@@ -752,7 +752,10 @@ test.serial(
         logger,
         features,
       });
-      const info = await startProxyExports.getDownloadUrl(state);
+      const info = await startProxyExports.getDownloadUrl(
+        state,
+        SAMPLE_DOTCOM_API_DETAILS,
+      );
 
       t.is(info.version, startProxyExports.UPDATEJOB_PROXY_VERSION);
       t.is(
@@ -778,7 +781,10 @@ test.serial(
     await withTmpDir(async (tempDir) => {
       const features = mockOfflineFeatures(tempDir, logger);
       const state = initAllState({ logger, features });
-      const info = await startProxyExports.getDownloadUrl(state);
+      const info = await startProxyExports.getDownloadUrl(
+        state,
+        SAMPLE_DOTCOM_API_DETAILS,
+      );
 
       t.is(info.version, startProxyExports.UPDATEJOB_PROXY_VERSION);
       t.is(
@@ -803,7 +809,10 @@ test.serial(
 
       for (const assets of testAssets) {
         const stub = mockGetReleaseByTag(assets);
-        const info = await startProxyExports.getDownloadUrl(state);
+        const info = await startProxyExports.getDownloadUrl(
+          state,
+          SAMPLE_DOTCOM_API_DETAILS,
+        );
 
         t.is(info.version, startProxyExports.UPDATEJOB_PROXY_VERSION);
         t.is(
@@ -833,7 +842,10 @@ test.serial("getDownloadUrl returns matching release asset", async (t) => {
 
   await withTmpDir(async (tempDir) => {
     const features = mockOfflineFeatures(tempDir, logger);
-    const info = await startProxyExports.getDownloadUrl({ ...state, features });
+    const info = await startProxyExports.getDownloadUrl(
+      { ...state, features },
+      SAMPLE_DOTCOM_API_DETAILS,
+    );
 
     t.is(info.version, defaults.cliVersion);
     t.is(info.url, "url-we-want");
 
@@ -9,10 +9,12 @@ import {
   getApiDetails,
   getGitHubVersion,
   InstanceApiClient,
+  type GitHubApiDetails,
 } from "./api-client";
 import * as artifactScanner from "./artifact-scanner";
 import { Config } from "./config-utils";
 import * as defaults from "./defaults.json";
+import type { ReadOnlyEnv } from "./environment";
 import {
   CodeQLDefaultVersionInfo,
   Feature,
@@ -395,8 +397,12 @@ export function getFallbackUrl(proxyPackage: string): string {
  *
  * @returns The response from the GitHub API.
  */
-async function getReleaseByVersion(version: string) {
-  return getApiClient().rest.repos.getReleaseByTag({
+async function getReleaseByVersion(
+  env: ReadOnlyEnv,
+  apiDetails: GitHubApiDetails,
+  version: string,
+) {
+  return getApiClient(env, apiDetails).rest.repos.getReleaseByTag({
     owner: "github",
     repo: "codeql-action",
     tag: version,
@@ -419,7 +425,8 @@ async function getCliVersionFromFeatures(
  * @returns Returns the download URL and version of the proxy package we plan to use.
  */
 export async function getDownloadUrl(
-  action: ActionState<["Base", "Logger", "FeatureFlags"]>,
+  action: ActionState<["Base", "ReadOnlyEnv", "Logger", "FeatureFlags"]>,
+  apiDetails: GitHubApiDetails,
 ): Promise<{ url: string; version: string }> {
   // Default to linux64 if we don't recognise the platform+arch pair.
   // This maintains the behaviour we had before switching to `getBundlePlatform` here.
@@ -448,7 +455,11 @@ export async function getDownloadUrl(
         };
 
     // Try to retrieve information about the CLI bundle release identified by `versionInfo`.
-    const cliRelease = await getReleaseByVersion(versionInfo.tagName);
+    const cliRelease = await getReleaseByVersion(
+      action.env,
+      apiDetails,
+      versionInfo.tagName,
+    );
 
     // Search the release's assets to find the one we are looking for.
     for (const asset of cliRelease.data.assets) {
@@ -569,13 +580,13 @@ export function getProxyFilename() {
  * @returns The path to the proxy binary.
  */
 export async function getProxyBinaryPath(
-  action: ActionState<["Base", "Logger", "FeatureFlags"]>,
+  action: ActionState<["Base", "ReadOnlyEnv", "Logger", "FeatureFlags"]>,
 ): Promise<string> {
   const logger = action.logger;
   const apiDetails = getApiDetails();
   const client = new InstanceApiClient(apiDetails);
   const proxyFileName = getProxyFilename();
-  const proxyInfo = await getDownloadUrl(action);
+  const proxyInfo = await getDownloadUrl(action, apiDetails);
 
   let proxyBin = toolcache.find(proxyFileName, proxyInfo.version);
   if (!proxyBin) {