diff --git a/NucleicRemote/NucleicRemote/Models/HostConnection.swift b/NucleicRemote/NucleicRemote/Models/HostConnection.swift
index 009af0a..029573c 100644
--- a/NucleicRemote/NucleicRemote/Models/HostConnection.swift
+++ b/NucleicRemote/NucleicRemote/Models/HostConnection.swift
@@ -71,6 +71,9 @@ final class HostConnection {
         var openSnapshot: (SessionSnapshot) -> Void = { _ in }
         /// New transcript events for the open session.
         var openEvents: (EventBatch) -> Void = { _ in }
+        /// Backfilled history for the open session (the full-transcript fetch). Merged into the
+        /// transcript by seq, not appended — these events precede the tail already on screen.
+        var openBackfill: (EventBatch) -> Void = { _ in }
         /// The open session's full diff arrived.
         var openDiff: (WireSessionDiff) -> Void = { _ in }
         /// An approval was requested (with the resolved session title) — post the notification and,