[WRONG BRANCH] fix(web-search): bound xAI error response bodies

src/web-search/xai-executor.ts

@@ -14,6 +14,7 @@ import type { OcxProviderConfig } from "../types";
 import { getValidAccessToken, publicOAuthAuthenticationErrorMessage } from "../oauth";
 import { fetchWithResetRetry } from "../lib/upstream-retry";
 import { cancelBodyOnAbort, signalWithTimeout } from "../lib/abort";
+import { readBoundedResponseBytes } from "../lib/bounded-body";
 import { sidecarEnter } from "../lib/sidecar-tracker";
 import { redactSecretString } from "../lib/redact";
 import { MAX_SIDECAR_RESPONSE_BYTES, type WebSearchSource } from "./parse";
@@ -114,10 +115,19 @@ export async function runXaiWebSearch(
     );
     const detachBodyGuard = cancelBodyOnAbort(res.body, linkedSignal.signal);
     if (!res.ok) {
-      const t = await res.text().catch(() => "");
-      detachBodyGuard();
-      const entitlement = res.status === 401 || res.status === 403 ? " (Grok OAuth entitlement — re-run ocx login xai?)" : "";
-      return { text: "", sources: [], error: `xai sidecar HTTP ${res.status}${entitlement}: ${redactSecretString(t.slice(0, 200))}` };
+      try {
+        const bounded = await readBoundedResponseBytes(res, {
+          maxBytes: MAX_SIDECAR_RESPONSE_BYTES,
+          signal: linkedSignal.signal,
+        });
+        const detail = bounded.oversized
+          ? "response body exceeded byte bound"
+          : redactSecretString(new TextDecoder().decode(bounded.bytes).slice(0, 200));
+        const entitlement = res.status === 401 || res.status === 403 ? " (Grok OAuth entitlement — re-run ocx login xai?)" : "";
+        return { text: "", sources: [], error: `xai sidecar HTTP ${res.status}${entitlement}: ${detail}` };
+      } finally {
+        detachBodyGuard();
+      }
     }
     try {
       return await parseXaiResponsesSSE(res);

tests/xai-web-search.test.ts

@@ -157,6 +157,34 @@ describe("credential pinning + loop fail-closed (review blockers)", () => {
       globalThis.fetch = realFetch;
     }
   });
+
+  test("non-OK response bodies are byte-bounded and canceled upstream", async () => {
+    let producedBytes = 0;
+    let canceled = false;
+    const chunk = new Uint8Array(1024).fill(0x61);
+    const realFetch = globalThis.fetch;
+    globalThis.fetch = (async () => new Response(new ReadableStream({
+      pull(controller) {
+        producedBytes += chunk.byteLength;
+        controller.enqueue(chunk);
+      },
+      cancel() {
+        canceled = true;
+      },
+    }), { status: 500 })) as typeof fetch;
+    try {
+      const { runXaiWebSearch } = await import("../src/web-search/xai-executor");
+      const out = await runXaiWebSearch("q", "xai", xaiProvider, { model: "grok-4.6", reasoning: "low", timeoutMs: 5000, describeImages: false });
+
+      expect(out.error).toContain("response body exceeded byte bound");
+      // The stream implementation may prefetch a small number of chunks, but it must
+      // stop near the cap rather than consume an arbitrarily large upstream body.
+      expect(producedBytes).toBeLessThanOrEqual(MAX_SIDECAR_RESPONSE_BYTES + (4 * chunk.byteLength));
+      expect(canceled).toBe(true);
+    } finally {
+      globalThis.fetch = realFetch;
+    }
+  });
 });
 
 import { runWithWebSearch, type WebSearchLoopDeps } from "../src/web-search/loop";