## Why
Selected rollouts can reference history stored in ancestor rollouts through `history_base`. Attaching only the selected files leaves that inherited history out of diagnostic reports.
## What changed
When `include_logs` is enabled, follow nested `history_base` references and attach ancestor prefixes up to the recorded byte offsets. Deduplicate ancestors, retain the largest requested prefix, and skip rollouts already selected for upload.
Bound discovery to 64 ancestors and five seconds, and enforce attachment size limits. Missing, unreadable, or incomplete ancestor prefixes are best effort and do not prevent the report upload.
## Testing
Add a unit test verifying that nested parent and grandparent history bases are attached with the expected filenames and contents.
GitOrigin-RevId: d9bba3e50573d25843d2eaedeae775946223ed0e
Dmitriy Kovalenko
5bfb04b247