On lockdown builds (MESHTASTIC_PHONEAPI_ACCESS_CONTROL, nRF52) the SerialConsole
is a process-lifetime singleton, so the per-connection admin-auth slot keyed by
its inherited PhoneAPI* is reused for every USB/serial client for the whole boot.
An operator's admin unlock stayed latched across serial client swaps: an attacker
plugging into the USB/serial port before the prior session's 15-minute inactivity
timeout inherited admin authorization -- the serial analog of the BLE stale-session
reuse bug closed by resetting state in onConnect()/onDisconnect().
Sample the USB-CDC host link (DTR/mount) state each runOnce(); on the link-drop
edge call close(), which frees the auth slot and resets PhoneAPI state so whoever
connects next re-locks via handleStartConfig()'s !isConnected() branch on their
first want_config -- the same physical-link boundary BLE enforces in onConnect().
On the nRF52 TinyUSB (Adafruit) core, (bool)Port == tud_cdc_n_connected(), which
goes false on cable unplug or host port-close. Console transports without a real
DTR line fall back to the existing inactivity timeout, no worse than before.
Entirely nRF52-lockdown-gated; non-lockdown builds are byte-identical.
Ben Meadors
f6f3284cfc