refactor(mesh): extract addOwnChannelMsg() for the "Me: " mirror framing

Four call sites (three bot reply paths, one app-originated-send mirror)
each hand-built the same "Me: <text>" + own_message=true framing that
MessagesScreen relies on to render an outgoing bubble -- one of them
(now fixed) had already drifted to the wrong prefix once. Centralizing
it in AbstractUITask::addOwnChannelMsg() means a caller can no longer
get the framing wrong.

examples/companion_radio/AbstractUITask.h

@@ -5,6 +5,7 @@
 #include <helpers/ui/UIScreen.h>
 #include <helpers/SensorManager.h>
 #include <helpers/BaseSerialInterface.h>
+#include <helpers/BaseChatMesh.h>   // MAX_TEXT_LEN, for addOwnChannelMsg() below
 #include <Arduino.h>
 
 #ifdef PIN_BUZZER
@@ -101,6 +102,24 @@ public:
   virtual int addChannelMsg(uint8_t channel_idx, const char* text, uint32_t timestamp = 0,
                             const uint8_t* path = nullptr, uint8_t path_len = 0,
                             bool own_message = false) { return -1; }
+  // Convenience wrapper around addChannelMsg() for mirroring a channel post
+  // this device just sent itself (bot trigger/command reply, a !gps fix
+  // result, an app-originated send) into the on-device history. Always frames
+  // it with the literal "Me: " prefix -- the convention MessagesScreen uses
+  // (see its bubble-side check) to tell an outgoing post from an incoming
+  // one -- and always passes own_message=true, so a caller can't reintroduce
+  // the bug this replaced: three separate MyMeshBot.h call sites used to
+  // build "<node_name>: " instead, which rendered the reply as an incoming
+  // bubble from a stranger who happened to share the device's own name.
+  // text_len < 0 (default) means text is null-terminated; otherwise only the
+  // first text_len bytes are used (a source buffer isn't always guaranteed
+  // to be null-terminated, e.g. the app-originated mirror).
+  int addOwnChannelMsg(uint8_t channel_idx, const char* text, int text_len = -1, uint32_t timestamp = 0) {
+    char buf[MAX_TEXT_LEN + 8];   // "Me: "(4) + text(MAX_TEXT_LEN) + margin
+    if (text_len < 0) snprintf(buf, sizeof(buf), "Me: %s", text);
+    else              snprintf(buf, sizeof(buf), "Me: %.*s", text_len, text);
+    return addChannelMsg(channel_idx, buf, timestamp, nullptr, 0, true);
+  }
   // Arms the "relayed into mesh" tracker (a heard repeater rebroadcast) on the
   // entry at ring position pos, e.g. right after addChannelMsg for a channel
   // send this device just originated. seq: MyMesh::lastChannelRelaySeq().

