### Why?
Should come up with better solution that does not block PRs with git
conflict
x-ref:
https://vercel.slack.com/archives/C02CDC2ALJH/p1785263902728189?thread_ts=1785263687.502649&cid=C02CDC2ALJH
### How?
- Delete `errors.json`, the error-code SWC plugin, generated WASM, merge
driver, and validation/build tooling.
- Stop attaching error codes to server-rendering digests, redboxes, and
telemetry; native `Error.code` and `Error.name` remain available where
applicable.
- Remove the development-overlay error feedback UI, middleware, and
telemetry event that depended on stable codes.
- Update fixtures, snapshots, and guidance for code-free errors and
numeric-only digests.
<!-- NEXT_JS_LLM -->
### What?
Flips the default `experimental.instantInsights.validationLevel` from
`'manual-warning'` to `'warning'` so Cache Components apps get
instant-navigation validation across all pages by default.
### Why?
`'manual-warning'` only validates pages that explicitly export
`unstable_instant`, so apps see nothing unless they opt in. `'warning'`
is what users have been turning on manually to actually see the feature
(`v0`, `vercel-site`).
### Test coverage
- Unit: `instant-config-normalization.test.ts` pins the framework
default at `'warning'`.
- Integration: new `instant-validation-level-default/` fixture (no
`instantInsights` in config) asserts implicit dev validation fires, and
that build is unaffected.
### Collateral test fixtures
Tests whose intent is unrelated to instant validation
(router-autoscroll, owner-stack, hmr-iframe, next-image,
server-source-maps, etc.) now hit new redboxes/console warnings because
their fixtures incidentally use dynamic data. Each opts out with
`experimental: { instantInsights: { validationLevel: 'manual-warning' }
}` in `next.config`.
### Open question
With no `'off'` / `'info'` tier today, silencing Insights after this
change requires setting `validationLevel: 'manual-warning'`. Is that
acceptable? Should we inform of this anywhere?
<!-- NEXT_JS_LLM_PR -->
- Moved source files from `_experimental/` to `ui/`.
- Moved `dev-indicators` sources out of `internal/`.
- Renamed files and variables to have explicit `app-`, `App`, `pages-`
or `Pages` prefixes for better distinguish.
- Updated snapshots that were caused by the name change.
- Added better type to `next-runtime.webpack-config.js`.
- Moved `font/` out of `ui/`.
---------
Co-authored-by: Jiachi Liu <inbox@huozhi.im>
Co-authored-by: Jimmy Lai <laijimmy0@gmail.com>
This PR removed the old overlay including the deprecated `buildActivity`
and `appIsrStatus` options.
Closes NDX-785
Closes NDX-855
Closes NDX-865
Closes NDX-866
Closes NDX-867
Closes NDX-868
- `newDevOverlay: true` by default (enables experimental React builds on
canary until owner stacks progress further)
- `run-tests` now sets the env var for tests that were relying on it for
forking behavior
- PPR runners now run with the flag disabled to help catch regressions
in the old overlay until we remove it
- Fixed a number of tests that had outdated snapshots or missed forking
behavior because they weren't running in CI
- Disabled a test that was failing in Turbopack + Experimental React
that is unrelated to the overlay (see:
https://github.com/vercel/next.js/pull/75989)
---------
Co-authored-by: devjiwonchoi <devjiwonchoi@gmail.com>
Jiwon Choi