Deprecate old config options for MQTT json light

[jbouwh]

Breaking change

Support for brightness is now assumed for mqtt lights with the json schema unless only color modes rgb, rgbw or rgbww are supported.

For light which only support color modes rgb, rgbw or rgbww, the brightness option flag can still be set to false if brightness is not supported, in this case brightness support is emulated in Home Assistant by scaling the RGBx-values.

For all other color modes except ColorMode.ONOFF, it is assumed brightness is supported and the brightness attribute will be included in the MQTT payload when the brightness attribute is supplied to the light.turn_on service.

Proposed change

Deprecate the flag settings color_mode, color_temp, hs, rgb and xy for the mqtt light schema. The options color_temp, hs, rgb and xy were already removed from the documentation, but the options were not marked deprecated in the schema yet.

The color_mode flag is not used anymore, and should be removed. Instead supported_color_modes is checked. If it is not set, then the color_temp, hs, rgbandxy` flags will still be evaluated.

Brightness is assumed to be supported by default. For rgbx lights that do not support brightness brightness should be explicitly set to false.

The deprecated options are planned to be removed with HA Core 2025.3, this is in line with the deprecation grace period on the light entity platform support.

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Deprecation (breaking change to happen in the future)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes MQTT JSON light options brightness and color_mode should be deprecated #110682
• This PR is related to issue:
• Link to documentation pull request: Remove deprecated color_mode flag, adjust brightness description for MQTT json light home-assistant.io#31707

Checklist

• The code change is tested and works locally.
• Local tests pass. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• I have followed the development checklist
• I have followed the perfect PR recommendations
• The code has been formatted using Ruff (ruff format homeassistant tests)
• Tests have been added to verify that the new code works.

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated for www.home-assistant.io

If the code communicates with devices, web services, or third-party tools:

• The manifest file has all fields filled out correctly.
  Updated and included derived files by running: python3 -m script.hassfest.
• New or updated dependencies have been added to requirements_all.txt.
  Updated by running python3 -m script.gen_requirements_all.
• For the updated dependencies - a link to the changelog, or at minimum a diff between library versions is added to the PR description.
• Untested files have been added to .coveragerc.

To help with the load of incoming pull requests:

• I have reviewed two other open pull requests in this repository.

[home-assistant]

Hey there @emontnemery, mind taking a look at this pull request as it has been labeled with an integration (mqtt) you are listed as a code owner for? Thanks!

Code owner commands

Code owners of mqtt can trigger bot actions by commenting:

• @home-assistant close Closes the pull request.
• @home-assistant rename Awesome new title Renames the pull request.
• @home-assistant reopen Reopen the pull request.
• @home-assistant unassign mqtt Removes the current integration label and assignees on the pull request, add the integration domain after the command.
• @home-assistant add-label needs-more-information Add a label (needs-more-information, problem in dependency, problem in custom component) to the pull request.
• @home-assistant remove-label needs-more-information Remove a label (needs-more-information, problem in dependency, problem in custom component) on the pull request.

[home-assistant]

Please take a look at the requested changes, and use the Ready for review button when you are done, thanks 👍

Learn more about our pull request process.

[emontnemery]

Thanks, @jbouwh 👍