Solid Query v6 loses derived updates when mounting with warm stale cache

[2wheeh]

Describe the bug

In 6.0.0-rc.1+, mounting a consumer for a warm, stale query starts an immediate refetch.

query.data contains the item, but an effect-derived signal remains empty. rc.0 passes; the repro does not use Router.

Your minimal, reproducible example

https://stackblitz.com/~/github.com/2wheeh/solid-query-cached-mount-repro

Steps to reproduce

1. Wait until query.data shows Example item.
2. Click Mount.
3. Observe that query.data contains the item while Mounted consumer output is [].

Expected behavior

Mounted consumer output should contain the same item as query.data.

How often does this bug happen?

Every time

Screenshots or Videos

No response

Platform

Reproduces on macOS and StackBlitz WebContainers; appears to be platform-neutral.

Tanstack Query adapter

solid-query

TanStack Query version

v6.0.0-rc.2

TypeScript version

5.9.2

Additional context

https://github.com/2wheeh/solid-query-cached-mount-repro/blob/main/README.md