diff --git a/src/main/utils/childProcess.ts b/src/main/utils/childProcess.ts
index c40678f0..a1f49e85 100644
--- a/src/main/utils/childProcess.ts
+++ b/src/main/utils/childProcess.ts
@@ -68,14 +68,21 @@ function needsShell(binaryPath: string): boolean {
 }
 
 /**
- * Minimal quoting for command‑line arguments when building a shell
- * invocation.  We only escape spaces and double quotes since our
- * callers only ever use simple strings (paths, flags, literals) and
- * the shell itself will handle most quoting rules.
+ * Quote an argument for cmd.exe shell invocation on Windows.
+ *
+ * cmd.exe rules:
+ * - Double-quote args containing spaces or special characters
+ * - Inside double quotes, escape literal `"` as `""`
+ * - `%` is expanded as env var even inside double quotes — escape as `%%`
+ * - `^`, `&`, `|`, `<`, `>` are safe inside double quotes
+ *
+ * Our callers only pass controlled strings (binary paths, CLI flags),
+ * NOT arbitrary user input.
  */
 function quoteArg(arg: string): string {
   if (/[^A-Za-z0-9_\-/.]/.test(arg)) {
-    return `"${arg.replace(/"/g, '\\"')}"`;
+    const escaped = arg.replace(/%/g, '%%').replace(/"/g, '""');
+    return `"${escaped}"`;
   }
   return arg;
 }
@@ -133,7 +140,7 @@ export function spawnCli(
   if (process.platform === 'win32' && needsShell(binaryPath)) {
     const cmd = [binaryPath, ...args].map(quoteArg).join(' ');
     // eslint-disable-next-line sonarjs/os-command -- cmd from known binaryPath+args, not user input (Windows EINVAL fallback)
-    return spawn(cmd, { shell: true, ...options });
+    return spawn(cmd, { ...options, shell: true });
   }
 
   try {
@@ -144,7 +151,7 @@ export function spawnCli(
     if (process.platform === 'win32' && code === 'EINVAL') {
       const cmd = [binaryPath, ...args].map(quoteArg).join(' ');
       // eslint-disable-next-line sonarjs/os-command -- cmd from known binaryPath+args, not user input (Windows EINVAL fallback)
-      return spawn(cmd, { shell: true, ...options });
+      return spawn(cmd, { ...options, shell: true });
     }
     throw err;
   }
diff --git a/test/main/utils/childProcess.test.ts b/test/main/utils/childProcess.test.ts
index 1c705c61..cc03192f 100644
--- a/test/main/utils/childProcess.test.ts
+++ b/test/main/utils/childProcess.test.ts
@@ -134,6 +134,34 @@ describe('cli child process helpers', () => {
       expect(result.stdout).toBe('1.2.3');
     });
 
+    it('escapes percent signs and quotes for cmd.exe in shell fallback', async () => {
+      setPlatform('win32');
+      const execMock = child.exec as unknown as vi.Mock;
+      execMock.mockImplementation((_cmd: string, _opts: unknown, cb: Function) => {
+        cb(null, 'ok', '');
+        return {} as any;
+      });
+
+      await execCli('C:\\Users\\Алексей\\bin\\claude.cmd', ['--model', 'test%PATH%"arg']);
+      const shellCmd = execMock.mock.calls[0][0] as string;
+      // %PATH% must become %%PATH%% to prevent cmd.exe env var expansion
+      expect(shellCmd).toContain('%%PATH%%');
+      // double quote inside arg must become "" (cmd.exe escaping)
+      expect(shellCmd).toContain('""arg');
+      // should NOT contain \" (Unix-style escaping)
+      expect(shellCmd).not.toContain('\\"');
+    });
+
+    it('shell: true cannot be overridden by caller options', () => {
+      setPlatform('win32');
+      const spawnMock = child.spawn as unknown as vi.Mock;
+      spawnMock.mockReturnValue({} as any);
+
+      spawnCli('C:\\Users\\Алексей\\bin\\claude.cmd', ['--version'], { shell: false } as any);
+      // shell: true must win over caller's shell: false
+      expect(spawnMock.mock.calls[0][1]).toMatchObject({ shell: true });
+    });
+
     it('falls back to shell when execFile throws EINVAL on windows', async () => {
       setPlatform('win32');
       const execFileMock = child.execFile as unknown as vi.Mock;