From d1379c55f62d7490f0e7407dc4a555159b771d74 Mon Sep 17 00:00:00 2001
From: Andrey Antukh <niwi@niwi.nz>
Date: Tue, 25 Nov 2025 10:47:48 +0100
Subject: [PATCH] :sparkles: Make i18n translation files load on demand

---
 CHANGES.md                                    |   2 +
 frontend/.storybook/preview.js                |   5 +
 frontend/resources/templates/index.mustache   |   1 -
 .../resources/templates/preview-head.mustache |   4 -
 frontend/scripts/_helpers.js                  |  46 ++-----
 frontend/scripts/build-app-assets.js          |   1 +
 frontend/scripts/build-storybook-assets.js    |   4 +
 frontend/scripts/watch.js                     |   3 +-
 frontend/src/app/config.cljs                  |   1 -
 frontend/src/app/main.cljs                    |   9 +-
 frontend/src/app/main/data/event.cljs         |   6 +-
 frontend/src/app/main/data/profile.cljs       |   7 +-
 frontend/src/app/main/ui/ds.cljs              |   8 +-
 frontend/src/app/util/i18n.cljs               | 129 +++++++++++-------
 frontend/vite.config.js                       |   1 +
 15 files changed, 124 insertions(+), 103 deletions(-)

diff --git a/CHANGES.md b/CHANGES.md
index 270e08fe55..3ff0053c81 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -12,6 +12,8 @@
 
 ### :sparkles: New features & Enhancements
 
+- Make i18n translation files load on-demand [Taiga #11474](https://tree.taiga.io/project/penpot/us/11474)
+
 ### :bug: Bugs fixed
 
 - Fix problem when drag+duplicate a full grid [Taiga #12565](https://tree.taiga.io/project/penpot/issue/12565)
diff --git a/frontend/.storybook/preview.js b/frontend/.storybook/preview.js
index a69e407c39..0345c004b8 100644
--- a/frontend/.storybook/preview.js
+++ b/frontend/.storybook/preview.js
@@ -1,5 +1,10 @@
 import { withThemeByClassName } from "@storybook/addon-themes";
 
+
+import Components from "@target/components";
+import translations from "@public/translation.en.js";
+Components.setDefaultTranslations(translations);
+
 import '../resources/public/css/ds.css';
 
 export const decorators = [
diff --git a/frontend/resources/templates/index.mustache b/frontend/resources/templates/index.mustache
index 66a4a05539..550120ee93 100644
--- a/frontend/resources/templates/index.mustache
+++ b/frontend/resources/templates/index.mustache
@@ -30,7 +30,6 @@
     {{/manifest}}
 
     <script type="module">
-      globalThis.penpotTranslations = JSON.parse({{& translations}});
       globalThis.penpotVersion = "%version%";
       globalThis.penpotBuildDate = "%buildDate%";
     </script>
diff --git a/frontend/resources/templates/preview-head.mustache b/frontend/resources/templates/preview-head.mustache
index 5ac5451b37..740482ff84 100644
--- a/frontend/resources/templates/preview-head.mustache
+++ b/frontend/resources/templates/preview-head.mustache
@@ -9,7 +9,3 @@
     height: 100%;
   }
 </style>
-
-<script>
-  window.penpotTranslations = JSON.parse({{& translations}});
-</script>
diff --git a/frontend/scripts/_helpers.js b/frontend/scripts/_helpers.js
index 72f9eee631..2469db6fa0 100644
--- a/frontend/scripts/_helpers.js
+++ b/frontend/scripts/_helpers.js
@@ -257,7 +257,7 @@ const markedOptions = {
 
 marked.use(markedOptions);
 
