feat(chat): read-only Chat sidebar tab (Phase 3)

Add the first user-visible HushChat surface: a Chat tab in the sidebar with a
two-pane, read-only conversation view — a conversation list on the left and the
selected thread on the right — reading from the App-owned ChatService store.

- New src/ui/windows/chat_tab.{h,cpp} (RenderChatTab(App*), mirroring the
  Contacts tab). Conversations are sorted by most-recent activity; peer
  z-addresses resolve to contact names via the address book when known; each
  message shows sender + timestamp + wrapped body, with a contact-request tag
  and a read-only footer (composing arrives in a later phase). Empty states
  cover "wallet locked / identity not ready" and "no conversations yet".
- Sidebar wiring: NavPage::Chat + registry entry (static_assert stays balanced),
  NavPageSurface + GetNavIconMD (ICON_MD_CHAT), dispatch in app.cpp, trace/sweep
  page names, and App::chatService() accessor. The tab is gated on the new
  WalletUiSurface::Chat, which returns DRAGONX_ENABLE_CHAT != 0 — so it only
  appears in chat-enabled builds and is hidden (and unreachable) by default.
- i18n: English defaults for the chat nav label + hint strings.

Verified: Linux + Windows(mingw) build with chat ON, ctest 100%, hygiene clean;
caches restored to the OFF default. The screenshot sweep now includes the Chat
tab (sweepPageName "chat") for per-theme visual review.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

CMakeLists.txt

@@ -476,6 +476,7 @@ set(APP_SOURCES
     src/ui/windows/qr_popup_dialog.cpp
     src/ui/windows/validate_address_dialog.cpp
     src/ui/windows/contacts_tab.cpp
+    src/ui/windows/chat_tab.cpp
     src/ui/windows/shield_dialog.cpp
     src/ui/windows/request_payment_dialog.cpp
     src/ui/windows/block_info_dialog.cpp
@@ -606,6 +607,7 @@ set(APP_HEADERS
     src/ui/windows/qr_popup_dialog.h
     src/ui/windows/validate_address_dialog.h
     src/ui/windows/contacts_tab.h
+    src/ui/windows/chat_tab.h
     src/ui/windows/contact_picker.h
     src/ui/windows/shield_dialog.h
     src/ui/windows/request_payment_dialog.h

src/app.cpp

@@ -42,6 +42,7 @@
 #include "ui/windows/qr_popup_dialog.h"
 #include "ui/windows/validate_address_dialog.h"
 #include "ui/windows/contacts_tab.h"
+#include "ui/windows/chat_tab.h"
 #include "ui/windows/shield_dialog.h"
 #include "ui/windows/request_payment_dialog.h"
 #include "ui/windows/block_info_dialog.h"
@@ -1709,6 +1710,9 @@ void App::render()
         case ui::NavPage::Contacts:
             ui::RenderContactsTab(this);
             break;
+        case ui::NavPage::Chat:
+            ui::RenderChatTab(this);
+            break;
         case ui::NavPage::Mining:
             ui::RenderMiningTab(this);
             break;

src/app.h

@@ -168,6 +168,8 @@ public:
     config::Settings* settings() { return settings_.get(); }
     // Lite wallet controller (non-null only in lite builds with a linked backend).
     wallet::LiteWalletController* liteWallet() { return lite_wallet_.get(); }
+    // HushChat service (identity + in-memory message store); the Chat tab reads its store.
+    chat::ChatService& chatService() { return chat_service_; }
     // Reason the lite wallet failed to auto-open this session (empty if none / opened OK).
     const std::string& liteOpenError() const { return lite_open_error_; }
     // Show the lite send-time unlock modal (called when a spend is attempted on a locked wallet).

