What is the problem you're trying to solve?

I'd like to require @layer and other at-rules around my declarations.

Allow:

@layer defaults {
  a { color: red; }
}

Disallow:

a { color: red; }

What solution would you like to see?

We typically enable users to do this on the configuration level by adding generic and configurable rules rather than specific ones.

A new rule to do this.

• Name: declaration-nesting-at-rule-required-list declaration-block-nesting-at-rule-required-list
• Description: Specify a list of required nesting at-rules for declarations.
• Message: Expected nesting at-rule "${atRule}" for declaration
• Primary option: array[string|regex]|string|regex
• Secondary options: None
• Category: Enforce conventions > Allowed, disallowed & required
• Autofix?: No
• Included in sharable configs?: No
• Expanded description: N/A

{ 
  "rules": {
     "declaration-nesting-at-rule-required-list": ["layer", "scope"]
  }
}

Prior art: use-layers.