MAS-WP-0009 T01: independent JS implementation (impl/js), differential test, SCP-9

impl/js (Node, zero deps, written from the specs): parser, v0.2
statute-aware rules, signing, outside master. Passes addresses.json,
statute-aware.json and auth.json unchanged; its master passes the 11
slave-setup mode flows against the Python email side (ExternalMaster).
Differential testing vs mas_core found two unstated stand-in rules, now
SCP-9 in the v0.2 draft with fixtures si-011..013, dt-109; ABNF comments
no longer say v0.1. Runner: external masters, step errors fail the flow.

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

Assistant: claude-code
Assistant-Model: opus
Assistant-Process: 5787@bnt-lap001
Assistant-Session: 5db26b82-138b-40cc-9856-4d5eb0f752fd

impl/js/test/address.test.mjs

@@ -0,0 +1,31 @@
+// mas-v0.2-spec/conformance/addresses.json, consumed unchanged (CONFORMANCE.md section 2).
+import { test } from "node:test";
+import assert from "node:assert/strict";
+import { readFileSync } from "node:fs";
+import { parseLocalPart, MasSyntaxError } from "../src/parser.mjs";
+
+const BUNDLE = new URL("../../../mas-v0.2-spec/", import.meta.url);
+const fixtures = JSON.parse(readFileSync(new URL("conformance/addresses.json", BUNDLE)));
+
+for (const f of fixtures) {
+  test(`${f.id} ${JSON.stringify(f.local_part)} (${f.profile})`, () => {
+    let got;
+    try {
+      got = parseLocalPart(f.local_part, f.profile);
+    } catch (e) {
+      assert.ok(e instanceof MasSyntaxError, e);
+      assert.equal(f.valid, false, `rejected (${e.code}) but fixture is valid`);
+      return;
+    }
+    assert.equal(f.valid, true, `accepted but fixture is invalid (${f.error})`);
+    const { required_profile, generator_allowed, ...parsed } = got;
+    assert.deepEqual(parsed, f.parsed);
+    if ("generator_allowed" in f) assert.equal(generator_allowed, f.generator_allowed);
+  });
+}
+
+test("a P2 parser also passes every P1 fixture (CONFORMANCE.md 2)", () => {
+  for (const f of fixtures.filter((x) => x.profile === "p1" && x.valid)) {
+    assert.deepEqual((({ required_profile, generator_allowed, ...p }) => p)(parseLocalPart(f.local_part, "p2")), f.parsed);
+  }
+});