Feature/screenshot privacy warning (#541)

* Screenshot privacy: warn on location sheet; gate screenshot broadcasts to chat only\n\n- Track sheet presentation in ChatViewModel\n- Show privacy alert when screenshot taken on location channels\n- Ignore screenshots for App Info and Location sheet for broadcast\n- ContentView wires sheet onAppear/onDisappear and presents alert\n- Fix location sheet subtitle wrapping: render as single Text to avoid orphaned bullets

* Fix duplicate messages after channel switch\n\n- Dedup on per-geohash append (skip if ID exists)\n- Dedup and sort timeline by timestamp when switching into a geohash\n- Keep content/layout unchanged; add lightweight debug logs for empty rows

---------

Co-authored-by: jack <jackjackbits@users.noreply.github.com>

bitchat/ViewModels/ChatViewModel.swift

@@ -382,6 +382,11 @@ class ChatViewModel: ObservableObject, BitchatDelegate {
     @Published var showBluetoothAlert = false
     @Published var bluetoothAlertMessage = ""
     @Published var bluetoothState: CBManagerState = .unknown
+
+    // Presentation state for privacy gating
+    @Published var isLocationChannelsSheetPresented: Bool = false
+    @Published var isAppInfoPresented: Bool = false
+    @Published var showScreenshotPrivacyWarning: Bool = false
     
     // Messages are naturally ephemeral - no persistent storage
     // Persist mesh public timeline across channel switches
@@ -1407,6 +1412,11 @@ class ChatViewModel: ObservableObject, BitchatDelegate {
         switch channel {
         case .mesh:
             messages = meshTimeline
+            // Debug: log if any empty messages are present
+            let emptyMesh = messages.filter { $0.content.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty }.count
+            if emptyMesh > 0 {
+                SecureLogger.log("RenderGuard: mesh timeline contains \(emptyMesh) empty messages", category: SecureLogger.session, level: .debug)
+            }
             stopGeoParticipantsTimer()
             geohashPeople = []
             teleportedGeo.removeAll()
@@ -1414,13 +1424,26 @@ class ChatViewModel: ObservableObject, BitchatDelegate {
             // Sanitize existing timeline (filter any prior empty-content entries)
             var arr = geoTimelines[ch.geohash] ?? []
             arr.removeAll { $0.content.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty }
-            // Ensure chronological order when returning to a geohash
+            // Deduplicate by ID while preserving order (from oldest to newest)
             if arr.count > 1 {
-                arr.sort { $0.timestamp < $1.timestamp }
+                var seen = Set<String>()
+                var dedup: [BitchatMessage] = []
+                for m in arr.sorted(by: { $0.timestamp < $1.timestamp }) {
+                    if !seen.contains(m.id) {
+                        dedup.append(m)
+                        seen.insert(m.id)
+                    }
+                }
+                arr = dedup
             }
             // Persist the cleaned/sorted timeline for this geohash
             geoTimelines[ch.geohash] = arr
             messages = arr
+            // Debug: log if any empty messages are present post-sanitize
+            let emptyGeo = messages.filter { $0.content.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty }.count
+            if emptyGeo > 0 {
+                SecureLogger.log("RenderGuard: geohash \(ch.geohash) timeline has \(emptyGeo) empty messages after sanitize", category: SecureLogger.session, level: .debug)
+            }
         }
         // Unsubscribe previous
         if let sub = geoSubscriptionID {
@@ -2588,6 +2611,17 @@ class ChatViewModel: ObservableObject, BitchatDelegate {
     
     @MainActor
     @objc private func userDidTakeScreenshot() {
+        // Respect privacy: do not broadcast screenshots taken from non-chat sheets
+        if isLocationChannelsSheetPresented {
+            // Show a warning about sharing location screenshots publicly
+            showScreenshotPrivacyWarning = true
+            return
+        }
+        if isAppInfoPresented {
+            // Silently ignore screenshots of app info
+            return
+        }
+
         // Send screenshot notification based on current context
         let screenshotMessage = "* \(nickname) took a screenshot *"
         
@@ -2607,7 +2641,7 @@ class ChatViewModel: ObservableObject, BitchatDelegate {
                 }
             }
             
