Diagnostics channel from node leak into edge environment in dev

Link to the code that reproduces this issue

https://codesandbox.io/p/devbox/happy-mclean-htz6qx

To Reproduce

1. Start the application (next dev)
2. Click on the button to trigger the edge API route
3. See the console.log finished fetch node request to: https://github.com

Current vs. Expected behavior

The problem seems to be as follows:

• Register a diagnostics channel subscription, which is a node-only API, in the register hook of instrumentation.ts.
• Then, if you trigger fetch in an edge route, where diagnostics channel should not even be a thing, observe that it is still triggering the diagnostics channel (in the node env)

It seems that the simulated edge environment (?) in dev does not properly isolate the fetch diagnostics channel. This should not happen and leads to hard-to-debug problems with observability, where fetch requests from edge requests weirdly trigger code in the node environment.

Provide environment information

Operating System:
  Platform: linux
  Arch: x64
  Version: #1 SMP PREEMPT_DYNAMIC Sun Aug  6 20:05:33 UTC 2023
  Available memory (MB): 4102
  Available CPU cores: 2
Binaries:
  Node: 20.9.0
  npm: 9.8.1
  Yarn: 1.22.19
  pnpm: 8.10.2
Relevant Packages:
  next: 15.4.0-canary.103 // Latest available version is detected (15.4.0-canary.103).
  eslint-config-next: N/A
  react: 19.1.0
  react-dom: 19.1.0
  typescript: 5.3.3
Next.js Config:
  output: N/A

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

Instrumentation

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

next dev (local)

Additional context

No response

Start with the linked CodeSandbox and reproduce the behavior using next dev, instrumentation.ts, and the edge API route. Trace how the diagnostics channel registered in the Node environment observes the edge route's fetch. Done means edge requests no longer trigger the Node diagnostics subscription while Node requests retain their expected behavior.