feat: preview the newest message in the chats section

bitchat/App/PeerListModel.swift

@@ -49,8 +49,26 @@ struct RecentChatRow: Identifiable, Equatable {
     let displayName: String
     let hasUnread: Bool
     let lastActivity: Date
+    /// One-line snippet of the newest message, or nil when there is nothing
+    /// worth showing (see `RecentChatPreview`). Nil rather than "" so the
+    /// row can collapse to a single line instead of reserving blank space.
+    let preview: String?
 
     var id: String { peerID.id }
+
+    init(
+        peerID: PeerID,
+        displayName: String,
+        hasUnread: Bool,
+        lastActivity: Date,
+        preview: String? = nil
+    ) {
+        self.peerID = peerID
+        self.displayName = displayName
+        self.hasUnread = hasUnread
+        self.lastActivity = lastActivity
+        self.preview = preview
+    }
 }
 
 @MainActor
@@ -169,6 +187,17 @@ final class PeerListModel: ObservableObject {
             }
             .store(in: &cancellables)
 
+        // Opening or closing a direct conversation adds and removes its chat
+        // row. Without this the suppression would only take effect on the
+        // next unrelated refresh, so the sheet would keep offering to open
+        // the thread already on screen until something else changed.
+        chatViewModel.privateChatManager.$selectedPeer
+            .receive(on: DispatchQueue.main)
+            .sink { [weak self] _ in
+                self?.refresh()
+            }
+            .store(in: &cancellables)
+
         chatViewModel.groupStore.$groups
             .receive(on: DispatchQueue.main)
             .sink { [weak self] _ in
@@ -315,9 +344,22 @@ final class PeerListModel: ObservableObject {
             visibleIdentities.insert(PeerID(nostr_: person.id).id)
         }
 
+        // The thread already on screen does not need a row pointing at it.
+        // Compare through the same identity keys used above: a conversation
+        // opened under the stable Noise ID must still suppress the row keyed
+        // by its ephemeral alias, or closing the sheet reopens what is open.
+        var openIdentities = Set<String>()
+        if let openPeerID = chatViewModel.selectedPrivateChatPeer {
+            openIdentities.insert(openPeerID.id)
+            if let fingerprint = chatViewModel.getFingerprint(for: openPeerID) {
+                openIdentities.insert(fingerprint)
+            }
+        }
+
         struct Candidate {
             let peerID: PeerID
             let lastActivity: Date
+            let preview: String?
         }
         var bestByIdentity: [String: Candidate] = [:]
 
@@ -332,13 +374,19 @@ final class PeerListModel: ObservableObject {
             let fingerprint = chatViewModel.getFingerprint(for: peerID)
             if visibleIdentities.contains(peerID.id) { continue }
             if let fingerprint, visibleIdentities.contains(fingerprint) { continue }
+            if openIdentities.contains(peerID.id) { continue }
+            if let fingerprint, openIdentities.contains(fingerprint) { continue }
 
             let identityKey = fingerprint ?? peerID.id
             if let existing = bestByIdentity[identityKey],
                existing.lastActivity >= lastMessage.timestamp {
                 continue
             }
-            bestByIdentity[identityKey] = Candidate(peerID: peerID, lastActivity: lastMessage.timestamp)
+            bestByIdentity[identityKey] = Candidate(
+                peerID: peerID,
+                lastActivity: lastMessage.timestamp,
+                preview: RecentChatPreview.snippet(for: lastMessage.content)
+            )
         }
 
         return bestByIdentity.values
@@ -348,7 +396,8 @@ final class PeerListModel: ObservableObject {
                     peerID: candidate.peerID,
                     displayName: displayName(for: candidate.peerID),
                     hasUnread: chatViewModel.hasUnreadMessages(for: candidate.peerID),
-                    lastActivity: candidate.lastActivity
+                    lastActivity: candidate.lastActivity,
+                    preview: candidate.preview
                 )
             }
     }

