i18n: Move translations to ui/public and enable dynamic loading to reduce bundle size

.github/CODEOWNERS

@@ -37,14 +37,14 @@
 
 # Translation Owners (i18n)
 # Note: Non committer engaged translators are listed in comments prevent making file syntax invalid
-# See: https://github.com/apache/airflow/blob/main/airflow-core/src/airflow/ui/src/i18n/README.md#43-engaged-translator
-airflow-core/src/airflow/ui/src/i18n/locales/ar/ @shahar1 @hussein-awala # + @ahmadtfarhan
-airflow-core/src/airflow/ui/src/i18n/locales/de/ @jscheffl # + @TJaniF @m1racoli
-airflow-core/src/airflow/ui/src/i18n/locales/he/ @eladkal @shahar1 @romsharon98 # +@Dev-iL
-airflow-core/src/airflow/ui/src/i18n/locales/nl/ @BasPH # + @DjVinnii
-airflow-core/src/airflow/ui/src/i18n/locales/pl/ @potiuk @mobuchowski # + @kacpermuda
-airflow-core/src/airflow/ui/src/i18n/locales/zh-TW/ @Lee-W @jason810496 # + @RoyLee1224 @guan404ming
-airflow-core/src/airflow/ui/src/i18n/locales/fr/ @pierrejeambrun @vincbeck
+# See: https://github.com/apache/airflow/blob/main/airflow-core/src/airflow/ui/public/i18n/README.md#43-engaged-translator
+airflow-core/src/airflow/ui/public/i18n/locales/ar/ @shahar1 @hussein-awala # + @ahmadtfarhan
+airflow-core/src/airflow/ui/public/i18n/locales/de/ @jscheffl # + @TJaniF @m1racoli
+airflow-core/src/airflow/ui/public/i18n/locales/he/ @eladkal @shahar1 @romsharon98 # +@Dev-iL
+airflow-core/src/airflow/ui/public/i18n/locales/nl/ @BasPH # + @DjVinnii
+airflow-core/src/airflow/ui/public/i18n/locales/pl/ @potiuk @mobuchowski # + @kacpermuda
+airflow-core/src/airflow/ui/public/i18n/locales/zh-TW/ @Lee-W @jason810496 # + @RoyLee1224 @guan404ming
+airflow-core/src/airflow/ui/public/i18n/locales/fr/ @pierrejeambrun @vincbeck
 
 # Security/Permissions
 /airflow-core/src/airflow/security/permissions.py @vincbeck

.github/boring-cyborg.yml

@@ -348,34 +348,34 @@ labelPRBasedOnFilePath:
     - airflow-core/src/airflow/ui/**/*
 
   area:translations:
-    - airflow-core/src/airflow/ui/src/i18n/**/*
+    - airflow-core/src/airflow/ui/public/i18n/**/*
 
   translation:default:
-    - airflow-core/src/airflow/ui/src/i18n/locales/en/*
+    - airflow-core/src/airflow/ui/public/i18n/locales/en/*
 
   translation:ar:
-    - airflow-core/src/airflow/ui/src/i18n/locales/ar/*
+    - airflow-core/src/airflow/ui/public/i18n/locales/ar/*
 
   translation:de:
-    - airflow-core/src/airflow/ui/src/i18n/locales/de/*
+    - airflow-core/src/airflow/ui/public/i18n/locales/de/*
 
   translation:fr:
-    - airflow-core/src/airflow/ui/src/i18n/locales/fr/*
+    - airflow-core/src/airflow/ui/public/i18n/locales/fr/*
 
   translation:he:
-    - airflow-core/src/airflow/ui/src/i18n/locales/he/*
+    - airflow-core/src/airflow/ui/public/i18n/locales/he/*
 
   translation:ko:
-    - airflow-core/src/airflow/ui/src/i18n/locales/ko/*
+    - airflow-core/src/airflow/ui/public/i18n/locales/ko/*
 
   translation:nl:
-    - airflow-core/src/airflow/ui/src/i18n/locales/nl/*
+    - airflow-core/src/airflow/ui/public/i18n/locales/nl/*
 
