[Feature]: Propagation of trace/span ID into shell (and perhaps webfetch) tools

[ivucica]

Is your feature request related to a problem?

Currently the models cannot inject trace IDs/parent span IDs into the requests they're making because they don't see them.

This FR is similar to #62 but relates to builtin tools (generic shell invocation, webfetch) rather than MCPs.

Describe the solution you'd like

Assuming it's reasonably possible to do it with opencode's plugin architecture:

Since traceparent IDs are reasonably opaque (less problematic than much of the environment that's not being cleared away by OpenCode anyway -- api keys, etc), if OpenCode allows setting environment before invoking shell tool to execute commands, it would make sense to propagate the context via envvars. Then a script using curl could attach it as a header.

If possible for webfetch, it would make sense to attach it directly via the header -- in which case an allowlist of domains could be used as well.

I have not checked whether there's a properly standardized way, but I've spotted OTEL_BASH_PARENT_SPAN_ID and TRACEPARENT as possible environment variables to propagate (spotted in otel-bash). I don't know if SDK supports it, but it looks like otel-bash, terragrunt (reference) and otel-cli (reference) support TRACEPARENT.

Of course, this should be configurable and default to off.

Describe alternatives you've considered

Clearly a bad idea: Hack opencode-plugin-otel to write out desired env into tempfiles. Disable builtin opencode tools, and write custom MCPs for running bash commands and webfetch as described above. Hack opencode-plugin-pty to support the hacked env files.

Telemetry type

Other

Additional context

No response

Checklist

• I have searched existing issues and discussions for similar feature requests
• I have checked the changelog to see if this already exists