fix: add circular dependency detection for tasks

backend/controllers/add_task.go

@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"os"
 )
 
 var GlobalJobQueue *JobQueue
@@ -62,9 +63,27 @@ func AddTaskHandler(w http.ResponseWriter, r *http.Request) {
 		}
 
 		// Validate dependencies
-		if err := utils.ValidateDependencies(depends, ""); err != nil {
-			http.Error(w, fmt.Sprintf("Invalid dependencies: %v", err), http.StatusBadRequest)
-			return
+		origin := os.Getenv("CONTAINER_ORIGIN")
+		existingTasks, err := tw.FetchTasksFromTaskwarrior(email, encryptionSecret, origin, uuid)
+		if err != nil {
+			if err := utils.ValidateDependencies(depends, ""); err != nil {
+				http.Error(w, fmt.Sprintf("Invalid dependencies: %v", err), http.StatusBadRequest)
+				return
+			}
+		} else {
+			taskDeps := make([]utils.TaskDependency, len(existingTasks))
+			for i, task := range existingTasks {
+				taskDeps[i] = utils.TaskDependency{
+					UUID:    task.UUID,
+					Depends: task.Depends,
+					Status:  task.Status,
+				}
+			}
+
+			if err := utils.ValidateCircularDependencies(depends, "", taskDeps); err != nil {
+				http.Error(w, fmt.Sprintf("Invalid dependencies: %v", err), http.StatusBadRequest)
+				return
+			}
 		}
 		dueDateStr, err := utils.ConvertOptionalISOToTaskwarriorFormat(dueDate)
 		if err != nil {

backend/controllers/edit_task.go

@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"os"
 )
 
 // EditTaskHandler godoc
@@ -62,9 +63,27 @@ func EditTaskHandler(w http.ResponseWriter, r *http.Request) {
 		}
 
 		// Validate dependencies
-		if err := utils.ValidateDependencies(depends, uuid); err != nil {
-			http.Error(w, fmt.Sprintf("Invalid dependencies: %v", err), http.StatusBadRequest)
-			return
+		origin := os.Getenv("CONTAINER_ORIGIN")
+		existingTasks, err := tw.FetchTasksFromTaskwarrior(email, encryptionSecret, origin, uuid)
+		if err != nil {
+			if err := utils.ValidateDependencies(depends, uuid); err != nil {
+				http.Error(w, fmt.Sprintf("Invalid dependencies: %v", err), http.StatusBadRequest)
+				return
+			}
+		} else {
+			taskDeps := make([]utils.TaskDependency, len(existingTasks))
+			for i, task := range existingTasks {
+				taskDeps[i] = utils.TaskDependency{
+					UUID:    task.UUID,
+					Depends: task.Depends,
+					Status:  task.Status,
+				}
+			}
+
+			if err := utils.ValidateCircularDependencies(depends, uuid, taskDeps); err != nil {
+				http.Error(w, fmt.Sprintf("Invalid dependencies: %v", err), http.StatusBadRequest)
+				return
+			}
 		}
 
 		logStore := models.GetLogStore()

backend/controllers/modify_task.go

@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"os"
 )
 
 // ModifyTaskHandler godoc
@@ -61,9 +62,27 @@ func ModifyTaskHandler(w http.ResponseWriter, r *http.Request) {
 		}
 
 		// Validate dependencies
-		if err := utils.ValidateDependencies(depends, uuid); err != nil {
-			http.Error(w, fmt.Sprintf("Invalid dependencies: %v", err), http.StatusBadRequest)
-			return
+		origin := os.Getenv("CONTAINER_ORIGIN")
+		existingTasks, err := tw.FetchTasksFromTaskwarrior(email, encryptionSecret, origin, uuid)
+		if err != nil {
+			if err := utils.ValidateDependencies(depends, uuid); err != nil {
+				http.Error(w, fmt.Sprintf("Invalid dependencies: %v", err), http.StatusBadRequest)
+				return
+			}
+		} else {
+			taskDeps := make([]utils.TaskDependency, len(existingTasks))
+			for i, task := range existingTasks {
+				taskDeps[i] = utils.TaskDependency{
+					UUID:    task.UUID,
+					Depends: task.Depends,
+					Status:  task.Status,
+				}
+			}
+
+			if err := utils.ValidateCircularDependencies(depends, uuid, taskDeps); err != nil {
+				http.Error(w, fmt.Sprintf("Invalid dependencies: %v", err), http.StatusBadRequest)
+				return
+			}
 		}
 
