"Building a Desktop LLM App with cpp-httplib" (#2403)

2026-04-12 11:48:30 +00:00 · 2026-03-21 23:31:55 -04:00
parent c2bdb1c5c1
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+---
+title: "6. Turning It into a Desktop App with WebView"
+order: 6
+
+---
+
+In Chapter 5, we completed a translation app you can use from a browser. But every time, you have to start the server, open the URL in a browser... Wouldn't it be nice to just double-click and start using it, like a normal app?
+
+In this chapter, we'll do two things:
+
+1. **WebView integration** — Use [webview/webview](https://github.com/webview/webview) to turn it into a desktop app that runs without a browser
+2. **Single binary packaging** — Use [cpp-embedlib](https://github.com/yhirose/cpp-embedlib) to embed HTML/CSS/JS into the binary, making the distributable a single file
+
+When finished, you'll be able to just run `./translate-app` to open a window and start translating.
+
+![Desktop App](../app.png#large-center)
+
+The model downloads automatically on first launch, so the only thing you need to give users is the single binary.
+
+## 6.1 Introducing webview/webview
+
+[webview/webview](https://github.com/webview/webview) is a library that lets you use the OS's native WebView component (WKWebView on macOS, WebKitGTK on Linux, WebView2 on Windows) from C/C++. Unlike Electron, it doesn't bundle its own browser, so the impact on binary size is negligible.
+
+We'll fetch it with CMake. Add the following to your `CMakeLists.txt`:
+
+```cmake
+# webview/webview
+FetchContent_Declare(webview
+    GIT_REPOSITORY https://github.com/webview/webview
+    GIT_TAG        master
+)
+FetchContent_MakeAvailable(webview)
+```
+
+This makes the `webview::core` CMake target available. When you link it with `target_link_libraries`, it automatically sets up include paths and platform-specific frameworks.
+
+> **macOS**: No additional dependencies are needed. WKWebView is built into the system.
+>
+> **Linux**: WebKitGTK is required. Install it with `sudo apt install libwebkit2gtk-4.1-dev`.
+>
+> **Windows**: The WebView2 runtime is required. It comes pre-installed on Windows 11. For Windows 10, download it from the [official Microsoft website](https://developer.microsoft.com/en-us/microsoft-edge/webview2/).
+
+## 6.2 Running the Server on a Background Thread
+
+Up through Chapter 5, the server's `listen()` was blocking the main thread. To use WebView, we need to run the server on a separate thread and run the WebView event loop on the main thread.
+
+```cpp
+#include "webview/webview.h"
+#include <thread>
+
+int main() {
+  // ... (server setup is the same as Chapter 5) ...
+
+  // Start the server on a background thread
+  auto port = svr.bind_to_any_port("127.0.0.1");
+  std::thread server_thread([&]() { svr.listen_after_bind(); });
+
+  std::cout << "Listening on http://127.0.0.1:" << port << std::endl;
+
+  // Display the UI with WebView
+  webview::webview w(false, nullptr);
+  w.set_title("Translate App");
+  w.set_size(1024, 768, WEBVIEW_HINT_NONE);
+  w.navigate("http://127.0.0.1:" + std::to_string(port));
+  w.run(); // Block until the window is closed
+
+  // Stop the server when the window is closed
+  svr.stop();
+  server_thread.join();
+}
+```
+
+Let's look at the key points:
+
+- **`bind_to_any_port`** — Instead of `listen("127.0.0.1", 8080)`, we let the OS choose an available port. Since desktop apps can be launched multiple times, using a fixed port would cause conflicts
+- **`listen_after_bind`** — Starts accepting requests on the port reserved by `bind_to_any_port`. While `listen()` does bind and listen in one call, we need to know the port number first, so we split the operations
+- **Shutdown order** — When the WebView window is closed, we stop the server with `svr.stop()` and wait for the thread to finish with `server_thread.join()`. If we reversed the order, WebView would lose access to the server
+
+The `signal_handler` from Chapter 5 is no longer needed. In a desktop app, closing the window means terminating the application.
