Antigravity tool calls denied by PreToolUse hook returning "{}" (Windows) #316

What happened
When Coucou's Antigravity hooks are installed on Windows (0.2.0), running any tool inside Google Antigravity fails immediately with:
tool call denied by pre-tool hook:

This happens because the relay returns {} on PreToolUse (commit 600fe70 / PR #307). Unlike other agents, the Google Antigravity runtime strictly requires {"decision":"allow"} from pre-tool hooks. An empty JSON object {} without a decision is treated as rejection/deny, which blocks all tool executions (file edits, terminal commands, file viewing).

What you expected
Antigravity should be able to execute tool calls without being blocked by the hook.

How to reproduce

1. On Windows with Coucou 0.2.0, open Settings → Antigravity → Install hooks.
2. In Google Antigravity, ask the agent to run any command or read a file.
3. Antigravity immediately aborts the call with tool call denied by pre-tool hook:.

Suggested solutions

• Option A (Recommended if avoiding auto-allow): Simply do not register PreToolUse in hooks.json for Antigravity — only register PostToolUse, PreInvocation, PostInvocation, and Stop. We tested this locally and it works perfectly: Coucou still tracks all session steps and lifecycle updates via PostToolUse, but never interferes with Antigravity's pre-execution permissions.
• Option B: Return {"decision":"allow"} on PreToolUse specifically for Antigravity.

Windows version
Windows 10 / 11 (x64)

Coucou version
0.2.0 (Windows)