@@ -43,9 +43,20 @@ module.exports.fetch = function fetch (init, options = undefined) {
   })
 }
 module.exports.FormData = require('./lib/web/fetch/formdata').FormData
-module.exports.Headers = require('./lib/web/fetch/headers').Headers
-module.exports.Response = require('./lib/web/fetch/response').Response
-module.exports.Request = require('./lib/web/fetch/request').Request
+const { Headers, HeadersList } = require('./lib/web/fetch/headers')
+module.exports.Headers = Headers
+module.exports.HeadersList = HeadersList
+const { Response, getResponseState } = require('./lib/web/fetch/response')
+module.exports.Response = Response
+module.exports.getResponseState = getResponseState
+const {
+  Request,
+  makeRequest,
+  fromInnerRequest
+} = require('./lib/web/fetch/request')
+module.exports.Request = Request
+module.exports.makeRequest = makeRequest
+module.exports.fromInnerRequest = fromInnerRequest
 
 const { CloseEvent, ErrorEvent, MessageEvent, createFastMessageEvent } = require('./lib/web/websocket/events')
 module.exports.WebSocket = require('./lib/web/websocket/websocket').WebSocket
 
@@ -4,9 +4,10 @@ const assert = require('node:assert')
 
 const { kConstruct } = require('../../core/symbols')
 const { urlEquals, getFieldValues } = require('./util')
-const { kEnumerableProperty, isDisturbed } = require('../../core/util')
+const { kEnumerableProperty } = require('../../core/util')
 const { webidl } = require('../webidl')
 const { cloneResponse, fromInnerResponse, getResponseState } = require('../fetch/response')
+const { isBodyStreamDisturbedOrLocked } = require('../fetch/body')
 const { Request, fromInnerRequest, getRequestState } = require('../fetch/request')
 const { fetching } = require('../fetch/index')
 const { urlIsHttpHttpsScheme, readAllBytes } = require('../fetch/util')
@@ -312,11 +313,9 @@ class Cache {
     }
 
     // 8.
-    // A lazily-materialized response body (e.g. `new Response('...')`) has a
-    // null stream until it is first observed; an unobserved body cannot be
-    // disturbed or locked, so treat a null stream as neither. The subsequent
-    // clone (step 9) materializes the stream before it is read in step 11.
-    if (innerResponse.body && innerResponse.body.stream != null && (isDisturbed(innerResponse.body.stream) || innerResponse.body.stream.locked)) {
+    // The subsequent clone (step 9) materializes a lazy body's stream before it
+    // is read in step 11, so an as-yet-unobserved (null) stream is fine here.
+    if (isBodyStreamDisturbedOrLocked(innerResponse.body)) {
       throw webidl.errors.exception({
         header: prefix,
         message: 'Response body is locked or disturbed'
 
@@ -616,6 +616,21 @@ function consumeBody (object, convertBytesToJSValue, instance, getInternalState)
   return promise.promise
 }
 
+/**
+ * Whether a body's stream is disturbed or locked.
+ *
+ * A lazily-materialized body (e.g. `new Response('...')`) has a null stream
+ * until it is first observed; an unobserved stream can be neither disturbed nor
+ * locked, so a null stream counts as neither.
+ *
+ * @param {{ stream: ReadableStream | null } | null | undefined} body a body, or null
+ * @returns {boolean}
+ */
+function isBodyStreamDisturbedOrLocked (body) {
+  return body != null && body.stream != null &&
+    (util.isDisturbed(body.stream) || body.stream.locked)
+}
+
 /**
  * @see https://fetch.spec.whatwg.org/#body-unusable
  * @param {any} object internal state
@@ -665,6 +680,7 @@ module.exports = {
   extractBody,
   safelyExtractBody,
   makeLazyByteStreamBody,
+  isBodyStreamDisturbedOrLocked,
   cloneBody,
   mixinBody,
   streamRegistry,
 
@@ -251,11 +251,12 @@ class Response {
   get bodyUsed () {
     webidl.brandCheck(this, Response)
 
-    // If the stream was never materialized it cannot have been disturbed, so a
-    // null stream means the body is unused (avoids forcing stream creation).
-    return !!this.#state.body &&
-      this.#state.body.stream != null &&
-      util.isDisturbed(this.#state.body.stream)
+    // `consumed` covers lazy bodies read via an embedder fast path where the stream is never built;
+    // otherwise fall back to the stream's disturbed state once it exists. A never-materialized
+    // stream cannot have been disturbed, so it reads as unused.
+    const body = this.#state.body
+    return !!body && (body.consumed === true ||
+      (body.stream != null && util.isDisturbed(body.stream)))
   }
 
   // Returns a clone of response.