src/app_network.cpp

@@ -104,6 +104,7 @@ const char* tracePageName(ui::NavPage page)
         case ui::NavPage::Receive: return "Receive tab";
         case ui::NavPage::History: return "History tab";
         case ui::NavPage::Contacts: return "Contacts tab";
+        case ui::NavPage::Chat: return "Chat tab";
         case ui::NavPage::Mining: return "Mining tab";
         case ui::NavPage::Market: return "Market tab";
         case ui::NavPage::Console: return "Console tab";
@@ -761,6 +762,7 @@ static const char* sweepPageName(ui::NavPage page)
         case ui::NavPage::Receive:  return "receive";
         case ui::NavPage::History:  return "history";
         case ui::NavPage::Contacts: return "contacts";
+        case ui::NavPage::Chat: return "chat";
         case ui::NavPage::Mining:   return "mining";
         case ui::NavPage::Market:   return "market";
         case ui::NavPage::Console:  return "console";

src/ui/sidebar.h

@@ -26,6 +26,7 @@ enum class NavPage {
     Receive,
     History,
     Contacts,
+    Chat,
     // --- separator ---
     Mining,
     Market,
@@ -53,6 +54,7 @@ inline const NavItem kNavItems[] = {
     { "Receive",   NavPage::Receive,  nullptr,    "receive",  nullptr     },
     { "History",   NavPage::History,  nullptr,    "history",  nullptr     },
     { "Contacts",  NavPage::Contacts, nullptr,    "contacts", nullptr     },
+    { "Chat",      NavPage::Chat,     nullptr,    "chat",     nullptr     },
     { "Mining",    NavPage::Mining,   "TOOLS",   "mining",   "tools"     },
     { "Market",    NavPage::Market,   nullptr,    "market",   nullptr     },
     { "Console",   NavPage::Console,     "ADVANCED","console",  "advanced"  },
@@ -81,6 +83,7 @@ inline wallet::WalletUiSurface NavPageSurface(NavPage page)
     case NavPage::Receive:  return wallet::WalletUiSurface::Receive;
     case NavPage::History:  return wallet::WalletUiSurface::History;
     case NavPage::Contacts: return wallet::WalletUiSurface::Contacts;
+    case NavPage::Chat:     return wallet::WalletUiSurface::Chat;
     case NavPage::Mining:   return wallet::WalletUiSurface::Mining;
     case NavPage::Market:   return wallet::WalletUiSurface::Market;
     case NavPage::Console:  return wallet::WalletUiSurface::Console;
@@ -107,6 +110,7 @@ inline const char* GetNavIconMD(NavPage page)
     case NavPage::Receive:   return ICON_MD_CALL_RECEIVED;
     case NavPage::History:   return ICON_MD_HISTORY;
     case NavPage::Contacts:  return ICON_MD_CONTACTS;
+    case NavPage::Chat:      return ICON_MD_CHAT;
     case NavPage::Mining:    return ICON_MD_CONSTRUCTION;
     case NavPage::Market:    return ICON_MD_TRENDING_UP;
     case NavPage::Console:   return ICON_MD_TERMINAL;

