## Why
Reports from a large thread tree can exceed the rollout attachment limit, making
the threads involved in a failed Guardian review harder to diagnose.
## What changed
- Prioritize descendants with retained failed reviews when selecting bounded
report rollouts, while always preserving the reported thread.
- Include each selected thread's available Guardian trunk rollout alongside its
conversation rollout.
- Add a thread index attachment with selected filenames, bounded omission details,
retained failure threads, and the process-wide discarded-record count.
- Link failed-review records to their reviewed turn and target item when available.
## Testing
- Cover failed-review prioritization, bounded omission metadata, discarded-record
accounting, and turn/item linkage in Guardian report records.
GitOrigin-RevId: ae7916c27a3c279e899cd5a6ead8a4b7e0cc26a1
2e5ee418ad