Hono App Scaffold Skill

Purpose

You are a specialized assistant for bootstrapping and reshaping Hono-based backends/APIs in TypeScript.

Use this skill to:

• Scaffold a new Hono app (standalone or part of a monorepo)
• Restructure an existing Hono project into a clean, feature-oriented layout
• Set up runtime targeting (Node, Cloudflare Workers, Vercel Edge, Bun)
• Wire up:
  • Basic routing structure (routes/)
  • Middleware: logging, CORS, error handling
  • Env management for the chosen runtime
• Prepare the project to later integrate:
  • Auth
  • TypeORM or other persistence
  • Cloudflare Workers / Edge deploy flows
  • API versioning

Do not use this skill for:

• Writing complex business logic → use feature-specific skills
• Detailed auth flows → use hono-authentication (once defined)
• Database/ORM design → use TypeORM-specific skills (typeorm-*)
• Frontend code or Next.js routing (covered by other skills)

If CLAUDE.md exists, follow its conventions (runtime choice, folder structure, linting tools, etc.).

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When To Apply This Skill

Trigger this skill when the user asks for something like:

• “Create a Hono API project.”
• “Move this ad-hoc Hono server into a proper structure.”
• “Set up a Hono app for Cloudflare Workers / Node / Bun.”
• “Give me a clean Hono + TS scaffold to build APIs on.”
• “Refactor this Hono file into routes + middlewares.”

Avoid when:

• The project is clearly NestJS-only or uses a different backend framework.
• We’re only adding one route to an already well-structured Hono project.

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Project Assumptions

Unless the project or CLAUDE.md says otherwise, assume:

• Language: TypeScript

• Package manager preference:

  1. pnpm if pnpm-lock.yaml exists
  2. yarn if yarn.lock exists
  3. otherwise npm

• Runtime: depends on context; default to Node when not specified, but be ready to target:

  • Node (Express-style server, serve/listen)
  • Cloudflare Workers / Pages
  • Vercel Edge / Node runtimes
  • Bun

• Testing: may be added later (Vitest/Jest + supertest/undici)

This skill should tailor the scaffold to the declared runtime when it’s clear.

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Target Project Structure

This skill aims to create or converge towards something like:

project-root/
  src/
    app.ts              # main Hono app builder (routes + middleware)
    index.ts            # runtime-specific entry (Node, Cloudflare, etc.)
    routes/
      index.ts          # main router aggregator
      health.routes.ts
      v1/
        users.routes.ts
        auth.routes.ts
    middlewares/
      logger.ts
      error-handler.ts
      cors.ts
    config/
      env.ts            # env loading per runtime
      runtime.ts        # runtime-specific helpers if needed
    types/
      env.d.ts          # bindings/env typing for Workers/Cloudflare
  test/
    app.spec.ts         # basic smoke/e2e tests (optional stub)
  .env.example          # for Node/Bun/Vercel environments
  tsconfig.json
  package.json
  README.md

For Cloudflare Workers, also expect:

  wrangler.toml

This layout can be adjusted to fit monorepos (e.g. apps/hono-api/), but the internal structure under src/ should remain consistent.

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High-Level Workflow

When this skill is active, follow this process:

1. Detect or create a Hono project

• If Hono is not installed / no project exists:
  • Install hono and runtime-specific packages (e.g. @hono/node-server, @cloudflare/workers-types if needed).
  • Create src/ with app.ts, routes/, middlewares/, config/.
• If a Hono project exists as a single file (e.g. index.ts):
  • Refactor into src/app.ts + src/routes/* + src/middlewares/*.
  • Keep behavior equivalent but structure improved.

2. Choose runtime & entrypoint

Depending on context:

Node runtime (default):

• Use @hono/node-server:

  // src/index.ts
  import { serve } from "@hono/node-server";
  import { app } from "./app";
  
  const port = Number(process.env.PORT ?? 3000);
  console.log(`Listening on http://localhost:${port}`);
  
  serve({
    fetch: app.fetch,
    port,
  });
  

Cloudflare Workers:

• Export app.fetch as the Worker handler:

  // src/index.ts
  import { app } from "./app";
  
  export default {
    fetch: app.fetch,
  };
  

• Configure wrangler.toml outside this skill or with minimal defaults if necessary.

This skill should pick the right pattern based on what’s already present or user preference.

3. Build the main app (app.ts)

Create a central Hono app with basic middleware + routes:

// src/app.ts
import { Hono } from "hono";
import { loggerMiddleware } from "./middlewares/logger";
import { errorHandler } from "./middlewares/error-handler";
import { corsMiddleware } from "./middlewares/cors";
import { bindRoutes } from "./routes";

export const app = new Hono();

app.use("*", loggerMiddleware);
app.use("*", corsMiddleware);
app.use("*", errorHandler);

bindRoutes(app);

Or, if project prefers, mount middleware per route group instead of globally.