-async function readTranslations() {
+export async function compileTranslations() {
   const langs = [
     "ar",
     "ca",
@@ -294,9 +294,10 @@ async function readTranslations() {
     ["uk", "ukr_UA"],
     "ha",
   ];
-  const result = {};
 
   for (let lang of langs) {
+    const result = {};
+
     let filename = `${lang}.po`;
     if (l.isArray(lang)) {
       filename = `${lang[1]}.po`;
@@ -315,11 +316,6 @@ async function readTranslations() {
     for (let key of Object.keys(trdata)) {
       if (key === "") continue;
       const comments = trdata[key].comments || {};
-
-      if (l.isNil(result[key])) {
-        result[key] = {};
-      }
-
       const isMarkdown = l.includes(comments.flag, "markdown");
 
       const msgs = trdata[key].msgstr;
@@ -329,9 +325,9 @@ async function readTranslations() {
           message = marked.parseInline(message);
         }
 
-        result[key][lang] = message;
+        result[key] = message;
       } else {
-        result[key][lang] = msgs.map((item) => {
+        result[key] = msgs.map((item) => {
           if (isMarkdown) {
             return marked.parseInline(item);
           } else {
@@ -340,22 +336,12 @@ async function readTranslations() {
         });
       }
     }
+
+    const esm = `export default ${JSON.stringify(result, null, 0)};\n`;
+    const outputDir = "resources/public/js/";
+    const outputFile = ph.join(outputDir, "translation." + lang + ".js");
+    await fs.writeFile(outputFile, esm);
   }
-
-  return result;
-}
-
-function filterTranslations(translations, langs = [], keyFilter) {
-  const filteredEntries = Object.entries(translations)
-    .filter(([translationKey, _]) => keyFilter(translationKey))
-    .map(([translationKey, value]) => {
-      const langEntries = Object.entries(value).filter(([lang, _]) =>
-        langs.includes(lang),
-      );
-      return [translationKey, Object.fromEntries(langEntries)];
-    });
-
-  return Object.fromEntries(filteredEntries);
 }
 
 async function generateSvgSprite(files, prefix) {
@@ -407,14 +393,6 @@ async function generateTemplates() {
   const isDebug = process.env.NODE_ENV !== "production";
   await fs.mkdir("./resources/public/", { recursive: true });
 
-  let translations = await readTranslations();
-  const storybookTranslations = JSON.stringify(
-    filterTranslations(translations, ["en"], (key) =>
-      key.startsWith("labels."),
-    ),
-  );
-  translations = JSON.stringify(translations);
-
   const manifest = await readShadowManifest();
   let content;
 
@@ -440,7 +418,6 @@ async function generateTemplates() {
     "resources/templates/index.mustache",
     {
       manifest: manifest,
-      translations: JSON.stringify(translations),
       isDebug,
     },
     partials,
@@ -468,7 +445,6 @@ async function generateTemplates() {
     "resources/templates/preview-head.mustache",
     {
       manifest: manifest,
-      translations: JSON.stringify(storybookTranslations),
     },
     partials,
   );
@@ -476,14 +452,12 @@ async function generateTemplates() {
 
   content = await renderTemplate("resources/templates/render.mustache", {
     manifest: manifest,
-    translations: JSON.stringify(translations),
   });
 
   await fs.writeFile("./resources/public/render.html", content);
 
   content = await renderTemplate("resources/templates/rasterizer.mustache", {
     manifest: manifest,
-    translations: JSON.stringify(translations),
   });
 
   await fs.writeFile("./resources/public/rasterizer.html", content);
diff --git a/frontend/scripts/build-app-assets.js b/frontend/scripts/build-app-assets.js
index 5008d9a098..6ccc435839 100644
--- a/frontend/scripts/build-app-assets.js
+++ b/frontend/scripts/build-app-assets.js
@@ -4,5 +4,6 @@ await h.compileStyles();
 await h.copyAssets();
 await h.copyWasmPlayground();
 await h.compileSvgSprites();
+await h.compileTranslations();
 await h.compileTemplates();
 await h.compilePolyfills();
diff --git a/frontend/scripts/build-storybook-assets.js b/frontend/scripts/build-storybook-assets.js
index c0eb37a36f..092762ceb6 100644
--- a/frontend/scripts/build-storybook-assets.js
+++ b/frontend/scripts/build-storybook-assets.js
@@ -1,7 +1,11 @@
+import fs from "node:fs/promises";
 import * as h from "./_helpers.js";
 
