diff --git a/src/pyrecest/filters/sequence_node_validation.py b/src/pyrecest/filters/sequence_node_validation.py
index d56ae3800..5a45910af 100644
--- a/src/pyrecest/filters/sequence_node_validation.py
+++ b/src/pyrecest/filters/sequence_node_validation.py
@@ -9,6 +9,4 @@ class SequenceAssociationNode(_SequenceAssociationNode):
     """Sequence-association node with consistent gap-node bookkeeping."""
 
     def __post_init__(self) -> None:
-        if self.is_missed_detection and self.candidate_index is not None:
-            raise ValueError("candidate_index must be None for explicit gap nodes")
         super().__post_init__()
diff --git a/tests/filters/test_public_sequence_node_flag_validation.py b/tests/filters/test_public_sequence_node_flag_validation.py
new file mode 100644
index 000000000..dd187c53e
--- /dev/null
+++ b/tests/filters/test_public_sequence_node_flag_validation.py
@@ -0,0 +1,11 @@
+import pytest
+from pyrecest.filters import SequenceAssociationNode
+
+
+def test_public_node_rejects_non_boolean_gap_flag_before_consistency_check():
+    with pytest.raises(ValueError, match="is_missed_detection must be a bool"):
+        SequenceAssociationNode(
+            frame_index=0,
+            candidate_index=1,
+            is_missed_detection="False",
+        )