Add mode parameter to frontend.set_theme service

[Velnius]

Describe the enhancement

Description

Currently, the frontend.set_theme service only allows setting the theme name (name) and optionally primary_color. However, it does not support changing the theme mode (light or dark). This limits the ability to dynamically switch between light and dark modes based on conditions such as time of day, sun position, or sensor data.

Why is this important?

• Users must create two separate themes (Light and Dark) even if they only want to switch modes.
• Adding this feature would simplify configuration and reduce duplication.
• It would improve user experience, especially for automations that depend on environmental conditions.

Proposed Solution

Extend the frontend.set_theme service to accept an optional mode parameter:

service: frontend.set_theme
data:
  name: Metro Green
  mode: light # or dark

If mode is not provided, keep the current behavior.

Benefits

• Easier automations.
• Fewer duplicated themes.
• Better integration with dynamic conditions (e.g., sun state, time-based triggers).

Currently, the only way to achieve this is by creating two separate themes and switching between them, which is not efficient. Adding mode support would make Home Assistant theming more flexible and user-friendly.

Use cases

Automatic selection of Theme mode (dark or light) based on the time of day. Currently, this can only be done manually. Or you need two separate Themes.

Visual examples

No response

Anything else?

No response

[karwosts]

frontend.set_theme already takes a mode argument, but it doesn't do what you think it does.

If what you're asking for were to be implemented there would probably need to be a new service like frontend.set_light_mode, and a new toggle would have to be added to the user profile like "use backend-selected light mode".

[Velnius]

I’m not an expert here, so I can’t suggest exactly how to implement this feature. It would probably need to be implemented in the way you suggested. I just wanted to express that I’d like to have it, and I believe others would appreciate it as well.