`SendChatMessage`'s language argument is spoken, as in 1.12.1: a racial language picked from the chat menu (`ChatFrame.lua:2404`, passed on by `ChatEdit_SendText` at `:1950-1954`) or named by an addon goes out in `CMSG_MESSAGECHAT`, where before every line went in the faction tongue.
- `0x49f1e0` starts from the speaker's default language (`0x5ec890`); when argument 3 passes `lua_isstring` (a string or a number) it is matched by name against every `Languages.dbc` row, case-insensitively (`0x49f8a0`, `SStrCmpI`), and a miss raises "Unknown language" (`0x49f2e1`). nil, an absent argument, a table or a boolean keep the default. A language the character has not learned is sent and left to the server, which drops it (vmangos `ChatHandler.cpp:175`).
- The packet builder writes the type, the language and a target for a whisper or a channel only, then the text (`0x49f6c3`-`0x49f72a`); fourteen per-type writers become one, with byte-exact goldens.
- Each new UI state is seeded with the language table.
Checked live against the local vmangos: a say, a yell, a whisper to self and a GM command round-trip through the new builder; a channel line reaches the server's channel lookup; an unknown language raises in Lua.
Fixes#164
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
