implemented dynamic quick reactions by surfacing emojis from message content in the chat options dialog

lib/utils/emoji_detection.dart

@@ -10,6 +10,8 @@ const int _zwj = 0x200D;
 const int _vs15 = 0xFE0E;
 const int _vs16 = 0xFE0F;
 const int _keycap = 0x20E3;
+const int _skinToneStart = 0x1F3FB;
+const int _skinToneEnd = 0x1F3FF;
 
 /// Codepoints that only ever glue an emoji sequence together and never stand
 /// on their own — they don't disqualify a cluster from counting as emoji.
@@ -18,7 +20,7 @@ bool _isModifier(int r) =>
     r == _vs15 ||
     r == _vs16 ||
     r == _keycap ||
-    (r >= 0x1F3FB && r <= 0x1F3FF) || // skin-tone modifiers
+    (r >= _skinToneStart && r <= _skinToneEnd) || // skin-tone modifiers
     (r >= 0xE0020 && r <= 0xE007F); // tag characters (flag sequences)
 
 /// The digits, `#` and `*` that become emoji only when combined with the
@@ -84,3 +86,31 @@ double? standaloneEmojiFontSize(String text) {
   if (count == 0) return null;
   return 34;
 }
+
+/// [emoji] with any Fitzpatrick skin-tone modifier stripped, so tone variants
+/// of the same emoji compare equal (👍🏻 → 👍). Used to dedupe reactions that
+/// only differ in skin tone.
+String emojiSkinToneNeutral(String emoji) => String.fromCharCodes(
+  emoji.runes.where((r) => r < _skinToneStart || r > _skinToneEnd),
+);
+
+/// Distinct emojis contained in [text], most-frequent first with ties broken
+/// by first appearance. Used to offer a message's own emojis as quick
+/// reactions.
+List<String> extractEmojis(String text) {
+  final counts = <String, int>{};
+  final firstSeen = <String, int>{};
+  var order = 0;
+  for (final cluster in text.characters) {
+    if (!_isEmojiCluster(cluster)) continue;
+    counts.update(cluster, (value) => value + 1, ifAbsent: () => 1);
+    firstSeen.putIfAbsent(cluster, () => order++);
+  }
+
+  final emojis = counts.keys.toList();
+  emojis.sort((a, b) {
+    final byCount = counts[b]!.compareTo(counts[a]!);
+    return byCount != 0 ? byCount : firstSeen[a]!.compareTo(firstSeen[b]!);
+  });
+  return emojis;
+}