fix(agent): bound proxy error response parsing (#97351)

zhangguiping-xydt · web-flow · commit 27c1685f106d · 2026-06-28T11:53:09.000-04:00
diff --git a/src/agents/runtime/proxy.test.ts b/src/agents/runtime/proxy.test.ts
@@ -60,6 +60,33 @@ function responseFromReaderText(text: string, releaseLock: () => void): Response
   } as Response;
 }
 
+function streamingProxyErrorResponse(params: { chunkCount: number; chunkSize: number }): {
+  response: Response;
+  getReadCount: () => number;
+} {
+  let reads = 0;
+  const encoder = new TextEncoder();
+  const stream = new ReadableStream<Uint8Array>({
+    pull(controller) {
+      if (reads >= params.chunkCount) {
+        controller.close();
+        return;
+      }
+      reads += 1;
+      controller.enqueue(encoder.encode("a".repeat(params.chunkSize)));
+    },
+  });
+
+  return {
+    response: new Response(stream, {
+      status: 502,
+      statusText: "Bad Gateway",
+      headers: { "Content-Type": "application/json" },
+    }),
+    getReadCount: () => reads,
+  };
+}
+
 describe("streamProxy", () => {
   afterEach(() => {
     vi.unstubAllGlobals();
@@ -168,6 +195,30 @@ describe("streamProxy", () => {
     expect(releaseLock).toHaveBeenCalledTimes(1);
   });
 
+  it("stops reading oversized proxy error JSON responses", async () => {
+    const streamed = streamingProxyErrorResponse({ chunkCount: 20, chunkSize: 1024 * 1024 });
+    vi.stubGlobal(
+      "fetch",
+      vi.fn(async () => streamed.response),
+    );
+
+    const stream = streamProxy(model, context, {
+      authToken: "token",
+      proxyUrl: "https://proxy.example",
+    });
+    const events = [];
+    for await (const event of stream) {
+      events.push(event);
+    }
+
+    expect(events.at(-1)?.type).toBe("error");
+    await expect(stream.result()).resolves.toMatchObject({
+      stopReason: "error",
+      errorMessage: "Proxy error: 502 Bad Gateway",
+    });
+    expect(streamed.getReadCount()).toBeLessThan(20);
+  });
+
   it("returns an error result when EOF arrives without a terminal event", async () => {
     vi.stubGlobal(
       "fetch",
diff --git a/src/agents/runtime/proxy.ts b/src/agents/runtime/proxy.ts
@@ -15,6 +15,7 @@ import type {
 } from "../../llm/types.js";
 import { EventStream } from "../../llm/utils/event-stream.js";
 import { parseStreamingJson } from "../../llm/utils/json-parse.js";
+import { readProviderJsonResponse } from "../provider-http-errors.js";
 
 type StreamingToolCall = ToolCall & { partialJson?: string };
 
@@ -181,13 +182,14 @@ export function streamProxy(
       if (!response.ok) {
         let errorMessage = `Proxy error: ${response.status} ${response.statusText}`;
         try {
-          const errorData = (await response.json()) as { error?: string };
+          const errorData = await readProviderJsonResponse<{ error?: string }>(
+            response,
+            "Proxy error response",
+          );
           if (errorData.error) {
             errorMessage = `Proxy error: ${errorData.error}`;
           }
-        } catch {
-          // Couldn't parse error response
-        }
+        } catch {}
         throw new Error(errorMessage);
       }
 
