## What changed
- Preserve the original title when importing an external-agent session and return it with successful session entries from `externalAgentConfig/import/readHistories`.
- Add dedicated history-record success types so externally completed imports can optionally supply a session title without changing the live import result type.
## Testing
- Verify imported session titles are returned by the app server and persisted when session import ledger entries are created or refreshed.
GitOrigin-RevId: e896688a5763c238f1e1dc8b4672a7aa7bc1ed4c