bitchat/App/RecentChatPreview.swift

@@ -0,0 +1,86 @@
+//
+// RecentChatPreview.swift
+// bitchat
+//
+// This is free and unencumbered software released into the public domain.
+// For more information, see <https://unlicense.org>
+//
+
+import Foundation
+
+/// Builds the one-line snippet shown under a name in the "chats" section.
+///
+/// Media messages carry their payload as `"[image] <filename>"` — the marker
+/// is part of the message content, not decoration added by the view (see
+/// `MimeType.Category.messagePrefix` and `BitchatMessage.mediaAttachment`).
+/// Rendering that content verbatim in a list row would put an opaque
+/// on-disk filename in front of the reader, which says nothing about the
+/// conversation. Keeping the marker and dropping the filename is what makes
+/// the row readable, and it matches how the thread itself presents the
+/// message.
+///
+/// Framework-free on purpose: this is the part of the row with rules worth
+/// pinning, and it stays testable without a view or a view model.
+enum RecentChatPreview {
+    /// Long enough to distinguish two conversations at a glance, short
+    /// enough that the row never wraps at the narrowest sheet width.
+    static let maxLength = 80
+
+    /// A snippet for `content`, or nil when there is nothing worth showing.
+    ///
+    /// Nil rather than empty string: an absent preview and a preview of ""
+    /// are different states, and the caller decides whether to reserve the
+    /// line. Whitespace-only content is treated as absent, since a row of
+    /// blank space reads as a rendering bug.
+    static func snippet(for content: String) -> String? {
+        if let marker = mediaMarker(for: content) {
+            return marker
+        }
+
+        // Newlines and runs of spaces would otherwise render as a ragged gap
+        // mid-row; a multi-line message has to become one line to fit at all.
+        let collapsed = content
+            .split(whereSeparator: { $0.isWhitespace })
+            .joined(separator: " ")
+        guard !collapsed.isEmpty else { return nil }
+        return truncated(collapsed)
+    }
+
+    /// The bare marker for a media message (`[image]`, `[voice]`, `[file]`),
+    /// or nil when the content is not media.
+    ///
+    /// Matched against the shared `messagePrefix` rather than a literal, so
+    /// adding a category cannot leave this behind still emitting a filename.
+    static func mediaMarker(for content: String) -> String? {
+        for category in mediaCategories {
+            let prefix = category.messagePrefix
+            guard content.hasPrefix(prefix) else { continue }
+            // `messagePrefix` ends with a space; the marker is what precedes
+            // it. A prefix with no filename after it is still that kind of
+            // message, so this does not require a non-empty remainder.
+            return String(prefix.dropLast())
+        }
+        return nil
+    }
+
+    /// Every category `mediaAttachment` can classify, plus `.file`, which it
+    /// does not resolve to an attachment but which still arrives as content
+    /// with a prefix — and so would otherwise fall through to the text path
+    /// and print its filename.
+    private static let mediaCategories: [MimeType.Category] = [.audio, .image, .file]
+
+    private static func truncated(_ text: String) -> String {
+        guard text.count > maxLength else { return text }
+        // Cut on a word boundary when one is close to the limit, so the
+        // snippet does not end mid-word for the sake of four characters.
+        let hardCut = text.prefix(maxLength)
+        let cut: Substring
+        if let lastSpace = hardCut.lastIndex(of: " "),
+           hardCut.distance(from: lastSpace, to: hardCut.endIndex) < 12 {
+            cut = hardCut[hardCut.startIndex..<lastSpace]
+        } else {
+            cut = hardCut
+        }
+        return cut + "…"
+    }
+}

bitchat/Views/RecentChatList.swift

@@ -45,24 +45,37 @@ struct RecentChatList: View {
                 )
 
                 ForEach(chats) { chat in
-                    HStack(spacing: 4) {
-                        Text(verbatim: chat.displayName)
-                            .bitchatFont(size: 14)
-                            .foregroundColor(palette.primary)
-                            .lineLimit(1)
-                            .truncationMode(.tail)
+                    VStack(alignment: .leading, spacing: 1) {
+                        HStack(spacing: 4) {
+                            Text(verbatim: chat.displayName)
+                                .bitchatFont(size: 14)
+                                .foregroundColor(palette.primary)
+                                .lineLimit(1)
+                                .truncationMode(.tail)
 
-                        Text(verbatim: Self.relativeFormatter.localizedString(for: chat.lastActivity, relativeTo: Date()))
-                            .bitchatFont(size: 11)
-                            .foregroundColor(palette.secondary.opacity(0.8))
+                            Text(verbatim: Self.relativeFormatter.localizedString(for: chat.lastActivity, relativeTo: Date()))
+                                .bitchatFont(size: 11)
+                                .foregroundColor(palette.secondary.opacity(0.8))
 
-                        Spacer()
+                            Spacer()
 