   translation:pl:
-    - airflow-core/src/airflow/ui/src/i18n/locales/pl/*
+    - airflow-core/src/airflow/ui/public/i18n/locales/pl/*
 
   translation:zh-TW:
-    - airflow-core/src/airflow/ui/src/i18n/locales/zh-TW/*
+    - airflow-core/src/airflow/ui/public/i18n/locales/zh-TW/*
 
   area:CLI:
     - airflow-core/src/airflow/cli/**/*.py

.pre-commit-config.yaml

@@ -355,9 +355,7 @@ repos:
           ^.*/kinglear\.txt$|
           ^.*pnpm-lock\.yaml$|
           .*/dist/.*|
-          ^airflow-core/src/airflow/ui/src/i18n/locales/de/|
-          ^airflow-core/src/airflow/ui/src/i18n/locales/fr/|
-          ^airflow-core/src/airflow/ui/src/i18n/locales/pl/
+          ^airflow-core/src/airflow/ui/public/i18n/locales/(?!en/).+/
         args:
           - --ignore-words=docs/spelling_wordlist.txt
           - --skip=providers/.*/src/airflow/providers/*/*.rst,providers/*/docs/changelog.rst,docs/*/commits.rst,providers/*/docs/commits.rst,providers/*/*/docs/commits.rst,docs/apache-airflow/tutorial/pipeline_example.csv,*.min.js,*.lock,INTHEWILD.md,*.svg
@@ -637,7 +635,7 @@ repos:
           (?x)
           ^airflow-core/src/airflow/ui/src/i18n/config\.ts$|
           ^airflow-core/src/airflow/ui/openapi-gen/|
-          ^airflow-core/src/airflow/ui/src/i18n/locales/de/README\.md$|
+          ^airflow-core/src/airflow/ui/public/i18n/locales/de/README\.md$|
           ^airflow-core/src/airflow/cli/commands/local_commands/fastapi_api_command\.py$|
           ^airflow-core/src/airflow/config_templates/|
           ^airflow-core/src/airflow/models/baseoperator\.py$|
@@ -1447,7 +1445,7 @@ repos:
         name: Check i18n files validity
         description: Check i18n files are valid json and have no TODOs
         language: python
-        files: ^airflow-core/src/airflow/ui/src/i18n/locales/.*\.json
+        files: ^airflow-core/src/airflow/ui/public/i18n/locales/.*\.json
         entry: ./scripts/ci/pre_commit/check_i18n_json.py
         additional_dependencies: ['rich>=12.4.4']
         pass_filenames: false

airflow-core/src/airflow/api_fastapi/core_api/app.py

@@ -55,6 +55,13 @@ def init_views(app: FastAPI) -> None:
 
     templates = Jinja2Templates(directory=directory)
 
+    if dev_mode:
+        app.mount(
+            "/static/i18n/locales",
+            StaticFiles(directory=Path(AIRFLOW_PATH) / "airflow/ui/public/i18n/locales"),
+            name="dev_i18n_static",
+        )
+
     app.mount(
         "/static",
         StaticFiles(

airflow-core/src/airflow/ui/.prettierignore

@@ -5,5 +5,5 @@ dist/
 *.yaml
 coverage/*
 .pnpm-store
-src/i18n/locales/*
+public/i18n/locales/*
 openapi-gen/

airflow-core/src/airflow/ui/package.json

@@ -39,6 +39,7 @@
     "html-to-image": "^1.11.13",
     "i18next": "^25.1.2",
     "i18next-browser-languagedetector": "^8.1.0",
+    "i18next-http-backend": "^3.0.2",
     "next-themes": "^0.3.0",
     "react": "^18.3.1",
     "react-chartjs-2": "^5.3.0",
@@ -85,6 +86,7 @@
     "eslint-plugin-unicorn": "^55.0.0",
     "globals": "^15.15.0",
     "happy-dom": "^17.4.6",
+    "jsonc-eslint-parser": "^2.4.0",
     "msw": "^2.7.5",
     "openapi-merge-cli": "^1.3.2",
     "prettier": "^3.5.3",

airflow-core/src/airflow/ui/src/i18n/README.md → airflow-core/src/airflow/ui/public/i18n/README.md

