Solid Suspense is triggered on data access after checking isSuccess when loaded by ensureQueryData #9955

Describe the bug

Hi there, I'm running into a weird issue where a suspense is being triggered even after checking that isSuccess is true, but only if the data was loaded from an ensureQueryData call (I've only tested this from a createFileRoute loader, maybe that's somehow related?).

It seems like somehow the Solid resource ends up behind the query. I'm not very familiar with the TanStack or Solid code, but in digging through the debugger in Chrome I found this suspect situation. The getter on the query identifies that the data exists (and while I'm here I can see the isSuccess set to true) and tries to load the latest data from the Solid resource:

But the Solid resource doesn't believe the fetcher was resolved yet, leading to it triggering a read which adds to the suspense context instead of just returning the value:

Your minimal, reproducible example

https://stackblitz.com/edit/tanstack-router-lwma9xac?file=src%2Froutes%2Fposts.tsx

Steps to reproduce

1. Visit the posts page (/posts) in the sandbox, and observe that the wasMounted signal remains false.
2. Uncomment the loader section (in src/routes/posts.tsx), and observe that the Suspense fallback is mounted.

Expected behavior

I expect that the query data getter would behave the same no matter how the data was initially loaded.

How often does this bug happen?

Every time

Screenshots or Videos

Platform

• OS: macOS
• Browser: Safari 26.1, Chrome 142.0

Tanstack Query adapter

solid-query

TanStack Query version

5.90.12

TypeScript version

5.9.3

Additional context

I realize this seems like a tiny bug, and in almost any case I don't think it'd even be perceptible, but unfortunately the suspense is a significant problem for me because it breaks the iframe that Square's web payments SDK generates.