Show each mod's size in the mod manager

Show each mod's size in the mod manager

A mod's size was only visible in the package overview and the install
prompt, so there was no telling from either list what a mod costs to
download or how much room the installed ones take.

- MY MODS: each row carries the size of the mod's folder on disk after
  the version ("v1.0.1 / 410 MB / by anton / 1 map"), and so does the
  line under the title in a mod's overview. The folders are measured
  when the Mods folder is scanned, so the figure follows an install, an
  update or Refresh. The game's merged patch hard links a mod's archives
  rather than copying them, so this is also what removing the mod gives
  back.
- GET MODS: each row carries the download size Thunderstore reports for
  the latest version, in the same place ("v1.0.0 / 101 MB / 0 downloads
  / 2026-10-04"), as the package overview already did.
- size_text moves out of gui_mods_browse.cpp's file-local namespace so
  both pages format a size the same way.

The two figures are not the same thing: one is the unpacked folder, the
other the zip, so a mod reads a little larger once installed.

Launcher/gui_internal.h

@@ -379,6 +379,9 @@ struct ModsPanel {
     bool scanned{};
     fs::path root;
     mods::ModList list;
+    // What each installed mod's folder holds on disk, by folder name; measured
+    // when the folder is scanned.
+    std::map<std::string, std::uint64_t, std::less<>> sizes;
     int selected{-1};                    // the mod whose overview is open
     bool overview{};                     // the overview popup is showing
     int tab{};                           // 0 MY MODS, 1 GET MODS
@@ -414,6 +417,8 @@ void start_install(ModsPanel& panel, const fs::path& source, bool replace);
 
 // ---------------------------------------------------------------- Thunderstore (gui_mods_browse.cpp)
 
+// "1.27 GB", "263 MB", "12 KB": a mod's size, on both pages.
+std::string size_text(std::uint64_t bytes);
 // Starts a listing fetch when none ran yet, or when `force`.
 void refresh_listing(ModsPanel& panel, double time, bool force = false);
 // Takes over a fetch the worker finished; call once a frame.

Launcher/gui_mods.cpp

@@ -80,9 +80,28 @@ fs::path pick(HWND owner, bool folder) {
     return result;
 }
 
-std::string summary(const mods::Mod& mod) {
+// Everything in the mod's folder, as Explorer would count it. The game's merged
+// patch hard links a mod's archives rather than copying them, so this is also
+// what removing the mod gives back.
+std::uint64_t folder_size(const fs::path& directory) {
+    std::uint64_t total{};
+    std::error_code error;
+    for (fs::recursive_directory_iterator it(directory, fs::directory_options::skip_permission_denied, error), end;
+         it != end && !error; it.increment(error)) {
+        std::error_code ignored;
+        if (it->is_regular_file(ignored) && !ignored) {
+            const auto size = it->file_size(ignored);
+            if (!ignored) total += size;
+        }
+    }
+    return total;
+}
+
+std::string summary(const ModsPanel& panel, const mods::Mod& mod) {
     std::vector<std::string> parts;
     if (!mod.version.empty()) parts.push_back("v" + mod.version);
+    if (const auto size = panel.sizes.find(mod.name); size != panel.sizes.end() && size->second)
+        parts.push_back(size_text(size->second));
     if (!mod.author.empty()) parts.push_back("by " + mod.author);
     if (!mod.levels.empty()) parts.push_back(mod.levels.size() == 1 ? "1 map" : std::to_string(mod.levels.size()) + " maps");
     else if (mod.provides_layout) parts.push_back("game data");
@@ -169,7 +188,7 @@ void installed_row(const Fonts& fonts, ModsPanel& panel, const thunderstore::Ins
     const auto title = std::to_string(index + 1) + ".  " + mod.title;
     draw->AddText(fonts.bold, fonts.bold->FontSize, ImVec2(text_x, start.y + S(16)),
         entry.enabled ? color::text : color::muted, title.c_str());
-    if (const auto detail = summary(mod); !detail.empty())
+    if (const auto detail = summary(panel, mod); !detail.empty())
         draw->AddText(fonts.body, fonts.body->FontSize, ImVec2(text_x, start.y + S(40)), color::muted, detail.c_str());
 
