Task header message is treated as different from conversation messages and cannot be edited and re-sent to retry

[oxysoft]

Major UX problem here for the users. To restart a task with a slightly updated prompt to steer the agent better, we need to manually copy the text, clear the window, paste, and then press enter. It needs to work exactly like Cursor on this front, implemented along with #1797

[Philippe2910]

I suggest to have hierarchical task view with collapsible/expandable trees would directly address this UX issue:

Visual task relationships: See parent tasks and their subtasks clearly
One-click task restart: Click any task in the hierarchy to restart from that point
Context preservation: Understand what succeeded/failed before restarting
No manual copy-paste: Tasks remain clickable and accessible in the history

This eliminates the current workflow of manual copying and provides the Cursor-like experience users want. The hierarchical structure makes it obvious which task to restart and with what context.
Implementation: Add parentId, depth, and hasChildren fields to HistoryItem schema + collapsible UI components.

Hierarchical task view with clickable restart functionality
┌─────────────────────────────────────────┐
│ Task History │
├─────────────────────────────────────────┤
│ ▼ Build authentication system │ ← Click to restart main task
│ 📅 2025-08-20 • 💰 $0.12 • ⚠️ Failed │
│ └─ ✅ Setup OAuth2 configuration │
│ └─ ❌ Implement JWT validation │ ← Failed subtask
│ └─ ⏸️ Add user session management │ ← Never started
├─────────────────────────────────────────┤
│ ✅ Create database schema │
│ 📅 2025-08-19 • 💰 $0.08 │
└─────────────────────────────────────────┘