Optional Union fails to set correct name/description

[fogrye]

Optional union type definition ignores annotation metadata added with typing.Annotated

Describe the Bug

Following the documentation create sample definition:

import strawberry
from typing import Annotated
from fastapi import FastAPI
from strawberry.fastapi import GraphQLRouter

@strawberry.type
class A:
    a: str

@strawberry.type
class B:
    b: str

@strawberry.type
class Query:
    u: Annotated[A | B | None, strawberry.union("C")]

schema = strawberry.Schema(query=Query)
app = FastAPI()
graphql_app = GraphQLRouter(schema)
app.include_router(graphql_app, prefix="/graphql")

Checking schema introspection in gql client will show u as "AB" type instead of "C".

Now remove None from annotation and check again - you'll see correct definition.

System Information

• Operating system: bookworm
• Python version: 3.13
• Strawberry version (if applicable): 0.282.0