feat(nav): navigate to / save a location shared in a message

Locations already travel as plain text ({loc} expands to "lat,lon"), so any
message carrying coordinates can now be acted on. In the fullscreen message
view, the context-menu (Hold Enter) gains Navigate and Save waypoint
entries whenever the message contains a coordinate — alongside Reply.

- geo::parseLatLon: shared scanner for an embedded "lat,lon" (the {loc}
  format), with an optional [WAY] tag that supplies a label. Range-checked,
  requires a decimal point to avoid matching plain integer pairs. Will also
  back the waypoint-share feature later.
- QuickMsgScreen: Navigate opens NavView inline (To/Hdg/distance, honouring
  the global Units setting) over the message, back returns to it; Save
  waypoint stores the point (label from [WAY], else auto-named). Works in
  both DM and channel histories, and on incoming or outgoing messages.

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

examples/companion_radio/GeoUtils.h

@@ -6,6 +6,9 @@
 
 #include <Arduino.h>
 #include <math.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ctype.h>
 
 #ifndef M_PI
   #define M_PI 3.14159265358979323846
@@ -58,4 +61,52 @@ static inline void fmtDist(char* buf, int n, float km, bool imperial) {
   }
 }
 
+// Tag marking a shared waypoint inside a message: "[WAY]<lat>,<lon> <label>".
+// A plain {loc} expansion ("<lat>,<lon>") parses too — the tag just adds intent
+// and a label, and keeps the text readable on apps/firmware that don't know it.
+#define WAYPOINT_MSG_TAG "[WAY]"
+
+// Scan a message for an embedded "lat,lon" location (decimal degrees, the same
+// text {loc} emits). If a WAYPOINT_MSG_TAG precedes it, the trailing text is
+// taken as the label. Returns true and fills lat/lon (1e6-scaled) on a valid,
+// in-range coordinate; label (optional) gets the trimmed tag suffix or "".
+static inline bool parseLatLon(const char* text, int32_t& lat_1e6, int32_t& lon_1e6,
+                               char* label = nullptr, int label_n = 0) {
+  if (label && label_n > 0) label[0] = '\0';
+  if (!text) return false;
+
+  const char* tag  = strstr(text, WAYPOINT_MSG_TAG);
+  const char* scan = tag ? tag + strlen(WAYPOINT_MSG_TAG) : text;
+
+  for (const char* p = scan; *p; p++) {
+    if (*p != '-' && *p != '+' && *p != '.' && !isdigit((unsigned char)*p)) continue;
+    char* end = nullptr;
+    double la = strtod(p, &end);
+    if (end == p) continue;
+    if (!memchr(p, '.', end - p)) continue;           // require a decimal point (skip "5,6")
+    const char* q = end;
+    while (*q == ' ') q++;
+    if (*q != ',') { p = end - 1; continue; }
+    q++;
+    while (*q == ' ') q++;
+    char* end2 = nullptr;
+    double lo = strtod(q, &end2);
+    if (end2 == q) continue;
+    if (la < -90.0 || la > 90.0 || lo < -180.0 || lo > 180.0) continue;
+
+    lat_1e6 = (int32_t)lroundf((float)(la * 1e6));
+    lon_1e6 = (int32_t)lroundf((float)(lo * 1e6));
+    if (label && label_n > 0 && tag) {                // label only from a tagged share
+      const char* s = end2;
+      while (*s == ' ') s++;
+      int n = 0;
+      while (s[n] && n < label_n - 1) { label[n] = s[n]; n++; }
+      while (n > 0 && label[n - 1] == ' ') n--;        // trim trailing spaces
+      label[n] = '\0';
+    }
+    return true;
+  }
+  return false;
+}
+
 }  // namespace geo

examples/companion_radio/ui-new/QuickMsgScreen.h

@@ -2,6 +2,8 @@
 // Custom screen — not part of upstream UITask.cpp
 // Included by UITask.cpp after SettingsScreen.h is defined.
 
