## What changed
Move `ThreadMetadataBuilder` into its own module, make its fields private, and replace direct field assignments with fluent `with_*` methods. Initialize `updated_at` and `recency_at` from the creation time and default the approval mode to `OnRequest`.
Update `apply_rollout_items` to accept a boxed `ThreadMetadata` seed, keeping callers' async frames small while preserving existing database fields except for the seed rollout path. Add `build_thread_metadata` to use the state runtime's configured provider, and use `thread_id_from_rollout_path` directly for the doctor's filename fallback.
GitOrigin-RevId: a27e4c6b22832e902922dbdd60d7f5c11b4a1a83
ioanbudea-OAI
ab541fb990