Follow-up to #39758, this PR makes sure that CSS imports (both global and CSS modules) from client components are not handled by mini-css-extract's HMR logic. Instead, we trigger a server component update and let the client to refetch the RSC payload.
However, we are still leveraging the mini-css-extract plugin to emit CSS assets. So in this PR we add a new pitch loader to calculate the original file hash, but replace the final content to eliminate HMR logic but only keep the hash (so hot reloader can keep tracking that).
## Bug
- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Errors have helpful link attached, see `contributing.md`
## Feature
- [ ] Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Documentation added
- [ ] Telemetry added. In case of a feature if it's used or not.
- [ ] Errors have helpful link attached, see `contributing.md`
## Documentation / Examples
- [ ] Make sure the linting passes by running `pnpm lint`
- [ ] The examples guidelines are followed from [our contributing doc](https://github.com/vercel/next.js/blob/canary/contributing.md#adding-examples)
## Bug
- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
## Feature
- [ ] Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Documentation added
- [ ] Telemetry added. In case of a feature if it's used or not.
## Documentation / Examples
- [ ] Make sure the linting passes
We previously used to remove our FOUC helper inside of the style injection to ensure content was shown as fast as possible.
This behavior, however, was problematic for a few reasons:
1. Large JavaScript chunks would take longer than an animation frame to parse, causing FOUC
1. Rendering would sometimes complete before an animation frame, causing improper effects
To fix the latter, we started removing the no FOUC helper **before** rendering, however, we never fixed the former by removing the dead code.
There's not a great way to test this because the FOUC is so fast and flaky, however, this code really shouldn't exist and isn't likely to be re-added (regress).
Also, we already have FOUC tests that occasionally flake, probably due to this.
Fixes#12448Fixes#13058Fixes#11195Fixes#10404
