refactor: apply 5-pass audit optimizations across mcp-memory codebase

server/src/handlers/tasks.rs

@@ -46,7 +46,7 @@ impl McpTool for TasksHandler {
                     acceptance_criteria: vec![],
                     expires_at: None,
                 };
-                let idx = state.get_search_index();
+                let idx = state.get_search_index().await;
                 drop(idx.index_task(&task));
                 state.project.tasks.modify(|tasks| {
                     tasks.push(task.clone());
@@ -187,7 +187,7 @@ impl McpTool for TasksHandler {
                 });
 
                 if deleted_count > 0 {
-                    let idx = state.get_search_index();
+                    let idx = state.get_search_index().await;
                     for deleted_id in actually_deleted {
                         drop(idx.delete_document(&deleted_id));
                     }
@@ -228,7 +228,8 @@ impl McpTool for TasksHandler {
                     if let Some(max_t) = req.max_tokens {
                         let char_limit = max_t * 4;
                         if json_str.len() > char_limit {
-                            json_str.truncate(char_limit);
+                            let boundary = json_str.floor_char_boundary(char_limit);
+                            json_str.truncate(boundary);
                             json_str.push_str(" ...[truncated due to max_tokens]");
                         }
                     }