MAS-WP-0005-T02: SCP-2 lower-case resource types (spec v0.1.1)

Grammar, statute schema key pattern, parser (is_resource_type, also used
by statute lint), reference parser, spec 6.1 and a new CHANGELOG. Fixtures
p1-042..045; prop-case-001 Ticket=PR42 is now invalid.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Assistant: claude-code
Assistant-Model: opus
Assistant-Process: 252470@bnt-lap001
Assistant-Session: ad628c8f-4be2-4979-94c9-76c7ed6f8241

mas_core/parser.py

@@ -11,6 +11,8 @@ class (P1 or P2) without re-parsing.
 
 from __future__ import annotations
 
+import re
+
 from dataclasses import dataclass
 from typing import Optional
 
@@ -28,11 +30,16 @@ LOCAL_PART_MAX_OCTETS = 64
 
 _ALNUM = frozenset("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789")
 ATOM_CHARS = _ALNUM | frozenset("#%&'*-/?_`{|}~")
-RESOURCE_TYPE_CHARS = _ALNUM | frozenset("-_")
+# v0.1.1 (SCP-2): lower-case words joined by single "-" or "_".
+_RESOURCE_TYPE = re.compile(r"[a-z0-9]+(?:[_-][a-z0-9]+)*")
 VALUE_CHARS = ATOM_CHARS | frozenset("=")  # resource-id-char and value-char
 RESERVED_OPERATORS = frozenset("$^")
 
 
+def is_resource_type(name: str) -> bool:
+    return _RESOURCE_TYPE.fullmatch(name) is not None
+
+
 class MasSyntaxError(ValueError):
     """A local-part is not canonical MAS v0.1 syntax.
 
@@ -102,7 +109,7 @@ def parse_local_part(value: str) -> ParsedLocalPart:
             raise MasSyntaxError("empty-resource-type", "resource type is empty")
         if not rid:
             raise MasSyntaxError("empty-resource-id", "resource id is empty")
-        if not all(c in RESOURCE_TYPE_CHARS for c in rtype):
+        if not is_resource_type(rtype):
             raise MasSyntaxError("invalid-resource-type", f"invalid resource type {rtype!r}")
         if not _dot_string(rid, VALUE_CHARS):
             raise MasSyntaxError("invalid-resource-id", f"invalid resource id {rid!r}")