skills: Instructions file for GitHub Copilot

Apollo Client Skill Writing Instructions

Follow these rules when working on the Apollo Client AI skill instructions.

General rules

• Do not make time-relative statements about the library, like "now provides feature X". If the content is version-specific, refer to the minimal version instead. Generally assume the user uses Apollo Client v4.x unless otherwise specified.

Rules for discussing fragments

Fragments are for colocation, not reuse. When discussing fragments, follow these guidelines based on GraphQL spec PR #1193:

• DO NOT describe fragments as being "for reuse" or "reusable units"
• DO NOT suggest sharing fragments between components just because they currently need the same fields
• DO emphasize that fragments are for component colocation - each component should have its own fragment
• DO explain that fragments enable independent evolution of component data requirements
• DO explain that sharing fragments creates artificial dependencies and leads to over-fetching when one component's needs change

Example of correct messaging:

• ✅ "Each component should declare its data needs in a dedicated fragment"
• ✅ "Fragments enable components to independently evolve their data requirements"
• ❌ "Fragments allow for the reuse of common repeated selections"
• ❌ "Create a shared fragment for fields used by multiple components"

Rules for code examples

• always ensure correct imports
  • imports should be complete for the example
  • React hooks need to be imported from @apollo/client/react, NOT from @apollo/client
• when an example needs a query, mutation, or fragment, use either of the following approaches:
  • in-example declaration
    • use the gql tag from @apollo/client to define queries/mutations/fragments
    • create a constant with an uppercase name (e.g., GET_USER, CREATE_POST)
    • declare types via TypedDocumentNode
  • import it from a generated file in the same directory as the example, treat it as a TypedDocumentNode with types defined:
    • queries.generated.ts for queries
    • mutations.generated.ts for mutations
    • fragments.generated.ts for fragments
• always use TypeScript for code examples unless the context specifically calls for something else
• React hooks should never be shown using explicit generics. Types should always be inferred from the typed query/mutation document.
  • do this: useQuery(GET_USER, { variables: { id: "1" } })
  • not this: useQuery<GetUserQuery, GetUserVariables>(GET_USER, { variables: { id: "1" } })
• If both hooks appear in an example, ALWAYS call useQueryRefHandlers before useReadQuery. These two hooks interact with the same queryRef, and calling them in the wrong order could cause subtle bugs.