4. Routes Organization

Use routes/index.ts as a router aggregator:

// src/routes/index.ts
import type { Hono } from "hono";
import { healthRoutes } from "./health.routes";
import { createV1Routes } from "./v1";

export function bindRoutes(app: Hono) {
  app.route("/health", healthRoutes());

  app.route("/v1", createV1Routes());
}

Example health.routes.ts:

// src/routes/health.routes.ts
import { Hono } from "hono";

export function healthRoutes() {
  const app = new Hono();

  app.get("/", (c) => c.json({ status: "ok" }));

  return app;
}

Example /v1 router:

// src/routes/v1/index.ts
import { Hono } from "hono";
import { usersRoutes } from "./users.routes";

export function createV1Routes() {
  const app = new Hono();

  app.route("/users", usersRoutes());

  return app;
}

Example users routes skeleton:

// src/routes/v1/users.routes.ts
import { Hono } from "hono";

export function usersRoutes() {
  const app = new Hono();

  app.get("/", async (c) => {
    // list users
    return c.json([]);
  });

  app.post("/", async (c) => {
    // create user
    const body = await c.req.json();
    return c.json({ id: "1", ...body }, 201);
  });

  app.get("/:id", async (c) => {
    const id = c.req.param("id");
    return c.json({ id });
  });

  return app;
}

This skill should keep routes small and composable.

5. Middleware Setup

Logger Middleware

// src/middlewares/logger.ts
import type { MiddlewareHandler } from "hono";

export const loggerMiddleware: MiddlewareHandler = async (c, next) => {
  const start = Date.now();
  await next();
  const ms = Date.now() - start;
  console.log(`${c.req.method} ${c.req.path} - ${ms}ms`);
};

Error Handler

// src/middlewares/error-handler.ts
import type { MiddlewareHandler } from "hono";

export const errorHandler: MiddlewareHandler = async (c, next) => {
  try {
    await next();
  } catch (err: any) {
    console.error("Unhandled error:", err);

    return c.json(
      {
        message: "Internal Server Error",
      },
      500,
    );
  }
};

CORS Middleware

Either a custom or hono/cors helper:

// src/middlewares/cors.ts
import type { MiddlewareHandler } from "hono";
import { cors } from "hono/cors";

// If project is fine with the helper:
export const corsMiddleware: MiddlewareHandler = cors({
  origin: "*", // adjust for security
  allowMethods: ["GET", "POST", "PUT", "PATCH", "DELETE", "OPTIONS"],
});

This skill should:

• Set secure defaults where possible (explicit origins in production).
• Ensure order of middleware is appropriate (e.g., error handler should wrap downstream).

6. Env & Config Management

For Node/Vercel/Bun env:

// src/config/env.ts
export type AppEnv = {
  NODE_ENV: "development" | "test" | "production";
  PORT?: string;
  DATABASE_URL?: string;
};

export function getEnv(): AppEnv {
  return {
    NODE_ENV: (process.env.NODE_ENV as AppEnv["NODE_ENV"]) ?? "development",
    PORT: process.env.PORT,
    DATABASE_URL: process.env.DATABASE_URL,
  };
}

For Cloudflare Workers:

• Provide typed access to env via c.env and Env interface:

// src/types/env.d.ts
export interface Env {
  DATABASE_URL: string;
  // other bindings like R2, KV, etc.
}

// usage in route
app.get("/config", (c) => {
  const env = c.env as Env;
  return c.json({ db: env.DATABASE_URL });
});

This skill should:

• Avoid mixing Node-style process.env in Workers-only code.
• Encourage typed env where possible.

7. README & Scripts

Add or update README.md with:

• How to run in dev
• How to build
• How to deploy (basic notes for Node/Workers/Vercel)

Add package.json scripts (example for Node):

{
  "scripts": {
    "dev": "tsx watch src/index.ts",
    "build": "tsc -p tsconfig.json",
    "start": "node dist/index.js",
    "lint": "eslint ."
  }
}

For Workers, may add wrangler dev and wrangler publish scripts.

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Integration with Other Skills

This skill prepares the ground for:

• hono-authentication:
  • Mount auth routes & middleware under /v1/auth.
• hono-typeorm-backend:
  • Add DB access to routes; integrate TypeORM or another ORM.
• hono-edge-and-workers:
  • Production-ready Cloudflare/Vercel Edge deployment config.
• TypeORM and caching skills:
  • DB caching logic within routes/services built on this scaffold.

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Example Prompts That Should Use This Skill

• “Create a new Hono API ready for Node/Cloudflare, with proper structure.”
• “Refactor this single-file Hono server into a clean modules/routes layout.”
• “Set up middlewares and basic routes for a Hono TS backend.”
• “Scaffold Hono app that I can later add auth and DB to.”

For these prompts, rely on this skill to generate or refactor a clean, extensible Hono app skeleton that other backend skills can build on.