src/ui/windows/chat_tab.cpp

@@ -0,0 +1,246 @@
+// DragonX Wallet - ImGui Edition
+// Copyright 2024-2026 The Hush Developers
+// Released under the GPLv3
+//
+// chat_tab.cpp — read-only HushChat view (Phase 3): a conversation list + the
+// selected thread, both read from the App-owned ChatService store.
+
+#include "chat_tab.h"
+#include "../../app.h"
+#include "../../data/address_book.h"
+#include "../../chat/chat_service.h"
+#include "../../util/i18n.h"
+#include "../material/colors.h"
+#include "../material/type.h"
+#include "imgui.h"
+
+#include <algorithm>
+#include <cfloat>
+#include <ctime>
+#include <string>
+#include <vector>
+
+namespace dragonx {
+namespace ui {
+
+namespace {
+
+// Selected conversation id (cid). Empty => none selected / auto-select first.
+std::string s_selected_cid;
+std::string s_scroll_to_cid;  // when set, scroll the thread to the bottom next frame
+
+// Effective draw-list font size for a material font (mirrors sidebar's ScaledFontSize).
+float scaledSize(ImFont* f) { return f->LegacySize * ImGui::GetStyle().FontScaleMain; }
+
+std::string shorten(const std::string& s, std::size_t head = 12, std::size_t tail = 6) {
+    if (s.size() <= head + tail + 3) return s;
+    return s.substr(0, head) + "..." + s.substr(s.size() - tail);
+}
+
+std::string formatTime(std::int64_t ts) {
+    if (ts <= 0) return "";
+    std::time_t t = static_cast<std::time_t>(ts);
+    std::tm* tm = std::localtime(&t);  // UI thread only
+    if (!tm) return "";
+    char buf[32];
+    std::strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M", tm);
+    return buf;
+}
+
+// One line of collapsed body text for the list preview (newlines flattened).
+std::string previewOf(const std::string& body) {
+    std::string out = body;
+    std::replace(out.begin(), out.end(), '\n', ' ');
+    std::replace(out.begin(), out.end(), '\r', ' ');
+    return out;
+}
+
+struct ConvSummary {
+    std::string cid;
+    std::string peerZaddr;
+    std::string peerName;   // contact label if known, else a shortened z-addr / cid
+    std::string lastBody;
+    std::int64_t lastTs = 0;
+    int count = 0;
+};
+
+// Centered, muted, wrapped hint for the empty states.
+void centeredHint(const char* text) {
+    ImVec2 avail = ImGui::GetContentRegionAvail();
+    ImGui::PushFont(material::Type().body2());
+    const float wrap = std::min(avail.x - 40.0f, 420.0f);
+    const ImVec2 sz = ImGui::CalcTextSize(text, nullptr, false, wrap);
+    ImGui::SetCursorPos(ImVec2(ImGui::GetCursorPos().x + std::max(0.0f, (avail.x - sz.x) * 0.5f),
+                               ImGui::GetCursorPos().y + std::max(0.0f, (avail.y - sz.y) * 0.5f)));
+    ImGui::PushStyleColor(ImGuiCol_Text, material::OnSurfaceMedium());
+    ImGui::PushTextWrapPos(ImGui::GetCursorPos().x + wrap);
+    ImGui::TextUnformatted(text);
+    ImGui::PopTextWrapPos();
+    ImGui::PopStyleColor();
+    ImGui::PopFont();
+}
+
+} // namespace
+
+void RenderChatTab(App* app)
+{
+    auto& service = app->chatService();
+    const auto& store = service.store();
+    auto& book = app->addressBook();
+
+    // Not unlocked / identity not derived yet → nothing to show.
+    if (!service.hasIdentity()) {
+        centeredHint(TR("chat_locked_hint"));
+        return;
+    }
+
+    // Build conversation summaries, sorted by most-recent activity.
+    std::vector<ConvSummary> convs;
+    for (const auto& cid : store.conversationIds()) {
+        const auto messages = store.conversation(cid);
+        if (messages.empty()) continue;
+        const auto& last = messages.back();
+        ConvSummary c;
+        c.cid = cid;
+        c.peerZaddr = last.peer_zaddr;
+        c.lastBody = last.body;
+        c.lastTs = last.timestamp;
+        c.count = static_cast<int>(messages.size());
+        const int idx = c.peerZaddr.empty() ? -1 : book.findByAddress(c.peerZaddr);
+        c.peerName = (idx >= 0) ? book.entries()[idx].label
+                                : shorten(!c.peerZaddr.empty() ? c.peerZaddr : cid);
+        convs.push_back(std::move(c));
+    }
+    std::sort(convs.begin(), convs.end(),
+              [](const ConvSummary& a, const ConvSummary& b) { return a.lastTs > b.lastTs; });
+
+    if (convs.empty()) {
+        centeredHint(TR("chat_empty_hint"));
+        return;
+    }
+
+    // Keep the selection valid; default to the most recent conversation.
+    if (std::none_of(convs.begin(), convs.end(),
+                     [](const ConvSummary& c) { return c.cid == s_selected_cid; })) {
+        s_selected_cid = convs.front().cid;
+        s_scroll_to_cid = s_selected_cid;
+    }
+
+    const ImVec2 avail = ImGui::GetContentRegionAvail();
+    const float listW = std::clamp(avail.x * 0.32f, 220.0f, 360.0f);
+    const float pad = 10.0f;
+    const float rowH = 52.0f;
+
+    ImFont* nameFont = material::Type().body2();
+    ImFont* metaFont = material::Type().caption();
+    const float nameSz = scaledSize(nameFont);
+    const float metaSz = scaledSize(metaFont);
+
+    // ---- Left: conversation list ----
+    ImGui::BeginChild("##ChatList", ImVec2(listW, avail.y), true);
+    {
