Add segment config parity regression tests (#100881)
## Summary
Add webpack-compatible regression coverage to
`test/production/segment-config-precedence/segment-config-precedence.test.ts`
for six parity findings identified while reviewing #100210:
- Node-only custom 404 under an Edge root layout, in production and
development.
- Unequal sibling `dynamic`, `dynamicParams`, `revalidate`, and
`fetchCache` values, including exports on a slot layout.
- Runtime and region exports on `global-not-found`.
- An ordinary page alongside an explicit `@children/page`.
- `maxDuration` immediately above the u32 boundary, reusing the existing
boundary controls.
- Conflicting layout runtimes across the default ordered page
extensions.
Existing tests, their registrations and gates, original fixtures, and
`next.config.ts` are preserved. New page cases share the existing
webpack app/build. New known build-failing Turbopack cases use the
file's existing `@force-gate !turbopack` and build-path exclusion
patterns. The explicit `@children` fixture is injected into webpack's
app only: Turbopack's route-structure validation runs before build-path
filtering. The global-404 runtime mismatch uses the existing `@gate
!turbopack` pattern, which still exercises the assertion and detects
when the gate becomes stale.
Separate builds remain for the expected-invalid configuration tests and
incompatible 404 root/global configurations. The new standalone 404
fixtures and dev suite use `@force-gate !cacheComponents`; no flag
pinning or Cache Components CI manifest changes.
This is tests-only coverage, not an implementation fix. The Edge-root
synthetic-404 tests pass on this canary base and guard against the
regression in #100210. Other findings describe pre-existing parity gaps.
Known failures are gated, so this PR is no longer an intentionally red
reproduction branch.
## Verification
Validated with the CI-built canary `4bfbf238` packages:
| Suite | webpack | Turbopack |
| --- | --- | --- |
| Production precedence suite | 46 passed | 28 passed, 12 explicitly
skipped |
| New standalone 404 fixtures with Cache Components | Both explicitly
force-skipped; no builds | Same |
| Development custom 404, unchanged | Previously verified passing |
Previously verified passing |
Eight new build-failing cases are skipped on Turbopack, alongside four
pre-existing skips. Six pre-existing table cases remain conditionally
absent on Turbopack. Runtime-only known failures emit expected gate
diagnostics. The passing Edge-root Node-only 404 remains enabled on both
bundlers.
The full webpack run includes browser interception coverage. ESLint,
formatting and `pnpm test-types` pass. Compared with the base, original
test bodies/registrations/gates and all original fixture files are
unchanged; only imports, new fixture provisioning, new filter entries
and new tests are added. `fetchCache` checks build acceptance and
rendering, not a separate caching-policy contract.
<!-- NEXT_JS_LLM -->
<!-- fleet bb50a592-84e4-4598-b155-9736bbef6d5a -->
---------
Co-authored-by: vercel-fleet-prod[bot] <318278635+vercel-fleet-prod[bot]@users.noreply.github.com>