examples/companion_radio/MyMesh.cpp

@@ -2028,22 +2028,22 @@ void MyMesh::handleCmdFrame(size_t len) {
       if (success && sendGroupMessage(msg_timestamp, channel.channel, _prefs.node_name, text, len - i)) {
         writeOKFrame();
 #ifdef DISPLAY_CLASS
-        // Mirror this app-originated channel post into the on-device history,
-        // same "Me: " framing MessagesScreen::afterSend uses for an on-device
-        // compose -- otherwise the two queues drift and a post sent from the
-        // phone app never shows up if that channel is later opened on-device.
-        // text isn't guaranteed null-terminated (len - i is its real length,
-        // same bound sendGroupMessage above was just given), so bound the copy.
+        // Mirror this app-originated channel post into the on-device history
+        // (addOwnChannelMsg applies the same "Me: " framing
+        // MessagesScreen::afterSend uses for an on-device compose) --
+        // otherwise the two queues drift and a post sent from the phone app
+        // never shows up if that channel is later opened on-device. text
+        // isn't guaranteed null-terminated (len - i is its real length, same
+        // bound sendGroupMessage above was just given), so bound the copy.
+        // own_message=true (inside addOwnChannelMsg): this is our own post,
+        // so it must never bump the channel's unread badge even though the
+        // device's own UI isn't necessarily showing this channel right now
+        // (unlike an on-device compose, which is always looking at the
+        // channel it just sent to).
         if (_ui) {
-          char entry[MAX_TEXT_LEN + 8];   // "Me: " + text
           int tlen = len - i;
           if (tlen > MAX_TEXT_LEN) tlen = MAX_TEXT_LEN;
-          snprintf(entry, sizeof(entry), "Me: %.*s", tlen, text);
-          // own_message=true: this is our own post, so it must never bump the
-          // channel's unread badge even though the device's own UI isn't
-          // necessarily showing this channel right now (unlike an on-device
-          // compose, which is always looking at the channel it just sent to).
-          int pos = _ui->addChannelMsg(channel_idx, entry, msg_timestamp, nullptr, 0, true);
+          int pos = _ui->addOwnChannelMsg(channel_idx, text, tlen, msg_timestamp);
           // Same "relayed into mesh" marker an on-device channel send arms (see
           // MessagesScreen::afterSend): sendGroupMessage above already went
           // through sendFloodScoped(GroupChannel&, ...), which calls

examples/companion_radio/MyMeshBot.h

@@ -199,14 +199,7 @@ void MyMesh::tryBotReplyChannel(uint8_t channel_idx, const char* text, uint8_t h
     _bot_last_ch_reply_ms = millis();
     _bot_reply_count++;
 #ifdef DISPLAY_CLASS
-    if (_ui) {
-      // "Me: " (not node_name) -- MessagesScreen recognises an outgoing bubble
-      // by that literal prefix (see computeBubbleBox's caller), same framing
-      // MessagesScreen::afterSend and the app-originated-post mirror use.
-      char with_sender[240];  // "Me: "(4) + expanded(200) + margin
-      snprintf(with_sender, sizeof(with_sender), "Me: %s", expanded);
-      _ui->addChannelMsg(channel_idx, with_sender, 0, nullptr, 0, true);  // own_message: our own bot reply, never unread
-    }
+    if (_ui) _ui->addOwnChannelMsg(channel_idx, expanded);
 #endif
   }
 }
@@ -499,11 +492,7 @@ bool MyMesh::tryBotChannelCommand(uint8_t channel_idx, const char* text, uint8_t
     _bot_last_ch_reply_ms = millis();
     _bot_reply_count++;
 #ifdef DISPLAY_CLASS
-    if (_ui) {
-      char with_sender[240];
-      snprintf(with_sender, sizeof(with_sender), "%s: %s", _prefs.node_name, out);
-      _ui->addChannelMsg(channel_idx, with_sender, 0, nullptr, 0, true);  // own_message: our own bot reply, never unread
-    }
+    if (_ui) _ui->addOwnChannelMsg(channel_idx, out);
 #endif
     if (_locfix_requested) startLocFix(LOCFIX_DEST_CHANNEL, nullptr, channel_idx);
     applyPendingBotActions();
@@ -658,11 +647,7 @@ void MyMesh::sendLocFixResult(const char* msg) {
       _bot_last_ch_reply_ms = millis();
       _bot_reply_count++;
 #ifdef DISPLAY_CLASS
-      if (_ui) {
-        char with_sender[240];
-        snprintf(with_sender, sizeof(with_sender), "%s: %s", _prefs.node_name, msg);
-        _ui->addChannelMsg(_loc_fix.channel_idx, with_sender, 0, nullptr, 0, true);  // own_message: our own bot reply, never unread
-      }
+      if (_ui) _ui->addOwnChannelMsg(_loc_fix.channel_idx, msg);
 #endif
     }
   } else {   // LOCFIX_DEST_CONTACT -- DM or room, both go through sendMessage