otellisted

# OpenTelemetry Instrumentation Skill When adding, changing, or reviewing OTel telemetry in the Copilot Chat extension, **always read the two source-of-truth docs first** and **always keep them in sync with the code you change**. ## 1. Authoritative Documents The `extensions/copilot/docs/monitoring/` directory contains the two specs that define the OTel contract for the extension. Treat them like the layout / layer specs in `vs/sessions`. | Document | Path | Audience | Covers | |---|---|---|---| | User-facing | `extensions/copilot/docs/monitoring/agent_monitoring.md` | Extension users | Quick start, settings, env vars, exported spans/metrics/events, backend setup guides | | Architecture | `extensions/copilot/docs/monitoring/agent_monitoring_arch.md` | Developers | Multi-agent strategies, span hierarchies, file structure, instrumentation points, `IOTelService`, configuration channels | | Visual flow | `extensions/copilot/docs/monitoring/otel-data-flow.html` | Developers | Renders the bridge data flow for the in-process Copilot CLI agent | If the implementation changes, **you must update the relevant doc in the same PR**. The arch doc is the most likely to drift; treat divergence as a bug. ## 2. Architecture at a Glance The extension has four agent execution paths, each with a different OTel strategy: | Agent | Process Model | Strategy | Debug Panel Source | |---|---|---|---| | **Foreground** (`toolCallingLoop`) | Extension host | Direct `IOTelService` spans | Extension