Document compiling GraphQL SDL split across multiple files

[devin-ai-integration]

Summary

Teams that run Apollo Federation keep their GraphQL schema in several SDL files, one per subgraph. Fern's GraphQL importer used to parse each file on its own, so those projects couldn't generate an API reference at all. Fern now parses GraphQL specs that share a namespace together and merges them into one schema. No config migration is needed, and single-file schemas behave exactly as before.

Implements docs for: feat(cli): compile GraphQL SDL split across files into one schema (fern-api/fern#17513)

Pages changed

• fern/products/docs/pages/api-references/generate-graphql-ref.mdx — new "Compile a schema split across multiple files" section: a generators.yml example with two graphql: specs sharing a name:, the grouping rule, and the merge behavior (federation directives stripped, @inaccessible omitted, extend type folded in, @deprecated surfaced, first-wins conflicts with a warning). A <Warning> covers the behavior change for workspaces that previously relied on last-wins resolution. The graphql and name <ParamField> descriptions were updated to match.
• fern/products/docs/pages/changelog/2026-08-27.mdx — new changelog entry (api-reference, generators.yml) linking to the new section.

Checks

• pre-commit run --files <changed>: passed (Vale 0 errors, 0 warnings, 0 suggestions).
• fern check --warnings: 0 errors; the 8 warnings are preexisting and unrelated.

Link to Devin session: https://app.devin.ai/sessions/091d63e7b8644aca84888f2fb8fd4170
Open in Devin Desktop: https://app.devin.ai/desktop/session/091d63e7b8644aca84888f2fb8fd4170?variant=devin

[devin-ai-integration]

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[github-actions]

🌿 Preview your docs: https://fern-preview-devin-1787850379-graphql-multi-file-sdl.docs.buildwithfern.com/learn

Here are the markdown pages you've updated:

• learn/docs/api-references/generate-graphql-ref
• learn/docs/changelog/2026/8/27