fix(sos): one click on a locked L1 no longer starts and cancels an SOS; the hold always works; the contact picker doesn't stall

The Back hold started at millis() | 2, up to 2 ms ahead of the clock. With the
screen off the loop comes round in under that, the unsigned difference wrapped
and read as 3 s held: the countdown started and the release cancelled it. The
same "| 1" sentinel ahead of millis() is fixed in the other places it was used
(L1 status screen, L2 prefs flush, WiFi test, live tiles, home edge flip, SD
retry).

A lock sequence left half done by a long Back hold (no click on release) kept
the SOS hold off until the next click: cleared 500 ms after Back is let go.

Picking an SOS contact no longer saves prefs on the way there and back (a flash
write stalls the L1); leaving the SOS screen saves it with the rest.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

examples/companion_radio/ui-lvgl/HomeScreen.h

@@ -331,7 +331,7 @@ static void onEditTile(lv_event_t* e) {
     if (!side) previewSlot(t, slotAt(p));
     int page = s_page + side;
     if (!side || page < APPS || page >= pageCount()) { s_edge_since = 0; return; }
-    if (!s_edge_since) { s_edge_since = millis() | 1; return; }
+    if (!s_edge_since) { s_edge_since = (millis() - 1) | 1; return; }   // never 0, never ahead of millis()
     if (millis() - s_edge_since < EDGE_MS) return;
     // Onto that page's nearest slot; the finger lifts to drag it on from there.
     int to = side > 0 ? (page - APPS) * PER_PAGE : (page - APPS) * PER_PAGE + PER_PAGE - 1;
@@ -621,7 +621,7 @@ void UITask::homeFieldText(uint8_t f, char* v, int n) {
   in.gps_on = _core->gpsEnabled();
   if (telemetry::isSensor(f)) {   // the sensors on the bus: read every few seconds, not per field
     if (_sensors && (s_lpp_ms == 0 || millis() - s_lpp_ms > 5000)) {
-      s_lpp_ms = millis() | 1;
+      s_lpp_ms = (millis() - 1) | 1;   // never 0, never ahead of millis()
       s_lpp.reset();
       queryLocalSensors(*_sensors, board.getMCUTemperature(), s_lpp);
     }

examples/companion_radio/ui-lvgl/LvglPort.h

@@ -310,7 +310,7 @@ static bool mountStorage() {
   if (s_sd_lent) return false;
   if (s_sd_mounted) return true;
   if (s_sd_last_try && millis() - s_sd_last_try < 5000) return false;
-  s_sd_last_try = millis() | 1;
+  s_sd_last_try = (millis() - 1) | 1;   // never 0, never ahead of millis()
   SD_MMC.setPins(2, 3, 1);
   s_sd_mounted = SD_MMC.begin("/sdcard", true /* 1-bit */);
   return s_sd_mounted;

examples/companion_radio/ui-lvgl/MapScreen.h

@@ -1807,7 +1807,7 @@ void UITask::mapDownloadTick() {
     // The WiFi goes 30 s after the map was left or the screen went off (a
     // quick look elsewhere keeps it).
     if (_screen != SCR_MAP || _asleep) {
-      if (!_map_left_ms) _map_left_ms = millis() | 1;
+      if (!_map_left_ms) _map_left_ms = (millis() - 1) | 1;   // never 0, never ahead of millis()
       else if (millis() - _map_left_ms > 30000) dl.liveEnd();
     }
   }

examples/companion_radio/ui-lvgl/Widgets.h

@@ -1257,7 +1257,7 @@ static void fmtDate(char* b, size_t n, const struct tm& ti) {
 // itself changes at once; shutdown() saves whatever is pending.
 static uint32_t s_prefs_dirty_ms = 0;   // when the first unsaved change came (0: none)
 static uint32_t s_prefs_save_at = 0;    // the screen was left: save from then (0: not yet)
-static void prefsSave() { if (!s_prefs_dirty_ms) s_prefs_dirty_ms = millis() | 1; }
+static void prefsSave() { if (!s_prefs_dirty_ms) s_prefs_dirty_ms = (millis() - 1) | 1; }   // never 0, never ahead of millis()
 static void prefsSaveSoon(uint32_t delay_ms) {
   if (s_prefs_dirty_ms && !s_prefs_save_at) s_prefs_save_at = (millis() + delay_ms) | 1;
 }

examples/companion_radio/ui-lvgl/WifiScreen.h

@@ -307,7 +307,7 @@ void UITask::wifiSave() {
   }
   lvport::netEnd();   // a scan might have left the radio on
   lvport::netJoin(s_wifi_test_ssid, s_wifi_test_pass);
-  s_wifi_test_ms = millis() | 1;
+  s_wifi_test_ms = (millis() - 1) | 1;   // never 0, never ahead of millis()
   snprintf(msg, sizeof(msg), LV_SYMBOL_REFRESH "  Connecting to %s...", s_wifi_test_ssid);
   wifiTestShow(msg, nullptr, nullptr);
 }

examples/companion_radio/ui-new/MessagesScreen.h

@@ -1433,10 +1433,7 @@ public:
 
