feat(companion): persist app/USB-entered room passwords on device

The on-device login path already saved room passwords to /room_pw; do the
same for logins issued by the phone/USB app (CMD_SEND_LOGIN). The password
is stashed when the login is sent and persisted once the server confirms,
gated to ADV_TYPE_ROOM contacts; a failed login forgets any stale saved
password, mirroring the on-device path. This lets the device post to a
room standalone after a reboot without re-prompting.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

examples/companion_radio/MyMesh.cpp

@@ -845,11 +845,13 @@ void MyMesh::onContactResponse(const ContactInfo &contact, const uint8_t *data,
     pending_login = 0;
 
     int i = 0;
+    bool login_ok = false;
     if (memcmp(&data[4], "OK", 2) == 0) { // legacy Repeater login OK response
       out_frame[i++] = PUSH_CODE_LOGIN_SUCCESS;
       out_frame[i++] = 0; // legacy: is_admin = false
       memcpy(&out_frame[i], contact.id.pub_key, 6);
       i += 6;                                     // pub_key_prefix
+      login_ok = true;
     } else if (data[4] == RESP_SERVER_LOGIN_OK) { // new login response
       uint16_t keep_alive_secs = ((uint16_t)data[5]) * 16;
       if (keep_alive_secs > 0) {
@@ -863,12 +865,21 @@ void MyMesh::onContactResponse(const ContactInfo &contact, const uint8_t *data,
       i += 4; // NEW: include server timestamp
       out_frame[i++] = data[7]; // NEW (v7): ACL permissions
       out_frame[i++] = data[12]; // FIRMWARE_VER_LEVEL
+      login_ok = true;
     } else {
       out_frame[i++] = PUSH_CODE_LOGIN_FAIL;
       out_frame[i++] = 0; // reserved
       memcpy(&out_frame[i], contact.id.pub_key, 6);
       i += 6; // pub_key_prefix
     }
+    // Persist app/USB-entered room passwords too, so the device can later post
+    // to that room standalone (after reboot, no phone) without re-prompting --
+    // same store the on-device login path uses. Rooms only; a failed login
+    // forgets any stale saved password, mirroring onRoomLoginResult().
+    if (contact.type == ADV_TYPE_ROOM) {
+      if (login_ok) saveRoomPassword(contact.id.pub_key, pending_login_pw);
+      else          forgetRoomPassword(contact.id.pub_key);
+    }
     _serial->writeFrame(out_frame, i);
   } else if (ui_pending_login && memcmp(&ui_pending_login, contact.id.pub_key, 4) == 0) { // check for on-device UI login response
     ui_pending_login = 0;
@@ -2185,6 +2196,8 @@ void MyMesh::handleCmdFrame(size_t len) {
       } else {
         clearPendingReqs();
         memcpy(&pending_login, recipient->id.pub_key, 4); // match this to onContactResponse()
+        strncpy(pending_login_pw, password, sizeof(pending_login_pw) - 1); // saved on success if it's a room
+        pending_login_pw[sizeof(pending_login_pw) - 1] = 0;
         out_frame[0] = RESP_CODE_SENT;
         out_frame[1] = (result == MSG_SEND_SENT_FLOOD) ? 1 : 0;
         memcpy(&out_frame[2], &pending_login, 4);

examples/companion_radio/MyMesh.h

@@ -320,6 +320,7 @@ private:
   NodePrefs _prefs;
   uint32_t pending_login;
   uint32_t ui_pending_login;  // like pending_login, but triggered by on-device UI instead of BLE/USB app
+  char pending_login_pw[16];  // password of the in-flight app/USB login, persisted on success for ADV_TYPE_ROOM (see saveRoomPassword)
   uint32_t pending_status;
   uint32_t pending_telemetry, pending_discovery;   // pending _TELEMETRY_REQ
   uint32_t pending_req;   // pending _BINARY_REQ

release-notes.md

@@ -10,7 +10,7 @@
 - **Trail auto-pause** — recording **freezes on stops** (banking elapsed time and breaking the map line across the idle gap) and **resumes on movement** without ending the session; the home-screen blink keeps going while paused.
 - **Collapsible Tools** — tools are grouped into fold-in-place **Location / Comms / System** sections, the same model as Settings (Tools always opens folded to the section list), and the home carousel now uses **page-indicator icons** instead of dots.
 - **Waypoint coordinate editor** — add a waypoint by scroll-editing its latitude/longitude digit by digit.
-- **On-device room login with saved passwords** — log in to a room server straight from the device (no phone app): pick the room and the password prompt appears automatically (a blank password works for open rooms), or re-login any time via the room's **context-menu "Login…"**. The password is **remembered across reboots**, so a room you've used before logs back in without retyping; a failed login (e.g. the server's password changed) forgets the stale password so the next attempt prompts again. Saved passwords are written with the same atomic, crash-safe persistence as contacts and channels.
+- **On-device room login with saved passwords** — log in to a room server straight from the device (no phone app): pick the room and the password prompt appears automatically (a blank password works for open rooms), or re-login any time via the room's **context-menu "Login…"**. The password is **remembered across reboots**, so a room you've used before logs back in without retyping; a failed login (e.g. the server's password changed) forgets the stale password so the next attempt prompts again. Room passwords entered via the **phone app** are saved on the device too, so it can post to that room standalone after a reboot. Saved passwords are written with the same atomic, crash-safe persistence as contacts and channels.
 
 ### Fixes