feat(visitor-plugin-common): support object form for the codegenScalarType extension

[ifeanyi-ugwu]

Description

The codegenScalarType scalar extension is read as a single string and copied into both the input and output slots of the generated Scalars map:

} else if (scalarType.extensions?.codegenScalarType) {
  result[name] = {
    input:  { isExternal: false, type: scalarType.extensions.codegenScalarType as string },
    output: { isExternal: false, type: scalarType.extensions.codegenScalarType as string },
  };
}

So a schema-first scalar (one that ships codegenScalarType in its type extensions) can't declare a stricter parsed/input type than its wider resolver-return/output type — the two positions the generated Scalars map already distinguishes.

The scalars config option already supports this, via the normalizeScalarType helper that accepts string | { input, output }. This PR routes the extension through that same helper, giving the extension parity:

• codegenScalarType: 'Foo' → { input: Foo; output: Foo } — unchanged
• codegenScalarType: { input: 'A', output: 'B' } → { input: A; output: B }

Motivation

Scalar libraries such as graphql-scalars ship one codegenScalarType string per scalar, which can only ever describe one of the two positions. This closes that gap for every schema-first scalar — e.g. DateTime can declare { input: 'Date', output: 'Date | string | number' } (parsed value is a Date; a resolver may return a Date, an ISO string, or a timestamp).

Notes

• Backward compatible — a string extension behaves exactly as before.
• The codegenScalarType extension previously had no test coverage; two tests are added (string form + object form).
• Changeset included (@graphql-codegen/visitor-plugin-common, minor).

[changeset-bot]

🦋 Changeset detected

Latest commit: ac97787

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

This PR includes changesets to release 1 package

Name	Type
@graphql-codegen/visitor-plugin-common	Minor

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