Add a legacy theme to the Salt (Next) Figma library

[pseys]

EOS: Legacy theme tested and released to Salt (Next) Figma library

[pseys]

Due to unforeseen theme tasks (tokens for #3325 , #3535, #3310 ) I haven't been able to start this task within the current sprint. However, I have been able to give it some thought and I know how the issue can be resolved. It's a sizeable piece of work, but it should be achievable within 1-2 sprints including QA testing.

[mark-tate]

Goal: L(11)
theme tested and released to Salt (Next) Figma library by EOS

[bhoppers2008]

@pseys to rescope to separate pieces of work (and create relevant new issues) + identify which will be completed in this sprint.

[pseys]

Rescoping into 3 parts:

• Create variables library containing Salt-current foundation colours published locally
• Create variables library containing Salt-current palette tokens published locally
• Add Mode options to Characteristics variables
  -- Salt Legacy light
  -- Salt Legacy dark
  -- Salt Next

[pseys]

Speaking with @bhoppers2008 this morning, there is an urgent need to publish a release note for Salt Next documentation by EOW. This will be a significant effort, so will take priority over the Salt (Next) Legacy theme.

[mark-tate]

Goal: agree the strategy by EOS

[pseys]

The proposed approach to enable Salt legacy theme within the Salt Next variables library is as follows:

• Map legacy color palette to variables and publish to Salt team only Map legacy color palette to Figma variables #3843
• Map legacy palette level tokens to variables using the legacy color palette variables and publish to Salt team only Map legacy palette tokens to variables #3844
• Connect legacy palette variables to characteristics within the Salt Next Styles Library Add 'legacy' theme variables to Salt Styles Library in Figma #3846

The last task will come with conditions:

• The characteristic variables will need modes applied; Salt Next and Salt Legacy (TBC)
• Each characteristic variable mode will need to be mapped to a different set of palette variables – the Salt Next characteristics are already aligned to Accent / Mode in the styles library. Salt Legacy will need to map to a 'Mode' only switch, either in the same file or from a different library (TBC)
• When creating a new design, components will default to Salt Next, but designers will have the ability to toggle to Salt Legacy if they wish, however, they will have to set mode separately

[pseys]

All follow-up tasks created as issues.