diff --git a/src/application/SupportedClients.ts b/src/application/SupportedClients.ts
index fef2fd32d9..241c36f18f 100644
--- a/src/application/SupportedClients.ts
+++ b/src/application/SupportedClients.ts
@@ -8,7 +8,10 @@ import {
 } from "./HermesClientHome.js";
 import { compareUnicodeCodePoints } from "../domain/unicodeCodePointOrder.js";
 import { resolveWindowsClaudeDesktopLocation } from "./ClaudeDesktopConfigLocation.js";
-import type { MsixPackageView } from "./MsixPackageStorage.js";
+import {
+  type MsixPackageView,
+  windowsAppDataRoots,
+} from "./MsixPackageStorage.js";
 
 /** One supported client configuration location. */
 export interface SetupClient {
@@ -117,11 +120,7 @@ const vscodeUserDirectory = ({
   env,
 }: ClientPathContext): string => {
   if (platform === "win32")
-    return join(
-      env.APPDATA ?? join(home, "AppData", "Roaming"),
-      "Code",
-      "User",
-    );
+    return join(windowsAppDataRoots(home, env).roaming, "Code", "User");
   if (platform === "darwin")
     return join(home, "Library", "Application Support", "Code", "User");
   return join(xdgConfigHome({ home, platform, env }), "Code", "User");
@@ -133,11 +132,7 @@ const traeUserDirectory = ({
   env,
 }: ClientPathContext): string => {
   if (platform === "win32")
-    return join(
-      env.APPDATA ?? join(home, "AppData", "Roaming"),
-      "Trae",
-      "User",
-    );
+    return join(windowsAppDataRoots(home, env).roaming, "Trae", "User");
   if (platform === "darwin")
     return join(home, "Library", "Application Support", "Trae", "User");
   return join(xdgConfigHome({ home, platform, env }), "Trae", "User");
@@ -479,7 +474,7 @@ const geminiSettings = ({
 
 const devinDirectory = ({ home, platform, env }: ClientPathContext): string =>
   platform === "win32"
-    ? join(env.APPDATA ?? join(home, "AppData", "Roaming"), "devin")
+    ? join(windowsAppDataRoots(home, env).roaming, "devin")
     : join(env.XDG_CONFIG_HOME || join(home, ".config"), "devin");
 
 /** Stable product metadata used to derive setup discovery and documentation. */
diff --git a/tests/boundary/filesystem/windowsAppDataClientPaths.test.ts b/tests/boundary/filesystem/windowsAppDataClientPaths.test.ts
new file mode 100644
index 0000000000..02c559aa03
--- /dev/null
+++ b/tests/boundary/filesystem/windowsAppDataClientPaths.test.ts
@@ -0,0 +1,30 @@
+import { join } from "node:path";
+
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+
+import { supportedClients } from "../../../src/application/SupportedClients.js";
+import { clearClientLocationEnvironment } from "../../fixtures/clientEnvironment.js";
+
+beforeEach(clearClientLocationEnvironment);
+afterEach(() => vi.unstubAllEnvs());
+
+const home = "C:\\Users\\a";
+const roaming = join(home, "AppData", "Roaming");
+
+const configPath = (
+  name: string,
+  env: Parameters<typeof supportedClients>[2],
+) =>
+  supportedClients(home, "win32", env).find((client) => client.name === name)
+    ?.configPath;
+
+describe("Windows AppData client paths", () => {
+  it.each([
+    ["vscode", join(roaming, "Code", "User", "mcp.json")],
+    ["trae", join(roaming, "Trae", "User", "mcp.json")],
+    ["devin", join(roaming, "devin", "mcp_config.json")],
+  ])("treats an empty APPDATA as unset for %s", (name, expected) => {
+    expect(configPath(name, {})).toBe(expected);
+    expect(configPath(name, { APPDATA: "" })).toBe(expected);
+  });
+});