+
+## 6.3 Embedding Static Files with cpp-embedlib
+
+In Chapter 5, we served files from the `public/` directory, so you'd need to distribute `public/` alongside the binary. With [cpp-embedlib](https://github.com/yhirose/cpp-embedlib), you can embed HTML, CSS, and JavaScript into the binary, packaging the distributable into a single file.
+
+### CMakeLists.txt
+
+Fetch cpp-embedlib and embed `public/`:
+
+```cmake
+# cpp-embedlib
+FetchContent_Declare(cpp-embedlib
+    GIT_REPOSITORY https://github.com/yhirose/cpp-embedlib
+    GIT_TAG        main
+)
+FetchContent_MakeAvailable(cpp-embedlib)
+
+# Embed the public/ directory into the binary
+cpp_embedlib_add(WebAssets
+    FOLDER    ${CMAKE_CURRENT_SOURCE_DIR}/public
+    NAMESPACE Web
+)
+
+target_link_libraries(translate-app PRIVATE
+    WebAssets                # Embedded files
+    cpp-embedlib-httplib     # cpp-httplib integration
+)
+```
+
+`cpp_embedlib_add` converts the files under `public/` into binary data at compile time and creates a static library called `WebAssets`. When linked, you can access the embedded files through a `Web::FS` object. `cpp-embedlib-httplib` is a helper library that provides the `httplib::mount()` function.
+
+### Replacing set_mount_point with httplib::mount
+
+Simply replace Chapter 5's `set_mount_point` with cpp-embedlib's `httplib::mount`:
+
+```cpp
+#include <cpp-embedlib-httplib.h>
+#include "WebAssets.h"
+
+// Chapter 5:
+// svr.set_mount_point("/", "./public");
+
+// Chapter 6:
+httplib::mount(svr, Web::FS);
+```
+
+`httplib::mount` registers handlers that serve the files embedded in `Web::FS` over HTTP. MIME types are automatically determined from file extensions, so there's no need to manually set `Content-Type`.
+
+The file contents are directly mapped to the binary's data segment, so no memory copies or heap allocations occur.
+
+## 6.4 macOS: Adding the Edit Menu
+
+If you try to paste text into the input field with `Cmd+V`, you'll find it doesn't work. On macOS, keyboard shortcuts like `Cmd+V` (paste) and `Cmd+C` (copy) are routed through the application's menu bar. Since webview/webview doesn't create one, these shortcuts never reach the WebView. We need to add a macOS Edit menu using the Objective-C runtime:
+
+```cpp
+#ifdef __APPLE__
+#include <objc/objc-runtime.h>
+
+void setup_macos_edit_menu() {
+  auto cls    = [](const char *n) { return (id)objc_getClass(n); };
+  auto sel    = sel_registerName;
+  auto msg    = reinterpret_cast<id (*)(id, SEL)>(objc_msgSend);
+  auto msg_s  = reinterpret_cast<id (*)(id, SEL, const char *)>(objc_msgSend);
+  auto msg_id = reinterpret_cast<id (*)(id, SEL, id)>(objc_msgSend);
+  auto msg_v  = reinterpret_cast<void (*)(id, SEL, id)>(objc_msgSend);
+  auto msg_mi = reinterpret_cast<id (*)(id, SEL, id, SEL, id)>(objc_msgSend);
+
+  auto str = [&](const char *s) {
+    return msg_s(cls("NSString"), sel("stringWithUTF8String:"), s);
+  };
+
+  id app      = msg(cls("NSApplication"), sel("sharedApplication"));
+  id mainMenu = msg(msg(cls("NSMenu"), sel("alloc")), sel("init"));
+  id editItem = msg(msg(cls("NSMenuItem"), sel("alloc")), sel("init"));
+  id editMenu = msg_id(msg(cls("NSMenu"), sel("alloc")),
+                       sel("initWithTitle:"), str("Edit"));
+
+  struct { const char *title; const char *action; const char *key; } items[] = {
+    {"Undo",       "undo:",      "z"},
+    {"Redo",       "redo:",      "Z"},
+    {"Cut",        "cut:",       "x"},
+    {"Copy",       "copy:",      "c"},
+    {"Paste",      "paste:",     "v"},
+    {"Select All", "selectAll:", "a"},
+  };
+
+  for (auto &[title, action, key] : items) {
+    id mi = msg_mi(msg(cls("NSMenuItem"), sel("alloc")),
+                   sel("initWithTitle:action:keyEquivalent:"),
+                   str(title), sel(action), str(key));
+    msg_v(editMenu, sel("addItem:"), mi);
+  }
+
+  msg_v(editItem, sel("setSubmenu:"), editMenu);
+  msg_v(mainMenu, sel("addItem:"), editItem);
+  msg_v(app, sel("setMainMenu:"), mainMenu);
+}
+#endif
+```
+
+Call this before `w.run()`:
+
+```cpp
+#ifdef __APPLE__
+  setup_macos_edit_menu();
+#endif
+  w.run();
+```
+
+On Windows and Linux, keyboard shortcuts are delivered directly to the focused control without going through the menu bar, so this workaround is macOS-specific.
