A Prefetched Infinity State Time Query Gets Fetched Again on Mount

[kivvvvv]

Describe the bug

A prefetched query with staleTime of Infinity always triggers an unexpected fetch again when the component with suspenseful query(staleTime: 0) is mounted.

Steps to reproduce

I would like to achieve these following requirements(a very contrived one):

1. Display a post list 1 to 3.
2. Initially display the details of the first post.
3. When the user clicks a list, always fetches the latest details.

I have provided an example here(StackBlitz): A Prefetched Infinity State Time Query Gets Fetched Again on Mount

Here is how I achieved those requirements:

1. For "Display a post list 1 to 3", I render(hardcoded) a list of 3 posts.
2. For "Initially display the details of the first post" I have read Prefetching & Router Integration. I know that the first post details will be needed ahead of time, so I prefetch early in the Suspense tree with the queryClient.defaultOptions.queries.staleTime of Infinity to avoid any refetching of a query down the Suspense tree.
3. For "When the user clicks a list, always fetches the latest details" I use a state of a selected post id as a query key of a suspenseful post query with staleTime of 0.

Expected behavior

The behavior seems to be as expected, but when I observed the network request, there are 2 unexpected requests for the first post(instead of only one request). If I try to make the post query to have staleTime of non-zero for example Infinity there would be only 1 request but I lose the ability to always fetch for the latest post.

How often does this bug happen?

Every time

Platform

• OS: macOS
• Browser: Chrome
• Version: 131.0.6778.205 (Official Build) (arm64)

TanStack Query version

v5.62.11

[kivvvvv]

After debugging locally, the behavior that I found is the prefetched data is not resolved yet then the query is fetched resulting in 2 fetches for the same thing(but different in stale time).

[kivvvvv]

Here is what I found in the source:

• When the query is executed for the first time, the QueryObserver is initialized with the query.
• To construct the QueryObserver, its constructor is called, in which, eventually, it overrides the current query options (in this case, the prefetch query with staleTime: Infinity) with query client options (in this case, the post query with staleTime: 0). The exact line of execution is this then this.
• From this point on, it loses track with an earlier prefetched query, and proceeds to fetch the post query.

At this point, I feel like, maybe, it is an expected behavior. For what I want to achieve, there might be some other way.