How to handle Prisma types in generated RPC hono-api.d.ts (via typegen)?

[mikr13]

Hi folks,

Thanks for all the great answers & support in this community. Love trying out Hono.

My issue is that I'm using Hono's typegen with rollup-plugin-dts to generate a typed RPC API interface that can be consumed by the frontend using hono/client. The problem I'm running into is related to how Prisma client types are referenced in the generated file.

---

Setup

I have a hono-api.d.ts file generated via:

"typegen": "rollup --config typegen/rollup.config.ts --configPlugin typescript"

Then I consume this file in the client using:

"generate:api": "source .env && curl -H \"Content-Type: text/plain\" ${VITE_API_URL}/api/v1/hono --output src/hono-api.d.ts"

Rollup Config

import { dts } from "rollup-plugin-dts";

const config = [
  {
    input: "src/routes/_app.ts",
    output: [{ file: "typegen/hono-api.d.ts", format: "es" }],
    plugins: [dts()],
  },
];

export default config;

The Issue

The generated file (hono-api.d.ts) contains:

import * as _prisma_client from '.prisma/client';

However, .prisma/client doesn't exist as a local path—it’s generated inside node_modules, as expected with Prisma. This leads to type resolution issues in the server as well as client projects (since Prisma isn’t installed on client and the paths are different on server).

As seen in the attached screenshot, this results in type errors in the consuming frontend code because Prisma types like PrismaJson.MasterCarrier can't be resolved.

---

Question

Is there a recommended way to:

1. Bundle Prisma types into the generated .d.ts at build time?
2. Replace Prisma-specific types with custom DTOs before typegen runs?

I'd prefer not to ship the entire Prisma client to the frontend just for type safety. Any suggestions on how to cleanly handle this? Appreciate any guidance! 🙏