+
+## 6.5 Complete Code
+
+<details>
+<summary data-file="CMakeLists.txt">Complete code (CMakeLists.txt)</summary>
+
+```cmake
+cmake_minimum_required(VERSION 3.20)
+project(translate-app CXX)
+set(CMAKE_CXX_STANDARD 20)
+
+include(FetchContent)
+
+# llama.cpp
+FetchContent_Declare(llama
+    GIT_REPOSITORY https://github.com/ggml-org/llama.cpp
+    GIT_TAG        master
+    GIT_SHALLOW    TRUE
+)
+FetchContent_MakeAvailable(llama)
+
+# cpp-httplib
+FetchContent_Declare(httplib
+    GIT_REPOSITORY https://github.com/yhirose/cpp-httplib
+    GIT_TAG        master
+)
+FetchContent_MakeAvailable(httplib)
+
+# nlohmann/json
+FetchContent_Declare(json
+    URL https://github.com/nlohmann/json/releases/download/v3.11.3/json.tar.xz
+)
+FetchContent_MakeAvailable(json)
+
+# cpp-llamalib
+FetchContent_Declare(cpp_llamalib
+    GIT_REPOSITORY https://github.com/yhirose/cpp-llamalib
+    GIT_TAG        main
+)
+FetchContent_MakeAvailable(cpp_llamalib)
+
+# webview/webview
+FetchContent_Declare(webview
+    GIT_REPOSITORY https://github.com/webview/webview
+    GIT_TAG        master
+)
+FetchContent_MakeAvailable(webview)
+
+# cpp-embedlib
+FetchContent_Declare(cpp-embedlib
+    GIT_REPOSITORY https://github.com/yhirose/cpp-embedlib
+    GIT_TAG        main
+)
+FetchContent_MakeAvailable(cpp-embedlib)
+
+# Embed the public/ directory into the binary
+cpp_embedlib_add(WebAssets
+    FOLDER    ${CMAKE_CURRENT_SOURCE_DIR}/public
+    NAMESPACE Web
+)
+
+find_package(OpenSSL REQUIRED)
+
+add_executable(translate-app src/main.cpp)
+
+target_link_libraries(translate-app PRIVATE
+    httplib::httplib
+    nlohmann_json::nlohmann_json
+    cpp-llamalib
+    OpenSSL::SSL OpenSSL::Crypto
+    WebAssets
+    cpp-embedlib-httplib
+    webview::core
+)
+
+if(APPLE)
+    target_link_libraries(translate-app PRIVATE
+        "-framework CoreFoundation"
+        "-framework Security"
+    )
+endif()
+
+target_compile_definitions(translate-app PRIVATE
+    CPPHTTPLIB_OPENSSL_SUPPORT
+)
+```
+
+</details>
+
+<details>
+<summary data-file="main.cpp">Complete code (main.cpp)</summary>
+
+```cpp
+#include <httplib.h>
+#include <nlohmann/json.hpp>
+#include <cpp-llamalib.h>
+#include <cpp-embedlib-httplib.h>
+#include "WebAssets.h"
+#include "webview/webview.h"
+
+#ifdef __APPLE__
+#include <objc/objc-runtime.h>
+#endif
+
+#include <algorithm>
+#include <filesystem>
+#include <fstream>
+#include <iostream>
+#include <mutex>
+#include <thread>
+
+using json = nlohmann::json;
+
+// -------------------------------------------------------------------------
+// macOS Edit menu (Cmd+C/V/X/A require an Edit menu on macOS)
+// -------------------------------------------------------------------------
+
+#ifdef __APPLE__
+void setup_macos_edit_menu() {
+  auto cls    = [](const char *n) { return (id)objc_getClass(n); };
+  auto sel    = sel_registerName;
+  auto msg    = reinterpret_cast<id (*)(id, SEL)>(objc_msgSend);
+  auto msg_s  = reinterpret_cast<id (*)(id, SEL, const char *)>(objc_msgSend);
+  auto msg_id = reinterpret_cast<id (*)(id, SEL, id)>(objc_msgSend);
+  auto msg_v  = reinterpret_cast<void (*)(id, SEL, id)>(objc_msgSend);
+  auto msg_mi = reinterpret_cast<id (*)(id, SEL, id, SEL, id)>(objc_msgSend);
+
+  auto str = [&](const char *s) {
+    return msg_s(cls("NSString"), sel("stringWithUTF8String:"), s);
+  };
+
+  id app      = msg(cls("NSApplication"), sel("sharedApplication"));
+  id mainMenu = msg(msg(cls("NSMenu"), sel("alloc")), sel("init"));
+  id editItem = msg(msg(cls("NSMenuItem"), sel("alloc")), sel("init"));
+  id editMenu = msg_id(msg(cls("NSMenu"), sel("alloc")),
