diff --git a/src/lib/cloudflaredTunnel.ts b/src/lib/cloudflaredTunnel.ts
index d706b7ed4..afb582a3b 100644
--- a/src/lib/cloudflaredTunnel.ts
+++ b/src/lib/cloudflaredTunnel.ts
@@ -24,6 +24,18 @@ type AssetSpec = {
   downloadUrl: string;
 };
 
+type CloudflaredRuntimeDirs = {
+  runtimeRoot: string;
+  homeDir: string;
+  configDir: string;
+  cacheDir: string;
+  dataDir: string;
+  tempDir: string;
+  userProfileDir: string;
+  appDataDir: string;
+  localAppDataDir: string;
+};
+
 type BinaryResolution = {
   binaryPath: string | null;
   source: CloudflaredInstallSource | null;
@@ -125,6 +137,24 @@ function getLogFilePath() {
   return path.join(getTunnelDir(), "quick-tunnel.log");
 }
 
+export function getCloudflaredRuntimeDirs(): CloudflaredRuntimeDirs {
+  const runtimeRoot = path.join(getTunnelDir(), "runtime");
+  const homeDir = path.join(runtimeRoot, "home");
+  const userProfileDir = path.join(runtimeRoot, "userprofile");
+
+  return {
+    runtimeRoot,
+    homeDir,
+    configDir: path.join(runtimeRoot, "config"),
+    cacheDir: path.join(runtimeRoot, "cache"),
+    dataDir: path.join(runtimeRoot, "data"),
+    tempDir: path.join(runtimeRoot, "tmp"),
+    userProfileDir,
+    appDataDir: path.join(userProfileDir, "AppData", "Roaming"),
+    localAppDataDir: path.join(userProfileDir, "AppData", "Local"),
+  };
+}
+
 function getLocalTargetUrl() {
   const { apiPort } = getRuntimePorts();
   return `http://127.0.0.1:${apiPort}`;
@@ -138,6 +168,13 @@ async function ensureTunnelDir() {
   await fs.mkdir(path.join(getTunnelDir(), "bin"), { recursive: true });
 }
 
+async function ensureTunnelRuntimeDirs() {
+  const runtimeDirs = getCloudflaredRuntimeDirs();
+  await Promise.all(
+    Object.values(runtimeDirs).map((dirPath) => fs.mkdir(dirPath, { recursive: true }))
+  );
+}
+
 async function readStateFile(): Promise<PersistedTunnelState> {
   try {
     const content = await fs.readFile(getStateFilePath(), "utf8");
@@ -202,7 +239,8 @@ export function extractTryCloudflareUrl(text: string) {
 }
 
 export function buildCloudflaredChildEnv(
-  sourceEnv: NodeJS.ProcessEnv = process.env
+  sourceEnv: NodeJS.ProcessEnv = process.env,
+  runtimeDirs: CloudflaredRuntimeDirs = getCloudflaredRuntimeDirs()
 ): NodeJS.ProcessEnv {
   const childEnv: NodeJS.ProcessEnv = {};
 
@@ -213,9 +251,25 @@ export function buildCloudflaredChildEnv(
     }
   }
 
+  childEnv.HOME = runtimeDirs.homeDir;
+  childEnv.XDG_CONFIG_HOME = runtimeDirs.configDir;
+  childEnv.XDG_CACHE_HOME = runtimeDirs.cacheDir;
+  childEnv.XDG_DATA_HOME = runtimeDirs.dataDir;
+  childEnv.USERPROFILE = runtimeDirs.userProfileDir;
+  childEnv.APPDATA = runtimeDirs.appDataDir;
+  childEnv.LOCALAPPDATA = runtimeDirs.localAppDataDir;
+
+  if (!childEnv.TMPDIR) childEnv.TMPDIR = runtimeDirs.tempDir;
+  if (!childEnv.TMP) childEnv.TMP = runtimeDirs.tempDir;
+  if (!childEnv.TEMP) childEnv.TEMP = runtimeDirs.tempDir;
+
   return childEnv;
 }
 