+await fs.mkdir("resources/public/js", {recursive: true});
+
 await h.compileStorybookStyles();
 await h.copyAssets();
 await h.compileSvgSprites();
+await h.compileTranslations();
 await h.compileTemplates();
 await h.compilePolyfills();
diff --git a/frontend/scripts/watch.js b/frontend/scripts/watch.js
index 57e9be6016..e2d9ff399d 100644
--- a/frontend/scripts/watch.js
+++ b/frontend/scripts/watch.js
@@ -52,6 +52,7 @@ await fs.mkdir("./resources/public/css/", { recursive: true });
 await compileSassAll();
 await h.copyAssets();
 await h.copyWasmPlayground();
+await h.compileTranslations();
 await h.compileSvgSprites();
 await h.compileTemplates();
 await h.compilePolyfills();
@@ -81,7 +82,7 @@ h.watch("resources/templates", null, async function (path) {
 log.info("watch: translations (~)");
 h.watch("translations", null, async function (path) {
   log.info("changed:", path);
-  await h.compileTemplates();
+  await h.compileTranslations();
 });
 
 log.info("watch: assets (~)");
diff --git a/frontend/src/app/config.cljs b/frontend/src/app/config.cljs
index 76879756c7..4fb2d171c7 100644
--- a/frontend/src/app/config.cljs
+++ b/frontend/src/app/config.cljs
@@ -86,7 +86,6 @@
 (def default-theme  "default")
 (def default-language "en")
 
-(def translations         (obj/get global "penpotTranslations"))
 (def themes               (obj/get global "penpotThemes"))
 
 (def build-date           (parse-build-date global))
diff --git a/frontend/src/app/main.cljs b/frontend/src/app/main.cljs
index d027e0ba57..f40e8b3b18 100644
--- a/frontend/src/app/main.cljs
+++ b/frontend/src/app/main.cljs
@@ -92,7 +92,7 @@
 (defn ^:export init
   []
   (mw/init!)
-  (i18n/init! cf/translations)
+  (i18n/init)
   (cur/init-styles)
   (thr/init!)
   (init-ui)
@@ -114,11 +114,4 @@
   []
   (reinit))
 
-;; Reload the UI when the language changes
-(add-watch
- i18n/locale "locale"
- (fn [_ _ old-value current-value]
-   (when (not= old-value current-value)
-     (reinit))))
-
 (set! (.-stackTraceLimit js/Error) 50)
diff --git a/frontend/src/app/main/data/event.cljs b/frontend/src/app/main/data/event.cljs
index dfba7479ef..0e6ac46b4a 100644
--- a/frontend/src/app/main/data/event.cljs
+++ b/frontend/src/app/main/data/event.cljs
@@ -68,7 +68,7 @@
   (let [uagent (new ua/UAParser)]
     (merge
      {:app-version (:full cf/version)
-      :locale @i18n/locale}
+      :locale i18n/*current-locale*}
      (let [browser (.getBrowser uagent)]
        {:browser (obj/get browser "name")
         :browser-version (obj/get browser "version")})
@@ -98,7 +98,9 @@
 (def context
   (atom (d/without-nils (collect-context))))
 
-(add-watch i18n/locale ::events #(swap! context assoc :locale %4))
+(add-watch i18n/state "events"
+           (fn [_ _ _ v]
+             (swap! context assoc :locale (get v :locale))))
 
 ;; --- EVENT TRANSLATION
 
diff --git a/frontend/src/app/main/data/profile.cljs b/frontend/src/app/main/data/profile.cljs
index 127567f7b9..e7828a0302 100644
--- a/frontend/src/app/main/data/profile.cljs
+++ b/frontend/src/app/main/data/profile.cljs
@@ -53,11 +53,16 @@
           (assoc :profile-id id)
           (assoc :profile profile)))
 
+    ptk/WatchEvent
+    (watch [_ state _]
+      (let [profile (:profile state)]
+        (->> (rx/from (i18n/set-locale (:lang profile)))
+             (rx/ignore))))
+
     ptk/EffectEvent
     (effect [_ state _]
       (let [profile (:profile state)]
         (swap! storage/user assoc :profile profile)
-        (i18n/set-locale! (:lang profile))
         (plugins.register/init)))))
 
