feat(violet): V4 arm-readiness reporter (PASS MM1)

Read-only aggregation module answering 'is V4 ready to ARM the live canary?'
by consuming gate outcomes into a typed StrictModel report.

Files:
- v4_readiness.py: V4ReadinessReport (6 bool gates + reasons) + assess_v4_readiness()
- test_violet_v4_readiness.py: 13 tests (happy, parametrized single-false,
  hypothesis 2^6 invariant, mutation litmus, StrictModel poison)

Co-Authored-By: mm_VIOLET1 <mm_VIOLET1@h5i>

prod/clean_arch/violet/test_violet_v4_readiness.py

@@ -0,0 +1,140 @@
+"""V4 arm-readiness reporter — self-test to death.
+
+Spec: prod/docs/VIOLET_PASS_MM1_V4_READINESS_REPORTER.md
+Style: follows test_violet_domain.py patterns.
+"""
+
+from __future__ import annotations
+
+import sys
+sys.path.insert(0, "/mnt/dolphinng5_predict")
+
+import pytest
+from hypothesis import given, settings
+from hypothesis import strategies as st
+
+from prod.clean_arch.violet.v4_readiness import (
+    V4ReadinessReport,
+    assess_v4_readiness,
+)
+
+ALL_FIELDS = [
+    "creds_ok", "canary_passed", "arming_gate_present",
+    "conviction_bit_identical", "selection_parity_ok", "feed_live",
+]
+
+
+def _all_true(**overrides: bool) -> dict:
+    return {f: overrides.get(f, True) for f in ALL_FIELDS}
+
+
+def _single_false(field: str) -> dict:
+    return _all_true(**{field: False})
+
+
+# ── happy path ────────────────────────────────────────────────────────────────
+
+def test_all_true_ready_to_arm():
+    r = assess_v4_readiness(**_all_true())
+    assert r.ready_to_arm is True
+    assert r.reasons == []
+
+
+# ── each single False yields ready_to_arm=False + correct reason ─────────────
+
+@pytest.mark.parametrize("field", ALL_FIELDS)
+def test_single_false_not_ready(field: str):
+    r = assess_v4_readiness(**_single_false(field))
+    assert r.ready_to_arm is False
+    assert len(r.reasons) == 1
+    assert field in r.reasons[0]
+
+
+# ── hypothesis: invariant holds across all 2^6 combos ────────────────────────
+
+@given(
+    creds_ok=st.booleans(),
+    canary_passed=st.booleans(),
+    arming_gate_present=st.booleans(),
+    conviction_bit_identical=st.booleans(),
+    selection_parity_ok=st.booleans(),
+    feed_live=st.booleans(),
+)
+@settings(max_examples=100)
+def test_ready_to_arm_equals_all_inputs(
+    creds_ok: bool,
+    canary_passed: bool,
+    arming_gate_present: bool,
+    conviction_bit_identical: bool,
+    selection_parity_ok: bool,
+    feed_live: bool,
+):
+    r = assess_v4_readiness(
+        creds_ok=creds_ok,
+        canary_passed=canary_passed,
+        arming_gate_present=arming_gate_present,
+        conviction_bit_identical=conviction_bit_identical,
+        selection_parity_ok=selection_parity_ok,
+        feed_live=feed_live,
+    )
+    expected = all((
+        creds_ok, canary_passed, arming_gate_present,
+        conviction_bit_identical, selection_parity_ok, feed_live,
+    ))
+    assert r.ready_to_arm is expected
+
+
+# ── mutation litmus: flipping all() to any() MUST break this test ────────────
+
+def test_mutation_litmus_all_must_be_true():
+    """If someone changes all() to any(), at least one all-False should become
+    ready_to_arm=True — this test catches it."""
+    r = assess_v4_readiness(**{f: False for f in ALL_FIELDS})
+    assert r.ready_to_arm is False
+    assert len(r.reasons) == 6
+
+
+# ── poison: StrictModel rejects non-bool / extra fields ─────────────────────
+
+def test_rejects_non_bool():
+    with pytest.raises(Exception):
+        V4ReadinessReport(
+            creds_ok={"ok": True},   # dict is not coercible to bool
+            canary_passed=True,
+            arming_gate_present=True,
+            conviction_bit_identical=True,
+            selection_parity_ok=True,
+            feed_live=True,
+            reasons=[],
+        )
+
+
+def test_rejects_extra_fields():
+    with pytest.raises(Exception):
+        V4ReadinessReport(
+            creds_ok=True,
+            canary_passed=True,
+            arming_gate_present=True,
+            conviction_bit_identical=True,
+            selection_parity_ok=True,
+            feed_live=True,
+            reasons=[],
+            unknown_field="oops",
+        )
+
+
+def test_rejects_frozen_mutation():
+    r = assess_v4_readiness(**_all_true())
+    with pytest.raises(Exception):
+        r.creds_ok = False  # type: ignore[misc]
+
+
+# ── reasons content check: False fields produce descriptive strings ──────────
+
+def test_reasons_mention_gate_name():
+    r = assess_v4_readiness(**_single_false("feed_live"))
+    assert any("PASS2.6" in reason for reason in r.reasons)
+
+
+if __name__ == "__main__":
+    raise SystemExit(pytest.main([__file__, "-v"]))