Session Cache Implementation

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

NucleicRemote/NucleicRemote/Views/SessionDetailView.swift

@@ -222,8 +222,40 @@ struct SessionDetailView: View {
     /// The floating action layer: one Liquid Glass bar carrying the queued pills, the working
     /// indicator, the session controls, and the composer — or the approval card when a gate is
     /// pending. Content scrolls beneath it; nothing renders when there's nothing to act on.
-    @ViewBuilder
     private var actionArea: some View {
+        VStack(spacing: 8) {
+            // Interacting with a chat while the owning Mac is unreachable surfaces this first, so a
+            // disabled composer reads as "offline / read-only history" rather than broken.
+            if !store.connectivity.isLive { disconnectedBanner }
+            actionContent
+        }
+        .padding(.horizontal, 12)
+        .padding(.bottom, 8)
+    }
+
+    /// The offline notice over the transcript: the chat's history is cached and readable, but the
+    /// composer + controls below stay disabled until the Mac that owns it is reachable again.
+    private var disconnectedBanner: some View {
+        HStack(spacing: 10) {
+            Image(systemName: "wifi.slash").foregroundStyle(.secondary)
+            VStack(alignment: .leading, spacing: 1) {
+                Text("Disconnected").font(.footnote.weight(.semibold))
+                Text("Showing saved history · reconnect to send")
+                    .font(.caption2).foregroundStyle(.secondary)
+            }
+            Spacer(minLength: 8)
+            Button("Reconnect") { store.reconnect() }
+                .font(.caption.weight(.semibold))
+                .buttonStyle(.borderless)
+                .disabled(!store.isPaired)
+        }
+        .frame(maxWidth: .infinity, alignment: .leading)
+        .padding(.horizontal, 14).padding(.vertical, 10)
+        .glassSurface(cornerRadius: 20)
+    }
+
+    @ViewBuilder
+    private var actionContent: some View {
         Group {
             if let approval = store.openApprovals.first {
                 // AskUserQuestion isn't a permission gate — it collects the user's answers and