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Trace Google Antigravity CLI and IDE turns, model calls, and tool invocations in Phoenix for full observability.
Google Antigravity is Google’s agentic development platform. The coding-harness-tracing toolkit instruments Antigravity hook events and streams OpenInference spans to Phoenix. Each user turn becomes one trace. No application code changes required. This harness is transcript-driven. Antigravity’s hooks are control-plane triggers that carry only pointers (transcriptPath, conversationId, workspacePaths), while the real model and tool content lives in the per-turn transcript_full.jsonl the agent writes. The Stop hook parses that transcript and reconstructs the spans.

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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

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. It writes credentials to ~/.arize/harness/config.json and registers hooks under the top-level arize-tracing key in ~/.gemini/config/hooks.json, Antigravity’s global hooks file.
~/.gemini/config/hooks.json is Antigravity’s hooks file and is distinct from the Gemini CLI’s ~/.gemini/settings.json. The two harnesses are separate, so installing one does not affect the other. For the Gemini CLI, see Gemini CLI.

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Configuration

Credentials live in ~/.arize/harness/config.json. Environment variables override values in config.json and can be set in your shell profile so they apply to every Antigravity session.
On the Phoenix backend, set the project name with PHOENIX_PROJECT (or PHOENIX_PROJECT_NAME); ARIZE_PROJECT_NAME is 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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Default settings

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Observe

Once tracing is enabled, Antigravity activity is streamed to Phoenix. You’ll see:
  • Turn traces — one Turn chain span per user turn, as the trace root
  • LLM spans — named LLM: {model}, one per model call in the turn
  • Tool spans — one tool span per tool invocation, carrying tool.name
  • Session grouping — turns from the same conversation grouped by session.id

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Hooks captured

Each hook has a 30-second timeout. See HOOK_TIMEOUT_SECONDS in the harness’s constants.py if you need to adjust it.

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Limitations

Token counts are not captured. Antigravity does not expose per-turn token usage on any local surface, neither the hook payload nor the transcript. Rather than report zeros, llm.token_count.* attributes are intentionally left off Antigravity spans.

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Reference

For the full list of environment variables, default file paths, and troubleshooting steps, see the Antigravity tracing README. Errors always land in ~/.arize/harness/logs/antigravity.log. Set export ARIZE_VERBOSE=true before launching Antigravity to also log routine hook activity.

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Uninstall

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Resources

Arize Coding Harness Tracing

OpenInference

Google Antigravity