Drop dead token constructors and add a parse-render round-trip test

[davesnx]

Two parser housekeeping items from the quality audit. Tokens.re loses three constructors nothing ever built (TYPE_SELECTOR, AT_KEYWORD, DESCENDANT_COMBINATOR), leftovers from before the lexer unification. And packages/parser/test gains the round-trip regression check it never had: for each CSS body, render(parse(css)) must equal render(parse(render(parse(css)))), and the re-parsed AST must equal the first parse modulo locations and the incidental whitespace tokens the renderer strips.

The corpus is 48 bodies: 30 copied from the css-support cram fixtures plus 18 edge cases (@supports, @container, calc(), var(), url(), :is()/:where()/:not()/:has(), attribute selectors, ::before, .5/-.5/1e3, escaped strings, comments). All 48 pass both checks. One real divergence is pinned as an explicit known-divergence test rather than hidden: an unquoted url(foo.png) parses to the dedicated Ast.Uri node, but the renderer always emits a quoted argument and the quoted form re-parses as a generic Function("url", …), so Ast.Uri never survives a render pass. Text output is unaffected; the AST shape is. Candidate defect for a follow-up.

Evidence at 8500fab:

• opam exec -- dune build --root . @test-parser: 334 tests, 99 of them the new Roundtrip_test module (48 render-stability, 48 AST-stability, 1 pinned divergence, 2 render-only).
• make format-check, make build, make test: all exit 0.

Risk: two-way door. Deletion of unused constructors and test-only code; no output changes.

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1 Skipped Deployment

Project	Deployment	Actions	Updated
styled-ppx	Ignored	Preview	Sep 23, 2026 6:40am UTC