diff --git a/packages/api/src/endpoints/bedrock/initialize.spec.ts b/packages/api/src/endpoints/bedrock/initialize.spec.ts
index decf9a7df9..a06dbb779c 100644
--- a/packages/api/src/endpoints/bedrock/initialize.spec.ts
+++ b/packages/api/src/endpoints/bedrock/initialize.spec.ts
@@ -129,6 +129,7 @@ describe('initializeBedrock', () => {
         guardrailIdentifier: 'test-guardrail-id',
         guardrailVersion: '1',
         trace: 'enabled' as const,
+        streamProcessingMode: 'async',
       };
 
       const params = createMockParams({
diff --git a/packages/api/src/types/bedrock.ts b/packages/api/src/types/bedrock.ts
index 8f34b2864d..6608c52fcf 100644
--- a/packages/api/src/types/bedrock.ts
+++ b/packages/api/src/types/bedrock.ts
@@ -19,6 +19,8 @@ export interface GuardrailConfiguration {
   guardrailVersion: string;
   /** The trace behavior for the guardrail */
   trace?: 'enabled' | 'disabled' | 'enabled_full';
+  /** The processing mode for guardrail; 'sync' is the default guardrail behavior if unset */
+  streamProcessingMode?: 'sync' | 'async';
 }
 
 /**