+                       sel("initWithTitle:"), str("Edit"));
+
+  struct { const char *title; const char *action; const char *key; } items[] = {
+    {"Undo",       "undo:",      "z"},
+    {"Redo",       "redo:",      "Z"},
+    {"Cut",        "cut:",       "x"},
+    {"Copy",       "copy:",      "c"},
+    {"Paste",      "paste:",     "v"},
+    {"Select All", "selectAll:", "a"},
+  };
+
+  for (auto &[title, action, key] : items) {
+    id mi = msg_mi(msg(cls("NSMenuItem"), sel("alloc")),
+                   sel("initWithTitle:action:keyEquivalent:"),
+                   str(title), sel(action), str(key));
+    msg_v(editMenu, sel("addItem:"), mi);
+  }
+
+  msg_v(editItem, sel("setSubmenu:"), editMenu);
+  msg_v(mainMenu, sel("addItem:"), editItem);
+  msg_v(app, sel("setMainMenu:"), mainMenu);
+}
+#endif
+
+// -------------------------------------------------------------------------
+// Model definitions
+// -------------------------------------------------------------------------
+
+struct ModelInfo {
+  std::string name;
+  std::string params;
+  std::string size;
+  std::string repo;
+  std::string filename;
+};
+
+const std::vector<ModelInfo> MODELS = {
+  {
+    .name     = "gemma-2-2b-it",
+    .params   = "2B",
+    .size     = "1.6 GB",
+    .repo     = "bartowski/gemma-2-2b-it-GGUF",
+    .filename = "gemma-2-2b-it-Q4_K_M.gguf",
+  },
+  {
+    .name     = "gemma-2-9b-it",
+    .params   = "9B",
+    .size     = "5.8 GB",
+    .repo     = "bartowski/gemma-2-9b-it-GGUF",
+    .filename = "gemma-2-9b-it-Q4_K_M.gguf",
+  },
+  {
+    .name     = "Llama-3.1-8B-Instruct",
+    .params   = "8B",
+    .size     = "4.9 GB",
+    .repo     = "bartowski/Meta-Llama-3.1-8B-Instruct-GGUF",
+    .filename = "Meta-Llama-3.1-8B-Instruct-Q4_K_M.gguf",
+  },
+};
+
+// -------------------------------------------------------------------------
+// Model storage directory
+// -------------------------------------------------------------------------
+
+std::filesystem::path get_models_dir() {
+#ifdef _WIN32
+  auto env = std::getenv("APPDATA");
+  auto base = env ? std::filesystem::path(env) : std::filesystem::path(".");
+  return base / "translate-app" / "models";
+#else
+  auto env = std::getenv("HOME");
+  auto base = env ? std::filesystem::path(env) : std::filesystem::path(".");
+  return base / ".translate-app" / "models";
+#endif
+}
+
+// -------------------------------------------------------------------------
+// Model download
+// -------------------------------------------------------------------------
+
+// Abort the download if progress_cb returns false
+bool download_model(const ModelInfo &model,
+                    std::function<bool(int)> progress_cb) {
+  httplib::Client cli("https://huggingface.co");
+  cli.set_follow_location(true);  // Hugging Face redirects to a CDN
+  cli.set_read_timeout(std::chrono::hours(1)); // Long timeout for large models
+
+  auto url = "/" + model.repo + "/resolve/main/" + model.filename;
+  auto path = get_models_dir() / model.filename;
+  auto tmp_path = std::filesystem::path(path).concat(".tmp");
+
+  std::ofstream ofs(tmp_path, std::ios::binary);
+  if (!ofs) { return false; }
+
+  auto res = cli.Get(url,
+    // content_receiver: Receive data chunk by chunk and write to file
+    [&](const char *data, size_t len) {
+      ofs.write(data, len);
+      return ofs.good();
+    },
+    // progress: Report download progress (return false to abort)
+    [&, last_pct = -1](size_t current, size_t total) mutable {
+      int pct = total ? (int)(current * 100 / total) : 0;
