fix(infonet): reject non-finite stalemate burn inputs (#514)

* fix(infonet): reject non-finite stalemate burn inputs

* test(infonet): cover non-finite stalemate burn inputs

backend/services/infonet/markets/stalemate_burn.py

@@ -30,28 +30,43 @@ specific branches in ``resolution.py`` that match the spec's
 
 from __future__ import annotations
 
-from typing import Iterable
+import math
+from typing import Any, Iterable
 
 from services.infonet.config import CONFIG
 
 
+def _finite_float(value: Any) -> float | None:
+    try:
+        parsed = float(value)
+    except (TypeError, ValueError):
+        return None
+    return parsed if math.isfinite(parsed) else None
+
+
 def stalemate_burn_pct() -> float:
     """Current burn percentage from CONFIG. Helper so callers don't
     need to remember the key name."""
-    return float(CONFIG["resolution_stalemate_burn_pct"])
+    pct = _finite_float(CONFIG["resolution_stalemate_burn_pct"])
+    if pct is None:
+        raise ValueError("resolution_stalemate_burn_pct must be finite")
+    return pct
 
 
 def split_burn_and_return(amount: float, burn_pct: float | None = None) -> tuple[float, float]:
     """Compute (burn_amount, returned_amount) for a single stake."""
-    if amount <= 0:
+    amt = _finite_float(amount)
+    if amt is None or amt <= 0:
         return 0.0, 0.0
-    pct = float(stalemate_burn_pct() if burn_pct is None else burn_pct)
+    pct = _finite_float(stalemate_burn_pct() if burn_pct is None else burn_pct)
+    if pct is None:
+        raise ValueError("burn_pct must be finite")
     if pct <= 0:
-        return 0.0, float(amount)
+        return 0.0, amt
     if pct >= 1:
-        return float(amount), 0.0
-    burn = float(amount) * pct
-    returned = float(amount) - burn
+        return amt, 0.0
+    burn = amt * pct
+    returned = amt - burn
     return burn, returned
 
 
@@ -67,18 +82,17 @@ def apply_to_stakes(
     folds these into the larger ``ResolutionResult`` rather than
     mutating any state directly.
     """
-    pct = float(stalemate_burn_pct() if burn_pct is None else burn_pct)
+    pct = _finite_float(stalemate_burn_pct() if burn_pct is None else burn_pct)
+    if pct is None:
+        raise ValueError("burn_pct must be finite")
     returns: dict[tuple[str, str], float] = {}
     total_burned = 0.0
     for s in stakes:
         node_id = s.get("node_id") if isinstance(s, dict) else getattr(s, "node_id", None)
         rep_type = s.get("rep_type") if isinstance(s, dict) else getattr(s, "rep_type", None)
         amount = s.get("amount") if isinstance(s, dict) else getattr(s, "amount", None)
-        try:
-            amt = float(amount) if amount is not None else 0.0
-        except (TypeError, ValueError):
-            amt = 0.0
-        if amt <= 0 or not isinstance(node_id, str) or rep_type not in ("oracle", "common"):
+        amt = _finite_float(amount)
+        if amt is None or amt <= 0 or not isinstance(node_id, str) or rep_type not in ("oracle", "common"):
             continue
         burn, ret = split_burn_and_return(amt, pct)
         if ret > 0:

backend/services/infonet/tests/test_stalemate_burn_nonfinite_values.py

@@ -0,0 +1,35 @@
+"""Regression coverage for non-finite stalemate burn inputs."""
+
+import math
+
+import pytest
+
+from services.infonet.markets.stalemate_burn import apply_to_stakes, split_burn_and_return
+
+
+def test_split_rejects_nonfinite_amounts():
+    assert split_burn_and_return(float("nan"), 0.1) == (0.0, 0.0)
+    assert split_burn_and_return(float("inf"), 0.1) == (0.0, 0.0)
+
+
+def test_apply_skips_nonfinite_stakes_without_poisoning_totals():
+    returns, burned = apply_to_stakes(
+        [
+            {"node_id": "alice", "rep_type": "oracle", "amount": 10.0},
+            {"node_id": "mallory", "rep_type": "oracle", "amount": float("nan")},
+            {"node_id": "eve", "rep_type": "common", "amount": float("inf")},
+        ],
+        burn_pct=0.1,
+    )
+
+    assert returns == {("alice", "oracle"): 9.0}
+    assert burned == 1.0
+    assert math.isfinite(burned)
+
+
+def test_nonfinite_burn_percentage_is_rejected():
+    with pytest.raises(ValueError, match="burn_pct must be finite"):
+        split_burn_and_return(10.0, float("nan"))
+
+    with pytest.raises(ValueError, match="burn_pct must be finite"):
+        apply_to_stakes([], burn_pct=float("inf"))