type: Reference
title: i18n — English and Arabic
description: The en/ar locale files, flat key naming, fallback order, RTL layout, and where every new user-facing string must land.
tags: i18n, arabic, rtl, locales, translation
status: stable
stale_after: Fri Apr 30 2027 02:00:00 GMT+0200 (Central European Summer Time)
generated: techwriter/mimo-v2.6-flash · Sat Oct 31 2026 11:02:38 GMT+0100 (Central European Standard Time)
sources: translator → internal/i18n/translator.go; config → config/config.go; langmw → internal/infrastructure/web/language.go; renderer → internal/infrastructure/web/localized_render.go; locales → web/locales/en.json

i18n

Two locales ship — en and ar, 542 keys each, identical key sets — and the UI is genuinely bilingual: Arabic gets RTL layout, not just translated words.

Piece	Where	Behaviour
Locale files	`web/locales/en.json`, `ar.json`	flat `key → string`; nested JSON is flattened to dotted keys at load, so either shape works
Loader	`internal/i18n`	one `Translator` at boot; a missing or unparseable locale file is a fatal boot error
Lookup `T(lang, key)`	everywhere	requested lang → default lang (prefers `en`) → the key itself as the last resort
Negotiation	`web.LanguageMiddleware`	runs globally before every route (the login page included); `?lang=` or the lang cookie, resolved into the request context
Rendering	`web.NewLocalizedHTMLRender`	one compiled template set per language, with `t`/`dir`/`lang`/date funcs bound to it — this removed an older request-shared atomic "current language" that could leak one request's locale into a concurrent render
RTL	`config.DirectionFor`	`ar`, `he`, `fa`, `ur` → `rtl`; everything else `ltr`. The layout template sets `dir` from it; the Cairo font stack (`web/assets/css/cairo-fonts.css`, vendored woff2) covers Arabic glyphs
Enabled languages	`LANGS` env	comma-separated, first is default; deployed tenants run `en,ar`

Key naming

Flat, snake_case, descriptive: add_student, cash_box, default_currency_not_enabled, attendance_summary_desc. Dots appear only where a nested object was flattened.
Errors are keys too: handlers call h.i18n.T(lang, "save_failed") and the form re-renders with the translated message.
Format strings keep %d/%s verbs (e.g. bulk_assigned: %d student(s) assigned) and are consumed with fmt.Sprintf on the Go side.

Where new strings must land

Every user-visible literal added to a template or a handler needs a key in both web/locales/en.json and web/locales/ar.json — the key sets are kept identical (this pass verified both files at 542 keys with no diff either way), and a missing key falls back to English and then to the raw key, which renders as a bug. Templates reach strings through the t func; handlers and view-model code through h.i18n.T(lang, key).

Plugin strings follow the same rule from the outside: the host translates a plugin field under plugin_<id>_<key> and falls back to the plugin's own Field.Label — see settings. Labels on the catalogue itself (the roles matrix) are dual-written in code: En/Ar columns on every rbac.Resource.

Not determined

Whether CI enforces en/ar key-set equality: no such check was found in the workflows or the test suite; the parity observed here is a convention the repo keeps, not a guard the repo runs.

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