Session Sync Repair

Nucleic-Session: 0C7BC346-0002-4533-ADDD-3B4C92E58527
Co-authored-by: Nucleic <[email protected]>

NucleicRemote/NucleicRemote/Models/RemoteStore.swift

@@ -560,6 +560,20 @@ final class RemoteStore: ObservableObject {
         }
     }
 
+    /// Merge transcript events by `seq` (monotonic, globally unique within a session), keeping the
+    /// union sorted. Lets a reconnect's snapshot fold its events into the transcript already on
+    /// screen without duplicating what's shown or dropping history outside the host's tail window.
+    /// A fresh open merges into `[]`, so it's just the tail — the same result as a plain replace.
+    private static func mergedEvents(_ existing: [AgentEvent], _ incoming: [AgentEvent]) -> [AgentEvent] {
+        guard !existing.isEmpty else { return incoming }
+        guard !incoming.isEmpty else { return existing }
+        var bySeq: [UInt64: AgentEvent] = [:]
+        bySeq.reserveCapacity(existing.count + incoming.count)
+        for e in existing { bySeq[e.seq] = e }
+        for e in incoming { bySeq[e.seq] = e }
+        return bySeq.values.sorted { $0.seq < $1.seq }
+    }
+
     /// The flat sessions list: every connected Mac's sessions, deduped by id (ids are globally
     /// unique). Views handle sorting/grouping.
     private func aggregatedSessions() -> [WireSessionSummary] {