+#include "NavView.h"   // navigate to a location shared inside a message
+
 class QuickMsgScreen : public UIScreen {
   UITask* _task;
 
@@ -58,6 +60,18 @@ class QuickMsgScreen : public UIScreen {
   char      _reply_prefix[36];   // "@[nick] " built when reply is triggered
   bool      _reply_mode;         // true while composing a reply (prefix is prepended)
 
+  // Fullscreen-message context menu actions. Built per-message: Reply (when
+  // applicable) plus Navigate / Save waypoint when the message carries a
+  // location (a {loc} string or a [WAY] share). _fs_act maps each visible row
+  // back to an action so the index math survives the conditional layout.
+  enum FsAct : uint8_t { FS_REPLY, FS_NAV, FS_SAVE };
+  uint8_t   _fs_act[3];
+  int       _fs_act_n = 0;
+  // Inline navigate-to-location view layered over the fullscreen message.
+  bool      _nav_active = false;
+  int32_t   _nav_lat = 0, _nav_lon = 0;
+  char      _nav_label[24] = "";
+
   struct ChHistEntry { uint8_t ch_idx; char text[140]; uint32_t timestamp; };
   ChHistEntry _hist[CH_HIST_MAX];
   int _hist_head, _hist_count;
@@ -121,6 +135,64 @@ class QuickMsgScreen : public UIScreen {
     _phase = MSG_PICK;
   }
 
+  // Build the fullscreen-message options popup: Reply (if allowed) plus
+  // Navigate / Save waypoint when `body` carries a location. Opens _ctx_menu
+  // only when there's at least one action. Parses the location once here and
+  // stashes it for the action handler.
+  void buildFsMenu(const char* body, bool reply_allowed) {
+    bool has_loc = geo::parseLatLon(body, _nav_lat, _nav_lon, _nav_label, sizeof(_nav_label));
+    int n = (reply_allowed ? 1 : 0) + (has_loc ? 2 : 0);
+    if (n == 0) return;
+    _fs_act_n = 0;
+    _ctx_menu.begin("Options", n);
+    if (reply_allowed) { _ctx_menu.addItem("Reply");         _fs_act[_fs_act_n++] = FS_REPLY; }
+    if (has_loc)       { _ctx_menu.addItem("Navigate");      _fs_act[_fs_act_n++] = FS_NAV;
+                         _ctx_menu.addItem("Save waypoint"); _fs_act[_fs_act_n++] = FS_SAVE; }
+  }
+
+  // Dispatch the selected fullscreen-options row. `channel` picks which
+  // fullscreen view to close when starting a reply.
+  void dispatchFsAction(bool channel) {
+    FsAct a = (FsAct)_fs_act[(_ctx_menu._sel >= 0 && _ctx_menu._sel < _fs_act_n) ? _ctx_menu._sel : 0];
+    _ctx_menu.active = false;
+    if (a == FS_REPLY) {
+      (channel ? _fs : _dm_fs).active = false;
+      startReply(channel);
+    } else if (a == FS_NAV) {
+      _nav_active = true;            // keep the message view active underneath
+    } else {
+      saveSharedWaypoint();
+    }
+  }
+
+  // Save the location parsed from the open message as a waypoint. Uses the
+  // [WAY] label when present, else auto-names it like a manually-marked point.
+  void saveSharedWaypoint() {
+    if (_task->waypoints().full()) { _task->showAlert("Waypoints full", 1000); return; }
+    char label[WAYPOINT_LABEL_LEN];
+    if (_nav_label[0]) {
+      strncpy(label, _nav_label, sizeof(label) - 1);
+      label[sizeof(label) - 1] = '\0';
+    } else {
+      snprintf(label, sizeof(label), "WP%d", _task->waypoints().count() + 1);
+    }
+    if (_task->waypoints().add(_nav_lat, _nav_lon,
+                               (uint32_t)rtc_clock.getCurrentTime(), label)) {
+      _task->saveWaypoints();
+      _task->showAlert("Waypoint saved", 800);
+    } else {
+      _task->showAlert("Waypoints full", 1000);
+    }
+  }
+
+  void renderNav(DisplayDriver& display) {
+    int32_t mylat, mylon; bool have = _task->currentLocation(mylat, mylon);
+    int cog; bool cogv = _task->currentCourse(cog);
+    NodePrefs* p = _task->getNodePrefs();
+    navview::draw(display, have, mylat, mylon, _nav_lat, _nav_lon,
+                  _nav_label[0] ? _nav_label : "Msg loc", cogv, cog, p && p->units_imperial);
+  }
+
   void setupMsgPick() {
     _msg_sel = _msg_scroll = 0;
     _active_msg_count = 0;
@@ -484,6 +556,7 @@ public:
 
