DataDog Tracing Question

Thanks for the DataDog tracing integration https://github.com/buildkite/agent/pull/1273!
We recently start incorporating that into our buildkite cluster and found some stuff that we want:

# Customizing/differentiating error
Right now the error stack trace is coming from the go agent codepath. Is there a way to override this value? Maybe sending the information from the shell that the command is currently running?
Also, canceled build polluted this, and having a way to filter out those would be very useful. We have the option cancel intermediate build checked, so the error trace is harder to use at a high level for now.

# Adding span from running the command
What can we do if we want to add more span from the currently running command? Right now I believe it's limited to the level of plugins/hooks level. If the command itself in has multiple steps, and we want to get the current trace id so we can add more span to the same trace, what can we do?

Sorry if this is not the correct place, please direct me to the right forum in that case 🙏🏼

Start by reading the DataDog tracing integration in pull request #1273 and the surrounding Go agent tracing entry points. Clarify how command and shell context are represented, then determine the desired APIs for overriding errors, filtering canceled builds, and propagating trace IDs. Done should cover the requested tracing scenarios with agreed behavior and tests.

Written by the indexing model from the issue text.