v0.8.6-alpha
Fixed: Option could not type the characters a keyboard layout puts there
Reported from a Turkish Q layout in #9: Option+Q should be @, Option+8 should be [, and neither arrived in an SSH session. The shell saw ESC q and ESC 8 instead.
The terminal library treats Option as the Meta key by default, and in that mode it sends ESC followed by the character the key would produce without the modifier applied — so the layout's composition is discarded before it can happen. Turkish, German, Polish, Spanish and Romanian all reach for Option to type everyday programming characters. A US layout almost never does, which is why this stood for eight releases without anyone running into it.
Option now composes characters the way the layout intends, which is what Terminal.app and iTerm2 do. Meta is a new setting under Settings → Appearance for anyone who wants M-x back.
Option+Left and Option+Right keep moving by word in both modes. With Meta off, macOS turns them into a text-editing command the terminal does not answer, so they are sent by hand rather than quietly lost.
The report's own guess — that an application hotkey was catching the combination first — was not the cause. Nothing in the app listens for Option; every menu shortcut is on Command.