@@ -28,7 +28,7 @@ This policy aims to avoid inconsistencies, maintenance issues, unclear ownership
 
 This policy applies to:
 
-- Each supported locale included in `airflow-core/src/airflow/ui/src/i18n/locales`.
+- Each supported locale included in `airflow-core/src/airflow/ui/public/i18n/locales`.
 - Contributors making changes in the default locale (English).
 - Contributors suggesting new locales to be added to the codebase.
 - Maintainers of supported locales in any role defined below.
@@ -42,7 +42,7 @@ This policy applies to:
 
 **Internationalization (i18n)** - The process of designing a software application so that it can be adapted to various languages and regions without engineering changes (see also the [Wikipedia article](https://en.wikipedia.org/wiki/Internationalization_and_localization)).
 
-**Supported locale** - An officially accepted locale in `airflow-core/src/airflow/ui/src/i18n/locales`.
+**Supported locale** - An officially accepted locale in `airflow-core/src/airflow/ui/public/i18n/locales`.
 
 **Default locale** - English (`en`), the primary locale and fallback for all other locales.
 
@@ -175,7 +175,7 @@ Translation conflicts MUST be resolved according to the procedures outlined in s
 The following steps outline the process for approving a new locale to be added to the supported locales:
 
 - Creating a PR for adding the suggested locale to the codebase ([see example](https://github.com/apache/airflow/pull/51258/files)), which includes:
-    - The locale files (translated according to the guidelines) in the `airflow-core/src/airflow/ui/src/i18n/locales/<LOCALE_CODE>` directory, where `<LOCALE_CODE>` is the code of the language according to ISO 639-1 standard (e.g., `fr` for French). Languages with regional variants should be handled in separate directories, where the name is suffixed with `-<VARIANT>`, and `<VARIANT>` is the variant that follows ISO 3166-1 or UN M.49 codes in lowercase (e.g., `zh-tw` for Taiwanese Mandarin).
+    - The locale files (translated according to the guidelines) in the `airflow-core/src/airflow/ui/public/i18n/locales/<LOCALE_CODE>` directory, where `<LOCALE_CODE>` is the code of the language according to ISO 639-1 standard (e.g., `fr` for French). Languages with regional variants should be handled in separate directories, where the name is suffixed with `-<VARIANT>`, and `<VARIANT>` is the variant that follows ISO 3166-1 or UN M.49 codes in lowercase (e.g., `zh-tw` for Taiwanese Mandarin).
     - Making the required modifications in `airflow-core/src/airflow/ui/src/i18n/config.ts` ([see example](https://github.com/apache/airflow/pull/51258/files#diff-bfb4d5fafd26d206fb4a545a41ba303f33d15a479d21e0a726fd743bdf9717ff)).
     - Changes to the `.github/CODEOWNERS` file to include the designated code owner(s) and translation owner(s) for the new locale, considering the following:
         - A code owner who is also a translation sponsor should be indicated in a comment as well.
@@ -234,21 +234,21 @@ Language proficiency for translation owners can be demonstrated through any of t
 All files:
 
 ```bash
-uv run ./check_translations_completeness.py
+uv run dev/i18n/check_translations_completeness.py
 ```
 
 Files for specific languages:
 
 ```bash
-uv run ./check_translations_completeness.py --language <language_code>
+uv run dev/i18n/check_translations_completeness.py --language <language_code>
 ```
 
 Where `<language_code>` is the code of the language you want to check, e.g., `en`, `fr`, `de`, etc.
 
 Adding missing translations (with `TODO: translate` prefix):
 
 ```bash
-uv run ./check_translations_completeness.py --language <language_code> --add-missing
+uv run dev/i18n/check_translations_completeness.py --language <language_code> --add-missing
 ```
 
 ## 9. Compliance & enforcement