+      if (pct == last_pct) return true; // Skip if the value hasn't changed
+      last_pct = pct;
+      return progress_cb(pct);
+    });
+
+  ofs.close();
+
+  if (!res || res->status != 200) {
+    std::filesystem::remove(tmp_path);
+    return false;
+  }
+
+  // Rename after download completes
+  std::filesystem::rename(tmp_path, path);
+  return true;
+}
+
+// -------------------------------------------------------------------------
+// Server
+// -------------------------------------------------------------------------
+
+int main() {
+  httplib::Server svr;
+  // Create the model storage directory
+  auto models_dir = get_models_dir();
+  std::filesystem::create_directories(models_dir);
+
+  // Auto-download the default model if not already present
+  std::string selected_model = MODELS[0].filename;
+  auto path = models_dir / selected_model;
+  if (!std::filesystem::exists(path)) {
+    std::cout << "Downloading " << selected_model << "..." << std::endl;
+    if (!download_model(MODELS[0], [](int pct) {
+          std::cout << "\r" << pct << "%" << std::flush;
+          return true;
+        })) {
+      std::cerr << "\nFailed to download model." << std::endl;
+      return 1;
+    }
+    std::cout << std::endl;
+  }
+  auto llm = llamalib::Llama{path};
+  std::mutex llm_mutex; // Protect access during model switching
+
+  // Set a long timeout since LLM inference takes time (default is 5 seconds)
+  svr.set_read_timeout(300);
+  svr.set_write_timeout(300);
+
+  svr.set_logger([](const auto &req, const auto &res) {
+    std::cout << req.method << " " << req.path << " -> " << res.status
+              << std::endl;
+  });
+
+  svr.Get("/health", [](const httplib::Request &, httplib::Response &res) {
+    res.set_content(json{{"status", "ok"}}.dump(), "application/json");
+  });
+
+  // --- Translation endpoint (Chapter 2) ------------------------------------
+
+  svr.Post("/translate",
+           [&](const httplib::Request &req, httplib::Response &res) {
+    auto input = json::parse(req.body, nullptr, false);
+    if (input.is_discarded()) {
+      res.status = 400;
+      res.set_content(json{{"error", "Invalid JSON"}}.dump(),
+                      "application/json");
+      return;
+    }
+
+    if (!input.contains("text") || !input["text"].is_string() ||
+        input["text"].get<std::string>().empty()) {
+      res.status = 400;
+      res.set_content(json{{"error", "'text' is required"}}.dump(),
+                      "application/json");
+      return;
+    }
+
+    auto text = input["text"].get<std::string>();
+    auto target_lang = input.value("target_lang", "ja");
+
+    auto prompt = "Translate the following text to " + target_lang +
+                  ". Output only the translation, nothing else.\n\n" + text;
+
+    try {
+      std::lock_guard<std::mutex> lock(llm_mutex);
+      auto translation = llm.chat(prompt);
+      res.set_content(json{{"translation", translation}}.dump(),
+                      "application/json");
+    } catch (const std::exception &e) {
+      res.status = 500;
+      res.set_content(json{{"error", e.what()}}.dump(), "application/json");
+    }
+  });
+
+  // --- SSE streaming translation (Chapter 3) -------------------------------
+
+  svr.Post("/translate/stream",
+           [&](const httplib::Request &req, httplib::Response &res) {
+    auto input = json::parse(req.body, nullptr, false);
+    if (input.is_discarded()) {
+      res.status = 400;
+      res.set_content(json{{"error", "Invalid JSON"}}.dump(),
+                      "application/json");
+      return;
+    }
