Multi-language support starting with integrating the German language

[Christian-B-Koller]

Do you agree that a full integration of the German language in the full UI, all application messages and LLM prompts allows DeepTutor to reach a broader audience in Germany, Austria and Switzerland?

[farfromexact]

German is a sensible first additional locale, but I would build an internationalization layer rather than translate strings one by one. Put UI labels and application messages in message catalogs, make prompts locale-aware templates, and keep safety or tool constraints separate from prose that is translated.

The minimum useful design is an explicit locale setting, English fallback for missing keys, stable message identifiers, and tests for dates, numbers, decimal separators, long German strings, and mixed-language model output. German also needs a consistent choice of formal or informal address.

A translation completeness check in CI and a small contributor guide for new strings would prevent the UI from drifting into a half-translated state. It would be useful to identify which prompts are sent to the LLM and whether users can choose the response language independently from the UI language.