     _ctx_menu.active = false;
     _ctx_dirty = false;
+    _nav_active = false;
     _pin_picker_active = false;
     _dm_direct_entry = false;
     _unread_at_entry = 0;
@@ -535,6 +608,9 @@ public:
     display.setTextSize(1);
     display.setColor(DisplayDriver::LIGHT);
 
+    // Navigate-to-location view sits over everything else while active.
+    if (_nav_active) { renderNav(display); return 1000; }
+
     int lh      = display.getLineHeight();
     int item_h  = display.lineStep();
     int start_y = display.listStart();
@@ -985,6 +1061,11 @@ public:
   }
 
   bool handleInput(char c) override {
+    // Navigate view: any back key returns to the message it was opened from.
+    if (_nav_active) {
+      if (c == KEY_CANCEL || c == KEY_ENTER || c == KEY_CONTEXT_MENU) _nav_active = false;
+      return true;
+    }
     if (_phase == MODE_SELECT) {
       // Context menu (Mark-all-read) takes precedence while active.
       if (_ctx_menu.active) {
@@ -1268,8 +1349,7 @@ public:
         if (_ctx_menu.active) {
           auto res = _ctx_menu.handleInput(c);
           if (res == PopupMenu::SELECTED) {
-            _dm_fs.active = false;
-            startReply(false);
+            dispatchFsAction(false);
           } else if (res != PopupMenu::NONE) {
             _ctx_menu.active = false;
           }
@@ -1284,11 +1364,13 @@ public:
           _dm_fs.active = false;
         } else if (res == FullscreenMsgView::REPLY) {
           int ring_pos = dmHistEntryForContact(_sel_contact.id.pub_key, _dm_hist_sel);
-          if (ring_pos >= 0 && !_dm_hist[ring_pos].outgoing) {
-            char _tname[32]; DisplayDriver::translateUTF8Static(_tname, _sel_contact.name, sizeof(_tname));
-            snprintf(_reply_prefix, sizeof(_reply_prefix), "@[%.31s] ", _tname);
-            _ctx_menu.begin("Options", 1);
-            _ctx_menu.addItem("Reply");
+          if (ring_pos >= 0) {
+            bool reply_ok = !_dm_hist[ring_pos].outgoing;
+            if (reply_ok) {
+              char _tname[32]; DisplayDriver::translateUTF8Static(_tname, _sel_contact.name, sizeof(_tname));
+              snprintf(_reply_prefix, sizeof(_reply_prefix), "@[%.31s] ", _tname);
+            }
+            buildFsMenu(_dm_hist[ring_pos].text, reply_ok);
           }
         }
         return true;
@@ -1356,8 +1438,7 @@ public:
         if (_ctx_menu.active) {
           auto res = _ctx_menu.handleInput(c);
           if (res == PopupMenu::SELECTED) {
-            _fs.active = false;
-            startReply(true);
+            dispatchFsAction(true);
           } else if (res != PopupMenu::NONE) {
             _ctx_menu.active = false;
           }
@@ -1372,10 +1453,8 @@ public:
           _fs.active = false;
         } else if (res == FullscreenMsgView::REPLY) {
           int ring_pos = histEntryForChannel(_sel_channel_idx, _hist_sel);
-          if (ring_pos >= 0 && buildChannelReplyPrefix(_hist[ring_pos].text)) {
-            _ctx_menu.begin("Options", 1);
-            _ctx_menu.addItem("Reply");
-          }
+          if (ring_pos >= 0)
+            buildFsMenu(_hist[ring_pos].text, buildChannelReplyPrefix(_hist[ring_pos].text));
         }
         return true;
       }