feat: support TanStack Query v5

[EliottGand]

What changed

• package.json: peerDependencies["@tanstack/query-core"] from "~4" to ">=4 <6"
• A real test suite (vitest), run against both majors, plus a test script
• .github/workflows/ci.yml: typecheck + build + tests, matrixed over query-core 4 and 5
• example/: a small Expo app that makes the detection visible on a device
• README.md: one sentence stating both supported majors

No source change was needed. WaterfallQueryDetector.getPendingQueries() already matches both "pending" (v5) and "loading" (v4). The peer range was the only thing stopping v5 apps from installing the package.

Proof

1. Automated tests, both majors

yarn test runs the same suite twice through two vitest projects. query-core-v5 uses the installed v5; query-core-v4 resolves @tanstack/query-core to a npm:@tanstack/query-core@^4 alias dev dependency, so the library source under test really imports v4.

The tests drive an actual QueryClient (the query cache is not mocked) and assert on the payload the detector hands to console.warn, not merely that it did not throw:

• two sequential queries produce exactly one waterfall, ["first"] --> ["second"]
• two parallel queries produce none
• a whitelisted pair produces none
• a whitelist only silences the exact pair, not the rest of the chain
• a three-query chain produces both links, in order
• the returned unsubscribe handle stops detection
• a query that settles alone is not treated as a waterfall source

$ yarn test
 ✓ |query-core-v4| src/__tests__/detectQueryWaterfalls.test.ts (7 tests) 143ms
 ✓ |query-core-v5| src/__tests__/detectQueryWaterfalls.test.ts (7 tests) 141ms

 Test Files  2 passed (2)
      Tests  14 passed (14)

The suite is a real gate, not a smoke test: temporarily reducing the status predicate to ["pending"] (dropping v4's loading) turns 4 of the 7 v4 tests red while v5 stays green.

2. CI

.github/workflows/ci.yml runs yarn install --immutable, yarn typecheck, yarn build and the suite, with one job per major. Both jobs are green on this branch.

3. On-device E2E with @tanstack/react-query v5

example/ is an Expo Go app on @tanstack/react-query@5.103.2, consuming this repo's built dist/ through file:.. (metro is configured so the library resolves the app's query-core, not its own). It taps console.warn, keeps the lines the detector actually emits and renders them on screen.

Run on an iPhone 17 Pro simulator, iOS 26.4, driven end to end:

• start state: Detected waterfalls: 0, "No waterfall detected yet"
• tap Run 2 SEQUENTIAL queries (["user",1], then ["posts-of-user",1] once the first resolves): the list shows ["user",1] --> ["posts-of-user",1], count 1
• tap Run 2 PARALLEL queries (["profile",2] and ["settings",2] at once): count stays 1, nothing added

The Metro log for the whole session contains exactly one Detected query waterfalls warning.

Still not proven

• Only v5.103.2 / v5.36.0 and v4.44.0 were exercised, not every release in the >=4 <6 range.
• The device run is iOS only; the library is pure JS, but Android was not run.
• Unrelated pre-existing issue, not touched here: dist/index.mjs emits import ... from "lodash/differenceBy" with no extension, which plain Node ESM refuses to resolve (ERR_MODULE_NOT_FOUND). Bundlers (Metro, webpack, vite) resolve it fine and the CJS build is unaffected, so normal usage is not impacted. Worth a separate fix if you want the ESM build to be Node-loadable.

Release

No version bump here, the release is left to you.

🤖 Generated with Claude Code