+
+    if (!input.contains("text") || !input["text"].is_string() ||
+        input["text"].get<std::string>().empty()) {
+      res.status = 400;
+      res.set_content(json{{"error", "'text' is required"}}.dump(),
+                      "application/json");
+      return;
+    }
+
+    auto text = input["text"].get<std::string>();
+    auto target_lang = input.value("target_lang", "ja");
+
+    auto prompt = "Translate the following text to " + target_lang +
+                  ". Output only the translation, nothing else.\n\n" + text;
+
+    res.set_chunked_content_provider(
+        "text/event-stream",
+        [&, prompt](size_t, httplib::DataSink &sink) {
+          std::lock_guard<std::mutex> lock(llm_mutex);
+          try {
+            llm.chat(prompt, [&](std::string_view token) {
+              sink.os << "data: "
+                      << json(std::string(token)).dump(
+                           -1, ' ', false, json::error_handler_t::replace)
+                      << "\n\n";
+              return sink.os.good(); // Abort inference on disconnect
+            });
+            sink.os << "data: [DONE]\n\n";
+          } catch (const std::exception &e) {
+            sink.os << "data: " << json({{"error", e.what()}}).dump() << "\n\n";
+          }
+          sink.done();
+          return true;
+        });
+  });
+
+  // --- Model list (Chapter 4) ----------------------------------------------
+
+  svr.Get("/models",
+          [&](const httplib::Request &, httplib::Response &res) {
+    auto models_dir = get_models_dir();
+    auto arr = json::array();
+    for (const auto &m : MODELS) {
+      auto path = models_dir / m.filename;
+      arr.push_back({
+        {"name",       m.name},
+        {"params",     m.params},
+        {"size",       m.size},
+        {"downloaded", std::filesystem::exists(path)},
+        {"selected",   m.filename == selected_model},
+      });
+    }
+    res.set_content(json{{"models", arr}}.dump(), "application/json");
+  });
+
+  // --- Model selection (Chapter 4) -----------------------------------------
+
+  svr.Post("/models/select",
+           [&](const httplib::Request &req, httplib::Response &res) {
+    auto input = json::parse(req.body, nullptr, false);
+    if (input.is_discarded() || !input.contains("model")) {
+      res.status = 400;
+      res.set_content(json{{"error", "'model' is required"}}.dump(),
+                      "application/json");
+      return;
+    }
+
+    auto name = input["model"].get<std::string>();
+
+    auto it = std::find_if(MODELS.begin(), MODELS.end(),
+      [&](const ModelInfo &m) { return m.name == name; });
+
+    if (it == MODELS.end()) {
+      res.status = 404;
+      res.set_content(json{{"error", "Unknown model"}}.dump(),
+                      "application/json");
+      return;
+    }
+
+    const auto &model = *it;
+
+    // Always respond with SSE (same format whether downloaded or not)
+    res.set_chunked_content_provider(
+        "text/event-stream",
+        [&, model](size_t, httplib::DataSink &sink) {
+          // SSE event sending helper
+          auto send = [&](const json &event) {
+            sink.os << "data: " << event.dump() << "\n\n";
+          };
+
+          // Download if not yet downloaded (report progress via SSE)
+          auto path = get_models_dir() / model.filename;
+          if (!std::filesystem::exists(path)) {
+            bool ok = download_model(model, [&](int pct) {
+              send({{"status", "downloading"}, {"progress", pct}});
+              return sink.os.good(); // Abort download on client disconnect