 		// if err := tw.ModifyTaskInTaskwarrior(uuid, description, project, priority, status, due, email, encryptionSecret, taskID); err != nil {

backend/utils/utils_test.go

@@ -85,20 +85,45 @@ func Test_ExecCommandForOutputInDir(t *testing.T) {
 	}
 }
 
-func Test_ValidateDependencies_ValidDependencies(t *testing.T) {
-	depends := []string{"task-uuid-1", "task-uuid-2"}
-	currentTaskUUID := "current-task-uuid"
-	err := ValidateDependencies(depends, currentTaskUUID)
-	assert.NoError(t, err)
-}
-
 func Test_ValidateDependencies_EmptyList(t *testing.T) {
 	depends := []string{}
 	currentTaskUUID := "current-task-uuid"
 	err := ValidateDependencies(depends, currentTaskUUID)
 	assert.NoError(t, err)
 }
 
+// Circular Dependency Detection Tests
+func Test_detectCycle_NoCycle(t *testing.T) { //A -> B -> C
+	graph := map[string][]string{
+		"A": {"B"},
+		"B": {"C"},
+		"C": {},
+	}
+
+	hasCycle := detectCycle(graph, "A")
+	assert.False(t, hasCycle, "Should not detect cycle in linear dependency")
+}
+
+func Test_detectCycle_SimpleCycle(t *testing.T) { // A -> B -> A
+	graph := map[string][]string{
+		"A": {"B"},
+		"B": {"A"},
+	}
+
+	hasCycle := detectCycle(graph, "A")
+	assert.True(t, hasCycle, "Should detect simple cycle A -> B -> A")
+}
+
+func Test_detectCycle_ComplexCycle(t *testing.T) { // A -> B -> C -> A
+	graph := map[string][]string{
+		"A": {"B"},
+		"B": {"C"},
+		"C": {"A"},
+	}
+
+	hasCycle := detectCycle(graph, "A")
+	assert.True(t, hasCycle, "Should detect complex cycle A -> B -> C -> A")
+}
 func TestConvertISOToTaskwarriorFormat(t *testing.T) {
 	tests := []struct {
 		name     string

backend/utils/validation.go

@@ -19,3 +19,67 @@ func ValidateDependencies(depends []string, currentTaskUUID string) error {
 
 	return nil
 }
+
+type TaskDependency struct {
+	UUID    string   `json:"uuid"`
+	Depends []string `json:"depends"`
+	Status  string   `json:"status"`
+}
+
+func ValidateCircularDependencies(depends []string, currentTaskUUID string, existingTasks []TaskDependency) error {
+	if len(depends) == 0 {
+		return nil
+	}
+
+	dependencyGraph := make(map[string][]string)
+	for _, task := range existingTasks {
+		if task.Status == "pending" {
+			dependencyGraph[task.UUID] = task.Depends
+		}
+	}
+
+	dependencyGraph[currentTaskUUID] = depends
+
+	if hasCycle := detectCycle(dependencyGraph, currentTaskUUID); hasCycle {
+		return fmt.Errorf("circular dependency detected: adding these dependencies would create a cycle")
+	}
+
+	return nil
+}
+
+// (0): unvisited,  (1): visiting,(2): visited
+func detectCycle(graph map[string][]string, startNode string) bool {
+	color := make(map[string]int)
+
+	for node := range graph {
+		color[node] = 0
+	}
+
+	for _, deps := range graph {
+		for _, dep := range deps {
+			if _, exists := color[dep]; !exists {
+				color[dep] = 0
+			}
+		}
+	}
+
+	return dfsHasCycle(graph, startNode, color)
+}
+
+func dfsHasCycle(graph map[string][]string, node string, color map[string]int) bool {
+	color[node] = 1
+
+	for _, dep := range graph[node] {
+		if color[dep] == 1 {
+			return true
+		}
+		if color[dep] == 0 {
+			if dfsHasCycle(graph, dep, color) {
+				return true
+			}
+		}
+	}
+
+	color[node] = 2
+	return false
+}

frontend/src/components/HomeComponents/Tasks/Tasks.tsx

@@ -229,6 +229,16 @@ export const Tasks = (
     return () => clearInterval(interval);
   }, []);
 
