On Tue, Aug 6, 2024, 17:34 João Távora wrote: > * lisp/progmodes/eglot.el (eglot-server-programs): Explicitly list modes > derived from tex-mode, so that the correct language id is guessed. > > Won't it break when another mode is derived from it? > Not really, since such a hypothetical mode has no support from the servers. May I ask why > don't you just use the :language-id cookie which is designed > exactly for this -- to avoid a guess? > That doesn't work, because apparently Eglot picks the language id of the first mode in the listing that applies, which previously was the generic tex-mode. That doesn't allow distinguishing latex and plain TeX. Again, the issue is not guessing the language id string from the mode name, but rather choosing the right mode symbol to guess from. (Above I say apparently because this is not documented behavior, although it's easy to check or verify reading the code.)