fix(security): pipe sudo password via stdin instead of shell cmdline

tools/environments/modal.py

@@ -106,7 +106,20 @@ class ModalEnvironment(BaseEnvironment):
                 marker = f"HERMES_EOF_{uuid.uuid4().hex[:8]}"
             command = f"{command} << '{marker}'\n{stdin_data}\n{marker}"
 
-        exec_command = self._prepare_command(command)
+        exec_command, sudo_stdin = self._prepare_command(command)
+
+        # Modal sandboxes execute commands via the Modal SDK and cannot pipe
+        # subprocess stdin directly the way a local Popen can.  When a sudo
+        # password is present, use a shell-level pipe from printf so that the
+        # password feeds sudo -S without appearing as an echo argument embedded
+        # in the shell string.  The password is still visible in the remote
+        # sandbox's command line, but it is not exposed on the user's local
+        # machine — which is the primary threat being mitigated.
+        if sudo_stdin is not None:
+            import shlex
+            exec_command = (
+                f"printf '%s\\n' {shlex.quote(sudo_stdin.rstrip())} | {exec_command}"
+            )
 
         # Run in a background thread so we can poll for interrupts
         result_holder = {"value": None, "error": None}