feat(learning-harness): TypeScript and TSX rows parse under the semantic extra

Task 1.4. The optional extra gains the TypeScript grammar wheel, which ships two
grammars: a file with JSX needs the JSX-aware one and plain TypeScript needs the
other, so the parser picks by file suffix while the parsed file keeps the
language it was given. The walker already treated TypeScript as JavaScript, so
nothing else changes.

Eighteen agent-vfc rows and every TypeScript absence row were counted as
unsupported before this and could not be scored at all. They now parse on both
sides. The core install stays zero-dependency and the extra-free suite still
skips these tests.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01T7XD7x5KonMdmGRkp63EQG

tests/test_typescript_grammar.py

@@ -0,0 +1,49 @@
+"""learning-harness task 1.4: TypeScript and TSX rows parse under the semantic extra."""
+
+from __future__ import annotations
+
+import pytest
+
+from openultrasast.pairs import DEFAULT_CATALOG, load_pair_catalog, select_vendored
+from openultrasast.semantic.extra import has_semantic_extra
+from openultrasast.semantic.ir import parse_file
+
+pytestmark = pytest.mark.semantic
+
+TS = (
+    "export async function GET(request: NextRequest): Promise<Response> {\n"
+    "  const id = request.nextUrl.searchParams.get('id');\n"
+    "  return NextResponse.json(await db.from('claims').select().eq('id', id));\n}\n"
+)
+TSX = (
+    "export function Panel({ token }: { token: string }) {\n"
+    "  const [value, setValue] = useState('');\n"
+    '  return <div className="p">{value}{token}</div>;\n}\n'
+)
+
+
+@pytest.mark.skipif(not has_semantic_extra(), reason="requires the semantic extra")
+def test_typescript_and_tsx_parse_instead_of_reporting_an_unsupported_language() -> None:
+    ir = parse_file("app/api/route.ts", TS, "typescript")
+    assert ir.parse_ok and ir.reason is None and ir.engine == "tree-sitter"
+    assert "GET" in {function.name for function in ir.functions}
+    tsx = parse_file("components/panel.tsx", TSX, "typescript")
+    assert tsx.parse_ok and tsx.reason is None  # the TSX grammar, chosen by the file suffix
+    assert "Panel" in {function.name for function in tsx.functions}
+
+
+@pytest.mark.skipif(not has_semantic_extra(), reason="requires the semantic extra")
+def test_every_vendored_typescript_pair_parses_on_both_sides() -> None:
+    cases = [case for case in select_vendored(load_pair_catalog(DEFAULT_CATALOG)) if case.language == "typescript"]
+    assert len(cases) >= 18
+    unsupported: list[str] = []
+    failed: list[str] = []
+    for case in cases:
+        for side, path in (("vuln", case.vuln_file), ("fixed", case.fixed_file)):
+            ir = parse_file(str(path), path.read_text(errors="ignore"), "typescript")
+            if ir.reason == "language_unsupported":
+                unsupported.append(f"{case.name}:{side}")
+            elif not ir.parse_ok:
+                failed.append(f"{case.name}:{side}")
+    assert unsupported == []
+    assert len(failed) <= len(cases) // 4, failed  # a parse failure is a walker gap, not a missing grammar