Next.js: Give App Router Prefetch serverside transactions different op

[lforst]

Description

It would be good to give these transactions a different op so that it is easier to identify what these transactions are about.

[lforst]

I need to note a few things/problems for posterity.

All versions:

• Next.js doesn't seem to forward the Next-Router-Prefetch: 1 header to the headers object we can access inside server components.
• Sometimes a prefetch header is sent, sometimes a Next-Router-State-Tree: asdfasdf header is sent. Seems like the prefetch header is sent when the current page is a dynamic page.

next@13:

• We can access the actual headers including the Next-Router-Prefetch: 1 header through the http integration because requests are properly instrumented.

next@14:

• The HTTP instrumentation doesn't work for Next.js 14 so there is no way to access the prefetch header.

next@15:

• The Next.js 15 RC doesn't seem to send a prefetch header

13, 14:

• Prefetch requests will be detached because these versions don't support clientTraceMetadata.

Low-key wtf @ the integration not working for Next.js 14.

[lforst]

Note: We shipped a very simple implementation for this which doesn't cover all the cases. Due to resource constraints and also the framework not exposing the necessary date at this point in time I'll move this back into the backlog.