support sending capability specific error codes

server/lib/aiGatewayAuthError.ts

@@ -0,0 +1,27 @@
+import {
+    AI_CAPABILITY_DEFS,
+    OPENAI_AUTH_ERROR_BODY,
+    type AiCapability
+} from "@server/lib/aiCapabilities";
+import HttpCode from "@server/types/HttpCode";
+
+export type ClientErrorResponse = {
+    statusCode?: number;
+    contentType?: string;
+    body: string;
+};
+
+export function buildInferenceAuthClientError(
+    capability: AiCapability | null
+): ClientErrorResponse {
+    const body =
+        capability != null
+            ? AI_CAPABILITY_DEFS[capability].authErrorBody
+            : OPENAI_AUTH_ERROR_BODY;
+
+    return {
+        statusCode: HttpCode.UNAUTHORIZED,
+        contentType: "application/json",
+        body: JSON.stringify(body)
+    };
+}