diff --git a/src/main/java/it/cnr/isti/workflow/manager/assistant/FlowAssistantService.java b/src/main/java/it/cnr/isti/workflow/manager/assistant/FlowAssistantService.java
index 2dd9208..3843235 100644
--- a/src/main/java/it/cnr/isti/workflow/manager/assistant/FlowAssistantService.java
+++ b/src/main/java/it/cnr/isti/workflow/manager/assistant/FlowAssistantService.java
@@ -1152,6 +1152,7 @@ public class FlowAssistantService {
         normalizedConfig.put("name", defaultIfBlank(draft.name(), defaultIfBlank(blockPlan.purpose(), blockPlan.blockType())));
         injectSystemManagedFields(normalizedConfig, descriptor, model);
         ensureRequiredTextDefaults(normalizedConfig, descriptor, blockPlan);
+        normalizeHumanDecisionOptions(normalizedConfig, descriptor);
         normalizeHttpServerCallAuthorization(normalizedConfig, blockPlan);
         normalizeMcpAgentSharedMemory(normalizedConfig, blockPlan, model, requireSharedMemorySemantics);
         ensureSequentialInputPlaceholder(normalizedConfig, descriptor, blockPlan, blockIndex, blockCount);
@@ -1340,6 +1341,44 @@ public class FlowAssistantService {
         }
     }
 
+    /**
+     * HumanDecisionOption is (name, label): name is the routing key / branch output, label the
+     * display text. Models routinely emit "value" (or only "label") instead of "name", leaving name
+     * null - which produces null-named branch outputs. Fill a missing option name from its "value"
+     * (the intended routing key) or from a slug of its "label", so the flow is valid and each branch
+     * has a real output name.
+     */
+    private void normalizeHumanDecisionOptions(ObjectNode config,
+            BlockCatalogService.AssistantPromptBlockDescriptor descriptor) {
+        if (!isConfigurationType(descriptor.configurationType(), "HumanDecisionBlockConfiguration")) {
+            return;
+        }
+        if (!(config.get("options") instanceof ArrayNode options)) {
+            return;
+        }
+        for (JsonNode option : options) {
+            if (!(option instanceof ObjectNode optionObject) || hasTextValue(optionObject.get("name"))) {
+                continue;
+            }
+            String derived = hasTextValue(optionObject.get("value"))
+                    ? textOrNull(optionObject.get("value")).trim()
+                    : hasTextValue(optionObject.get("label"))
+                            ? slugifyOptionName(textOrNull(optionObject.get("label")))
+                            : null;
+            if (derived != null && !derived.isBlank()) {
+                optionObject.put("name", derived);
+            }
+        }
+    }
+
+    private String slugifyOptionName(String label) {
+        String slug = label.trim().toLowerCase(Locale.ROOT).replaceAll("[^a-z0-9]+", "-").replaceAll("(^-+|-+$)", "");
+        if (slug.isBlank()) {
+            return "option";
+        }
+        return Character.isLetter(slug.charAt(0)) ? slug : "opt-" + slug;
+    }
+
     private void removeSystemManagedFields(ObjectNode config) {
         config.remove(List.of("provider", "model", "llmDescriptor", "ids", "inputs", "outputs", "skills"));
     }
diff --git a/src/main/java/it/cnr/isti/workflow/manager/ios/IODescriptor.java b/src/main/java/it/cnr/isti/workflow/manager/ios/IODescriptor.java
index 00ab3d4..82ce70e 100644
--- a/src/main/java/it/cnr/isti/workflow/manager/ios/IODescriptor.java
+++ b/src/main/java/it/cnr/isti/workflow/manager/ios/IODescriptor.java
@@ -81,7 +81,7 @@ public class IODescriptor {
 
     @Override
     public int hashCode() {
-        return name.hashCode();
+        return java.util.Objects.hashCode(name);
     }
 
