Tasks how get assigned a default predecessor.

src/modules/manager/workflowTemplates/components/CapabilityEditors/TaskCoreEditor.tsx

@@ -8,6 +8,7 @@ import { renderTaskField } from "../taskEditorHelpers";
 import { TaskValidationResult } from "../TasksEditor";
 import { Namespaces } from "../../../../../i18n/i18n";
 import { useTranslation } from "react-i18next";
+import { getAllDescendants } from "../workflowGraphUtils";
 
 interface TaskCoreEditorProps {
   task: TaskDefinition;
@@ -58,6 +59,11 @@ export const TaskCoreEditor: React.FC<TaskCoreEditorProps> = ({
     [allowedTasks, task.type, tTaskType],
   );
 
+  useEffect(() => {
+    // Reset the guard when a new task is loaded
+    hasAssignedDefaultName.current = false;
+  }, [task.config.guid]);
+
   useEffect(() => {
     if (!hasAssignedDefaultName.current && !task.config.name) {
       hasAssignedDefaultName.current = true;
@@ -66,18 +72,28 @@ export const TaskCoreEditor: React.FC<TaskCoreEditorProps> = ({
         (t) => t.taskType === task.type,
       )?.displayName;
 
+      const newConfig = { ...task.config };
+
+      // Assign default name
       if (displayName) {
-        const newName = formatNewTaskName(allTasks);
+        newConfig.name = formatNewTaskName(allTasks);
+      }
+
+      // Assign default predecessor (the task immediately before this one)
+      const index = allTasks.findIndex(
+        (t) => t.config.guid === task.config.guid,
+      );
+
+      if (index > 0) {
+        const previousTask = allTasks[index - 1];
+        newConfig.predecessors = [previousTask.config.guid as string];
+      }
 
       onChange({
         ...task,
-          config: {
-            ...task.config,
-            name: newName,
-          },
+        config: newConfig,
       });
     }
-    }
   }, [allTasks, allowedTasks, formatNewTaskName, onChange, task]);
 
   const runValidation = useCallback(() => {
@@ -163,6 +179,21 @@ export const TaskCoreEditor: React.FC<TaskCoreEditorProps> = ({
     onValidate,
   ]);
 
+  const currentGuid = task.config.guid as string;
+  const descendants = getAllDescendants(currentGuid, allTasks);
+
+  const allowedPredecessors = allTasks.filter((t) => {
+    const guid = t.config.guid as string;
+
+    // Exclude self
+    if (guid === currentGuid) return false;
+
+    // Exclude descendants (direct or indirect)
+    if (descendants.has(guid)) return false;
+
+    return true;
+  });
+
   return (
     <div>
       {renderTaskField(
@@ -193,9 +224,7 @@ export const TaskCoreEditor: React.FC<TaskCoreEditorProps> = ({
         "",
         0,
         {
-          options: allTasks
-            .filter((t) => t.config.guid !== task.config.guid)
-            .map((t) => ({
+          options: allowedPredecessors.map((t) => ({
             value: t.config.guid as string,
             label: t.config.name as string,
           })),

src/modules/manager/workflowTemplates/components/workflowGraphUtils.ts

@@ -0,0 +1,27 @@
+import { TaskDefinition } from "../services/WorkflowTemplateService";
+
+export const getAllDescendants = (
+  guid: string,
+  tasks: TaskDefinition[],
+): Set<string> => {
+  const descendants = new Set<string>();
+
+  const visit = (current: string) => {
+    for (const t of tasks) {
+      const preds = (t.config.predecessors as string[]) ?? [];
+
+      // If t depends on current, it's a child
+      if (
+        preds.includes(current) &&
+        !descendants.has(t.config.guid as string)
+      ) {
+        const childGuid = t.config.guid as string;
+        descendants.add(childGuid);
+        visit(childGuid); // recursively find grandchildren
+      }
+    }
+  };
+
+  visit(guid);
+  return descendants;
+};