B3.1 + B3.2 + B3.3: ChildRouter fan-out + commandRegistry 'none' + UnitPolicy dual-shape

B3.1 ChildRouter per-listener fan-out (drop emit monkey-patch):
  Partial-filter subscriptions enumerate every concrete
  <type>.measured.<position> event name (cartesian product over
  the canonical POSITIONS list + 19 KNOWN_TYPES) and register a
  plain emitter.on() per combo. Multi-parent semantics are trivial:
  each ChildRouter's listeners are independent. Drop the wrap/unwrap
  bookkeeping in tearDown. ChildRouter.js 184→164 lines.

B3.2 commandRegistry 'none' + description:
  Add 'none' to payloadSchema.type — handler still fires; logs warn
  if msg.payload is non-empty (catches accidental passes). Add
  optional `description` field per descriptor; surfaced via .list()
  so wikiGen can render per-topic effect text.
  commandRegistry.js 157→164 lines. 23/23 tests pass.

B3.3 UnitPolicy dual-shape:
  policy.canonical/output/curve are now BOTH callable methods AND
  frozen property bags. policy.canonical('flow') === 'm3/s' and
  policy.canonical.flow === 'm3/s' both work. Property bags are
  frozen (assign/delete/redefine throw in strict). Drops the
  _unitView workaround in MGC + rotatingMachine specificClass.
  UnitPolicy.js 149→163 lines, 15/15 tests pass.

CONTRACTS.md §4 + §6 updated.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

test/basic/UnitPolicy.basic.test.js

@@ -34,6 +34,53 @@ test('declare returns a policy whose canonical/output match the input', () => {
   assert.equal(policy.curve('control'), '%');
 });
 
+test('canonical/output/curve are also frozen property bags (dot access)', () => {
+  const policy = UnitPolicy.declare(baseSpec);
+  // Property-access form — equivalent to the method-call form above.
+  assert.equal(policy.canonical.flow, 'm3/s');
+  assert.equal(policy.canonical.pressure, 'Pa');
+  assert.equal(policy.output.flow, 'm3/h');
+  assert.equal(policy.output.temperature, 'C');
+  assert.equal(policy.curve.flow, 'm3/h');
+  assert.equal(policy.curve.control, '%');
+  // Method-call form keeps working alongside it.
+  assert.equal(policy.canonical('flow'), 'm3/s');
+  assert.equal(policy.output('power'), 'kW');
+});
+
+test('canonical/output/curve property bags are frozen — no assignment / delete / redefine', () => {
+  'use strict';
+  const policy = UnitPolicy.declare(baseSpec);
+  // Existing own-properties are non-writable.
+  assert.throws(() => { policy.canonical.flow = 'tampered'; }, TypeError);
+  // Existing own-properties are non-configurable: delete throws.
+  assert.throws(() => { delete policy.canonical.pressure; }, TypeError);
+  // Redefining an existing prop throws.
+  assert.throws(
+    () => Object.defineProperty(policy.canonical, 'flow', { value: 'tampered' }),
+    TypeError
+  );
+  // Object.isFrozen reports the accessor as frozen.
+  assert.equal(Object.isFrozen(policy.canonical), true);
+  assert.equal(Object.isFrozen(policy.output), true);
+  assert.equal(Object.isFrozen(policy.curve), true);
+  // Original values survive the failed attempts.
+  assert.equal(policy.canonical.flow, 'm3/s');
+  assert.equal(policy.canonical.pressure, 'Pa');
+});
+
+test('curve property bag is present (empty) even when no curve was declared', () => {
+  const policy = UnitPolicy.declare({
+    canonical: baseSpec.canonical,
+    output: baseSpec.output,
+  });
+  // Method form returns null for unknown types.
+  assert.equal(policy.curve('flow'), null);
+  // Property form is an empty frozen function — accessing missing keys is undefined.
+  assert.equal(policy.curve.flow, undefined);
+  assert.equal(Object.isFrozen(policy.curve), true);
+});
+
 test('declare throws when canonical or output is missing', () => {
   assert.throws(() => UnitPolicy.declare({ output: {} }), /canonical/);
   assert.throws(() => UnitPolicy.declare({ canonical: {} }), /output/);