---

This section details on the original issue you should resolve

<issue_title>Valibot plugin: additionalProperties with type converts to v.object({}) instead of v.record()</issue_title>
<issue_description>### Description

The Valibot plugin incorrectly handles additionalProperties when it contains a type definition. Instead of generating v.record(), it generates v.object({}), which causes silent data loss at runtime.
Valibot's v.object({}) removes unknown keys by default. This means all additional properties are stripped during validation without any error or warning.

Current Behavior

OpenAPI Spec:

CreateChallengeBody:
  type: object
  properties:
    headers:
      type: object
      additionalProperties:
        type: string

Generated Valibot Schema:

export const vCreateChallengeBody = v.object({
    headers: v.optional(v.object({}))
});

Runtime Result:

const input = {
  headers: {
    'Authorization': 'Bearer token',
    'Content-Type': 'application/json'
  }
};

const result = v.parse(vCreateChallengeBody, input);
console.log(result.headers); // {} ❌ All properties are lost!

Expected Behavior

Expected Valibot Schema:

export const vCreateChallengeBody = v.object({
    headers: v.optional(v.record(v.string(), v.string()))
});

Expected Runtime Result:

const result = v.parse(vCreateChallengeBody, input);
console.log(result.headers); 
// { 'Authorization': 'Bearer token', 'Content-Type': 'application/json' } ✅

Root Cause

The issue is in packages/openapi-ts/src/plugins/valibot/v1/toAst/object.ts at lines 75-78:

if (
  schema.additionalProperties &&
  schema.additionalProperties.type === 'object' &&  // ❌ Only handles 'object' type
  !Object.keys(properties).length
) {

This condition only converts to v.record() when:

• additionalProperties.type === 'object'
• No named properties exist

It fails to handle:

• type: 'string', type: 'number', etc.
• additionalProperties: true
• additionalProperties: {}

Reproducible example or configuration

import { defineConfig } from '@hey-api/openapi-ts';

export default defineConfig({
  client: '@hey-api/client-fetch',
  input: 'openapi.yaml',
  output: 'src/client',
  plugins: [
    '@hey-api/typescript',
    {
      name: 'valibot',
    },
  ],
});

1. Use the OpenAPI spec below
2. Run npx @hey-api/openapi-ts
3. Check the generated Valibot schema
4. Try validating data with additional properties
5. Observe data loss

OpenAPI specification (optional)

openapi: 3.0.0
info:
title: Minimal Example
version: 1.0.0
paths:
/test:
post:
operationId: CreateChallenge
requestBody:
required: true
content:
application/json:
schema:
type: object
properties:
headers:
type: object
additionalProperties:
type: string
responses:
'200':
description: Success

System information (optional)

• @hey-api/openapi-ts version: 0.83.1
• Node.js version: v20.x
• OS: macOS
• Valibot version: Latest</issue_description>

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