PR #58889 fixed the CLI-fallback transport; review of that fix found the
same leak class at four sibling spawn sites of the third-party cua-driver
binary:
- _resolve_mcp_invocation (cua-driver manifest): no env= at all — full
parent environment inherited
- cua_driver_update_check (check-update --json): telemetry env but no
secret sanitization
- doctor._drive_health_report (<binary> mcp Popen): telemetry env only
- permissions._run (every macOS/Linux permission probe): telemetry env only
All now route through _sanitize_subprocess_env(cua_driver_child_env()),
matching the sanctioned MCP spawn and the #53503/#55709/#58889 strip-by-
default policy for non-terminal spawns. Sanitization degrades gracefully
(falls back to the telemetry env) so doctor/permission probes never break
on an import error.
4 regression tests covering each site.
