Trace lazy App Route module loading (#97439)
### What?
Adds a public OpenTelemetry span for the cold evaluation of an App
Route's
lazy userland module:
- span type: `AppRouteRouteModule.loadUserland`
- display name: `load app route module`
- route-specific attribute: the normalized `next.route` pattern
### Why?
`LoadComponents.loadRouteModule` measures loading Next.js's compiled
route
entry. App Routes then defer the actual userland module behind a
`LazyModule`, so expensive top-level module evaluation can occur after
that
existing span has ended and remain invisible in traces.
### How?
The App Route module wraps only its lazy userland factory with the
Next.js
tracer. `LazyModule` still memoizes that factory, so each route-module
instance
emits one span for its successful cold initialization and warm requests
reuse
the initialized value. The HMR getter remains untraced, and the span
records no
resolved filename or request URL.
The integration fixture uses top-level await to exercise the
asynchronous
module path. Coverage verifies the span is a descendant of the request,
appears exactly once across cold and warm requests, and works with the
direct
entrypoint handler.
### Verification
- `pnpm exec jest packages/next/src/server/lib/trace/tracer.test.ts
--runInBand`
- `HEADLESS=true pnpm test-dev-turbo
test/e2e/opentelemetry/instrumentation/opentelemetry.test.ts -t 'should
trace cold App Route module loading'`
- `HEADLESS=true pnpm test-dev-webpack
test/e2e/opentelemetry/instrumentation/opentelemetry.test.ts -t 'should
trace cold App Route module loading'`
- `HEADLESS=true pnpm test-start-turbo
test/e2e/opentelemetry/instrumentation/opentelemetry.test.ts -t 'should
trace cold App Route module loading'`
- `HEADLESS=true pnpm test-start-webpack
test/e2e/opentelemetry/instrumentation/opentelemetry.test.ts -t 'should
trace cold App Route module loading'`
- Exact-head GitHub build-and-test run `31950299347`: 102/102 jobs
passed.
- Exact-head Generate Stats run `31950299340`: passed.
