## Why
Guardian reviews need the original conversation evidence even after the parent context has been compacted, while rollback must still remove evidence from reverted turns.
## What changed
- Build synchronous and asynchronous Guardian transcripts from the retained review-history snapshot.
- Use the shared Guardian transcript collector for consistent entry formatting, tool attribution, and per-entry truncation while preserving the existing transcript retention budgets.
## Testing
- Add app-server coverage for retaining user and tool evidence after compaction and discarding it after rollback.
- Extend transcript tests for standalone tool outputs, shell calls, attribution, truncation, and retention limits.
GitOrigin-RevId: a18b1176f14a4d006c263aa82d4e593afee66bc3
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