-                        if chat.hasUnread {
-                            Image(systemName: "envelope.fill")
-                                .font(.bitchatSystem(size: 10))
-                                .foregroundColor(.orange)
-                                .help(Strings.newMessagesTooltip)
+                            if chat.hasUnread {
+                                Image(systemName: "envelope.fill")
+                                    .font(.bitchatSystem(size: 10))
+                                    .foregroundColor(.orange)
+                                    .help(Strings.newMessagesTooltip)
+                            }
+                        }
+
+                        // Only when there is something to show: an empty
+                        // second line reserves height and reads as a
+                        // rendering fault rather than an empty conversation.
+                        if let preview = chat.preview {
+                            Text(verbatim: preview)
+                                .bitchatFont(size: 11)
+                                .foregroundColor(palette.secondary)
+                                .lineLimit(1)
+                                .truncationMode(.tail)
                         }
                     }
                     .padding(.horizontal)
@@ -83,6 +96,9 @@ struct RecentChatList: View {
             chat.displayName,
             Self.relativeFormatter.localizedString(for: chat.lastActivity, relativeTo: Date())
         ]
+        // The row ignores its children for accessibility, so a preview left
+        // out here is a line sighted users can read and VoiceOver cannot.
+        if let preview = chat.preview { parts.append(preview) }
         if chat.hasUnread { parts.append(Strings.unread) }
         return parts.joined(separator: ", ")
     }

bitchatTests/AppArchitectureTests.swift

@@ -602,6 +602,84 @@ struct AppArchitectureTests {
         #expect(peerListModel.recentChatRows.map(\.peerID) == [offlinePeerID])
     }
 
+    @Test("Recent chat rows preview the newest message and hide the open thread")
+    @MainActor
+    func peerListModelPreviewsRecentChatsAndHidesTheOpenThread() async {
+        let viewModel = makeArchitectureViewModel()
+        let textPeerID = PeerID(str: "00000000000000b1")
+        let mediaPeerID = PeerID(str: "00000000000000b2")
+
+        viewModel.seedPrivateChat([
+            BitchatMessage(
+                id: "dm-text-1",
+                sender: "passerby",
+                content: "older message",
+                timestamp: Date(timeIntervalSince1970: 100),
+                isRelay: false,
+                isPrivate: true,
+                recipientNickname: "me",
+                senderPeerID: textPeerID
+            ),
+            BitchatMessage(
+                id: "dm-text-2",
+                sender: "passerby",
+                content: "meet me\nby the bridge",
+                timestamp: Date(timeIntervalSince1970: 200),
+                isRelay: false,
+                isPrivate: true,
+                recipientNickname: "me",
+                senderPeerID: textPeerID
+            )
+        ], for: textPeerID)
+
+        // Media content carries its on-disk filename. The row must show the
+        // marker alone — the filename is meaningless to the reader.
+        viewModel.seedPrivateChat([
+            BitchatMessage(
+                id: "dm-media-1",
+                sender: "stranger",
+                content: MimeType.Category.image.messagePrefix + "9F2A7C41-B0E3.jpg",
+                timestamp: Date(timeIntervalSince1970: 300),
+                isRelay: false,
+                isPrivate: true,
+                recipientNickname: "me",
+                senderPeerID: mediaPeerID
+            )
+        ], for: mediaPeerID)
+
+        let peerListModel = PeerListModel(
+            chatViewModel: viewModel,
+            conversations: viewModel.conversations
+        )
+
+        await waitUntil {
+            peerListModel.recentChatRows.contains { $0.peerID == textPeerID }
+                && peerListModel.recentChatRows.contains { $0.peerID == mediaPeerID }
+        }
+
+        // Newest message wins, and it is flattened to one line.
+        let textRow = peerListModel.recentChatRows.first { $0.peerID == textPeerID }
+        #expect(textRow?.preview == "meet me by the bridge")
+
+        let mediaRow = peerListModel.recentChatRows.first { $0.peerID == mediaPeerID }
+        #expect(mediaRow?.preview == "[image]")
+
+        // A row pointing at the conversation already on screen is noise: the
+        // sheet offers to open what is open.
+        viewModel.selectedPrivateChatPeer = mediaPeerID
+        await waitUntil {
+            !peerListModel.recentChatRows.contains { $0.peerID == mediaPeerID }
+        }
+        #expect(peerListModel.recentChatRows.contains { $0.peerID == textPeerID })
+
+        // Closing it brings the row back — the suppression is a view of the
+        // current selection, not a durable removal.
+        viewModel.selectedPrivateChatPeer = nil
+        await waitUntil {
+            peerListModel.recentChatRows.contains { $0.peerID == mediaPeerID }
+        }
+    }
+
     @Test("PrivateConversationModel resolves canonical header state for the selected DM")
     @MainActor
     func privateConversationModelResolvesSelectedHeaderState() async {