakera, type KakeraOptions } from 'kakera-worker'

const options: KakeraOptions = {
  dir: 'routes',
  extensions: ['js', 'mjs']
}

export default kakera(options)
// A request to /users/42 will probe:
//   ASSETS /routes/users.js   → if 200, load and forward /42
//   ASSETS /routes/users.mjs  → fallback
//   404 if neither found
```

--------------------------------

### Kakera Worker Dispatch Flow

Source: https://context7.com/yusukebe/kakera/llms.txt

Illustrates how the host worker extracts the route name, fetches the bundle from ASSETS, and uses the LOADER cache. On a cache miss, the bundle source is fetched and provided as a single module. This simplified implementation shows the core logic.

```plaintext
GET /users/42
│
├─ routeName = "users"
├─ env.ASSETS.fetch HEAD /users.js  → 200 OK
├─ env.LOADER.get("users", loader)
│    └─ cache miss → fetch GET /users.js → pass source as { "index.js": "<source>" }
├─ subPath = "/42"
└─ worker.getEntrypoint().fetch(new Request("/42", original))
```

```typescript
// Simplified internal implementation (src/index.ts)
import { kakera, type KakeraBindings } from 'kakera-worker'

// The factory returns this handler:
const handler: ExportedHandler<KakeraBindings> = {
  async fetch(request, env) {
    const url = new URL(request.url)
    const segments = url.pathname.split('/').filter(Boolean)
    const routeName = segments[0] || 'index'   // "/" → "index"

    // Probe extensions in order
    let path: string | null = null
    for (const ext of ['js']) {
      const res = await env.ASSETS.fetch(
        new Request(`http://dummy/${routeName}.${ext}`, { method: 'HEAD' })
      )
      if (res.ok) { path = `${routeName}.${ext}`; break }
    }
    if (path === null) return new Response('Not Found', { status: 404 })

    // Load (or retrieve cached) isolated worker
    const worker = env.LOADER.get(routeName, async () => {
      const res = await env.ASSETS.fetch(new Request(`http://dummy/${path}`))
      return {
        compatibilityDate: '2026-03-24',
        mainModule: 'index.js',
        modules: { 'index.js': await res.text() },
        globalOutbound: null
      }
    })

    // Strip first segment, forward the rest
    const subPath = '/' + segments.slice(1).join('/')
    const forwarded = new URL(subPath + url.search, url.origin)
    return worker.getEntrypoint().fetch(new Request(forwarded, request))
  }
}
```

--------------------------------

### Custom Kakera Factory with Options

Source: https://context7.com/yusukebe/kakera/llms.txt

Use the `kakera` factory function to customize asset directory and file extensions. This factory is tree-shakeable.

```typescript
// src/app.ts — serve bundles from a subdirectory and support both .js and .mjs
import { kakera } from 'kakera-worker'

export default kakera({
  dir: 'workers',
  extensions: ['js', 'mjs']
})
```

--------------------------------

### Pure Annotation for Tree-Shaking

Source: https://github.com/yusukebe/kakera/blob/main/AGENTS.md

Use `/* @__PURE__ */` annotations to help bundlers tree-shake exported variables when they are not directly used. This is a cheap optimization to keep.

```typescript
export const app = /* @__PURE__ */ kakera()
```

--------------------------------

### Kakera Public API

Source: https://github.com/yusukebe/kakera/blob/main/AGENTS.md

The public API of the kakera-worker package includes imports for `app`, `kakera`, `KakeraBindings`, and `KakeraOptions`. `app` is a pre-built default handler, while `kakera` is a factory function for creating custom handlers. `KakeraBindings` defines the required Cloudflare Worker bindings, and `KakeraOptions` allows customization of the worker's directory and file extensions.

```APIDOC
## Imports

```ts
import { app, kakera, type KakeraBindings, type KakeraOptions } from 'kakera-worker'
```

### `app`

- **Description**: A pre-built default `ExportedHandler<KakeraBindings>` instance. This is the zero-configuration entry point for Kakera.
- **Usage**: `export { app as default } from 'kakera-worker'`

### `kakera(options?)`

- **Description**: A factory function that returns an `ExportedHandler<KakeraBindings>`. Use this when you need to override default options like `dir` or `extensions`.
- **Parameters**:
  - `options` (KakeraOptions) - Optional. Configuration options for the Kakera handler.

### `KakeraBindings`

- **Description**: Type definition for the required Cloudflare Worker bindings. This specifies the shape of the environment variables your worker needs.
- **Shape**: `{ ASSETS: Fetcher; LOADER: WorkerLoader }`

### `KakeraOptions`

- **Description**: Type definition for options that can be passed to the `kakera` factory function.
- **Shape**: `{ dir?: string; extensions?: string[] }`
- **Properties**:
  - `dir` (string) - Optional. The directory where route files are located. Defaults to `''`.
  - `extensions` (string[]) - Optional. An array of file extensions to consider as routes. Defaults to `['ts', 'tsx']`.
```

--------------------------------

### KakeraBindings TypeScript Interface Usage

Source: https://context7.com/yusukebe/kakera/llms.txt

Use the `KakeraBindings` interface as a generic parameter for `ExportedHandler` to access `env.ASSETS` and `env.LOADER` in custom handlers.

```typescript
// TypeScript usage — the generic parameter unlocks env.ASSETS and env.LOADER
import { type KakeraBindings } from 'kakera-worker'

// When building a custom handler that wraps kakera:
const handler: ExportedHandler<KakeraBindings> = {
  async fetch(request, env) {
    // env.ASSETS — Fetcher for pre-built bundles
    // env.LOADER — WorkerLoader for isolated worker instantiation
    console.log(env.ASSETS, env.LOADER)
    return new Response('ok')
  }
}
```

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