🚧 feat: Support Guardrail Config Option streamProcessingMode (#12815)

`streamProcessingMode` affects how guardrail processes the stream from
the model. If it's in "sync" mode, it chunks up the response and processes
them before returning them to the user. If it's in "async" mode, it
both processes the chunk & sends it to the user at the same time, allowing
for smoother streaming (at the cost of guardrail only reacting *after*
offending content starts to stream, in some cases).

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({

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';
 }
 
 /**