feat: enforce layer0 gate and add tests

layer0/shadow_classifier.py

@@ -0,0 +1,93 @@
+from enum import Enum
+from typing import Optional, List
+import uuid
+
+
+class Classification(str, Enum):
+    BLESSED = "blessed"
+    AMBIGUOUS = "ambiguous"
+    FORBIDDEN = "forbidden"
+    CATASTROPHIC = "catastrophic"
+
+
+class ShadowEvalResult:
+    def __init__(
+        self,
+        classification: Classification,
+        reason: Optional[str] = None,
+        risk_score: int = 0,
+        flags: Optional[List[str]] = None,
+    ):
+        self.classification = classification
+        self.reason = reason
+        self.risk_score = risk_score
+        self.flags = flags or []
+        self.trace_id = str(uuid.uuid4())
+
+    def to_routing_action(self) -> str:
+        if self.classification == Classification.CATASTROPHIC:
+            return "FAIL_CLOSED"
+        if self.classification == Classification.FORBIDDEN:
+            return "HANDOFF_TO_GUARDRAILS"
+        if self.classification == Classification.AMBIGUOUS:
+            return "PROMPT_FOR_CLARIFICATION"
+        return "HANDOFF_TO_LAYER1"
+
+
+class ShadowClassifier:
+    """
+    Minimal doctrinal classifier for Layer 0 (Shadow Eval).
+    """
+
+    def classify(self, query: str) -> ShadowEvalResult:
+        """Return a doctrinal classification for the incoming query."""
+
+        q = query.lower().strip()
+
+        # 1. Catastrophic (fail closed)
+        if any(x in q for x in [
+            "disable guardrails",
+            "override agent permissions",
+            "bypass governance",
+            "self-modifying",
+        ]):
+            return ShadowEvalResult(
+                classification=Classification.CATASTROPHIC,
+                reason="catastrophic_indicator",
+                risk_score=5,
+                flags=["permission_override", "guardrail_disable"],
+            )
+
+        # 2. Forbidden (governance violation)
+        if any(x in q for x in [
+            "skip git",
+            "apply directly",
+            "dashboard",
+            "manual change",
+        ]):
+            return ShadowEvalResult(
+                classification=Classification.FORBIDDEN,
+                reason="governance_violation",
+                risk_score=3,
+                flags=["gitops_bypass"],
+            )
+
+        # 3. Ambiguous (needs clarification)
+        if any(x in q for x in [
+            "fix it",
+            "change this",
+            "update stuff",
+        ]) or len(q.split()) <= 2:
+            return ShadowEvalResult(
+                classification=Classification.AMBIGUOUS,
+                reason="insufficient_context",
+                risk_score=1,
+                flags=["needs_clarification"],
+            )
+
+        # 4. Blessed (valid + lawful)
+        return ShadowEvalResult(
+            classification=Classification.BLESSED,
+            reason=None,
+            risk_score=0,
+        )