Auto-install protocol handler when exe run without args

agent/src/main.rs

@@ -138,9 +138,15 @@ fn main() -> Result<()> {
             if let Some(code) = cli.support_code {
                 run_agent_mode(Some(code))
             } else {
-                // No args: check if we should auto-detect mode
-                // For now, default to agent mode
-                run_agent_mode(None)
+                // No args: check if protocol handler is installed
+                // If not, run install mode (user likely downloaded from web)
+                if !install::is_protocol_handler_registered() {
+                    info!("Protocol handler not registered, running installer");
+                    run_install(false)
+                } else {
+                    // Protocol handler exists, run as agent
+                    run_agent_mode(None)
+                }
             }
         }
     }