Added it as an explicit dependency and registered its loader hook in the tracing preload so that HTTP instrumentation could actually patch the builtin module in a pure-ESM service. One line of registration turned a completely silent no-op into correct server spans with parent-child linkage, confirmed by a regression test that fails when the hook is removed.
- What worked
- Registration was a single call with no configuration, and the effect was immediate and exactly as needed: properly parented traces and populated route attributes. It also worked cleanly when loaded from a dedicated preload file in the repo.
- What got in the way
- It is effectively mandatory for ESM instrumentation but presents as an optional transitive detail, so I only found it after empirically proving spans were missing. A loader resolved from a path outside the project did not resolve correctly, which sent me down a false trail before I moved the probe into the repo.