Inconsistent cached values

[tsoos99dev]

Summary

I'm experimenting with use cache, but it's behaving unexpectedly.
I'm trying to imitate what would happen on a dashboard when I want to refresh a specific value. I'm tagging the refreshable component with a unique value via cacheTag, then I call updateTag(id) in a server action from a different component which uses useActionState to keep track of the interaction. The action itself simply waits a random amount of time and returns a random number.

In dev:

The good:

• Hard refresh triggers the suspense boundaries around both cached values as expected
• Further refreshes do nothing as expected
• Navigating to the Settings page and back does nothing to the values as expected
• Clicking Refresh eventually updates the refreshable value only, while the other value stays the same as expected.

The bad:

• Clicking Refresh, then quickly going to the Settings page and trying to go back to the Values page causes a Prerender, and I'm stuck on the Settings page while the new value loads, this is unexpected. I was hoping to immediately see the Values page in the same state as I left it in, with the old value and the Refresh button disabled, or at least only that one value being suspended.
• Prefetching is even triggered if I first click Refresh, wait for the value to load, go to Settings and then try to go back. This also refershes the value a second time.

In build:

The good:

• Hard refresh does nothing to the values as expected (I suppose)
• Further refreshes do nothing as expected
• Navigating to the Settings page and back does nothing to the values as expected
• Clicking Refresh eventually updates the refreshable value only, while the other value stays the same as expected, except at first.

The bad:

• Clicking Refresh, then quickly going to the Settings page and trying to go back to the Values page now shows the stale value, with the Refresh button enabled, and the value never updates.
• Even worse, first waiting for the value to update, then going to Settings and back causes the value to switch back to the previous one.
• The suspense boundary around the refreshable value is actually triggered occasionally. Usually when I click on Settings and then Values fast enough, but it's completely inconsistent.

What am I doing wrong?

Additional information

next info:

Operating System:
  Platform: darwin
  Arch: arm64
  Version: Darwin Kernel Version 24.6.0: Mon Jul 14 11:30:29 PDT 2025; root:xnu-11417.140.69~1/RELEASE_ARM64_T6000
  Available memory (MB): 32768
  Available CPU cores: 10
Binaries:
  Node: 22.16.0
  npm: 11.4.2
  Yarn: 1.22.19
  pnpm: 10.13.1
Relevant Packages:
  next: 16.1.0-canary.16 // Latest available version is detected (16.1.0-canary.16).
  eslint-config-next: N/A
  react: 19.2.1
  react-dom: 19.2.1
  typescript: 5.9.3
Next.js Config:
  output: N/A

Example

https://github.com/tsoos99dev/next-playground

[icyJoseph]

Hiyo, I took a quick look, I think there's something up with the browser cache. In production only, if you disable cache (in devTools network tool), can you reproduce staleness?

[tsoos99dev]

Hi, I think you're right. When I disable the cache in devtools, the built version no longer displays stale data. It properly triggers the suspense boundary every time I call updateTag by clicking Refresh, then go to the Settings page and immediately go back to Values. This would be considered a bug, right?

What do you think about the Refresh button becoming enabled still? Is that expected? I started a transition inside an Activity, right? If I stay on the same page, it finishes together with the value update, but if I leave the page and come back the button - which is tied to the action's state is enabled, even though suspense is triggered on the value.

On a separate note after watching this video, I think I misunderstood use cache. It's supposed to be used for data that definitely isn't user specific, or where the cardinality of the dataset is relatively small, and doesn't change often, right? The cache is also global, like if I were to update the list of featured products from an admin page and invalidate the tag for example, every user would get the updated list, right?