+  // Listen for sync events from WebSocket handler
+  useEffect(() => {
+    const handleSyncTasks = () => {
+      syncTasksWithTwAndDb();
+    };
+
+    window.addEventListener('syncTasks', handleSyncTasks);
+    return () => window.removeEventListener('syncTasks', handleSyncTasks);
+  }, [syncTasksWithTwAndDb]);
+
   useEffect(() => {
     const fetchTasksForEmail = async () => {
       try {
@@ -397,7 +407,7 @@ export const Tasks = (
         annotations,
       });
 
-      console.log('Task edited successfully!');
+      // Don't show success message here - wait for WebSocket confirmation
       setIsAddTaskOpen(false);
     } catch (error) {
       console.error('Failed to edit task:', error);
@@ -682,28 +692,31 @@ export const Tasks = (
     );
   };
 
-  const handleDependsSaveClick = (task: Task, depends: string[]) => {
-    task.depends = depends;
-
+  const handleDependsSaveClick = async (task: Task, depends: string[]) => {
     setUnsyncedTaskUuids((prev) => new Set([...prev, task.uuid]));
 
-    handleEditTaskOnBackend(
-      props.email,
-      props.encryptionSecret,
-      props.UUID,
-      task.description,
-      task.tags,
-      task.uuid.toString(),
-      task.project,
-      task.start,
-      task.entry || '',
-      task.wait || '',
-      task.end || '',
-      task.depends,
-      task.due || '',
-      task.recur || '',
-      task.annotations || []
-    );
+    try {
+      console.log('Calling backend...');
+      await handleEditTaskOnBackend(
+        props.email,
+        props.encryptionSecret,
+        props.UUID,
+        task.description,
+        task.tags,
+        task.uuid.toString(),
+        task.project,
+        task.start,
+        task.entry || '',
+        task.wait || '',
+        task.end || '',
+        depends,
+        task.due || '',
+        task.recur || '',
+        task.annotations || []
+      );
+    } catch (error) {
+      console.error('Failed to update dependencies:', error);
+    }
   };
 
   const handleRecurSaveClick = (task: Task, recur: string) => {

frontend/src/components/HomeComponents/Tasks/UseEditTask.tsx

@@ -34,7 +34,7 @@ export const useEditTask = (selectedTask: Task | null) => {
     annotationInput: '',
   });
 
-  // Update edited tags when selected task changes
+  // Sync all editable fields from selectedTask when it changes
   useEffect(() => {
     if (selectedTask) {
       setState((prev) => ({
@@ -46,6 +46,7 @@ export const useEditTask = (selectedTask: Task | null) => {
         editedRecur: selectedTask.recur || '',
         originalRecur: selectedTask.recur || '',
         editedAnnotations: selectedTask.annotations || [],
+        editedDepends: selectedTask.depends || [],
       }));
     }
   }, [selectedTask]);

frontend/src/components/HomePage.tsx

@@ -78,8 +78,12 @@ export const HomePage: React.FC = () => {
       try {
         const data = JSON.parse(event.data);
         if (data.status === 'success') {
-          // Skip refresh for Edit Task to prevent dialog blinking
-          if (data.job !== 'Edit Task') {
+          // Use syncTasksWithTwAndDb to update both backend and IndexedDB
+          // This ensures the Tasks component sees the updated data
+          if (data.job === 'Edit Task') {
+            // For Edit Task, we need to trigger a sync to update the UI
+            window.dispatchEvent(new CustomEvent('syncTasks'));
+          } else {
             getTasks(userInfo.email, userInfo.encryption_secret, userInfo.uuid);
           }
 
@@ -128,7 +132,15 @@ export const HomePage: React.FC = () => {
           }
         } else if (data.status == 'failure') {
           console.log(`Failed to ${data.job || 'perform action'}`);
-          toast.error(`Failed to ${data.job || 'perform action'}`, {
+
+          // Show specific message for Edit Task failures
+          let errorMessage = `Failed to ${data.job || 'perform action'}`;
+          if (data.job === 'Edit Task') {
+            errorMessage =
+              'Failed to add dependency: Circular dependency detected';
+          }
+
+          toast.error(errorMessage, {
             position: 'bottom-left',
             autoClose: 3000,
             hideProgressBar: false,