feat(namespace): aggregation reads under the law + epoch 3 (the key-split rebuild) + THE ARMING COMMIT — the capability constant, the law module, and the typed refusals export from the package root; both engines' conformance suites light on this signal

tests/unit/brainy/migration-deference.test.ts

@@ -245,9 +245,10 @@ describe('rc.8 no-freeze migration deference (isMigrating / stampBrainFormat / b
   it('the brain-format marker module exports the compiled epoch + data-format constants', () => {
     // cor imports these from '@soulcraft/brainy/brain-format' (Hook 3) so both
     // sides share ONE source of truth — no duplicated constant to drift.
-    // Epoch 2: user metadata named `level` became indexable (the reserved-name
-    // shadow fix, 2026-08-03) — pre-fix brains rebuild derived indexes at open.
-    expect(EXPECTED_INDEX_EPOCH).toBe(2)
+    // Epoch 3: the namespace-law key split (bare user keys · literal
+    // 'system.<field>' scalars, 2026-08-03) — every brain rebuilds onto the
+    // frozen keys at first open. (Epoch 2 same day: `level` indexability.)
+    expect(EXPECTED_INDEX_EPOCH).toBe(3)
     expect(CURRENT_DATA_FORMAT).toBe('8.0')
   })
 })