+        ImDrawList* dl = ImGui::GetWindowDrawList();  // the list child's draw list (correct clip/z-order)
+        const ImU32 selBg = ImGui::GetColorU32(ImGuiCol_Header);
+        const ImU32 hoverBg = ImGui::GetColorU32(ImGuiCol_HeaderHovered);
+        for (std::size_t i = 0; i < convs.size(); ++i) {
+            const ConvSummary& c = convs[i];
+            ImGui::PushID(static_cast<int>(i));
+            const ImVec2 p = ImGui::GetCursorScreenPos();
+            const float rowW = ImGui::GetContentRegionAvail().x;
+            const bool clicked = ImGui::InvisibleButton("##row", ImVec2(rowW, rowH));
+            const bool hovered = ImGui::IsItemHovered();
+            const bool selected = (c.cid == s_selected_cid);
+            if (clicked) { s_selected_cid = c.cid; s_scroll_to_cid = c.cid; }
+            if (selected || hovered)
+                dl->AddRectFilled(p, ImVec2(p.x + rowW, p.y + rowH), selected ? selBg : hoverBg, 6.0f);
+
+            // Name (top-left).
+            dl->AddText(nameFont, nameSz, ImVec2(p.x + pad, p.y + pad), material::OnSurface(),
+                        c.peerName.c_str());
+            // Time (top-right, muted).
+            const std::string when = formatTime(c.lastTs);
+            if (!when.empty()) {
+                const ImVec2 wsz = metaFont->CalcTextSizeA(metaSz, FLT_MAX, 0.0f, when.c_str());
+                dl->AddText(metaFont, metaSz, ImVec2(p.x + rowW - pad - wsz.x, p.y + pad + 1.0f),
+                            material::OnSurfaceMedium(), when.c_str());
+            }
+            // Preview (bottom, clipped, muted).
+            const std::string preview = previewOf(c.lastBody);
+            dl->PushClipRect(p, ImVec2(p.x + rowW - pad, p.y + rowH), true);
+            dl->AddText(metaFont, metaSz, ImVec2(p.x + pad, p.y + rowH - pad - metaSz),
+                        material::OnSurfaceMedium(), preview.c_str());
+            dl->PopClipRect();
+            ImGui::PopID();
+        }
+    }
+    ImGui::EndChild();
+
+    ImGui::SameLine();
+
+    // ---- Right: selected conversation thread ----
+    ImGui::BeginChild("##ChatThread", ImVec2(0, avail.y), true);
+    {
+        const ConvSummary* sel = nullptr;
+        for (const auto& c : convs) if (c.cid == s_selected_cid) { sel = &c; break; }
+
+        if (sel) {
+            // Header: peer name + z-address.
+            ImGui::PushFont(material::Type().subtitle1());
+            ImGui::TextUnformatted(sel->peerName.c_str());
+            ImGui::PopFont();
+            if (!sel->peerZaddr.empty()) {
+                ImGui::PushFont(metaFont);
+                ImGui::PushStyleColor(ImGuiCol_Text, material::OnSurfaceMedium());
+                ImGui::TextUnformatted(shorten(sel->peerZaddr, 20, 12).c_str());
+                ImGui::PopStyleColor();
+                ImGui::PopFont();
+            }
+            ImGui::Separator();
+
+            const float footerH = ImGui::GetTextLineHeightWithSpacing() + 12.0f;
+            ImGui::BeginChild("##ChatMessages", ImVec2(0, ImGui::GetContentRegionAvail().y - footerH), false);
+            {
+                const auto messages = store.conversation(s_selected_cid);
+                for (const auto& m : messages) {
+                    const bool outgoing = (m.direction == chat::ChatDirection::Outgoing);
+                    const bool request = (m.kind == chat::ChatMessageKind::ContactRequest);
+                    // Meta line: who + time (+ request tag).
+                    std::string who = outgoing ? std::string(TR("chat_you")) : sel->peerName;
+                    const std::string when = formatTime(m.timestamp);
+                    if (!when.empty()) who += "  " + when;
+                    if (request) who += "  [" + std::string(TR("chat_contact_request")) + "]";
+                    ImGui::PushFont(metaFont);
+                    ImGui::PushStyleColor(ImGuiCol_Text,
+                        outgoing ? material::Primary() : material::OnSurfaceMedium());
+                    ImGui::TextUnformatted(who.c_str());
+                    ImGui::PopStyleColor();
+                    ImGui::PopFont();
+                    // Body (wrapped).
+                    ImGui::PushFont(nameFont);
+                    ImGui::PushTextWrapPos(0.0f);
+                    ImGui::TextWrapped("%s", m.body.c_str());
+                    ImGui::PopTextWrapPos();
+                    ImGui::PopFont();
+                    ImGui::Dummy(ImVec2(0.0f, 6.0f));
+                }
+                if (s_scroll_to_cid == s_selected_cid) {
+                    ImGui::SetScrollHereY(1.0f);
+                    s_scroll_to_cid.clear();
+                }
+            }
+            ImGui::EndChild();
+
+            // Read-only footer: composing arrives in a later phase.
+            ImGui::Separator();
+            ImGui::PushFont(metaFont);
+            ImGui::PushStyleColor(ImGuiCol_Text, material::OnSurfaceMedium());
+            ImGui::TextUnformatted(TR("chat_readonly_note"));
+            ImGui::PopStyleColor();
+            ImGui::PopFont();
+        }
+    }
+    ImGui::EndChild();
+}
+
+} // namespace ui
+} // namespace dragonx