     // The widgets that sit on the row, over its Selectable.
@@ -316,7 +335,7 @@ void mod_overview(const Fonts& fonts, ModsPanel& panel, const thunderstore::Inst
     ImGui::TextUnformatted(mod.title.c_str());
     ImGui::PopTextWrapPos();
     ImGui::PopFont();
-    ImGui::TextDisabled("%s", summary(mod).c_str());
+    ImGui::TextDisabled("%s", summary(panel, mod).c_str());
     ImGui::Spacing();
     if (update) {
         ImGui::BeginDisabled(installing);
@@ -463,6 +482,8 @@ void refresh_mods(Launcher& launcher, ModsPanel& panel) {
 void scan(ModsPanel& panel, const launcher_app::Session& session) {
     panel.root = launcher_mods::mods_root(session.paths.directory);
     panel.list = mods::scan_mods(panel.root.parent_path());
+    panel.sizes.clear();
+    for (const auto& entry : panel.list.entries) panel.sizes[entry.mod.name] = folder_size(entry.mod.directory);
     panel.scanned = true;
     if (panel.selected >= static_cast<int>(panel.list.entries.size())) panel.selected = -1;
 }

Launcher/gui_mods_browse.cpp

@@ -137,12 +137,6 @@ std::string count_text(std::uint64_t value) {
     return std::to_string(value);
 }
 
-std::string size_text(std::uint64_t bytes) {
-    if (bytes >= 1024ull * 1024 * 1024) return std::format("{:.2f} GB", static_cast<double>(bytes) / (1024.0 * 1024 * 1024));
-    if (bytes >= 1024ull * 1024) return std::format("{:.0f} MB", static_cast<double>(bytes) / (1024.0 * 1024));
-    return std::format("{} KB", std::max<std::uint64_t>(1, bytes / 1024));
-}
-
 std::string date_text(const std::string& iso) { return iso.substr(0, std::min<std::size_t>(iso.size(), 10)); }
 
 void set_activity(ModsPanel& panel, std::string text) {
@@ -252,6 +246,12 @@ void mod_icon(ModsPanel& panel, const thunderstore::Package* package, ImVec2 pos
         draw->AddRectFilled(position, end, rgba(255, 255, 255, 0.06f), S(4));
 }
 
+std::string size_text(std::uint64_t bytes) {
+    if (bytes >= 1024ull * 1024 * 1024) return std::format("{:.2f} GB", static_cast<double>(bytes) / (1024.0 * 1024 * 1024));
+    if (bytes >= 1024ull * 1024) return std::format("{:.0f} MB", static_cast<double>(bytes) / (1024.0 * 1024));
+    return std::format("{} KB", std::max<std::uint64_t>(1, bytes / 1024));
+}
+
 void refresh_listing(ModsPanel& panel, double time, bool force) {
     auto& store = panel.store;
     // Once per launch, unless asked; a failed fetch retries after a minute.
@@ -569,8 +569,9 @@ void browse_page(Launcher& launcher, const Fonts& fonts, ModsPanel& panel, float
         draw->AddText(fonts.body, fonts.body->FontSize, ImVec2(text_x, start.y + S(32)), color::text, line.c_str(),
             nullptr, 0, &clip);
         draw->AddText(fonts.caption, fonts.caption->FontSize, ImVec2(text_x, start.y + S(55)), color::muted,
-            std::format("v{}  /  {} downloads  /  {}", version.number, count_text(package.downloads),
-                date_text(package.date_updated)).c_str());
+            std::format("v{}{}  /  {} downloads  /  {}", version.number,
+                version.file_size ? "  /  " + size_text(version.file_size) : std::string(),
+                count_text(package.downloads), date_text(package.date_updated)).c_str());
         ImGui::PopID();
     });
     ImGui::EndDisabled();