+export function getCloudflaredStartArgs(targetUrl: string) {
+  return ["tunnel", "--url", targetUrl, "--no-autoupdate"];
+}
+
 export function getCloudflaredAssetSpec(
   platform = process.platform,
   arch = process.arch
@@ -493,6 +547,7 @@ export async function startCloudflaredTunnel(): Promise<CloudflaredTunnelStatus>
 
     await stopExistingTunnel();
     await ensureTunnelDir();
+    await ensureTunnelRuntimeDirs();
     await fs.writeFile(getLogFilePath(), "", "utf8");
 
     await writeStateFile({
@@ -509,7 +564,7 @@ export async function startCloudflaredTunnel(): Promise<CloudflaredTunnelStatus>
 
     const child = spawn(
       binary.binaryPath as string,
-      ["tunnel", "--url", targetUrl, "--no-autoupdate", "--protocol", "http2"],
+      getCloudflaredStartArgs(targetUrl),
       {
         stdio: ["ignore", "pipe", "pipe"],
         env: buildCloudflaredChildEnv(),
diff --git a/tests/unit/cloudflaredTunnel.test.mjs b/tests/unit/cloudflaredTunnel.test.mjs
index dcde778cc..30650f23a 100644
--- a/tests/unit/cloudflaredTunnel.test.mjs
+++ b/tests/unit/cloudflaredTunnel.test.mjs
@@ -4,6 +4,7 @@ import assert from "node:assert/strict";
 import {
   buildCloudflaredChildEnv,
   extractTryCloudflareUrl,
+  getCloudflaredStartArgs,
   getCloudflaredAssetSpec,
 } from "../../src/lib/cloudflaredTunnel.ts";
 
@@ -47,18 +48,45 @@ test("getCloudflaredAssetSpec returns null for unsupported platforms", () => {
   assert.equal(getCloudflaredAssetSpec("freebsd", "x64"), null);
 });
 
-test("buildCloudflaredChildEnv keeps runtime essentials but drops secrets", () => {
+test("buildCloudflaredChildEnv keeps runtime essentials, isolates runtime dirs, and drops secrets", () => {
   const env = buildCloudflaredChildEnv({
     PATH: "/usr/bin",
-    HOME: "/tmp/home",
     HTTPS_PROXY: "http://proxy.internal:8080",
     JWT_SECRET: "top-secret",
     API_KEY_SECRET: "another-secret",
+  }, {
+    runtimeRoot: "/managed/runtime",
+    homeDir: "/managed/runtime/home",
+    configDir: "/managed/runtime/config",
+    cacheDir: "/managed/runtime/cache",
+    dataDir: "/managed/runtime/data",
+    tempDir: "/managed/runtime/tmp",
+    userProfileDir: "/managed/runtime/userprofile",
+    appDataDir: "/managed/runtime/userprofile/AppData/Roaming",
+    localAppDataDir: "/managed/runtime/userprofile/AppData/Local",
   });
 
   assert.deepEqual(env, {
     PATH: "/usr/bin",
-    HOME: "/tmp/home",
     HTTPS_PROXY: "http://proxy.internal:8080",
+    HOME: "/managed/runtime/home",
+    XDG_CONFIG_HOME: "/managed/runtime/config",
+    XDG_CACHE_HOME: "/managed/runtime/cache",
+    XDG_DATA_HOME: "/managed/runtime/data",
+    USERPROFILE: "/managed/runtime/userprofile",
+    APPDATA: "/managed/runtime/userprofile/AppData/Roaming",
+    LOCALAPPDATA: "/managed/runtime/userprofile/AppData/Local",
+    TMPDIR: "/managed/runtime/tmp",
+    TMP: "/managed/runtime/tmp",
+    TEMP: "/managed/runtime/tmp",
   });
 });
+
+test("getCloudflaredStartArgs relies on cloudflared protocol auto-negotiation", () => {
+  assert.deepEqual(getCloudflaredStartArgs("http://127.0.0.1:20128"), [
+    "tunnel",
+    "--url",
+    "http://127.0.0.1:20128",
+    "--no-autoupdate",
+  ]);
+});