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- M2 head: honor M1 vocabulary (ApiCall/Delivered), harden InsertIfNotExistsAsync (race window — first concurrent writer arrives in M2), add keyset-tiebreaker test (Bundle D reviewer's deferred recommendation), reuse MsSqlMigrationFixture + Xunit.SkippableFact pattern. - M6-T4 (AuditLogPurgeActor): replace M1's NotSupportedException stub with the drop-and-rebuild dance for the non-aligned UX_AuditLog_EventId unique index; acknowledge the small outage window during partition SWITCH. - M6-T5 (partition maintenance): note M1 ships 24 monthly boundaries (Jan 2026 - Dec 2027); service rolls the function forward via SPLIT RANGE.