Wrong type resolution - a non optional type resolved as optional

[vokrik]

Prerequisites

• I have written a descriptive issue title
• I have searched existing issues to ensure the bug has not already been reported

Fastify version

5.6.1

Plugin version

6.1.0

Node.js version

24.0.2

Operating system

macOS

Operating system version (i.e. 20.04, 11.3, 10)

15.7.1

Description

I have this code that works perfectly fine in 5.2.0

import { type FastifyPluginAsyncTypebox } from '@fastify/type-provider-typebox';
import { Type } from '@sinclair/typebox';

export const ExecutionIdSchema = Type.String({
	format: 'uuid',
});
export const executionController: FastifyPluginAsyncTypebox = async (app) => {
	app.post(
		'/v1/workflows/run',
		{
			schema: {
				body: Type.Object({
					executionId: ExecutionIdSchema,
				}),
				consumes: ['application/json'],
			},
		},
		async (request) => {
			const log = request.log.child({ executionId: request.body.executionId });

			const executionId = request.body.executionId; // <-- type of the executionId is string
		},
	);
};

When I upgrade to 6.1.0 (and 6.0.0), the executionId is typed as string | undefined

Link to code that reproduces the bug

fastify/fastify#3617 (comment)

Expected Behavior

The type of the executionId is string (it's not marked as Type.Optional)

[kinch-tech]

same problem!

[inyourtime]

v6+ is compatible with TypeBox 1.0

npm i typebox

and import from this

import { Type } from 'typebox';
// or
import { Type } from '@fastify/type-provider-typebox';