Invalid references in schema after using TypeBox Modules

[zdila]

Prerequisites

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

Fastify version

5.2.1

Plugin version

9.4.1

Node.js version

22

Operating system

Linux

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

Debian Testing

Description

I am not sure if it is issue of @fastify/type-provider-typebox or of this package. After migrating TypeBox to 0.34 I had to use its Type.Module:

  const Module = Type.Module({
    Foo: Type.Ref("Bar"),
    Bar: Type.String(),
  });

  const Foo = Module.Import("Foo");

  type FooRequest = FastifyRequest<{
    Reply: Static<typeof Foo>;
  }>;

  fastify.withTypeProvider<TypeBoxTypeProvider>().get("/foo", {
    schema: {
      produces: ["application/json"],
      response: {
        200: Foo,
      },
    },

    async handler(_: FooRequest, reply) {
      await reply.send("OK");
    },
  });

Response handling works correctly, but /documentation generates invalid references:

{
  "openapi": "3.1.0",
  "info": {
    "title": "Test",
    "version": "0.1.0"
  },
  "components": {
    "schemas": {}
  },
  "paths": {
    "/foo": {
      "get": {
        "responses": {
          "200": {
            "description": "Default Response",
            "content": {
              "application/json": {
                "schema": {
                  "$defs": {
                    "Foo": {
                      "$ref": "#/components/schemas/def-1",
                      "title": "Foo"
                    },
                    "Bar": {
                      "type": "string",
                      "title": "Bar"
                    }
                  },
                  "$ref": "#/components/schemas/def-0"
                }
              }
            }
          }
        }
      }
    }
  }
}

Link to code that reproduces the bug

included in the description

Expected Behavior

Schema should be valid.

[mcollina]

Thanks for reporting! Would you like to send a Pull Request to address this issue? Remember to add unit tests.