fix(explorer): /api/decisions returns 422 — coerce decision timestamp to str

semantica/explorer/routes/decisions.py

@@ -23,7 +23,7 @@ def _node_to_decision(node: dict) -> DecisionResponse:
         reasoning=properties.get("reasoning", ""),
         outcome=properties.get("outcome", ""),
         confidence=float(properties.get("confidence", 0.0) or 0.0),
-        timestamp=properties.get("timestamp"),
+        timestamp=None if properties.get("timestamp") is None else str(properties.get("timestamp")),
         metadata=properties,
     )
 

tests/explorer/test_decision_route_timestamp.py

@@ -0,0 +1,92 @@
+"""Unit tests for the explorer decision route adapter.
+
+Regression coverage for the ``/api/decisions`` 422 bug: a decision node
+whose ``timestamp`` is stored as a POSIX float (the format
+``ContextGraph.record_decision`` writes) must not break Pydantic
+validation of ``DecisionResponse`` (typed ``Optional[str]``).
+"""
+
+import math
+
+from semantica.explorer.routes.decisions import _node_to_decision
+from semantica.explorer.schemas import DecisionResponse
+
+
+def _decision_node(timestamp):
+    """Build a minimal decision node dict shaped like ContextGraph.to_dict()."""
+    return {
+        "id": "d-1",
+        "type": "decision",
+        "properties": {
+            "category": "loan_underwriting",
+            "scenario": "A-7291 review",
+            "reasoning": "DTI within policy",
+            "outcome": "approved",
+            "confidence": 0.94,
+            "timestamp": timestamp,
+        },
+    }
+
+
+def test_timestamp_float_is_coerced_to_str():
+    """A POSIX-float timestamp (what record_decision stores) must validate.
+
+    Before the fix this raised a ValidationError (422 on the endpoint).
+    """
+    node = _decision_node(timestamp=1786513069.694965)
+
+    decision = _node_to_decision(node)
+
+    assert isinstance(decision, DecisionResponse)
+    assert decision.timestamp == "1786513069.694965"
+    # round-trips through Pydantic strict str validation
+    assert decision.confidence == 0.94
+    assert decision.outcome == "approved"
+
+
+def test_timestamp_int_is_coerced_to_str():
+    """Integer timestamps (some stores serialize without sub-second precision)
+    are handled by the same coercion path."""
+    decision = _node_to_decision(_decision_node(timestamp=1786513069))
+
+    assert decision.timestamp == "1786513069"
+
+
+def test_timestamp_none_is_preserved():
+    """A missing timestamp must stay None, not become the string 'None'."""
+    decision = _node_to_decision(_decision_node(timestamp=None))
+
+    assert decision.timestamp is None
+
+
+def test_timestamp_str_passes_through():
+    """An already-string timestamp is left intact."""
+    decision = _node_to_decision(_decision_node(timestamp="2026-08-12T10:04:20"))
+
+    assert decision.timestamp == "2026-08-12T10:04:20"
+
+
+def test_timestamp_missing_key_defaults_to_none():
+    """A decision node without a timestamp key at all should not raise."""
+    node = {
+        "id": "d-2",
+        "type": "decision",
+        "properties": {"category": "x", "outcome": "y"},
+    }
+
+    decision = _node_to_decision(node)
+
+    assert decision.timestamp is None
+
+
+def test_float_timestamp_not_nan_or_inf():
+    """Sanity guard: degenerate float values still coerce to a finite string
+    rather than crashing validation."""
+    for value in (float("nan"), float("inf")):
+        node = _decision_node(timestamp=value)
+        decision = _node_to_decision(node)
+        assert isinstance(decision.timestamp, str)
+        if math.isnan(value):
+            assert "nan" in decision.timestamp.lower()
+        else:
+            assert "inf" in decision.timestamp.lower()