diff --git a/src/oauth/nous.ts b/src/oauth/nous.ts
index 56d74b5e48..94eb7780ab 100644
--- a/src/oauth/nous.ts
+++ b/src/oauth/nous.ts
@@ -39,6 +39,7 @@ import { join } from "node:path";
 import type { OAuthController, OAuthCredentials } from "./types";
 import { getAuthStorePath } from "./store";
 import { atomicWriteFile, hardenConfigDir, hardenExistingSecret } from "../config";
+import { BOUNDED_BODY_MAX_BYTES, readBoundedResponseBytes } from "../lib/bounded-body";
 
 export const NOUS_PORTAL_BASE_URL = "https://portal.nousresearch.com";
 export const NOUS_INFERENCE_BASE_URL = "https://inference-api.nousresearch.com/v1";
@@ -87,6 +88,27 @@ interface NousJwtPayload {
   [key: string]: unknown;
 }
 
+async function readOAuthJson(response: Response): Promise<unknown> {
+  const { bytes, oversized } = await readBoundedResponseBytes(response, {
+    maxBytes: BOUNDED_BODY_MAX_BYTES,
+  });
+  if (oversized) {
+    throw new NousTokenError(
+      response.status,
+      "response_too_large",
+      `Nous Portal OAuth response exceeded the ${BOUNDED_BODY_MAX_BYTES}-byte limit`,
+    );
+  }
+  return JSON.parse(new TextDecoder("utf-8", { fatal: true }).decode(bytes));
+}
+
+async function readOAuthJsonOrEmpty(response: Response): Promise<unknown> {
+  return readOAuthJson(response).catch((error) => {
+    if (error instanceof NousTokenError && error.oauthError === "response_too_large") throw error;
+    return {};
+  });
+}
+
 // ── Durable refresh-intent (review blocker #2) ──────────────────────────────
 // A refresh-intent file records that we submitted `refreshToken` to the Portal
 // and whether we are certain the rotated token was persisted. It lives next to
@@ -505,12 +527,12 @@ async function requestDeviceAuthorization(signal?: AbortSignal): Promise<{
     redirect: "error",
     signal: requestSignal(signal),
   });
-  if (!response.ok) throw tokenErrorFromPayload(response.status, await response.json().catch(() => ({})));
+  if (!response.ok) throw tokenErrorFromPayload(response.status, await readOAuthJsonOrEmpty(response));
   // A successful HTTP response may still carry an empty/HTML/non-JSON body.
   // Fall back to an empty object so the required-field check below produces the
   // clear "missing required fields" validation error instead of leaking a raw
   // JSON parser exception.
-  const payload = (await response.json().catch(() => ({}))) as NousDeviceAuthorizationResponse;
+  const payload = (await readOAuthJsonOrEmpty(response)) as NousDeviceAuthorizationResponse;
   const userCode = nonEmptyString(payload.user_code);
   const deviceCode = nonEmptyString(payload.device_code);
   const verificationUri = nonEmptyString(payload.verification_uri_complete) ?? nonEmptyString(payload.verification_uri);
@@ -576,7 +598,7 @@ async function pollForToken(
     // Normalize a successful-but-non-object body (for example valid JSON
     // `null`) to an empty object so the required-field validation below
     // produces a terminal NousTokenError instead of a raw TypeError.
-    const parsed = (await response.json().catch(() => ({}))) as unknown;
+    const parsed = await readOAuthJsonOrEmpty(response);
     const payload = (parsed && typeof parsed === "object" ? parsed : {}) as NousTokenResponse;
     if (Date.now() >= deadline) break;
     if (response.ok) return parseTokenPayload(payload, "");
@@ -703,7 +725,6 @@ export async function refreshNousToken(refreshToken: string, signal?: AbortSigna
 
   if (!response.ok) {
     const status = response.status;
-    const payload = await response.json().catch(() => ({}));
     // The request reached the Portal's token endpoint. A non-2xx response does
     // NOT establish that the single-use refresh token was not consumed: 429
     // rate limits, unknown/custom 4xx, and gateway-generated client-class
@@ -719,6 +740,7 @@ export async function refreshNousToken(refreshToken: string, signal?: AbortSigna
       // The pre-dispatch "submitted" intent is still on disk, which also
       // blocks replay; surface the original HTTP error below.
     }
+    const payload = await readOAuthJsonOrEmpty(response);
     throw tokenErrorFromPayload(status, payload);
   }
 
