From db39522bbb446a6e89b0715564448514862a457f Mon Sep 17 00:00:00 2001
From: infi <infi@infi.sh>
Date: Sat, 6 Jun 2026 18:40:39 +0200
Subject: [PATCH] feat: handle PUA characters

---
 app/src/main/java/chat/stoat/composables/chat/Message.kt  | 8 +++++---
 app/src/main/java/chat/stoat/internals/text/Gigamoji.kt   | 1 +
 app/src/main/java/chat/stoat/internals/text/PUAChars.kt   | 6 ++++++
 .../screens/chat/views/channel/ChannelScreenViewModel.kt  | 3 ++-
 4 files changed, 14 insertions(+), 4 deletions(-)
 create mode 100644 app/src/main/java/chat/stoat/internals/text/PUAChars.kt

diff --git a/app/src/main/java/chat/stoat/composables/chat/Message.kt b/app/src/main/java/chat/stoat/composables/chat/Message.kt
index c89bb144..f543939b 100644
--- a/app/src/main/java/chat/stoat/composables/chat/Message.kt
+++ b/app/src/main/java/chat/stoat/composables/chat/Message.kt
@@ -87,6 +87,7 @@ import chat.stoat.core.model.schemas.User
 import chat.stoat.internals.text.Gigamoji
 import chat.stoat.internals.text.GigamojiState
 import chat.stoat.internals.text.MessageProcessor
+import chat.stoat.internals.text.stripPUAChars
 import chat.stoat.persistence.KVStorage
 import com.mikepenz.markdown.model.State
 import kotlinx.coroutines.launch
@@ -438,9 +439,10 @@ fun Message(
 
                         key(message.content) {
                             message.content?.let {
-                                if (message.content!!.isBlank()) return@let // if only an attachment is sent
+                                val content = it.stripPUAChars()
+                                if (content.isBlank()) return@let // if only an attachment is sent
 
-                                val gigamoji = Gigamoji.useGigamojiForMessage(message.content!!)
+                                val gigamoji = Gigamoji.useGigamojiForMessage(content)
                                 val fontSizeMultiplier = when (gigamoji) {
                                     GigamojiState.Single -> 5f
                                     GigamojiState.Multiple -> 2f
@@ -455,7 +457,7 @@ fun Message(
                                     )
                                 } else {
                                     ChatMarkdown(
-                                        content = message.content!!,
+                                        content = content,
                                         serverId = StoatAPI.channelCache[message.channel]?.server,
                                         fontSizeMultiplier = fontSizeMultiplier,
                                     )
diff --git a/app/src/main/java/chat/stoat/internals/text/Gigamoji.kt b/app/src/main/java/chat/stoat/internals/text/Gigamoji.kt
index a025f770..8b429a71 100644
--- a/app/src/main/java/chat/stoat/internals/text/Gigamoji.kt
+++ b/app/src/main/java/chat/stoat/internals/text/Gigamoji.kt
@@ -26,6 +26,7 @@ object Gigamoji {
                 Character.isWhitespace(codepoint) -> lastWasZwj = false
                 codepoint == 0x200D -> lastWasZwj = true
                 codepoint == 0xFE0F || codepoint == 0xFE0E || codepoint == 0x20E3 -> Unit
+                codepoint in PUA_MIN..PUA_MAX -> Unit
                 codepoint in 0x1F3FB..0x1F3FF -> lastWasZwj = false
                 MessageProcessor.emoji.codepointIsEmoji(codepoint) -> {
                     if (!lastWasZwj) count++
diff --git a/app/src/main/java/chat/stoat/internals/text/PUAChars.kt b/app/src/main/java/chat/stoat/internals/text/PUAChars.kt
new file mode 100644
index 00000000..d97326c5
--- /dev/null
+++ b/app/src/main/java/chat/stoat/internals/text/PUAChars.kt
@@ -0,0 +1,6 @@
+package chat.stoat.internals.text
+
+internal const val PUA_MIN = 0xE0E0
+internal const val PUA_MAX = 0xE0E6
+
+internal fun String.stripPUAChars(): String = filter { it.code !in PUA_MIN..PUA_MAX }
diff --git a/app/src/main/java/chat/stoat/screens/chat/views/channel/ChannelScreenViewModel.kt b/app/src/main/java/chat/stoat/screens/chat/views/channel/ChannelScreenViewModel.kt
index 200e35e4..38c4f82c 100644
--- a/app/src/main/java/chat/stoat/screens/chat/views/channel/ChannelScreenViewModel.kt
+++ b/app/src/main/java/chat/stoat/screens/chat/views/channel/ChannelScreenViewModel.kt
@@ -49,6 +49,7 @@ import chat.stoat.callbacks.UiCallbacks
 import chat.stoat.core.model.schemas.Channel
 import chat.stoat.core.model.schemas.Message
 import chat.stoat.internals.text.MessageProcessor
+import chat.stoat.internals.text.stripPUAChars
 import chat.stoat.composables.markdown.prose.easyLineBreaks
 import chat.stoat.markdown.StoatMarkdownFlavour
 import chat.stoat.persistence.KVStorage
@@ -264,7 +265,7 @@ class ChannelScreenViewModel(
 
     private suspend fun parseAst(content: String?): State? =
         content?.takeIf { it.isNotBlank() }?.let { c ->
-            val prepared = injectMassMentionMarkers(easyLineBreaks(c))
+            val prepared = injectMassMentionMarkers(easyLineBreaks(c.stripPUAChars()))
             parseMarkdownFlow(prepared, flavour = StoatMarkdownFlavour(prepared))
                 .first { it !is State.Loading }
         }