feat: improve error messaging for tool-call limit in chat UI

Author: vinhnx

README.md

@@ -780,6 +780,8 @@ default_policy = "prompt"
 max_tool_loops = 100
 ```
 
+When a turn hits this guard, the chat UI now surfaces a clear error explaining that tool execution stopped and points you to `[tools].max_tool_loops` in `vtagent.toml` so you can raise the limit before retrying.
+
 ### Distribution & Releases
 
 VTCode supports multiple distribution channels for easy installation:

docs/project/TODO.md

@@ -216,6 +216,3 @@ can we let the agent output text as ansi codes directly, and not markdown, so we
 ▌ mode is Full Auto in welcome message
 
 ---
-
-▌ check dead code: vtagent-core/src/core/agent/runner.rs
-▌ if can be used, if not remove it

src/agent/runloop/unified.rs

@@ -261,7 +261,7 @@ pub(crate) async fn run_single_agent_loop_unified(
                     "I reached the configured tool-call limit of {} for this turn and paused further tool execution. Increase `tools.max_tool_loops` in vtcode.toml if you need more, then ask me to continue.",
                     max_tool_loops
                 );
-                renderer.line(MessageStyle::Response, &notice)?;
+                renderer.line(MessageStyle::Error, &notice)?;
                 ensure_turn_bottom_gap(&mut renderer, &mut bottom_gap_applied)?;
                 working_history.push(uni::Message::assistant(notice));
                 break 'outer;