format custom error codes according to capability

server/lib/aiGatewayAuthError.ts

@@ -1,7 +1,7 @@
 import {
     AI_CAPABILITY_DEFS,
-    OPENAI_AUTH_ERROR_BODY,
-    type AiCapability
+    type AiCapability,
+    type AiProtocolFamily
 } from "@server/lib/aiCapabilities";
 import HttpCode from "@server/types/HttpCode";
 
@@ -11,17 +11,129 @@ export type ClientErrorResponse = {
     body: string;
 };
 
+export type AiCapabilityErrorKind =
+    | "authentication"
+    | "invalid_request"
+    | "not_found"
+    | "permission"
+    | "rate_limit"
+    | "internal";
+
+const AUTH_MESSAGE = "Invalid API key provided.";
+
+type KindFields = {
+    openaiType: string;
+    openaiCode: string | null;
+    anthropicType: string;
+    googleStatus: string;
+};
+
+const KIND_FIELDS: Record<AiCapabilityErrorKind, KindFields> = {
+    authentication: {
+        openaiType: "authentication_error",
+        openaiCode: "invalid_api_key",
+        anthropicType: "authentication_error",
+        googleStatus: "UNAUTHENTICATED"
+    },
+    invalid_request: {
+        openaiType: "invalid_request_error",
+        openaiCode: null,
+        anthropicType: "invalid_request_error",
+        googleStatus: "INVALID_ARGUMENT"
+    },
+    not_found: {
+        openaiType: "invalid_request_error",
+        openaiCode: null,
+        anthropicType: "not_found_error",
+        googleStatus: "NOT_FOUND"
+    },
+    permission: {
+        openaiType: "invalid_request_error",
+        openaiCode: null,
+        anthropicType: "permission_error",
+        googleStatus: "PERMISSION_DENIED"
+    },
+    rate_limit: {
+        openaiType: "rate_limit_error",
+        openaiCode: "rate_limit_exceeded",
+        anthropicType: "rate_limit_error",
+        googleStatus: "RESOURCE_EXHAUSTED"
+    },
+    internal: {
+        openaiType: "api_error",
+        openaiCode: null,
+        anthropicType: "api_error",
+        googleStatus: "INTERNAL"
+    }
+};
+
+function resolveProtocolFamily(
+    capability: AiCapability | null
+): AiProtocolFamily {
+    if (capability == null) {
+        return "openai";
+    }
+    return AI_CAPABILITY_DEFS[capability].protocolFamily;
+}
+
+/**
+ * Build a protocol-native error body for the given capability.
+ * Message stays contextual; only the envelope/machine fields follow the
+ * capability's native API shape.
+ */
+export function buildAiCapabilityErrorBody(
+    capability: AiCapability | null,
+    kind: AiCapabilityErrorKind,
+    message: string,
+    httpStatus?: number
+): Record<string, unknown> {
+    const family = resolveProtocolFamily(capability);
+    const fields = KIND_FIELDS[kind];
+
+    switch (family) {
+        case "openai":
+            return {
+                error: {
+                    message,
+                    type: fields.openaiType,
+                    param: null,
+                    code: fields.openaiCode
+                }
+            };
+        case "anthropic":
+            return {
+                type: "error",
+                error: {
+                    type: fields.anthropicType,
+                    message
+                }
+            };
+        case "google":
+            return {
+                error: {
+                    code: httpStatus ?? HttpCode.BAD_REQUEST,
+                    message,
+                    status: fields.googleStatus
+                }
+            };
+        case "bedrock":
+            return { message };
+    }
+}
+
 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)
+        body: JSON.stringify(
+            buildAiCapabilityErrorBody(
+                capability,
+                "authentication",
+                AUTH_MESSAGE,
+                HttpCode.UNAUTHORIZED
+            )
+        )
     };
 }