diff --git a/backend/services/infonet/tests/test_dispute_nonfinite_values.py b/backend/services/infonet/tests/test_dispute_nonfinite_values.py
new file mode 100644
index 0000000..5375654
--- /dev/null
+++ b/backend/services/infonet/tests/test_dispute_nonfinite_values.py
@@ -0,0 +1,78 @@
+"""Regression coverage for malformed and non-finite dispute numerics."""
+
+from services.infonet.markets.dispute import collect_disputes
+
+
+def test_collect_disputes_normalizes_invalid_numeric_values():
+    chain = [
+        {
+            "event_type": "dispute_open",
+            "event_id": "dispute-1",
+            "node_id": "challenger",
+            "timestamp": "not-a-timestamp",
+            "payload": {
+                "market_id": "market-1",
+                "challenger_stake": "nan",
+            },
+        },
+        {
+            "event_type": "dispute_stake",
+            "node_id": "oracle-1",
+            "timestamp": 1.0,
+            "payload": {
+                "dispute_id": "dispute-1",
+                "side": "confirm",
+                "rep_type": "oracle",
+                "amount": float("nan"),
+            },
+        },
+        {
+            "event_type": "dispute_resolve",
+            "timestamp": float("inf"),
+            "payload": {
+                "dispute_id": "dispute-1",
+                "outcome": "upheld",
+            },
+        },
+    ]
+
+    disputes = collect_disputes("market-1", chain)
+
+    assert len(disputes) == 1
+    dispute = disputes[0]
+    assert dispute.challenger_stake == 0.0
+    assert dispute.opened_at == 0.0
+    assert dispute.confirm_stakes == []
+    assert dispute.resolved_outcome == "upheld"
+    assert dispute.resolved_at == 0.0
+
+
+def test_collect_disputes_preserves_finite_numeric_strings():
+    chain = [
+        {
+            "event_type": "dispute_open",
+            "event_id": "dispute-2",
+            "node_id": "challenger",
+            "timestamp": "12.5",
+            "payload": {
+                "market_id": "market-2",
+                "challenger_stake": "3.5",
+            },
+        },
+        {
+            "event_type": "dispute_stake",
+            "node_id": "oracle-2",
+            "payload": {
+                "dispute_id": "dispute-2",
+                "side": "reverse",
+                "rep_type": "oracle",
+                "amount": "2.25",
+            },
+        },
+    ]
+
+    dispute = collect_disputes("market-2", chain)[0]
+
+    assert dispute.challenger_stake == 3.5
+    assert dispute.opened_at == 12.5
+    assert dispute.reverse_stakes[0]["amount"] == 2.25