feat: add GEMINI_CLI environment variable to spawned shell commands (#4791)

packages/cli/src/ui/hooks/shellCommandProcessor.ts

@@ -72,6 +72,10 @@ function executeShellCommand(
       cwd,
       stdio: ['ignore', 'pipe', 'pipe'],
       detached: !isWindows, // Use process groups on non-Windows for robust killing
+      env: {
+        ...process.env,
+        GEMINI_CLI: '1',
+      },
     });
 
     // Use decoders to handle multi-byte characters safely (for streaming output).