-            // Show local notification immediately as system message
+            // Show local notification immediately as system message (only in chat)
             let localNotification = BitchatMessage(
                 sender: "system",
                 content: "you took a screenshot",
@@ -2658,7 +2692,7 @@ class ChatViewModel: ObservableObject, BitchatDelegate {
             }
             
 
-            // Show local notification immediately as system message
+            // Show local notification immediately as system message (only in chat)
             let localNotification = BitchatMessage(
                 sender: "system",
                 content: "you took a screenshot",
@@ -5781,9 +5815,12 @@ class ChatViewModel: ObservableObject, BitchatDelegate {
         if isGeo && finalMessage.sender != "system" {
             if let gh = currentGeohash {
                 var arr = geoTimelines[gh] ?? []
-                arr.append(finalMessage)
-                if arr.count > geoTimelineCap { arr = Array(arr.suffix(geoTimelineCap)) }
-                geoTimelines[gh] = arr
+                // Dedup by message ID before appending to per-geohash timeline
+                if !arr.contains(where: { $0.id == finalMessage.id }) {
+                    arr.append(finalMessage)
+                    if arr.count > geoTimelineCap { arr = Array(arr.suffix(geoTimelineCap)) }
+                    geoTimelines[gh] = arr
+                }
             }
         }
 

bitchat/Views/ContentView.swift

@@ -165,6 +165,8 @@ struct ContentView: View {
         }
         .sheet(isPresented: $showAppInfo) {
             AppInfoView()
+                .onAppear { viewModel.isAppInfoPresented = true }
+                .onDisappear { viewModel.isAppInfoPresented = false }
         }
         .sheet(isPresented: Binding(
             get: { viewModel.showingFingerprintFor != nil },
@@ -279,8 +281,10 @@ struct ContentView: View {
                         }
                     }()
                     let items = windowedMessages.map { (uiID: "\(contextKey)|\($0.id)", message: $0) }
-                    
-                    ForEach(items, id: \.uiID) { item in
+                    // Filter out empty/whitespace-only messages to avoid blank rows
+                    let filteredItems = items.filter { !$0.message.content.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty }
+
+                    ForEach(filteredItems, id: \.uiID) { item in
                         let message = item.message
                         VStack(alignment: .leading, spacing: 0) {
                             // Check if current user is mentioned
@@ -1182,6 +1186,13 @@ struct ContentView: View {
         .padding(.horizontal, 12)
         .sheet(isPresented: $showLocationChannelsSheet) {
             LocationChannelsSheet(isPresented: $showLocationChannelsSheet)
+                .onAppear { viewModel.isLocationChannelsSheetPresented = true }
+                .onDisappear { viewModel.isLocationChannelsSheetPresented = false }
+        }
+        .alert("heads up", isPresented: $viewModel.showScreenshotPrivacyWarning) {
+            Button("ok", role: .cancel) {}
+        } message: {
+            Text("screenshots of location channels will reveal your location. think before sharing publicly.")
         }
         .background(backgroundColor.opacity(0.95))
     }

bitchat/Views/LocationChannelsSheet.swift

@@ -304,22 +304,17 @@ struct LocationChannelsSheet: View {
                                 .foregroundColor(.secondary)
                         }
                     }
-                    HStack(spacing: 0) {
-                        Text(subtitlePrefix)
-                            .font(.system(size: 12, design: .monospaced))
-                            .foregroundColor(.secondary)
-                        if let name = subtitleName {
-                            Text(" • ")
-                                .font(.system(size: 12, design: .monospaced))
-                                .foregroundColor(.secondary)
-                            Text(name)
-                                .font(.system(size: 12, design: .monospaced))
-                                .fontWeight(subtitleNameBold ? .bold : .regular)
-                                .foregroundColor(.secondary)
-                                .lineLimit(1)
-                                .truncationMode(.tail)
-                        }
+                let subtitleFull: String = {
+                    if let name = subtitleName, !name.isEmpty {
+                        return subtitlePrefix + " • " + name
                     }
+                    return subtitlePrefix
+                }()
+                Text(subtitleFull)
+                    .font(.system(size: 12, design: .monospaced))
+                    .foregroundColor(.secondary)
+                    .lineLimit(1)
+                    .truncationMode(.tail)
                 }
                 Spacer()
                 if isSelected {