   void commitPickSos(const ContactInfo& ci) {
     NodePrefs* p = _task->getNodePrefs();
-    if (p) {
-      memcpy(p->sos_dm[_pick_sos_slot], ci.id.pub_key, NodePrefs::FAVOURITE_PREFIX_LEN);
-      the_mesh.savePrefs();
-    }
+    if (p) memcpy(p->sos_dm[_pick_sos_slot], ci.id.pub_key, NodePrefs::FAVOURITE_PREFIX_LEN);   // saved on leaving SOS
     _pick_sos_slot = -1;
     _task->gotoSosScreen();
   }

examples/companion_radio/ui-new/SosScreen.h

@@ -13,6 +13,7 @@ class SosScreen : public UIScreen {
   NodePrefs*      _prefs;
   KeyboardWidget* _kb;
   bool _dirty  = false;
+  bool _picking = false;    // off to the contact picker: the changes stay unsaved until we leave
   int  _sel    = 0;
   int  _scroll = 0;
   int  _kb_row = -1;        // >=0: the keyboard is open on that row
@@ -135,7 +136,9 @@ class SosScreen : public UIScreen {
         if (enter) openChannels();
         break;
       case K_DM1: case K_DM2: case K_DM3:
-        if (enter) { _task->savePrefsIfDirty(_dirty); _task->pickSosContact(k - K_DM1); }
+        // No save on the way: a prefs write stalls the L1 for a moment, and
+        // leaving this screen saves the pick with the rest.
+        if (enter) { _picking = true; _task->pickSosContact(k - K_DM1); }
         else { memset(_prefs->sos_dm[k - K_DM1], 0, NodePrefs::FAVOURITE_PREFIX_LEN); _dirty = true; }
         break;
       case K_ACK: case K_NOTE:
@@ -156,7 +159,12 @@ class SosScreen : public UIScreen {
 public:
   SosScreen(UITask* task, NodePrefs* prefs, KeyboardWidget* kb) : _task(task), _prefs(prefs), _kb(kb) {}
 
-  void onShow() override { _dirty = false; _kb_row = -1; _ch_list = false; }   // the row stays: the contact list comes back here
+  void onShow() override {   // the row stays: the contact list comes back here
+    _dirty = _picking;   // back from the picker: what was changed, and the pick, still to save
+    _picking = false;
+    _kb_row = -1;
+    _ch_list = false;
+  }
 
   int render(DisplayDriver& display) override {
     if (_kb_row >= 0) return _kb->render(display);

examples/companion_radio/ui-new/StatusScreen.h

@@ -242,7 +242,7 @@ private:
     if (!_lpp_at || millis() - _lpp_at > 5000) {   // both passes (measure, draw) read one query
       _lpp.reset();
       { CardKBBusLock bus_lock; queryLocalSensors(sensors, board.getMCUTemperature(), _lpp); }   // shares the CardKB's bus
-      _lpp_at = millis() | 1;
+      _lpp_at = (millis() - 1) | 1;   // never 0, never ahead of millis()
     }
     static const struct { uint8_t type; const char* name; } NAMES[] = {
       { LPP_TEMPERATURE, "Temperature" }, { LPP_RELATIVE_HUMIDITY, "Humidity" },
@@ -428,7 +428,7 @@ public:
     static unsigned long at = 0;
     static int n = 0;
     if (at && millis() - at < 10000) return n;
-    at = millis() | 1;
+    at = (millis() - 1) | 1;   // never 0, never ahead of millis()
     n = 0;
     const uint32_t now = rtc_clock.getCurrentTime();
     const int nc = the_mesh.getNumContacts();

examples/companion_radio/ui-new/UITask.cpp

@@ -1456,12 +1456,21 @@ void UITask::loop() {
   if (_lock_seq_used && millis() - _lock_seq_ms > 5000) {
     _lock_seq_used = false;  // safety reset if Back release event was missed
   }
+  // The lock sequence lives while Back is held. A long hold gives no click on
+  // release, so a sequence left half done stayed and kept the SOS hold off:
+  // cleared once Back has been up past the click window.
+  if (back_btn.isPressed()) _back_up_at = 0;
+  else if (!_back_up_at) _back_up_at = (millis() - 1) | 1;
+  else if ((_lock_seq_count > 0 || _lock_seq_used) && millis() - _back_up_at > 500) {
+    _lock_seq_count = 0;
+    _lock_seq_used = false;
+  }
   // Back held on its own: past the button's long press, so no click comes of it.
   // Enter during the hold is the lock sequence, not this.
   if (!back_btn.isPressed() || user_btn.isPressed() || _lock_seq_count > 0 || _lock_seq_used) {
     _back_held_at = back_btn.isPressed() ? 1 : 0;   // 1: spoken for until released
   } else if (_back_held_at == 0) {
-    _back_held_at = millis() | 2;
+    _back_held_at = (millis() - 2) | 2;   // never 0 or 1, never ahead of millis(): ahead, the next pass read 3 s held
   } else if (_back_held_at != 1 && millis() - _back_held_at >= SOS_HOLD_MS) {
     _back_held_at = 1;
     onBackHeld();

examples/companion_radio/ui-new/UITask.h

@@ -158,6 +158,7 @@ class UITask : public UITaskBase, public UiCoreHost {
   unsigned long _sos_view_until = 0;   // 0 = closed
   int      _sos_left = 0;              // countdown second last beeped
   unsigned long _back_held_at = 0;     // 0 = not held, or already acted on
+  unsigned long _back_up_at = 0;       // when Back was let go (0: held)