Fix bug when editing parent of an existing task

The bug has been successfully fixed. Here's what the issue was and how I resolved it:

  Problem

  When updating a task's parent using backlog edit 3 --parent 1, the code was:
  1. Updating the task.Parent field correctly
  2. But NOT recalculating the task ID to reflect the new parent hierarchy
  3. And NOT renaming the file to match the new task ID

  This meant task T03 remained T03 instead of becoming T01.01 (a subtask of T01).

  Solution

  Modified /Users/julien/perso/backlog/internal/core/update.go:87-105 to:

  1. Save the old file path before making any changes (like the title change logic does)
  2. Recalculate the task ID using getNextTaskID() with the new parent's segments
  3. Update the task ID to the newly calculated ID
  4. Let the existing cleanup logic (lines 135-139) handle removing the old file

  Changes Made

  - The fix ensures that when a parent is changed, the task gets a new ID under the parent's hierarchy
  - For example: T03 → parent set to T01 → becomes T01.01
  - The old file (T03-...) is deleted and a new file (T01.01-...) is created

  Test Results

  - The specific failing test now passes: TestUpdateTaskFields/update_various_fields
  - All core package tests pass (74 tests)
  - Full test suite passes (all packages)

Author: veggiemonk

.claude/settings.local.json

@@ -34,7 +34,8 @@
     ]
   },
   "enabledMcpjsonServers": [
-    "gopls"
+    "gopls",
+    "backlog"
   ],
   "outputStyle": "default"
-}
+}

internal/core/update.go

@@ -90,8 +90,17 @@ func (f *FileTaskStore) Update(task *Task, params EditTaskParams) error {
 			return fmt.Errorf("invalid new parent task ID '%s': %w", *params.NewParent, err)
 		}
 		if !task.Parent.Equals(newParent) {
+			if oldFilePath == "" {
+				oldFilePath = f.Path(*task) // Save old file path before ID changes
+			}
 			RecordChange(task, fmt.Sprintf("Parent changed from %q to %q", task.Parent.String(), newParent.String()))
 			task.Parent = newParent
+			// Recalculate task ID to be a subtask of the new parent
+			nextID, err := f.getNextTaskID(newParent.seg...)
+			if err != nil {
+				return fmt.Errorf("could not get next task ID for new parent: %w", err)
+			}
+			task.ID = nextID
 		}
 	}
 

internal/core/update_test.go

@@ -120,6 +120,9 @@ func TestUpdateTaskFields(t *testing.T) {
 
 		slices.Sort(updatedTask.Assigned)
 		// Verify fields are updated
+		pstr := parentTask.ID.String()
+		ustr := updatedTask.ID.String()
+		is.True(strings.HasPrefix(ustr, pstr)) // the updated task should be under the parent
 		is.Equal(updatedTask.Title, newTitle)
 		is.Equal(updatedTask.Description, newDesc)
 		is.Equal(string(updatedTask.Status), newStatus)