fix(types): validate nonstreaming JSON contracts (#10258)

open-sse/handlers/chatCore.ts

@@ -104,7 +104,13 @@ import { resolveAgentGoalPolicy } from "../utils/agentGoalPolicy.ts";
 import { createStreamController } from "../utils/streamHandler.ts";
 import * as streamFailure from "../utils/streamFailureFinalization.ts";
 import { createSseHeartbeatTransform, shapeForClientFormat } from "../utils/sseHeartbeat.ts";
-import { addBufferToUsage, filterUsageForFormat, estimateUsage, sanitizeUsagePayloadForRequest } from "../utils/usageTracking.ts";
+import {
+  addBufferToUsage,
+  filterUsageForFormat,
+  estimateUsage,
+  normalizeUsage,
+  sanitizeUsagePayloadForRequest,
+} from "../utils/usageTracking.ts";
 import {
   refreshWithRetry,
   isUnrecoverableRefreshError,
@@ -271,7 +277,10 @@ import {
   appendNonStreamingSseTerminalSignal,
   type NonStreamingSseTerminalState,
 } from "./chatCore/nonStreamingSse.ts";
-import { parseNonStreamingResponseBody } from "./chatCore/nonStreamingResponseParse.ts";
+import {
+  isJsonRecord,
+  parseNonStreamingResponseBody,
+} from "./chatCore/nonStreamingResponseParse.ts";
 import { unwrapClinepassEnvelope } from "../utils/clinepassEnvelope.ts";
 import { recordNonStreamingUsageStats } from "./chatCore/nonStreamingUsageStats.ts";
 import {
@@ -4226,6 +4235,12 @@ export async function handleChatCore({
         trackPendingRequest(model, provider, connectionId, false);
         return createErrorResult(HTTP_STATUS.BAD_GATEWAY, envError.message);
       }
+      if (!isJsonRecord(unwrapped)) {
+        const invalidEnvelopeMessage = "Invalid JSON response from provider";
+        persistFailureUsage(HTTP_STATUS.BAD_GATEWAY, "clinepass_envelope_error");
+        trackPendingRequest(model, provider, connectionId, false);
+        return createErrorResult(HTTP_STATUS.BAD_GATEWAY, invalidEnvelopeMessage);
+      }
       responseBody = unwrapped;
     }
     responseBody = unwrapClineNonStreamingEnvelope(provider, responseBody);
@@ -4512,13 +4527,14 @@ export async function handleChatCore({
     );
     translatedResponse = postCallGuardrails.response;
 
-    const responseUsage =
-      (usage && typeof usage === "object" ? usage : null) ||
-      (translatedResponse?.usage && typeof translatedResponse.usage === "object"
+    const responseUsage = isJsonRecord(usage)
+      ? usage
+      : isJsonRecord(translatedResponse.usage)
         ? translatedResponse.usage
-        : null);
-    const estimatedCost = responseUsage
-      ? await calculateCost(provider, model, responseUsage, { serviceTier: effectiveServiceTier })
+        : null;
+    const costUsage = normalizeUsage(responseUsage);
+    const estimatedCost = costUsage
+      ? await calculateCost(provider, model, costUsage, { serviceTier: effectiveServiceTier })
       : 0;
 
     if (postCallGuardrails.blocked) {

open-sse/handlers/chatCore/clineResponseEnvelope.ts

@@ -8,6 +8,11 @@ function hasOpenAIChoices(value: unknown): value is JsonRecord & { choices: unkn
   return isRecord(value) && Array.isArray(value.choices);
 }
 
+export function unwrapClineNonStreamingEnvelope(
+  provider: string,
+  responseBody: JsonRecord
+): JsonRecord;
+export function unwrapClineNonStreamingEnvelope(provider: string, responseBody: unknown): unknown;
 export function unwrapClineNonStreamingEnvelope(provider: string, responseBody: unknown): unknown {
   if (provider !== "cline" || !isRecord(responseBody)) {
     return responseBody;

open-sse/handlers/chatCore/nonStreamingResponseParse.ts

@@ -28,10 +28,16 @@ type LoggerLike =
   | null
   | undefined;
 
