Agent Skills: Investigating & Diagnosing Google Antigravity

Investigating & Diagnosing Google Antigravity

This skill provides procedures, tools, and symbol references for investigating, diagnosing, and reverse-engineering the internal behavior of Google Antigravity, its execution harness (jetski / localharness), and the Agent Client Protocol (ACP) server.

Overview & Binary Assets

Antigravity's runtime divides responsibilities between an outer orchestrator and an execution harness:

1. ~/.local/bin/agy_acp_server.par: Outer Python/C++ executable implementing the ACP JSON-RPC server and communicating with Gemini APIs.
2. ~/.local/bin/localharness_external: Production stripped Go binary executing tool calls, shell sandboxing, and diff generation.
3. ~/.local/share/antigravity/localharness.debug: Extracted 987 MB unstripped Go binary containing 827,093 symbols, full DWARF debug info (.debug_info, .debug_line), and source path line tables.

Always query ~/.local/share/antigravity/localharness.debug directly for static analysis and debugging to avoid extracting from the archive repeatedly.

Core Investigation Workflows

0. Binary Acquisition and Automated Setup

To acquire or re-extract the unstripped debug binary after an Antigravity update, execute scripts/extract_debug_binary.py:

~/.gemini/skills/investigate-antigravity/scripts/extract_debug_binary.py

For the manual acquisition procedure from the upstream ACP Agent Registry, consult references/binary_acquisition.md.

1. Querying Internal Symbols and Packages

To find internal structs, functions, or package boundaries, execute scripts/query_symbols.py:

# Search for methods on a specific subsystem (e.g., Policy Guardian)
~/.gemini/skills/investigate-antigravity/scripts/query_symbols.py "policyguardian" --methods-only

# List all Go package paths matching a keyword
~/.gemini/skills/investigate-antigravity/scripts/query_symbols.py "cortex" --packages-only

# Filter for terminal command execution methods
~/.gemini/skills/investigate-antigravity/scripts/query_symbols.py "command" --methods-only --limit 20

For an overview of the 229 internal packages in the jetski codebase, consult references/architecture.md.

2. Extracting Embedded Prompts and Safety Rubrics

Antigravity embeds its internal system instructions, security rubrics, and subagent prompts directly in the binary's read-only data sections (.rodata).

To extract and view these prompts, execute scripts/inspect_prompts.py:

# List available prompt categories
~/.gemini/skills/investigate-antigravity/scripts/inspect_prompts.py --list

# View the Policy Guardian code-vetting rubric
~/.gemini/skills/investigate-antigravity/scripts/inspect_prompts.py "Code Vetting"

# View the anti-circumvention rubric (VetDeniedRepeat)
~/.gemini/skills/investigate-antigravity/scripts/inspect_prompts.py "Anti-Circumvention"

# View the configuration downgrade rubric
~/.gemini/skills/investigate-antigravity/scripts/inspect_prompts.py "Config Vetting"

3. Diagnosing Runtime Behavior & Crashes

When Antigravity misbehaves, crashes, or rejects commands:

1. Inspect Log Streams:
   • CLI daemon log: tail -n 100 ~/.antigravity/agy_daemon.log
   • Active CLI session logs: ~/.gemini/antigravity-cli/log/
   • Check for crash dumps: ls -la ~/.gemini/antigravity-cli/crashes/
2. Inspect Conversation Trajectories:
   • Open the session SQLite database:

     sqlite3 ~/.gemini/antigravity-cli/conversations/<session-id>.db "SELECT step_index, step_type, status FROM steps;"
     

3. Trace Live Process Execution:
   • Attach GDB or eBPF probes using ~/.local/share/antigravity/localharness.debug as the symbol provider.
   • For exact GDB commands, breakpoints, and bpftrace scripts, consult references/debug_workflow.md.

Key Subsystems Reference

Policy Guardian

• Path: google3/third_party/jetski/cortex/policyguardian/
• Role: Automated safety and security supervisor developed with DeepMind (gdm/security/agi_control/).
• Key Components:
  • deterministic_vetting_configs: Zero-latency pre-checks (path normalization, $PATH hijacking, sensitive file blocks).
  • vetting: SafeBrowsing API queries, GitHub repo star/fork checks, dependency typosquatting checks, and data exfiltration tracking.
  • CallLLMSync: Synchronous Gemini Flash Lite evaluation for ambiguous actions.

Cortex Execution Engine

• Path: google3/third_party/jetski/cortex/
• Role: The core agent loop and state machine.
• Key Components:
  • core/contrib/variants/minisweagent: Software engineering task agent.
  • command/sandboxproxy: PTY allocation, process isolation, and shell streaming.
  • chatconverters/browser: Chrome DevTools Protocol (CDP) client for browser automation.

Supporting Resources

• references/binary_acquisition.md: Upstream ACP registry URLs, download endpoints, and manual extraction procedures.
• references/architecture.md: Complete map of internal Go packages, data structures, and binary layouts.
• references/debug_workflow.md: Step-by-step instructions for GDB live debugging, bpftrace probes, and SQLite trajectory analysis.
• scripts/extract_debug_binary.py: Automated extraction tool for localharness.debug.
• scripts/query_symbols.py: High-speed symbol parser querying .symtab in ~30ms.
• scripts/inspect_prompts.py: Embedded prompt and rubric extractor.