Support type extensions with unreachable types policy rule

[jdolle]

Background

The policy schema is a merged version of the subgraph schemas. It contains directives and type extensions as it is not yet converted to an API schema... (Confusing, right?)

Since this can contain type extensions, and linting runs against it, the linting rules must handle type extensions

Internal ref: https://linear.app/the-guild/issue/GW-594/investigate-unreachable-types-policy-issue-in-hive

Description

This change adds support for type extensions with the unreachable types rule by ensuring it visits these extension nodes.

Checklist

• Testing

[gemini-code-assist]

Code Review

The changes update the no-unreachable-types rule within the @graphql-eslint/eslint-plugin patch to include extensionASTNodes when traversing reachable types. A test case was added to validate this fix, though the provided GraphQL SDL in the test is syntactically invalid and requires a proper base type definition as suggested.

[gemini-code-assist]

The GraphQL SDL provided in the test case is syntactically invalid. A base type definition like type Query requires a field set (e.g., { id: ID }), and it should be separated from the extension. To properly test that Foo is reachable via an extension, the SDL should define a valid base type and then extend it.

Suggested change

	source: `type Query extend type Query { foo: Foo } type Foo { id: ID! }`,
	schema: `type Query extend type Query { foo: Foo } type Foo { id: ID! }`,
	source: "type Query { id: ID } extend type Query { foo: Foo } type Foo { id: ID! }",
	schema: "type Query { id: ID } extend type Query { foo: Foo } type Foo { id: ID! }",

[github-actions]

🐋 This PR was built and pushed to the following Docker images:

Targets: build

Platforms: linux/amd64

Image Tag: 31a155f9dda3b3b8738906c01d5400c688ea6c61

[n1ru4l]

add a changeset before merging 👍

[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-hive/laboratory	0.1.4-alpha-20260415145334-31a155f9dda3b3b8738906c01d5400c688ea6c61	npm ↗︎ unpkg ↗︎
@graphql-hive/render-laboratory	0.1.4-alpha-20260415145334-31a155f9dda3b3b8738906c01d5400c688ea6c61	npm ↗︎ unpkg ↗︎
hive	11.0.3-alpha-20260415145334-31a155f9dda3b3b8738906c01d5400c688ea6c61	npm ↗︎ unpkg ↗︎