 (def profile-fetched?
diff --git a/frontend/src/app/main/ui/ds.cljs b/frontend/src/app/main/ui/ds.cljs
index 147a34bfa4..05e904d8cb 100644
--- a/frontend/src/app/main/ui/ds.cljs
+++ b/frontend/src/app/main/ui/ds.cljs
@@ -6,7 +6,6 @@
 
 (ns app.main.ui.ds
   (:require
-   [app.config :as cf]
    [app.main.ui.ds.buttons.button :refer [button*]]
    [app.main.ui.ds.buttons.icon-button :refer [icon-button*]]
    [app.main.ui.ds.controls.checkbox :refer [checkbox*]]
@@ -44,8 +43,6 @@
    [app.util.i18n :as i18n]
    [rumext.v2 :as mf]))
 
-(i18n/init! cf/translations)
-
 (def default
   "A export used for storybook"
   (mf/object
@@ -80,6 +77,11 @@
     :Milestone milestone*
     :MilestoneGroup milestone-group*
     :Date date*
+
+    :set-default-translations
+    (fn [data]
+      (i18n/set-translations "en" data))
+
     ;; meta / misc
     :meta
     {:icons (clj->js (sort icon-list))
diff --git a/frontend/src/app/util/i18n.cljs b/frontend/src/app/util/i18n.cljs
index 5560586d31..69b90a89f1 100644
--- a/frontend/src/app/util/i18n.cljs
+++ b/frontend/src/app/util/i18n.cljs
@@ -10,12 +10,14 @@
    [app.common.data :as d]
    [app.common.logging :as log]
    [app.common.time :as ct]
-   [app.config :as cfg]
+   [app.config :as cf]
    [app.util.globals :as globals]
+   [app.util.modules :as mod]
    [app.util.storage :as storage]
    [cuerdas.core :as str]
    [goog.object :as gobj]
    [okulary.core :as l]
+   [promesa.core :as p]
    [rumext.v2 :as mf]))
 
 (log/set-level! :info)
@@ -67,6 +69,12 @@
     (-> (.-language globals/navigator)
         (parse-locale))))
 
+
+;; Set initial translation loading state as globaly stored variable;
+;; this facilitates hot reloading
+(when-not (exists? (unchecked-get globals/global "penpotTranslations"))
+  (unchecked-set globals/global "penpotTranslations" #js {}))
+
 (defn- autodetect
   []
   (let [supported (into #{} (map :value supported-locales))]
@@ -75,43 +83,69 @@
         (if (contains? supported locale)
           locale
           (recur (rest locales)))
-        cfg/default-language))))
+        cf/default-language))))
 
-(defonce translations #js {})
-(defonce locale (l/atom nil))
+(defn get-current
+  "Get the currently memoized locale or execute the autodetection"
+  []
+  (or (get storage/global ::locale) (autodetect)))
 
-(add-watch locale "common.time"
-           (fn [_ _ pv cv]
-             (when (not= pv cv)
-               (ct/set-default-locale! cv))))
+(def ^:dynamic *current-locale*
+  (get-current))
 
-(defn init!
-  "Initialize the i18n module with translations.
+(defonce state
+  (l/atom {:render 0 :locale *current-locale*}))
 
-  The `data` is a javascript object for performance reasons. This code
-  is executed in the critical part (application bootstrap) and used in
-  many parts of the application."
-  [data]
-  (set! translations data)
-  (reset! locale (or (get storage/global ::locale) (autodetect))))
+(defn- assign-current-locale
+  [state locale]
+  (-> state
+      (update :render inc)
+      (assoc :locale locale)))
 
+(defn- get-translations
+  "Get globaly stored mutable object with all loaded translations"
+  []
+  (unchecked-get globals/global "penpotTranslations"))
 
