feat(openapi-react-query): add queryKeyFn option to createClient

[codr]

Problem

When an app uses two openapi-fetch clients targeting different servers (e.g. an app API at :8000 and a PDM API at :8100), any endpoint path shared between them produces identical TanStack Query keys [method, path, init]. TanStack Query fires only one request and both hooks receive the same cached data — even though they point at different servers.

Fix

Add an optional queryKeyFn to createClient. When provided, it replaces the default [method, path, init] key, giving callers a way to namespace keys per client instance:

const pdmClient = createClient(fetchClient, {
  queryKeyFn: (method, path, init) => ["pdm", method, path, init],
});

This is purely additive — default behaviour is unchanged.

Implementation note

The existing shared queryFn destructured [method, path, init] from the TanStack-provided queryKey context. Allowing custom key shapes would have silently broken that destructuring. This PR refactors queryFn into a per-call closure that captures method, path, and init from the outer queryOptions call instead. The same fix is applied to the useInfiniteQuery inline queryFn.

Changes

• src/index.ts — exports QueryKeyFn and CreateClientOptions types; threads queryKeyFn through createClient; inlines the queryFn as a closure
• test/index.test.tsx — new describe("queryKeyFn") block: default key shape, custom key shape, and no-dedup-across-clients
• README.md — new Options section documenting queryKeyFn with two-client example
• .changeset/query-key-fn.md — minor bump changeset

Breaking changes

None — purely additive; passing no clientOptions gives identical behaviour to before.

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🦋 Changeset detected

Latest commit: caad8ea

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

This PR includes changesets to release 1 package

Name	Type
openapi-react-query	Minor

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