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Trace GitHub Copilot sessions in VS Code and the Copilot CLI in Phoenix for full observability.
Trace your GitHub Copilot sessions — in VS Code or the CLI — in Phoenix with the coding-harness-tracing toolkit. Every turn shows up as a trace, with each tool call and any subagents captured as nested spans and grouped into its session. No application code changes required: the toolkit hooks into Copilot’s own events and streams OpenInference spans to Phoenix. VS Code uses per-event hook files; the CLI uses a single hooks.json.

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Launch Phoenix

The fastest way to get started with Phoenix is by signing up for a free Phoenix Cloud account. If you prefer, you can also run Phoenix in a notebook, self-host it, or use it directly from your terminal. Go to the settings page in your Phoenix instance to find your endpoint and API key. A self-hosted Phoenix defaults to http://localhost:6006; the API key is only required when auth is enabled.

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Install

Copilot hooks are installed at the project level under .github/hooks/. Run the installer from the root of each repository where you want tracing. The curl installer is the simplest — it runs a short wizard that saves your Phoenix credentials for you. Use a local clone if you’d rather run the installer from a checkout of the source. macOS / Linux:
Windows (PowerShell):

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Local clone

The installer prompts for your backend — select Phoenix, then enter your endpoint and optional API key — and your project name, writes them to ~/.arize/harness/config.json, and registers VS Code (.github/hooks/*.json) and Copilot CLI (.github/hooks/hooks.json) hooks in the current project.

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Configuration

Credentials live in ~/.arize/harness/config.json and apply across all projects. Per-project environment variables override config.json and can be set in your shell profile.
On the Phoenix backend, set the project name with PHOENIX_PROJECT (or PHOENIX_PROJECT_NAME); ARIZE_PROJECT_NAME is Arize-only and ignored here. ARIZE_TRACE_ENABLED is a backend-agnostic harness setting and keeps the ARIZE_ prefix regardless of destination.

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Redaction controls

Each ARIZE_LOG_* flag accepts "true" or "false" and defaults to "true". Set to "false" to opt out per category:

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Observe

Once tracing is enabled, Copilot activity from both VS Code and the CLI streams to Phoenix. You’ll see:
  • Turn traces — each prompt → response cycle as a parent span
  • Tool spans — nested spans for each tool call with inputs, outputs, and duration
  • Subagent spans — activity from any subagents Copilot spawns (VS Code)
  • Error spans — errorOccurred events from the CLI
  • Session grouping — all turns from the same session grouped by session_id

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Reference

For the full list of environment variables, default file paths, and troubleshooting steps, see the Copilot tracing README.

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Uninstall

Run from the project root where you installed the hooks:

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Resources

Arize Coding Harness Tracing

OpenInference

GitHub Copilot