Limitations

Empty interpolations leave a space

An interpolation is not re-normalized once it has a value, so one that evaluates to nothing leaves behind the space that separated it:

cls`flex ${maybeEmpty} p-2`
// runtime:  'flex p-2'
// compiled: 'flex  p-2'

The class list is the same, which is all the DOM and Tailwind read, but the string differs. tw is not affected: tailwind-merge splits on whitespace and joins with single spaces, so its output is normalized either way.

prettier-plugin-tailwindcss flattens these templates

prettier-plugin-tailwindcss sorts class names inside any template literal it finds in a className, regardless of the tag. On a multi-line template that means the newlines are collapsed and the comments are moved to the front, away from the classes they annotated. tailwindPreserveWhitespace keeps the shape of the lines but still reorders tokens across them.

There is no setting that makes the two work together today. // prettier-ignore on the attribute is the escape hatch, or leave the plugin out.

Templates the runtime cannot read either

A template containing an escape that has no cooked value — cls`\unicode` — is left alone. The runtime cannot read it either, so guessing would be worse than doing nothing.