fix(sandbox): reject non-finite ownership timings (#4960)

backend/packages/harness/deerflow/config/sandbox_config.py

@@ -29,6 +29,7 @@ class SandboxOwnershipConfig(BaseModel):
     renewal_interval_seconds: float = Field(
         default=30.0,
         gt=0,
+        allow_inf_nan=False,
         description=(
             "How often an owning instance refreshes its leases. The lease TTL is derived from this (interval x ttl_multiplier), so ownership liveness is independent of sandbox.idle_timeout: "
             "renewal keeps running even when idle cleanup is disabled (idle_timeout: 0)."
@@ -37,6 +38,7 @@ class SandboxOwnershipConfig(BaseModel):
     ttl_multiplier: float = Field(
         default=4.0,
         ge=2,
+        allow_inf_nan=False,
         description="Lease TTL as a multiple of renewal_interval_seconds. At least 2, so a single missed renewal (slow host, brief Redis blip) cannot expire a live owner's lease. Default 4 tolerates three consecutive misses.",
     )
     key_prefix: str = Field(

backend/tests/test_sandbox_ownership_store.py

@@ -356,6 +356,13 @@ def test_ttl_multiplier_below_two_is_rejected():
         SandboxOwnershipConfig(ttl_multiplier=1.0)
 
 
+@pytest.mark.parametrize("field", ["renewal_interval_seconds", "ttl_multiplier"])
+@pytest.mark.parametrize("value", [float("inf"), float("-inf"), float("nan")])
+def test_lease_timing_rejects_non_finite_values(field, value):
+    with pytest.raises(ValueError):
+        SandboxOwnershipConfig(**{field: value})
+
+
 def test_owner_ids_are_unique_per_instance():
     """Two workers on one host must not share an owner id."""
     assert generate_owner_id() != generate_owner_id()