chore(react-query): update peer-deps for react19 in v4

[gwansikk]

related: #8441

I'm the maintainer of Suspensive (a community project for React Query), who previously submitted a PR regarding React 19 support in React Query v4.

This time, I'd like to explicitly specify React 19 in the peerDependencies instead of the dependencies. React Query v4 is already compatible with React 19 without any code changes, and we've confirmed this through the following steps:

• Built a custom tarball package(pnpm pack) with React 19 specified in peerDependencies
• Linked the tarball in a React 19 environment for testing
• Confirmed that it works without issues (we were able to resolve previously occurring warnings and errors)

There are no breaking changes in React 19 that affect compatibility, and v4 works reliably without special handling. If issues do arise, they would likely be due to changes in React 19, not React Query v4 itself.

Currently, since React 19 is not listed in peerDependencies, using react-query@v4 in a React 19 environment causes the following problems:

• Peer dependency warnings are triggered by the package manager
• Community libraries built on top of React Query v4 may face confusion when trying to support React 19

[nx-cloud]

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☁️ Nx Cloud last updated this comment at 2025-06-28 13:26:50 UTC

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[gwansikk]

I can't reproduce the issue in the local test environment. Is there a problem with the CI pipeline?

[manudeli]

I’m in favor of adding React 19 to the peerDependencies of @tanstack/react-query v4.
Since it seems that @TkDodo previously opposed this change, I wanted to tag you and check if you’re okay with it before merging.

From what I understand, there’s nothing in @tanstack/react-query v4 that should cause issues with React 19.
If there are any problems, I’d expect them to be due to changes in React itself — so I think it should be safe to go ahead with the merge. Would that be alright with you?