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

tests/test_js_impl.py

@@ -0,0 +1,24 @@
+"""The independent JS implementation (impl/js, MAS-WP-0009), where node is available."""
+import shutil
+import subprocess
+from pathlib import Path
+
+import pytest
+
+ROOT = Path(__file__).resolve().parents[1]
+pytestmark = pytest.mark.skipif(not shutil.which("node"), reason="node not available")
+
+
+def test_js_passes_the_bundles_unchanged():
+    # addresses.json, statute-aware.json and auth.json, read from the bundles in place
+    proc = subprocess.run(["node", "--test"], cwd=ROOT / "impl/js", capture_output=True, text=True)
+    assert proc.returncode == 0, proc.stdout[-2000:] + proc.stderr[-2000:]
+    assert "# fail 0" in proc.stdout or "ℹ fail 0" in proc.stdout
+
+
+def test_js_outside_master_passes_the_slave_flows():
+    from mas_modes.external import ExternalMaster
+    from mas_modes.runner import run_mode_corpus
+    rep = run_mode_corpus(master_factory=ExternalMaster.js, roles=("slave",))
+    assert rep.ok, rep.failures
+    assert rep.passed == 11