Strengthen validation retries and checkpoint safety

internal/modules/dnd/validate/npcoccurrences/registry/validator.go

@@ -105,9 +105,10 @@ func (v *Validator) Validate(_ context.Context, req contracts.TypedValidationReq
 
 func rejection(issues []string) contracts.ValidationResult {
 	return contracts.ValidationResult{
-		Approved:   false,
-		ReasonCode: ReasonCode,
-		Message:    diagnostics.Aggregate("invalid NPC occurrence registry", issues),
+		Approved:           false,
+		ReasonCode:         ReasonCode,
+		Message:            diagnostics.Aggregate("invalid NPC occurrence registry", issues),
+		CorrectionGuidance: "Return NPC occurrences using contextual NPC names that match an NPC in the supplied registry; omit occurrences that cannot be matched unambiguously.",
 	}
 }
 

internal/modules/dnd/validate/npcoccurrences/registry/validator_test.go

@@ -29,6 +29,12 @@ func TestValidatorRecognizesExactRegistryPairsAndRejectsUnknownIDs(t *testing.T)
 	if err != nil || result.Approved || result.ReasonCode != ReasonCode || !strings.Contains(result.Message, "occurrences[0].npc_id") {
 		t.Fatalf("unknown result = %#v, %v", result, err)
 	}
+	if err := contracts.ValidateValidationResult(result); err != nil {
+		t.Fatalf("ValidateValidationResult() error = %v for %#v", err, result)
+	}
+	if !strings.Contains(result.CorrectionGuidance, "contextual NPC names") || strings.Contains(result.CorrectionGuidance, value.Occurrences[0].NPCID) {
+		t.Fatalf("correction guidance = %q, want contextual names without opaque IDs", result.CorrectionGuidance)
+	}
 	value = validList("Mira Thorn")
 	value.Occurrences[0].Name = "Hooded Guard"
 	result, err = validator.Validate(context.Background(), request(references, value))