From 4395b2ecf9aa200004884f0bce350f123c010511 Mon Sep 17 00:00:00 2001
From: Tom Boucher <trekkie@nomorestars.com>
Date: Sat, 21 Mar 2026 14:08:32 -0400
Subject: [PATCH] fix: use BeforeTool hook event for Gemini CLI instead of
 PreToolUse

Gemini CLI uses BeforeTool (not PreToolUse) for pre-tool hooks, matching
the existing pattern where AfterTool is used instead of PostToolUse. The
prompt injection guard hook was hardcoded to PreToolUse, causing Gemini
CLI to log "Invalid hook event name: PreToolUse" on startup.

Apply the same runtime-conditional mapping used for post-tool hooks, and
update the uninstall cleanup to iterate both event names.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---
 bin/install.js | 39 +++++++++++++++++++++------------------
 1 file changed, 21 insertions(+), 18 deletions(-)

diff --git a/bin/install.js b/bin/install.js
index d4ded0b27..c80e2abec 100755
--- a/bin/install.js
+++ b/bin/install.js
@@ -3214,24 +3214,26 @@ function uninstall(isGlobal, runtime = 'claude') {
       }
     }
 
-    // Remove GSD hooks from PreToolUse (prompt injection guard)
-    if (settings.hooks && settings.hooks.PreToolUse) {
-      const before = settings.hooks.PreToolUse.length;
-      settings.hooks.PreToolUse = settings.hooks.PreToolUse.filter(entry => {
-        if (entry.hooks && Array.isArray(entry.hooks)) {
-          const hasGsdHook = entry.hooks.some(h =>
-            h.command && h.command.includes('gsd-prompt-guard')
-          );
-          return !hasGsdHook;
+    // Remove GSD hooks from PreToolUse and BeforeTool (Gemini uses BeforeTool)
+    for (const eventName of ['PreToolUse', 'BeforeTool']) {
+      if (settings.hooks && settings.hooks[eventName]) {
+        const before = settings.hooks[eventName].length;
+        settings.hooks[eventName] = settings.hooks[eventName].filter(entry => {
+          if (entry.hooks && Array.isArray(entry.hooks)) {
+            const hasGsdHook = entry.hooks.some(h =>
+              h.command && h.command.includes('gsd-prompt-guard')
+            );
+            return !hasGsdHook;
+          }
+          return true;
+        });
+        if (settings.hooks[eventName].length < before) {
+          settingsModified = true;
+          console.log(`  ${green}✓${reset} Removed prompt injection guard hook from settings`);
+        }
+        if (settings.hooks[eventName].length === 0) {
+          delete settings.hooks[eventName];
         }
-        return true;
-      });
-      if (settings.hooks.PreToolUse.length < before) {
-        settingsModified = true;
-        console.log(`  ${green}✓${reset} Removed prompt injection guard hook from settings`);
-      }
-      if (settings.hooks.PreToolUse.length === 0) {
-        delete settings.hooks.PreToolUse;
       }
     }
 
@@ -4117,7 +4119,8 @@ function install(isGlobal, runtime = 'claude') {
     }
 
     // Configure PreToolUse hook for prompt injection detection
-    const preToolEvent = 'PreToolUse';
+    // Gemini and Antigravity use BeforeTool instead of PreToolUse for pre-tool hooks
+    const preToolEvent = (runtime === 'gemini' || runtime === 'antigravity') ? 'BeforeTool' : 'PreToolUse';
     if (!settings.hooks[preToolEvent]) {
       settings.hooks[preToolEvent] = [];
     }