Hono Electron IPC Setup

This skill provides comprehensive knowledge for setting up type-safe IPC communication in Electron applications using Hono RPC.

When This Skill Applies

• Setting up IPC communication in Electron
• Creating type-safe communication between main and renderer processes
• Migrating from ipcRenderer.invoke / ipcMain.handle to Hono
• Implementing factory pattern with dependency injection for IPC
• Adding new IPC routes with full TypeScript support

Quick Start

1. Install Dependencies

pnpm add hono @hono/zod-validator zod

2. Create Directory Structure

src/
├── shared/
│   └── callable/
│       ├── index.ts          # Factory and app creation
│       └── types.d.ts        # Type export for client
├── main/
│   └── callable/
│       └── index.ts          # Service injection
└── renderer/
    └── src/
        └── adapters/
            └── client.ts     # Type-safe hc client

3. Core Files

See FACTORY-PATTERN.md for complete factory implementation. See REFERENCE.md for Hono RPC API reference.

Architecture Overview

┌─────────────────────────────────────────────────────────────┐
│                      RENDERER PROCESS                        │
│                                                              │
│  React/Vue/etc Component                                     │
│       │                                                      │
│       ▼                                                      │
│  client.users[':id'].$get({ param: { id: 'xxx' } })         │
│       │                                                      │
│       ▼                                                      │
│  hc<CallableType> with custom fetch                          │
│       │                                                      │
│       ▼                                                      │
│  ipcRenderer.invoke('hono-rpc-electron', url, method, ...)  │
└──────────────────────────────────────────────────────────────┘
                           │
                           ▼
┌──────────────────────────────────────────────────────────────┐
│                       MAIN PROCESS                            │
│                                                               │
│  ipcMain.handle('hono-rpc-electron', handler)                 │
│       │                                                       │
│       ▼                                                       │
│  callable.request(url, { method, headers, body })             │
│       │                                                       │
│       ▼                                                       │
│  Hono Router                                                  │
│       │                                                       │
│       ▼                                                       │
│  Route Handler: (c) => c.var.services.xxx.method()            │
│       │                                                       │
│       ▼                                                       │
│  Service Layer (injected via DI)                              │
└───────────────────────────────────────────────────────────────┘

Type Safety Flow

The key to type safety is the CallableType:

// src/shared/callable/types.d.ts
import type { createApp } from '.';
export type CallableType = ReturnType<typeof createApp>;

// src/renderer/src/adapters/client.ts
import type { CallableType } from '@shared/callable/types';
export const client = hc<CallableType>('http://internal.localhost', { ... });

// Now client has full autocomplete:
// client.users.$get()         - GET /users
// client.users[':id'].$get()  - GET /users/:id
// client.auth.sign_in.$post() - POST /auth/sign_in

Key Benefits

Aspect	Traditional IPC	Hono IPC
Type Safety	Manual typing	Full inference
API Design	Ad-hoc channels	RESTful routes
Validation	Manual	Zod middleware
Testing	Mock IPC	Standard HTTP
Error Handling	Per-handler	Centralized
Scalability	One channel each	Single channel

Common Patterns

Route with Zod Validation

import { zValidator } from '@hono/zod-validator';
import { z } from 'zod';

const CreateUserBody = z.object({
  name: z.string().min(1),
  email: z.string().email(),
});

.post('/users', zValidator('json', CreateUserBody), (c) => {
  const body = c.req.valid('json'); // Fully typed
  return c.json(body, 201);
})

Route with Path Parameters

.get('/users/:id', (c) => {
  const id = c.req.param('id');
  return c.var.services.users.get(id).then(user => c.json(user));
})

Route with Query Parameters

const QueryParams = z.object({
  limit: z.coerce.number().default(10),
  offset: z.coerce.number().default(0),
});

.get('/users', zValidator('query', QueryParams), (c) => {
  const { limit, offset } = c.req.valid('query');
  return c.var.services.users.list({ limit, offset });
})

Serialization Notes

Only JSON-serializable data can be sent through IPC:

Supported:

• Primitives (string, number, boolean, null)
• Objects and arrays
• ISO date strings (parse with dayjs on receive)

Not Supported (need manual conversion):

• Date objects (convert to ISO string)
• Map/Set (convert to array/object)
• ArrayBuffer/Blob (use base64 encoding)
• Class instances (serialize to plain object)

Files Reference

• FACTORY-PATTERN.md - Complete DI factory pattern
• REFERENCE.md - Hono RPC API reference
• examples/auth-route.ts - Auth route example
• examples/users-route.ts - Users route example