diff --git a/apps/backend/core/auth.py b/apps/backend/core/auth.py
index 78faac550e..48ee0082a6 100644
--- a/apps/backend/core/auth.py
+++ b/apps/backend/core/auth.py
@@ -975,6 +975,13 @@ def get_sdk_env_vars() -> dict[str, str]:
     # The empty string ensures Python doesn't add any extra paths to sys.path.
     env["PYTHONPATH"] = ""
 
+    # Disable user's pre-commit hooks during Auto-Claude managed git operations
+    env["HUSKY"] = "0"
+
+    # NOTE: Git environment variable isolation (GIT_INDEX_FILE, GIT_DIR, etc.) is handled
+    # in client.py by deleting these vars from os.environ before SDK instantiation.
+    # We cannot set them to "" here because git interprets empty string as a path value.
+
     return env
 
 
diff --git a/apps/backend/core/client.py b/apps/backend/core/client.py
index de777f0624..038a1afa00 100644
--- a/apps/backend/core/client.py
+++ b/apps/backend/core/client.py
@@ -21,7 +21,12 @@
 from pathlib import Path
 from typing import Any
 
+<<<<<<< HEAD
 from core.fast_mode import ensure_fast_mode_in_user_settings
+=======
+# Git environment isolation - prevents worktree operation failures from inherited env vars
+from core.git_executable import GIT_ENV_VARS_TO_CLEAR
+>>>>>>> refs/remotes/upstream/pr/1599
 from core.platform import (
     is_windows,
     validate_cli_path,
@@ -505,6 +510,7 @@ def create_client(
     # Collect env vars to pass to SDK (ANTHROPIC_BASE_URL, CLAUDE_CONFIG_DIR, etc.)
     sdk_env = get_sdk_env_vars()
 
+<<<<<<< HEAD
     # Get the config dir for profile-specific credential lookup
     # CLAUDE_CONFIG_DIR enables per-profile Keychain entries with SHA256-hashed service names
     config_dir = sdk_env.get("CLAUDE_CONFIG_DIR")
@@ -532,6 +538,16 @@ def create_client(
         )
     else:
         logger.info("[Fast Mode] inactive — not requested for this client")
+=======
+    # CRITICAL: Clear git environment variables from os.environ BEFORE SDK instantiation.
+    # The SDK merges os.environ with our env dict, so contaminated git vars (GIT_INDEX_FILE,
+    # GIT_DIR, etc.) inherited from parent processes would leak through and cause
+    # git operation errors in worktree operations.
+    # We must DELETE these vars from os.environ, not set them to "" (empty string is a value
+    # that git interprets as "use empty path", which fails).
+    for var in GIT_ENV_VARS_TO_CLEAR:
+        os.environ.pop(var, None)
+>>>>>>> refs/remotes/upstream/pr/1599
 
     # Debug: Log git-bash path detection on Windows
     if "CLAUDE_CODE_GIT_BASH_PATH" in sdk_env:
diff --git a/apps/frontend/src/main/agent/agent-process.ts b/apps/frontend/src/main/agent/agent-process.ts
index 58f9731674..d07a22250d 100644
--- a/apps/frontend/src/main/agent/agent-process.ts
+++ b/apps/frontend/src/main/agent/agent-process.ts
@@ -24,6 +24,7 @@ import { readSettingsFile } from '../settings-utils';
 import type { AppSettings } from '../../shared/types/settings';
 import { getOAuthModeClearVars } from './env-utils';
 import { getAugmentedEnv } from '../env-utils';
+import { getIsolatedGitEnv } from '../utils/git-isolation';
 import { getToolInfo, getClaudeCliPathForSdk } from '../cli-tool-manager';
 import { killProcessGracefully, isWindows } from '../platform';
 import { debugLog } from '../../shared/utils/debug-logger';
@@ -203,8 +204,11 @@ export class AgentProcessManager {
     });
 
     // Use getAugmentedEnv() to ensure common tool paths (dotnet, homebrew, etc.)
-    // are available even when app is launched from Finder/Dock
-    const augmentedEnv = getAugmentedEnv();
+    // are available even when app is launched from Finder/Dock.
+    // Wrap with getIsolatedGitEnv() to clear GIT_DIR, GIT_WORK_TREE, GIT_INDEX_FILE,
+    // and other git env vars that can contaminate worktree operations when inherited
+    // from parent processes (pre-commit hooks, IDE integrations, Electron app).
+    const augmentedEnv = getIsolatedGitEnv(getAugmentedEnv());
 
     // On Windows, detect and pass git-bash path for Claude Code CLI
     // Electron can detect git via where.exe, but Python subprocess may not have the same PATH