diff --git a/HellionChat/Util/DbOperationGate.cs b/HellionChat/Util/DbOperationGate.cs
index 7adc8c6..da720aa 100644
--- a/HellionChat/Util/DbOperationGate.cs
+++ b/HellionChat/Util/DbOperationGate.cs
@@ -14,12 +14,17 @@ internal enum DbOperation
 // frame. Generalises the retention-sweep lock, which already did exactly this
 // for a single case.
 //
-// The reason it has to cover all of them together, not one each: an export
-// leaves a reader open on the primary connection deliberately outside _readLock,
-// because the enumerator is consumed lazily by its caller. If a VACUUM starts
-// while that reader lives, it meets an active reader on a connection Microsoft
-// documents as not thread-safe, and PerformMaintenance sets no command timeout
-// so it inherits five seconds before throwing.
+// The reason it has to cover all of them together, not one each: an export can
+// leave a reader open on the primary connection outside _readLock, because
+// StreamForExport hands back an enumerator its caller consumes lazily. A VACUUM
+// starting while that reader lives fails immediately with "cannot VACUUM - SQL
+// statements in progress".
+//
+// That is SQLITE_ERROR, not SQLITE_BUSY, so no timeout applies and no retry
+// helps -- busy handling only covers contention between different connections.
+// And it fails after the DELETE has committed, so the rows are gone and the file
+// is not compacted. PerformMaintenance runs VACUUM, REINDEX and ANALYZE as one
+// batch, so the latter two never run either.
 //
 // Pure state machine, no ImGui and no database, so the build suite can pin the
 // transitions without standing up either.