diff --git a/lib/src/onehz/human/overreaching_conjunction.dart b/lib/src/onehz/human/overreaching_conjunction.dart
index 62449fb..4cde0c3 100644
--- a/lib/src/onehz/human/overreaching_conjunction.dart
+++ b/lib/src/onehz/human/overreaching_conjunction.dart
@@ -107,7 +107,13 @@ Metric<OverreachingConjunction> overreachingConjunction({
   final base = robustBaseline(rhrBaselineWindow, minValid: minBaseline);
   final centre = base.center;
   final scale = base.scale;
-  final gate = (scale != null && scale > 0) ? 0.5 * scale : null;
+  // Nightly RHR is whole-bpm; an alternating baseline (e.g. 58/59) can carry
+  // a small nonzero MAD that is unresolvable rounding noise, not real
+  // dispersion — the same guard illness_cusum.dart and readiness_composite.dart
+  // already apply to this exact channel.
+  final rhrBelowQuantum = dispersionBelowQuantum(rhrBaselineWindow, 1.0);
+  final gate =
+      (!rhrBelowQuantum && scale != null && scale > 0) ? 0.5 * scale : null;
   if (centre == null || gate == null || !base.sufficient) {
     return Metric<OverreachingConjunction>.absent(
       tier: Tier.estimate,
diff --git a/test/onehz/overreaching_conjunction_test.dart b/test/onehz/overreaching_conjunction_test.dart
new file mode 100644
index 0000000..b1f457d
--- /dev/null
+++ b/test/onehz/overreaching_conjunction_test.dart
@@ -0,0 +1,51 @@
+// Regression for the whole-bpm RHR quantization false positive: a baseline
+// alternating between two adjacent integers carries a small nonzero MAD that
+// is unresolvable rounding noise, not real dispersion. Without
+// dispersionBelowQuantum this let a 1 bpm rise clear the gate.
+
+import 'package:test/test.dart';
+import 'package:openstrap_analytics/onehz.dart';
+
+void main() {
+  group('overreachingConjunction RHR quantum guard', () {
+    final load = Metric<LoadState>(
+      value: const LoadState(40.0, 65.0, -25.0), // atl/ctl = 1.625 >= 1.5
+      confidence: 0.8,
+      tier: Tier.high,
+      inputs_used: const ['daily_trimp'],
+    );
+
+    test('alternating whole-bpm baseline abstains instead of firing', () {
+      final baseline = <double>[
+        58, 59, 58, 59, 58, 59, 58, 59, 58, 59, 58, 59, 58, 59,
+      ];
+      // 1 bpm above the median baseline on every recent night — exactly the
+      // rounding-noise case the guard exists to catch.
+      final recent = <double?>[60.0, 60.0, 60.0, 60.0, 60.0];
+
+      final m = overreachingConjunction(
+        load: load,
+        rhrRecent: recent,
+        rhrBaselineWindow: baseline,
+      );
+
+      expect(m.present, isFalse);
+    });
+
+    test('real dispersion in the baseline still lets it fire', () {
+      final baseline = <double>[
+        54, 56, 58, 60, 55, 57, 59, 61, 54, 58, 60, 56, 59, 55,
+      ];
+      final recent = <double?>[65.0, 65.0, 65.0, 65.0, 65.0];
+
+      final m = overreachingConjunction(
+        load: load,
+        rhrRecent: recent,
+        rhrBaselineWindow: baseline,
+      );
+
+      expect(m.present, isTrue);
+      expect(m.value!.bothPointSameWay, isTrue);
+    });
+  });
+}