Servers started by test_server's OneServer and LocalMode tests got no
FRAME_CONTROL_SSH_DIR, so each one imported the real ~/.ssh/config into a
fresh throwaway devices.json and seeded a pin into the real
~/.ssh/frame-control-hosts: about a dozen files per suite run.
tests/sandbox.py now gives the whole run a throwaway HOME/USERPROFILE and
FRAME_CONTROL_SSH_DIR (inherited by child processes), every test module
imports it first, and frame_connect.SSH_DIR honours FRAME_CONTROL_SSH_DIR
like frame_devices.ssh_dir(). test_sandbox checks the paths and reruns the
tests that leaked from the original environment, asserting nothing under
the real ~/.ssh changed.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