+export type JsonRecord = Record<string, unknown>;
+
+export function isJsonRecord(value: unknown): value is JsonRecord {
+  return !!value && typeof value === "object" && !Array.isArray(value);
+}
+
 export type NonStreamingParseResult =
   | {
       kind: "ok";
-      responseBody: unknown;
+      responseBody: JsonRecord;
       responsePayloadFormat: string;
       looksLikeSSE: boolean;
       normalizedProviderPayload: unknown;
@@ -113,7 +119,16 @@ export async function parseNonStreamingResponseBody(opts: {
   }
 
   try {
-    const responseBody = rawBody ? JSON.parse(rawBody) : {};
+    const responseBody: unknown = rawBody ? JSON.parse(rawBody) : {};
+    if (!isJsonRecord(responseBody)) {
+      return {
+        kind: "invalid_json",
+        message: "Invalid JSON response from provider",
+        detailedError: "Invalid JSON response from provider: expected an object payload",
+        looksLikeSSE: false,
+        normalizedProviderPayload,
+      };
+    }
     return {
       kind: "ok",
       responseBody,

open-sse/handlers/responseSanitizer.ts

@@ -257,6 +257,14 @@ export interface SanitizeOpenAIResponseOptions {
   parseTextualReasoningTags?: boolean;
 }
 
+export function sanitizeOpenAIResponse(
+  body: JsonRecord,
+  options?: SanitizeOpenAIResponseOptions
+): JsonRecord;
+export function sanitizeOpenAIResponse(
+  body: unknown,
+  options?: SanitizeOpenAIResponseOptions
+): unknown;
 export function sanitizeOpenAIResponse(
   body: unknown,
   options: SanitizeOpenAIResponseOptions = {}
@@ -310,6 +318,8 @@ export function sanitizeOpenAIResponse(
   return sanitized;
 }
 
+export function sanitizeResponsesApiResponse(body: JsonRecord): JsonRecord;
+export function sanitizeResponsesApiResponse(body: unknown): unknown;
 export function sanitizeResponsesApiResponse(body: unknown): unknown {
   const bodyRecord = toRecord(body);
   if (!bodyRecord) return body;

open-sse/handlers/responseTranslator.ts

@@ -133,6 +133,18 @@ function findBestMessageText(output: unknown[]): {
  *
  * @param toolNameMap - Optional Map<prefixedName, originalName> for Claude OAuth tool name stripping
  */
+export function translateNonStreamingResponse(
+  responseBody: JsonRecord,
+  targetFormat: string,
+  sourceFormat: string,
+  toolNameMap?: Map<string, string> | null
+): JsonRecord;
+export function translateNonStreamingResponse(
+  responseBody: unknown,
+  targetFormat: string,
+  sourceFormat: string,
+  toolNameMap?: Map<string, string> | null
+): unknown;
 export function translateNonStreamingResponse(
   responseBody: unknown,
   targetFormat: string,

tests/unit/chatcore-non-streaming-response-parse.test.ts

@@ -62,6 +62,18 @@ test("invalid JSON → invalid_json with short message + detailed error", async
   assert.equal(res.looksLikeSSE, false);
 });
 
+test("valid JSON with a non-object root → invalid_json", async () => {
+  for (const body of ["null", '"text"', "[]"]) {
+    const res = await parseNonStreamingResponseBody({
+      ...baseOpts,
+      providerResponse: makeResponse(body, "application/json"),
+    });
+    assert.equal(res.kind, "invalid_json");
+    if (res.kind !== "invalid_json") continue;
+    assert.match(res.detailedError, /expected an object payload/);
+  }
+});
+
 test("valid SSE payload (by content-type) → ok with SSE-derived format", async () => {
   const sse =
     'data: {"id":"c1","object":"chat.completion.chunk","choices":[{"delta":{"content":"hello"},"index":0,"finish_reason":null}]}\n\n' +