+            });
+            if (!ok) {
+              send({{"status", "error"}, {"message", "Download failed"}});
+              sink.done();
+              return true;
+            }
+          }
+
+          // Load and switch to the model
+          send({{"status", "loading"}});
+          {
+            std::lock_guard<std::mutex> lock(llm_mutex);
+            llm = llamalib::Llama{path};
+            selected_model = model.filename;
+          }
+
+          send({{"status", "ready"}});
+          sink.done();
+          return true;
+        });
+  });
+
+  // --- Embedded file serving (Chapter 6) ------------------------------------
+  // Chapter 5: svr.set_mount_point("/", "./public");
+  httplib::mount(svr, Web::FS);
+
+  // Start the server on a background thread
+  auto port = svr.bind_to_any_port("127.0.0.1");
+  std::thread server_thread([&]() { svr.listen_after_bind(); });
+
+  std::cout << "Listening on http://127.0.0.1:" << port << std::endl;
+
+  // Display the UI with WebView
+  webview::webview w(false, nullptr);
+  w.set_title("Translate App");
+  w.set_size(1024, 768, WEBVIEW_HINT_NONE);
+  w.navigate("http://127.0.0.1:" + std::to_string(port));
+
+#ifdef __APPLE__
+  setup_macos_edit_menu();
+#endif
+  w.run(); // Block until the window is closed
+
+  // Stop the server when the window is closed
+  svr.stop();
+  server_thread.join();
+}
+```
+
+</details>
+
+To summarize the changes from Chapter 5:
+
+- `#include <csignal>` replaced with `#include <thread>`, `<cpp-embedlib-httplib.h>`, `"WebAssets.h"`, `"webview/webview.h"`
+- Removed the `signal_handler` function
+- `svr.set_mount_point("/", "./public")` replaced with `httplib::mount(svr, Web::FS)`
+- `svr.listen("127.0.0.1", 8080)` replaced with `bind_to_any_port` + `listen_after_bind` + WebView event loop
+
+Not a single line of handler code has changed. The REST API, SSE streaming, and model management built through Chapter 5 all work as-is.
+
+## 6.6 Building and Testing
+
+```bash
+cmake -B build
+cmake --build build -j
+```
+
+Launch the app:
+
+```bash
+./build/translate-app
+```
+
+No browser is needed. A window opens automatically. The same UI from Chapter 5 appears as-is, and translation and model switching all work just the same.
+
+When you close the window, the server shuts down automatically. There's no need for `Ctrl+C`.
+
+### What Needs to Be Distributed
+
+You only need to distribute:
+
+- The single `translate-app` binary
+
+That's it. You don't need the `public/` directory. HTML, CSS, and JavaScript are embedded in the binary. Model files download automatically on first launch, so there's no need to ask users to prepare anything in advance.
+
+## Next Chapter
+
+Congratulations! 🎉
+
+In Chapter 1, `/health` just returned `{"status":"ok"}`. Now we have a desktop app where you type text and translations stream in real time, pick a different model from a dropdown and it downloads automatically, and closing the window cleanly shuts everything down — all in a single distributable binary.
+
+What we changed in this chapter was just the static file serving and the server startup. Not a single line of handler code changed. The REST API, SSE streaming, and model management we built through Chapter 5 all work as a desktop app, as-is.
+
+In the next chapter, we'll shift perspective and read through the code of llama.cpp's own `llama-server`. Let's compare our simple server with a production-quality one and see what design decisions differ and why.
+
+**Next:** [Reading the llama.cpp Server Source Code](../ch07-code-reading)