[ckhatton-pvfscaffolding]

Problem

An optional enum-like argument logs a warning on every schema build, although the schema it generates is correct. In our API:

export type CompanyActivityCategory = 'people' | 'company' | 'operational'

async staffGetActivity(
  companyId: number,
  page: number = 1,
  pageSize: number = 50,
  category?: CompanyActivityCategory
)

WARN  Warning: Union types in input fields are not supported yet. Defaulting to the first type (CompanyActivityCategory) at path: staffCompanyGetActivity > category

The built schema still has the full enum, so nothing is actually narrowed to the first type:

staffCompanyGetActivity(companyId: Number!, page: Number, pageSize: Number, category: CompanyActivityCategoryInput): StaffCompanyGetActivity!

enum CompanyActivityCategoryInput {
	people
	company
	operational
}

Cause

In makeReferenceSchema, an optional argument's type is the literal union plus undefined. isPrimitiveUnion requires every member to be a literal, so it rejects the type and the inputs branch takes over. That branch removes null and undefined with getNonNullableType(), sees that the result is still a union, and warns, without checking that the result is now an enum.

Fix

The inputs branch no longer warns when the type left after removing null and undefined is a primitive union. recLoop receives that union and registers it through its existing enum branch, which is how a non-optional enum argument (for example state: 'Open' | 'Closed' = 'Open') is already handled, so the generated schema is unchanged. Unions of object types still warn as before.

The same code is in packages/pylon/src/cli/builder/schema/schema-parser.ts on feat/v3-fullstack. I'm happy to make the same change there.

Testing

I built a small entry file with SchemaBuilder from this branch and from main (TypeScript 5.9.3). Its query arguments, and whether each warns:

Argument	Warns on main	Warns on this branch
category?: CompanyActivityCategory	yes	no
category?: CompanyActivityCategory | null	yes	no
state: 'Open' | 'Closed' = 'Open'	no	no
flag?: boolean	no	no
input?: {a: string} | {b: number}	yes	yes

The generated SDL is identical on both, with category: CompanyActivityCategoryInput and the enum holding all three values. The only warning left is the object union's, which is a real union input.

🤖 Generated with Claude Code

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Latest commit: 6715a18

The changes in this PR will be included in the next version bump.

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Name	Type
@getcronit/pylon-builder	Patch

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