fix(companion): show the sender's own timestamp for synced/queued messages

DM, room and channel history always stamped a message with receipt time
(rtc_clock.getCurrentTime()), even though the sender's real timestamp was
already available (and, for DMs/rooms, already threaded through to
addDMMsg -- just never used for display). Live-received messages hid this
because receipt lags origination by only seconds, but a room-sync replay or
an offline-queued message held by a repeater can arrive long after it was
sent, so a burst of backlog messages all showed as "just now".

storeDMMsg() now prefers msg_ts (falling back to receipt time only when
unknown). addChannelMsg() gained a timestamp parameter, threaded from
onChannelMessageRecv() down through AbstractUITask/UITask, with the same
fallback. The DM dedup check and outgoing-message timestamps are unaffected
(they use msg_ts directly, already correct).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

examples/companion_radio/AbstractUITask.h

@@ -65,7 +65,7 @@ public:
   virtual void msgRead(int msgcount) = 0;
   virtual void newMsg(uint8_t path_len, const char* from_name, const char* text, int msgcount, uint8_t contact_type = 0, const uint8_t* pub_key = nullptr) = 0;
   virtual void notify(UIEventType t = UIEventType::none) = 0;
-  virtual void addChannelMsg(uint8_t channel_idx, const char* text) {}
+  virtual void addChannelMsg(uint8_t channel_idx, const char* text, uint32_t timestamp = 0) {}
   virtual void addDMMsg(const uint8_t* pub_key, bool outgoing, const char* text, uint32_t sender_timestamp = 0) {}
   // A node shared its current position via a [LOC] message. pub_key is the
   // sender's key prefix for a verified DM share, or null for a channel share

examples/companion_radio/MyMesh.cpp

@@ -721,7 +721,7 @@ void MyMesh::onChannelMessageRecv(const mesh::GroupChannel &channel, mesh::Packe
     _serial->writeFrame(frame, 1);
   }
 #ifdef DISPLAY_CLASS
-  if (_ui) _ui->addChannelMsg(channel_idx, text);
+  if (_ui) _ui->addChannelMsg(channel_idx, text, timestamp);
   if (_ui) _ui->notify(UIEventType::channelMessage);
   const char *channel_name = "Unknown";
   ChannelDetails channel_details;

examples/companion_radio/ui-new/QuickMsgScreen.h

@@ -398,7 +398,11 @@ class QuickMsgScreen : public UIScreen {
     }
     memcpy(_dm_hist[pos].prefix, pub_key, 4);
     _dm_hist[pos].outgoing = outgoing ? 1 : 0;
-    _dm_hist[pos].timestamp = rtc_clock.getCurrentTime();
+    // Prefer the sender's own timestamp — a room-sync replay or an
+    // offline-queued message held by a repeater can arrive long after it was
+    // actually sent, so "now" would mislabel every backlog message as fresh.
+    // Fall back to receipt time only when the sender's timestamp is unknown.
+    _dm_hist[pos].timestamp = msg_ts ? msg_ts : rtc_clock.getCurrentTime();
     strncpy(_dm_hist[pos].text, text, sizeof(DmHistEntry::text) - 1);
     _dm_hist[pos].text[sizeof(DmHistEntry::text) - 1] = '\0';
     _dm_hist[pos].ack_status      = (outgoing && ack_tag) ? ACK_PENDING : ACK_NONE;
@@ -677,8 +681,10 @@ public:
   }
 
   // Returns the ring position the message was stored at, or -1 if rejected, so
-  // the outgoing path can attach a relay seq to that exact entry.
+  // the outgoing path can attach a relay seq to that exact entry. `timestamp`
-  int addChannelMsg(uint8_t ch_idx, const char* text) {
+  // is the sender's own send time (0 = unknown/outgoing — use receipt time);
+  // see storeDMMsg() for why this matters for synced/queued backlog messages.
+  int addChannelMsg(uint8_t ch_idx, const char* text, uint32_t timestamp = 0) {
     // Guard against bogus channel indices (e.g. findChannelIdx() returned -1
     // and was cast to uint8_t → 255). Storing such an entry would burn a ring
     // slot for a message that no visible channel can ever surface.
@@ -698,7 +704,7 @@ public:
       _hist_head = (_hist_head + 1) % CH_HIST_MAX;
     }
     _hist[pos].ch_idx = ch_idx;
-    _hist[pos].timestamp = rtc_clock.getCurrentTime();
+    _hist[pos].timestamp = timestamp ? timestamp : rtc_clock.getCurrentTime();
     strncpy(_hist[pos].text, text, sizeof(_hist[pos].text) - 1);
     _hist[pos].text[sizeof(_hist[pos].text) - 1] = '\0';
     _hist[pos].relay_status = ACK_NONE;

examples/companion_radio/ui-new/UITask.cpp

@@ -1628,9 +1628,9 @@ int UITask::getRecentDMContacts(uint8_t out[][NodePrefs::FAVOURITE_PREFIX_LEN],
   return ((QuickMsgScreen*)quick_msg)->getRecentDMContacts(out, max);
 }
 
-void UITask::addChannelMsg(uint8_t channel_idx, const char* text) {
+void UITask::addChannelMsg(uint8_t channel_idx, const char* text, uint32_t timestamp) {
   _last_notif_ch_idx = (int)channel_idx;
-  ((QuickMsgScreen*)quick_msg)->addChannelMsg(channel_idx, text);
+  ((QuickMsgScreen*)quick_msg)->addChannelMsg(channel_idx, text, timestamp);
 }
 
 int UITask::getChannelUnreadCount() const {

examples/companion_radio/ui-new/UITask.h

@@ -261,7 +261,7 @@ public:
   void stopMelody();
   bool isMelodyPlaying();
   void showAlert(const char* text, int duration_millis);
-  void addChannelMsg(uint8_t channel_idx, const char* text) override;
+  void addChannelMsg(uint8_t channel_idx, const char* text, uint32_t timestamp = 0) override;
   void addDMMsg(const uint8_t* pub_key, bool outgoing, const char* text, uint32_t sender_timestamp = 0) override;
   void onMsgAck(uint32_t ack_crc) override;
   void onChannelRelayed(uint32_t seq) override;