Centralize validator classification and malformed output handling

internal/validators/metadata/metadata_test.go

@@ -16,6 +16,16 @@ func (u unclassifiedValidator) Validate(_ context.Context, _ contracts.Validatio
 	return frameworkvalidators.Result{ValidatorName: u.Name(), Decisions: nil}, nil
 }
 
+type namedUnclassifiedValidator struct {
+	name string
+}
+
+func (n namedUnclassifiedValidator) Name() string { return n.name }
+
+func (n namedUnclassifiedValidator) Validate(_ context.Context, _ contracts.ValidationRequest) (frameworkvalidators.Result, error) {
+	return frameworkvalidators.Result{ValidatorName: n.Name(), Decisions: nil}, nil
+}
+
 func TestClassOfDefaultsToDeterministic(t *testing.T) {
 	if got := ClassOf(unclassifiedValidator{}); got != ExecutionClassDeterministic {
 		t.Fatalf("expected deterministic default class, got %q", got)
@@ -28,3 +38,22 @@ func TestWrapExposesExecutionClass(t *testing.T) {
 		t.Fatalf("expected llm_backed class, got %q", got)
 	}
 }
+
+func TestClassForKey(t *testing.T) {
+	if got := ClassForKey(KeyProposalShape); got != ExecutionClassDeterministic {
+		t.Fatalf("expected deterministic class for %q, got %q", KeyProposalShape, got)
+	}
+	if got := ClassForKey(KeySpokenFormPlausibility); got != ExecutionClassLLMBacked {
+		t.Fatalf("expected llm_backed class for %q, got %q", KeySpokenFormPlausibility, got)
+	}
+	if got := ClassForKey("unknown"); got != ExecutionClassDeterministic {
+		t.Fatalf("expected deterministic fallback for unknown key, got %q", got)
+	}
+}
+
+func TestClassOfFallsBackToStableValidatorKey(t *testing.T) {
+	v := namedUnclassifiedValidator{name: KeyEditorialReview}
+	if got := ClassOf(v); got != ExecutionClassLLMBacked {
+		t.Fatalf("expected llm_backed fallback by key, got %q", got)
+	}
+}