Enforce task hierarchy rules: should task→task nesting be forbidden?

[kitikonti]

Description

Currently OwnChart allows arbitrary parent/child nesting — a regular task can be a parent of another regular task. Should we enforce that only summary tasks can have children (i.e., only summary→task, summary→summary→task, etc.)?

Questions to Discuss

1. Should task→task parent/child relationships be forbidden?

   • Only allow summary→task or summary→summary→…→task
   • Or keep the current permissive behavior?

2. If forbidden: what happens when indenting a task below another task?

   • Option A: Block the indent — show feedback that the parent must be a summary
   • Option B: Auto-convert parent to summary — the task above becomes a summary automatically
   • Option C: Auto-insert a new summary — create a new summary task as parent
   • Option D: Other approaches?

3. Backward compatibility — How to handle existing .ownchart files that contain task→task nesting?

   • Silent migration on file open (auto-convert parents to summaries)?
   • Warning dialog with migration options?
   • Keep existing structures valid but prevent new ones?

Acceptance Criteria

• Decision documented on which hierarchy rules to enforce
• All indent/outdent operations respect the chosen rules
• Existing files with legacy nesting are handled gracefully
• Drag-and-drop reordering respects hierarchy rules
• Undo/redo works correctly with any auto-conversions
• Unit and integration tests cover all hierarchy edge cases
• No regressions in existing functionality