The localization layer was hardcoded to English and Japanese: an enum with two
variants, an `is_japanese()` gate compiled into the format macro, and one
catalog pair. Adding a language meant editing the menus, the settings row, the
checkmark logic, the format macro and the font stack — each in a different place.
A language is now one entry in `i18n::language_table!`: BCP-47 code, endonym,
ISO 15924 script and catalog. The Language menu, the settings row, the shortcut
sheet and the control channel are all built from that table, and `build.rs`
picks up `locales/<code>-formats.json` by name, so a further language is a table
entry plus two catalogs (docs/localization.md).
Simplified Chinese (`zh-hans`) ships as the second translation: `zh-hans.json`
(1019 entries, key-set and placeholder-identical to `ja.json`) and
`zh-hans-formats.json` (102 entries). Its glyphs come from craft-fonts' Noto
Sans CJK SC, whose `Hans` faces the UI now installs *before* the Japanese ones
for a Chinese reader, so shared Han characters keep the language's forms
(`fonts::cjk_fallback`); the export watermark accepts every CJK face.
`tr_format!` keeps its compile-time check. It formats the English source at the
call site — a runtime template cannot be handed to `format!` — and names those
values so a translation can place them by name (`{n}`) or position (`{_1}`).
Every translation is still checked by `format!`, so a translation with an
unknown placeholder fails the build. The Japanese catalog was rewritten from the
old `{:.0}` plural-discard trick to that by-name form; behaviour is unchanged.
Also: settings persist the BCP-47 code (never the Rust variant name),
`LIGHTCRAFT_LANGUAGE` accepts system-style tags (`zh_CN`, `ja_JP.UTF-8`),
`xtask parity` reads the second command table, and the glyph tests cover every
catalog character plus the interface symbols (`▸`/`▾` turned out to have no
glyph in any installed font and are gone from the Chinese text).
Chinese and Japanese both need `CRAFT_FONTS_DIR` as before; the web build still
embeds only the Japanese face (Noto Sans CJK SC alone would push the wasm past
Cloudflare's 25 MiB per-file cap), documented in docs/localization-zh-hans.md.
Co-Authored-By: DeepSeek V3.2 <noreply@deepseek.com>
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