Instrumentation hook is not called in standalone output

Link to the code that reproduces this issue

https://github.com/AOEChamp/nextjs-standalone-instrumentation-bug

To Reproduce

npm run build
node .next/standalone/server.js

Current vs. Expected behavior

Standalone build run will pickup the instrumentation.ts from the src directory and print "instrumentation SRC." If the instrumentation.ts is not in the src directory, it will not run. npm run dev works correctly with the root instrumentation. This is confusing and not clearly explained in the docs: https://nextjs.org/docs/app/guides/instrumentation

Provide environment information

Operating System:
  Platform: darwin
  Arch: arm64
  Version: Darwin Kernel Version 23.6.0: Thu Mar  6 21:58:56 PST 2025; root:xnu-10063.141.1.704.6~1/RELEASE_ARM64_T6020
  Available memory (MB): 65536
  Available CPU cores: 12
Binaries:
  Node: 22.14.0
  npm: 10.9.2
  Yarn: N/A
  pnpm: N/A
Relevant Packages:
  next: 15.3.4 // Latest available version is detected (15.3.4).
  eslint-config-next: 15.3.4
  react: 19.1.0
  react-dom: 19.1.0
  typescript: 5.8.3
Next.js Config:
  output: standalone

Which area(s) are affected? (Select all that apply)

Not sure

Which stage(s) are affected? (Select all that apply)

next build (local)

Additional context

No response