feat(tui): update system message for clarity and conciseness in tool usage instructions

apps/infrastructure/src/tools/utility/todowrite.rs

@@ -33,13 +33,26 @@ impl Tool for Todowrite {
         })
     }
 
-    fn run(&self, _ctx: &ToolCtx, args: &Value) -> Result<String> {
+    fn run(&self, ctx: &ToolCtx, args: &Value) -> Result<String> {
         let item = crate::tools::arg_str(args, "item")?;
         let priority = args
             .get("priority")
             .and_then(|v| v.as_str())
             .unwrap_or("medium");
 
+        let todo_line = format!("- [{}] {}\n", priority, item);
+        
+        let todo_path = ctx.session_dir.join("TODO.md");
+        let mut content = std::fs::read_to_string(&todo_path).unwrap_or_default();
+        content.push_str(&todo_line);
+        
+        let _ = std::fs::write(&todo_path, &content);
+
+        if let Some(events) = &ctx.turn_events {
+            let mut q = events.lock().unwrap();
+            q.push_back(crate::TurnEvent::TodoUpdate(content));
+        }
+
         Ok(format!("[{}] TODO added: {}", priority, item))
     }
 }