f7e7ba0263
SQL Server's DbUpdateException for one duplicate names every entry in the statement batch, so detaching ex.Entries dropped the whole flush. On a row-level rejection the writer now asks the database which of the batch's EventIds it already holds, drops exactly those, re-saves the rest, and falls back to row-by-row only if a non-duplicate row is still refused. Fresh context + entities per attempt. Pinned against the real central SQL Server (new SqlServerTestDatabase harness) and a faithful whole-batch interceptor. Refs #733 Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT