fix(qr): Preserve incoming channels when adding from QR (#6013)

core/ui/src/commonMain/kotlin/org/meshtastic/core/ui/qr/ScannedQrCodeDialog.kt

@@ -63,6 +63,7 @@ import org.meshtastic.core.resources.replace
 import org.meshtastic.core.resources.replace_channels_and_settings_description
 import org.meshtastic.core.ui.component.ChannelSelection
 import org.meshtastic.core.ui.theme.AppTheme
+import org.meshtastic.core.ui.util.mergeChannelSettingsForAdd
 import org.meshtastic.proto.ChannelSet
 
 @Composable
@@ -107,9 +108,7 @@ fun ScannedQrCodeDialog(
                     ),
                 )
             } else {
-                // To guarantee consistent ordering, using a LinkedHashSet which iterates through
-                // its entries according to the order an item was *first* inserted.
-                val result = (channels.settings + incoming.settings).distinct()
+                val result = mergeChannelSettingsForAdd(channels.settings, incoming.settings)
                 channels.copy(settings = result)
             }
         }

core/ui/src/commonMain/kotlin/org/meshtastic/core/ui/util/ProtoExtensions.kt

@@ -154,3 +154,20 @@ suspend fun applyReplacementChannelSet(
     }
     radioConfigRepository.replaceAllSettings(channelSet.settings)
 }
+
+/**
+ * Builds the ADD-mode preview list for QR import. Existing channels are preserved at their positions; every incoming
+ * channel is appended in order without deduplication.
+ *
+ * Structural `.distinct()` was previously used here, but it silently dropped incoming channels that matched existing
+ * entries, shifting later channels to wrong indices and hiding them from the user. The caller (UI) lets the user select
+ * which incoming channels to keep.
+ *
+ * @param existing The current [ChannelSettings] list on the radio. Preserved in order.
+ * @param incoming The imported [ChannelSettings] list. Appended in order.
+ * @return The concatenated list `[existing..., incoming...]`.
+ */
+fun mergeChannelSettingsForAdd(
+    existing: List<ChannelSettings>,
+    incoming: List<ChannelSettings>,
+): List<ChannelSettings> = existing + incoming

core/ui/src/commonTest/kotlin/org/meshtastic/core/ui/util/ProtoExtensionsTest.kt

@@ -141,4 +141,75 @@ class ProtoExtensionsTest {
         assertEquals(2, result[2].index)
         assertEquals(secondaryB, result[2].settings)
     }
+
+    // --- mergeChannelSettingsForAdd tests ---
+
+    @Test
+    fun merge_preserves_all_existing_channels_in_order() {
+        val existing = listOf(ChannelSettings(name = "A"), ChannelSettings(name = "B"))
+
+        val result = mergeChannelSettingsForAdd(existing, incoming = emptyList())
+
+        assertEquals(2, result.size)
+        assertEquals("A", result[0].name)
+        assertEquals("B", result[1].name)
+    }
+
+    @Test
+    fun merge_appends_all_incoming_channels_in_order() {
+        val incoming = listOf(ChannelSettings(name = "C"), ChannelSettings(name = "D"))
+
+        val result = mergeChannelSettingsForAdd(existing = emptyList(), incoming)
+
+        assertEquals(2, result.size)
+        assertEquals("C", result[0].name)
+        assertEquals("D", result[1].name)
+    }
+
+    @Test
+    fun merge_preserves_structurally_equal_channels() {
+        val channel = ChannelSettings(name = "LongFast", psk = byteArrayOf(1).toByteString())
+
+        val result = mergeChannelSettingsForAdd(existing = listOf(channel), incoming = listOf(channel))
+
+        assertEquals(2, result.size)
+    }
+
+    @Test
+    fun merge_preserves_same_name_different_psk() {
+        val existingChan = ChannelSettings(name = "A", psk = byteArrayOf(1).toByteString())
+        val incomingChan = ChannelSettings(name = "A", psk = byteArrayOf(2).toByteString())
+
+        val result = mergeChannelSettingsForAdd(listOf(existingChan), listOf(incomingChan))
+
+        assertEquals(2, result.size)
+    }
+
+    @Test
+    fun merge_preserves_same_psk_different_name() {
+        val psk = byteArrayOf(1, 2).toByteString()
+        val existingChan = ChannelSettings(name = "A", psk = psk)
+        val incomingChan = ChannelSettings(name = "B", psk = psk)
+
+        val result = mergeChannelSettingsForAdd(listOf(existingChan), listOf(incomingChan))
+
+        assertEquals(2, result.size)
+    }
+
+    @Test
+    fun merge_preserves_duplicate_inside_incoming() {
+        val a = ChannelSettings(name = "A", psk = byteArrayOf(1).toByteString())
+        val b = ChannelSettings(name = "B", psk = byteArrayOf(2).toByteString())
+
+        val result = mergeChannelSettingsForAdd(existing = emptyList(), incoming = listOf(a, a, b))
+
+        assertEquals(3, result.size)
+    }
+
+    @Test
+    fun merge_both_empty_produces_empty_list() {
+        val result = mergeChannelSettingsForAdd(existing = emptyList(), incoming = emptyList())
+
+        assertTrue(result.isEmpty())
+    }
 }