fix a looping error in iterations

crates/g3-core/src/lib.rs

@@ -1086,12 +1086,16 @@ The tool will execute immediately and you'll receive the result (success or erro
                         }
 
                         if chunk.finished {
-                            // Stream finished naturally without tool calls
+                            // Stream finished - check if we should continue or return
+                            if !tool_executed {
+                                // No tools were executed in this iteration, we're done
                                 full_response.push_str(&current_response);
                                 println!();
                                 let ttft = first_token_time.unwrap_or_else(|| stream_start.elapsed());
                                 return Ok((full_response, ttft));
                             }
+                            break; // Tool was executed, break to continue outer loop
+                        }
                     }
                     Err(e) => {
                         error!("Streaming error: {}", e);