perf: replace inefficient memory cloning vectors with fast zero-allocation read iterators

server/src/handlers_v2/tasks.rs

@@ -263,15 +263,18 @@ impl McpTool for ListActiveTasksHandler {
 
     async fn execute(&self, args: Value, state: Arc<MemoryState>) -> Result<String, String> {
         let req: ListActiveTasksTool = serde_json::from_value(args).map_err(|e| e.to_string())?;
-        let mut tasks = state.tasks.read();
-        tasks.retain(|t| t.status != "done");
-        if let Some(branch) = req.git_branch {
-            tasks.retain(|t| {
-                t.git_branch.is_none() || t.git_branch.as_deref() == Some(branch.as_str())
-            });
-        }
-        let data = serde_json::to_string(&tasks).unwrap_or_default();
-        Ok(data.to_string())
+        let data = state.tasks.read_with(|tasks| {
+            let filtered: Vec<_> = tasks.iter().filter(|t| {
+                let status_match = t.status != "done";
+                let branch_match = match &req.git_branch {
+                    Some(branch) => t.git_branch.is_none() || t.git_branch.as_deref() == Some(branch.as_str()),
+                    None => true,
+                };
+                status_match && branch_match
+            }).collect();
+            serde_json::to_string(&filtered).unwrap_or_default()
+        });
+        Ok(data)
     }
 }
 
@@ -313,7 +316,7 @@ impl McpTool for SetAcceptanceCriteriaHandler {
             }
         });
         if success {
-            Ok(vec!["Acceptance criteria set successfully.".to_string()][0].clone())
+            Ok("Acceptance criteria set successfully.".to_string())
         } else {
             Ok("Task not found.".to_string())
         }
@@ -360,15 +363,14 @@ impl McpTool for VerifyAcceptanceCriteriaHandler {
             }
         });
         if success {
-            Ok(vec![format!(
+            Ok(format!(
                 "Acceptance criteria verified with proof: {}",
                 req.proof
-            )][0]
-                .clone())
+            ))
         } else if already_met {
             Ok("Acceptance criteria was already met.".to_string())
         } else {
-            Ok(vec!["Acceptance criteria or task not found.".to_string()][0].clone())
+            Ok("Acceptance criteria or task not found.".to_string())
         }
     }
 }
@@ -446,11 +448,16 @@ impl McpTool for ListMilestonesHandler {
 
     async fn execute(&self, args: Value, state: Arc<MemoryState>) -> Result<String, String> {
         let req: ListMilestonesTool = serde_json::from_value(args).map_err(|e| e.to_string())?;
-        let mut items = state.milestones.read();
-        if let Some(ns) = req.namespace {
-            items.retain(|i| i.namespace == ns);
-        }
-        let data = serde_json::to_string(&items).unwrap_or_default();
-        Ok(data.to_string())
+        let data = state.milestones.read_with(|items| {
+            let filtered: Vec<_> = items.iter().filter(|i| {
+                if let Some(ns) = &req.namespace {
+                    &i.namespace == ns
+                } else {
+                    true
+                }
+            }).collect();
+            serde_json::to_string(&filtered).unwrap_or_default()
+        });
+        Ok(data)
     }
 }