Add default dark mode to config.toml

[hayescode]

Adds option to config.toml to set default theme:

• Options: "dark", "light", "system"
• Default: "system"

Relevant Discord Thread

Python portion works. This prints the config selection, and "system" if left un-configured.

from chainlit.config import config

@cl.on_chat_start
async def main():
    print(config.ui.default_theme)

[zboyles]

Does preferredTheme start off as null or undefined? If so, I think the priorities should be slightly adjusted to avoid forcing the server-configured theme. Consider using the following order of precedence:

const theme = preferredTheme ?? serverDefaultTheme ?? defaultTheme;

This change should prioritize the user's preferred theme, then the server-configured theme, and finally the default theme. This approach should also maintain existing user preferences and allow new users to change their theme.

[tpatel]

Thanks for your contribution ✨

I've added a comment for the frontend implementation

[tpatel]

There is an issue here, the server value shouldn't be read from the browser localstorage. It should be read from projectSettings?.ui.default_theme, I think this should happen in a hook when we get the project settings.

[hayescode]

Makes sense! Would you be able to to commit the change I'm still running into permission issues on my companies computer preventing full testing.