Session Cache Implementation

Nucleic-Session: B2346642-3353-4BD5-9DE2-A8B77BD66C98
Co-authored-by: Nucleic <[email protected]>

NucleicRemote/NucleicRemote/Models/RemoteStore.swift

@@ -647,6 +647,48 @@ final class RemoteStore: ObservableObject {
         return bySeq.values.sorted { $0.seq < $1.seq }
     }
 
+    // MARK: - Offline cache (SessionCache)
+
+    /// Debounced write of the live session list to disk, so a read-only history survives a
+    /// disconnect / relaunch.
+    private func persistSummaries(_ list: [WireSessionSummary]) {
+        summaryPersistTask?.cancel()
+        summaryPersistTask = Task { [list] in
+            try? await Task.sleep(nanoseconds: 2_000_000_000)
+            guard !Task.isCancelled else { return }
+            await SessionCache.saveSummaries(list)
+        }
+    }
+
+    /// Seed the open transcript from disk so a cached session's history shows instantly — even fully
+    /// offline. A live snapshot/backfill merges on top by seq (dedup), so this never double-counts.
+    private func loadCachedTranscript(_ sessionID: SessionID) {
+        Task { [weak self] in
+            let cached = await SessionCache.loadEvents(sessionID)
+            guard let self, self.openSessionID == sessionID, !cached.isEmpty else { return }
+            self.openEvents = Self.mergedEvents(cached, self.openEvents)
+        }
+    }
+
+    /// Debounced write of the open transcript, called after each batch of events lands.
+    private func persistOpenTranscript() {
+        guard !demoMode, let id = openSessionID, !openEvents.isEmpty else { return }
+        let events = openEvents
+        transcriptPersistTask?.cancel()
+        transcriptPersistTask = Task { [events, id] in
+            try? await Task.sleep(nanoseconds: 1_500_000_000)
+            guard !Task.isCancelled else { return }
+            await SessionCache.saveEvents(events, for: id)
+        }
+    }
+
+    /// Flush the open transcript to disk immediately (on close), cancelling any pending debounce.
+    private func flushOpenTranscript(_ id: SessionID, _ events: [AgentEvent]) {
+        transcriptPersistTask?.cancel()
+        guard !demoMode, !events.isEmpty else { return }
+        Task { await SessionCache.saveEvents(events, for: id) }
+    }
+
     /// The flat sessions list: every connected Mac's sessions, deduped by id (ids are globally
     /// unique). Views handle sorting/grouping.
     private func aggregatedSessions() -> [WireSessionSummary] {