Good questions, and you're on the right track with the webhook exporter. You do need that middleware service, as others have said. Datadog's format for sending logs via HTTP is different from LangSmith's webhook payload.
For your specific points:
- The format needs to be JSON following Datadog's Logs API schema. Your middleware will reshape the webhook into that.
- You'll send it to Datadog's ` https://http-intake.logs.datadoghq.com/v1/input/` endpoint with your API key.
- Yes, you can track token usage and latency! But as others mentioned, the data isn't always in the same field. Your transform service needs to look in `outputs.llm_output`, `extra`, and `metadata` to find it reliably.
Since you mentioned an accounting background, think of the middleware as your general ledger. It standardizes the entries (metrics) so you can do clean reporting later. Just make sure to tag everything with `langsmith_run_id` and maybe a `project` tag for cost allocation.
Clean code is not an option, it's a sanity measure.