@@ -727,7 +749,7 @@ export async function refreshNousToken(refreshToken: string, signal?: AbortSigna
   // replay it. On success we deliberately LEAVE the intent as "submitted"
   // (the store clears it once the rotated token is persisted).
   try {
-    const creds = parseTokenPayload((await response.json()) as NousTokenResponse, refreshToken);
+    const creds = parseTokenPayload((await readOAuthJson(response)) as NousTokenResponse, refreshToken);
     return creds;
   } catch (e) {
     try {
diff --git a/tests/nous-oauth.test.ts b/tests/nous-oauth.test.ts
index 8accc3b117..e61c3cace1 100644
--- a/tests/nous-oauth.test.ts
+++ b/tests/nous-oauth.test.ts
@@ -6,6 +6,7 @@ import { clearNousRefreshIntent, identityFromNousTokens, loginNous, nousRefreshI
 import { getCredential, listAccounts, saveCredential } from "../src/oauth/store";
 import type { OAuthController } from "../src/oauth/types";
 import * as configModule from "../src/config";
+import { BOUNDED_BODY_MAX_BYTES } from "../src/lib/bounded-body";
 
 const TEST_DIR = join(import.meta.dir, ".tmp-nous-oauth-test");
 const TEST_PORTAL = "https://portal.test";
@@ -149,6 +150,47 @@ describe("Nous token-response wiring", () => {
     expect(cred.accountId).toBe("device-user");
   });
 
+  test.each([200, 400])("rejects oversized device-authorization responses with HTTP %i", async (status) => {
+    globalThis.fetch = (async () =>
+      new Response("x".repeat(BOUNDED_BODY_MAX_BYTES + 1), { status })) as typeof fetch;
+
+    await expect(loginNous({ onAuth() {} })).rejects.toMatchObject({
+      name: "NousTokenError",
+      oauthError: "response_too_large",
+    });
+  });
+
+  test("rejects oversized device-token responses at the bounded OAuth reader", async () => {
+    globalThis.fetch = (async (input: RequestInfo | URL) => {
+      if (String(input).endsWith("/api/oauth/device/code")) {
+        return new Response(JSON.stringify({
+          device_code: "dev-123",
+          user_code: "ABCD-EFGH",
+          verification_uri: "https://portal.nousresearch.com/activate",
+          expires_in: 60,
+          interval: 1,
+        }), { status: 200 });
+      }
+      return new Response("x".repeat(BOUNDED_BODY_MAX_BYTES + 1), { status: 200 });
+    }) as typeof fetch;
+
+    await expect(loginNous({ onAuth() {} })).rejects.toMatchObject({
+      name: "NousTokenError",
+      oauthError: "response_too_large",
+    });
+  });
+
+  test.each([200, 400])("rejects oversized refresh responses with HTTP %i", async (status) => {
+    globalThis.fetch = (async () =>
+      new Response("x".repeat(BOUNDED_BODY_MAX_BYTES + 1), { status })) as typeof fetch;
+
+    await expect(refreshNousToken(`old-refresh-${status}`)).rejects.toMatchObject({
+      name: "NousTokenError",
+      oauthError: "response_too_large",
+    });
+    expect(nousRefreshIntentBlocksReplay(`old-refresh-${status}`)).toBe(true);
+  });
+
   test("an implausible JWT exp falls back to expires_in instead of pinning a never-expiring credential", async () => {
     // A too-large `exp` (e.g. milliseconds instead of seconds, or clock skew)
     // must not produce an expiry so far in the future that the credential is