     @Override
@@ -91,6 +91,6 @@ public class IODescriptor {
         if (obj == null || getClass() != obj.getClass())
             return false;
         IODescriptor other = (IODescriptor) obj;
-        return name.equals(other.name);
+        return java.util.Objects.equals(name, other.name);
     }
 }
diff --git a/src/test/java/it/cnr/isti/workflow/manager/controllers/AssistantControllerTest.java b/src/test/java/it/cnr/isti/workflow/manager/controllers/AssistantControllerTest.java
index 7a7f8e9..b9a5ebb 100644
--- a/src/test/java/it/cnr/isti/workflow/manager/controllers/AssistantControllerTest.java
+++ b/src/test/java/it/cnr/isti/workflow/manager/controllers/AssistantControllerTest.java
@@ -2759,6 +2759,51 @@ public class AssistantControllerTest {
         assertEquals("Help the user plan a trip", configuration.getGoalDescription());
     }
 
+    @Test
+    public void draftNormalizesHumanDecisionOptionNamesFromValueOrLabel() {
+        // Models routinely emit HumanDecision options as {label, value} instead of {name, label},
+        // leaving the routing key (name) null - which used to make null-named branch outputs and a
+        // 500. The backend now fills name from value (or a slug of label) so the flow is valid.
+        Answer<String> answer = invocation -> {
+            String prompt = invocation.getArgument(1, String.class);
+            if (prompt.contains("TASK: PLAN")) {
+                return TestAssistantResponses.wrap(java.util.Map.of("rationale", "One review decision.",
+                        "plan", java.util.Map.of("name", "Review", "description", "desc",
+                                "blocks", java.util.List.of(java.util.Map.of("blockId", "b1",
+                                        "blockType", "HumanDecisionBlock", "purpose", "Approve or reject")))));
+            }
+            if (prompt.contains("TASK: BLOCK_CONFIG")) {
+                return TestAssistantResponses.wrap(java.util.Map.of("rationale", "decision config",
+                        "block", java.util.Map.of("blockId", "b1", "name", "review",
+                                "config", java.util.Map.of(
+                                        "question", "Is it ready for approval?",
+                                        "options", java.util.List.of(
+                                                java.util.Map.of("label", "Approve", "value", "yes"),
+                                                java.util.Map.of("label", "Reject")), // only label, no value
+                                        "rationaleRequired", true))));
+            }
+            throw new IllegalStateException("Unexpected assistant prompt:\n" + prompt);
+        };
+        Mockito.when(internalOllamaLLMProvider.generate(Mockito.eq(MODEL), Mockito.anyString())).thenAnswer(answer);
+        Mockito.when(internalOllamaLLMProvider.generateJson(Mockito.eq(MODEL), Mockito.anyString())).thenAnswer(answer);
+
+        AssistantFlowResponse response = assistantController.draft(
+                new AssistantGenerationRequest("a human review that approves or rejects", MODEL, 1));
+
+        assertNotNull(response);
+        assertTrue(response.valid(), () -> "Unexpected validation errors: " + response.validationErrors());
+        it.cnr.isti.workflow.manager.blocks.configurations.HumanDecisionBlockConfiguration configuration =
+                (it.cnr.isti.workflow.manager.blocks.configurations.HumanDecisionBlockConfiguration)
+                        response.flow().flow().getBlocks().getFirst().getSpecificConfiguration();
+        java.util.List<String> optionNames = configuration.getOptions().stream()
+                .map(it.cnr.isti.workflow.manager.blocks.configurations.HumanDecisionOption::name).toList();
+        // "yes" taken from value; "reject" slugged from the label (no value given).
+        assertEquals(java.util.List.of("yes", "reject"), optionNames);
+        // The branch outputs are named accordingly (never null).
+        assertTrue(response.flow().flow().getBlocks().getFirst().getOutputs().stream()
+                .allMatch(output -> output.getName() != null && !output.getName().isBlank()));
+    }
+
     static class TestAssistantResponses {
         private static final String PROVIDER = "InternalOllama";