-(defn set-locale!
+(defn set-translations
+  "A helper for synchronously set translations data for specified locale"
+  [locale data]
+  (let [translations (get-translations)]
+    (unchecked-set translations locale data)
+    nil))
+
+(defn- load
+  [locale]
+  (let [path (str "./translation." locale ".js")]
+    (->> (mod/import path)
+         (p/fmap (fn [result] (unchecked-get result "default")))
+         (p/fnly (fn [data cause]
+                   (if cause
+                     (js/console.error "unexpected error on fetching locale" cause)
+                     (do
+                       (set! *current-locale* locale)
+                       (set-translations locale data)
+                       (swap! state assign-current-locale locale))))))))
+
+(defn init
+  "Initialize the i18n module"
+  []
+  (load *current-locale*))
+
+(defn set-locale
   [lname]
-  (if (or (nil? lname)
-          (str/empty? lname))
-    (let [lname (autodetect)]
-      (swap! storage/global dissoc ::locale)
-      (reset! locale lname))
-    (let [supported (into #{} (map :value) supported-locales)
-          lname     (loop [locales (seq (parse-locale lname))]
-                      (if-let [locale (first locales)]
-                        (if (contains? supported locale)
-                          locale
-                          (recur (rest locales)))
-                        cfg/default-language))]
-      (swap! storage/global assoc ::locale lname)
-      (reset! locale lname))))
+  (let [lname (if (or (nil? lname)
+                      (str/empty? lname))
+                (autodetect)
+                (let [supported (into #{} (map :value) supported-locales)]
+                  (loop [locales (seq (parse-locale lname))]
+                    (if-let [locale (first locales)]
+                      (if (contains? supported locale)
+                        locale
+                        (recur (rest locales)))
+                      cf/default-language))))]
+
+    (load lname)))
 
 (deftype C [val]
   IDeref
@@ -136,22 +170,24 @@
 
 (defn t
   ([locale code]
-   (let [code  (name code)
-         value (gobj/getValueByKeys translations code locale)]
+   (let [translations (get-translations)
+         code  (d/name code)
+         value (gobj/getValueByKeys translations locale code)]
      (if (empty-string? value)
-       (if (= cfg/default-language locale)
+       (if (= cf/default-language locale)
          code
-         (t cfg/default-language code))
+         (t cf/default-language code))
        (if (array? value)
          (aget value 0)
          value))))
   ([locale code & args]
-   (let [code   (name code)
-         value  (gobj/getValueByKeys translations code locale)]
+   (let [translations (get-translations)
+         code   (d/name code)
+         value  (gobj/getValueByKeys translations locale code)]
      (if (empty-string? value)
-       (if (= cfg/default-language locale)
+       (if (= cf/default-language locale)
          code
-         (apply t cfg/default-language code args))
+         (apply t cf/default-language code args))
        (let [plural (first (filter c? args))
              value  (if (array? value)
                       (if (= @plural 1) (aget value 0) (aget value 1))
@@ -159,8 +195,8 @@
          (apply str/fmt value (map #(if (c? %) @% %) args)))))))
 
 (defn tr
-  ([code] (t @locale code))
-  ([code & args] (apply t @locale code args)))
+  ([code] (t *current-locale* code))
+  ([code & args] (apply t *current-locale* code args)))
 
 (mf/defc tr-html*
   {::mf/props :obj}
@@ -170,8 +206,9 @@
                   :className class
                   :on-click on-click}]))
 
-;; DEPRECATED
-(defn use-locale
-  []
-  (mf/deref locale))
-
+(add-watch state "common.time"
+           (fn [_ _ pv cv]
+             (let [pv (get pv :locale)
+                   cv (get cv :locale)]
+               (when (not= pv cv)
+                 (ct/set-default-locale! cv)))))
diff --git a/frontend/vite.config.js b/frontend/vite.config.js
index 4896f667bb..bf815d2368 100644
--- a/frontend/vite.config.js
+++ b/frontend/vite.config.js
@@ -47,6 +47,7 @@ export default defineConfig({
   resolve: {
     alias: {
       "@target": resolve(__dirname, "./target/storybook"),
+      "@public": resolve(__dirname, "./resources/public/js/"),
     },
   },
 });