[visitor-plugin-common] feat: add documentMode plainString

[eddeee888]

Description

This PR adds documentMode: 'plainString', which makes _gql() return a bare template string with fragments embedded, so the generated output has no TypedDocumentString class, no import and no type cast.

#10873 asks for documentMode: string to produce plain strings with no runtime class. Existing string mode is unchanged, so this is opt-in and non-breaking.

With string:

export const PersonDocument = new TypedDocumentString(`
    query Person { person(id: 1) { ...PersonDetails } }
    fragment PersonDetails on Person { id name }`) as unknown as TypedDocumentString<PersonQuery, PersonQueryVariables>;

With plainString:

export const PersonDetailsFragmentDoc = `
    fragment PersonDetails on Person { id name }
    `;
export const PersonDocument = `
    query Person { person(id: 1) { ...PersonDetails } }
    fragment PersonDetails on Person { id name }`;

Related #10873

What changed

• visitor-plugin-common (client-side-base-visitor.ts):
  • Adds DocumentMode.plainString.
  • Embeds fragments in this mode the same way string mode does.
  • _gql() returns the bare template string.
  • The documentMode docs now describe both string and plainString. string wasn't described there before.
• typed-document-node: no source change. Its string branches don't match plainString, so the class template, the DocumentTypeDecoration import and the as unknown as ... cast are all skipped. Adds an inline-snapshot test.
• A minor changeset for both packages.

Type of change

• New feature (non-breaking change which adds functionality)
• This change requires a documentation update

How Has This Been Tested?

• New typed-document-node inline-snapshot test: plainString output with an embedded fragment. It checks that no import, class or cast is generated.
• Lint, format and type check pass.
• Full vitest run: 88 failures in cli, graphql-modules-preset and examples-typescript-graphql-request. The same 88 fail on master without this change; the only difference is the new passing test.

Test Environment:

• OS: Linux
• @graphql-codegen/visitor-plugin-common, @graphql-codegen/typed-document-node: from this branch
• NodeJS: 22.22.2

Further comments

Known gaps:

• No operation types. In plainString mode, documents are typed as string, so they don't carry result or variables types. This is intentional: the mode exists to emit plain strings without a type cast.
• No metadata. plainString documents carry no __meta__: no onExecutableDocumentNode output, no fragment fragmentName, and no @defer deferredFields.
• Client preset. The client preset doesn't special-case plainString; it already passes any documentMode through unvalidated. This is left as-is until it becomes an issue.
• Community plugins. typescript-react-query and typescript-rtk-query in graphql-code-generator-community force documentMode: string and type their fetchers as TypedDocumentString. The reporter's setup needs a matching change there to use this mode.

🤖 Generated with Claude Code

https://claude.ai/code/session_013F2QpCXY9jqU8vHpGPwbXu

[changeset-bot]

🦋 Changeset detected

Latest commit: c6e04d7

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

This PR includes changesets to release 2 packages

Name	Type
@graphql-codegen/visitor-plugin-common	Minor
@graphql-codegen/typed-document-node	Minor

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[github-actions]

🚀 Snapshot Release (alpha)

The latest changes of this PR are available as alpha on npm (based on the declared changesets):

Package	Version	Info
@graphql-codegen/fragment-matcher	7.1.1-alpha-20261012105020-c6e04d7a8566a8caca3735cf74cd45f366ef80a2	npm ↗︎ unpkg ↗︎
@graphql-codegen/visitor-plugin-common	7.3.0-alpha-20261012105020-c6e04d7a8566a8caca3735cf74cd45f366ef80a2	npm ↗︎ unpkg ↗︎
@graphql-codegen/typed-document-node	7.2.0-alpha-20261012105020-c6e04d7a8566a8caca3735cf74cd45f366ef80a2	npm ↗︎ unpkg ↗︎