src/ui/windows/chat_tab.h

@@ -0,0 +1,27 @@
+// DragonX Wallet - ImGui Edition
+// Copyright 2024-2026 The Hush Developers
+// Released under the GPLv3
+
+#pragma once
+
+namespace dragonx {
+
+class App;
+
+namespace ui {
+
+/**
+ * @brief Render the Chat tab (read-only HushChat conversation view — Phase 3).
+ *
+ * A two-pane view: a conversation list on the left and the selected thread on
+ * the right, both read from the App-owned ChatService store (App::chatService()).
+ * Peer z-addresses are resolved to contact names via the address book when known.
+ * Read-only for now — composing/sending arrives in a later phase. The tab is only
+ * reachable when built with DRAGONX_ENABLE_CHAT (gated via WalletUiSurface::Chat).
+ *
+ * @param app Pointer to the app instance.
+ */
+void RenderChatTab(App* app);
+
+} // namespace ui
+} // namespace dragonx

src/util/i18n.cpp

@@ -211,6 +211,12 @@ void I18n::loadBuiltinEnglish()
         strings_["transactions"] = "Transactions";
         strings_["history"] = "History";
         strings_["contacts"] = "Contacts";
+        strings_["chat"] = "Chat";
+        strings_["chat_locked_hint"] = "Unlock your wallet to load your chats.";
+        strings_["chat_empty_hint"] = "No conversations yet. Messages you receive will appear here.";
+        strings_["chat_you"] = "You";
+        strings_["chat_contact_request"] = "contact request";
+        strings_["chat_readonly_note"] = "Read-only — sending messages arrives in a later update.";
         strings_["contacts_search_placeholder"] = "Search contacts...";
         strings_["contacts_search_no_match"] = "No matching contacts";
         strings_["address_book_confirm_delete"] = "Confirm delete?";

src/wallet/wallet_capabilities.h

@@ -16,6 +16,10 @@
 #define DRAGONX_ENABLE_LITE_BACKEND 0
 #endif
 
+#ifndef DRAGONX_ENABLE_CHAT
+#define DRAGONX_ENABLE_CHAT 0
+#endif
+
 namespace dragonx {
 namespace wallet {
 
@@ -35,6 +39,7 @@ enum class WalletUiSurface {
     Receive,
     History,
     Contacts,   // address book / chat roster; available in both variants (default: return true)
+    Chat,       // HushChat conversations; gated on DRAGONX_ENABLE_CHAT (default OFF)
     Mining,
     Market,
     Console,
@@ -159,6 +164,8 @@ constexpr bool isUiSurfaceAvailable(const WalletCapabilities& capabilities,
         case WalletUiSurface::LiteNetwork:
         case WalletUiSurface::LiteConsole:
             return !capabilities.fullNodePagesAvailable;  // lite builds only
+        case WalletUiSurface::Chat:
+            return DRAGONX_ENABLE_CHAT != 0;  // experimental; compiled-in only when the feature is on
         case WalletUiSurface::BootstrapDownload:
         case WalletUiSurface::SetupWizard:
         case WalletUiSurface::NodeSettings: