Background tasks: aggregate progress bar for parent tasks with children

Goal

When a background task has multiple child subtasks (e.g., importing multiple assets as part of a batch operation), display a single aggregate progress bar in the taskbar instead of showing the per-subtask progress. This gives users a cleaner overview of overall progress.

Context / integration points

  • Background tasks API (editor/ or studio/services/).
  • Asset importing spawns one task per asset, which shows as individual progress entries.
  • Taskbar currently shows each subtask's progress individually.
  • Parent/child task relationship already exists in the task system.

Design

  • If a task has children, the taskbar shows an aggregate progress bar for the parent instead of individual child progress bars.
  • The aggregate progress = (completed children / total children).
  • Expand/collapse toggle on the parent to show/hide individual child progress (optional, for debugging).
  • The parent task title summarizes the operation (e.g., "Importing 12 textures...").
  • Subtasks are still tracked internally and individually cancellable if needed.

Tasks

  • Detect parent-child task relationships in the progress display
  • Implement aggregate progress computation for parent tasks
  • Show aggregate bar in the taskbar for parent tasks
  • Hide individual child progress by default
  • Add optional expand/collapse to show children
  • Test with batch import of 10+ assets

Acceptance criteria

  • Batch tasks show one aggregate progress bar instead of many individual ones.
  • The aggregate bar correctly reflects overall completion.
  • Individual subtask progress is still accessible (expand to view).
  • The taskbar is less cluttered during batch operations.