- Added throttling and debouncing to HUD data rendering and observer UI synchronization to coalesce update bursts.
- Constrained the subagent HUD display to a maximum of 8 rows with a truncation notice for hidden sessions.
- Enhanced the session observer registry to categorize update types, enabling more granular UI reconciliation.
- Verified render coalescing and display truncation behavior with comprehensive integration tests using fake timers.
- Added detached spawn metadata to lifecycle, progress, and executor session payloads so task and evaluator runs can mark background jobs.
- Updated subagent session tracking and HUD rendering to only show active detached spawns.
- Extended HUD tests to verify non-detached sync and eval spawns are excluded while detached flags propagate through events.
- Added `parentToolCallId` and `index` fields to subagent session records and propagated them from task lifecycle and progress events.
- Reworked subagent ordering to sort by parent-group order, spawn index, and stable creation order so out-of-order updates no longer reshuffled active HUD rows.
- Updated task execution to pass spawn indices through sync and async paths, switched the `tool.task` icon to Octicons tasklist, and added a registry test for out-of-order progress ordering.
- Added an anchored Subagents HUD renderer that formats active subagent sessions as `Id: description` rows.
- Integrated a new interactive-mode container and observer-driven render path so the HUD updates with session events and clears when no subagents are active.
- Exported `formatTaskId` for shared HUD formatting and added tests covering active-only filtering, fallback task/progress text, and line truncation.
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