automerge? it's in OP

Merging text documents automatically can easily be shown to produce garbage results; it is not conflict-free.

If it did not have this problem, then that would give use the solution for syntax, right? Syntax trees can be turned into text documents. Oh, and those are a CRDT: and we have automerge. QED.

Conflict-free refers to the datatype under the specific criterion of distributed consensus, it says nothing about the semantic meaning of the resulting data. You can take ANY CRDT and assign an arbitrary semantic meaning to it that induces a conflict, that does not suddenly make it conflict-free.

Point is we now have CRDTs for free text that are reasonably useful because most of the transformations that are encoded map to human expectations for resolution.

OK, so without the semantics, the data is syntax.

So there we have the CRDT for syntax; it's every CRDT.

Every type has shapes, which are syntax, and those are invariant, as are some other constraints which can be shoehorned into syntax. E.g we can make it a matter of syntax, not semantics, that in {3, "foo", bar, 3.14}, the 3 must be the count of the remaining elements.