diff --git a/lib/foundation/fabro-api/tests/workflow_version_round_trip.rs b/lib/foundation/fabro-api/tests/workflow_version_round_trip.rs
index 894c1c910..3bf0c8835 100644
--- a/lib/foundation/fabro-api/tests/workflow_version_round_trip.rs
+++ b/lib/foundation/fabro-api/tests/workflow_version_round_trip.rs
@@ -1,12 +1,14 @@
 use std::any::{TypeId, type_name};
 
 use fabro_api::types::{
-    WorkflowPath as ApiWorkflowPath, WorkflowVersion as ApiWorkflowVersion,
-    WorkflowVersionId as ApiWorkflowVersionId,
+    CreateWorkflowVersionResponse, WorkflowPath as ApiWorkflowPath,
+    WorkflowVersion as ApiWorkflowVersion, WorkflowVersionId as ApiWorkflowVersionId,
 };
 use fabro_types::{WorkflowPath, WorkflowVersion, WorkflowVersionId};
 use serde_json::json;
 
+const DEPENDENCY_ID: &str = "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef";
+
 #[test]
 fn workflow_version_schemas_reuse_domain_types() {
     assert_same_type::<ApiWorkflowPath, WorkflowPath>();
@@ -22,13 +24,38 @@ fn workflow_version_round_trips_exact_wire_shape() {
             "prompts/goal.md": "Ship it",
             "workflow.fabro": "digraph W { start [shape=Mdiamond] exit [shape=Msquare] start -> exit }"
         },
-        "workflow_dependencies": {}
+        "workflow_dependencies": { "children/check.fabro": DEPENDENCY_ID }
     });
 
     let version: ApiWorkflowVersion = serde_json::from_value(value.clone()).unwrap();
     assert_eq!(serde_json::to_value(version).unwrap(), value);
 }
 
+#[test]
+fn create_workflow_version_response_round_trips_exact_wire_shape() {
+    let value = json!({ "workflow_version_id": DEPENDENCY_ID });
+
+    let response: CreateWorkflowVersionResponse = serde_json::from_value(value.clone()).unwrap();
+    assert_eq!(serde_json::to_value(&response).unwrap(), value);
+}
+
+#[test]
+fn workflow_version_id_emits_the_documented_lowercase_pattern() {
+    // Input is accepted case-insensitively, but serialization must match the
+    // OpenAPI schema pattern `^[0-9a-f]{64}$`.
+    let id = serde_json::from_value::<ApiWorkflowVersionId>(json!(DEPENDENCY_ID.to_uppercase()))
+        .unwrap();
+    let emitted = serde_json::to_value(id).unwrap();
+    assert_eq!(emitted, json!(DEPENDENCY_ID));
+
+    let text = emitted.as_str().unwrap();
+    assert_eq!(text.len(), 64);
+    assert!(
+        text.bytes()
+            .all(|byte| matches!(byte, b'0'..=b'9' | b'a'..=b'f'))
+    );
+}
+
 #[test]
 fn workflow_version_replacement_rejects_unknown_fields() {
     let value = json!({