fix: short channel id in connection details

app/src/main/java/to/bitkit/ext/ShortChannelId.kt

@@ -0,0 +1,21 @@
+package to.bitkit.ext
+
+/**
+ * Decodes a BOLT short channel id into Core Lightning `block x tx x output` form
+ * (e.g. `777477x916x0`): block height in the high 24 bits, transaction index in the next 24,
+ * funding output index in the low 16.
+ */
+fun ULong.formattedAsShortChannelId(): String {
+    val blockHeight = this shr 40
+    val txIndex = (this shr 16) and 0xFFFFFFu
+    val outputIndex = this and 0xFFFFu
+    return "${blockHeight}x${txIndex}x$outputIndex"
+}
+
+/**
+ * Short channel id for display. Uses the channel's own scid (open channels) and, for closed
+ * channels which carry none, the scid from the confidently-linked order. Null when unavailable.
+ */
+internal fun resolveDisplayShortChannelId(channelScid: ULong?, linkedOrderScid: String?): String? =
+    channelScid?.formattedAsShortChannelId()
+        ?: linkedOrderScid?.toULongOrNull()?.formattedAsShortChannelId()

app/src/main/java/to/bitkit/ui/settings/lightning/ChannelDetailScreen.kt

@@ -59,6 +59,7 @@ import to.bitkit.env.Env
 import to.bitkit.ext.DatePattern
 import to.bitkit.ext.amountOnClose
 import to.bitkit.ext.createChannelDetails
+import to.bitkit.ext.resolveDisplayShortChannelId
 import to.bitkit.ext.setClipboardText
 import to.bitkit.models.Toast
 import to.bitkit.models.msatFloorOf
@@ -220,6 +221,15 @@ private fun ChannelDetailContent(
 
         val order = blocktankOrder ?: cjitEntry
 
+        val linkedOrderScid = when (order) {
+            is IBtOrder -> order.channel?.shortChannelId
+            is IcJitEntry -> order.channel?.shortChannelId
+            else -> null
+        }
+        val displayShortChannelId = remember(channel, linkedOrderScid) {
+            resolveDisplayShortChannelId(channel.details.shortChannelId, linkedOrderScid)
+        }
+
         val capacity = channel.details.channelValueSats.toLong()
         val localBalance = channel.details.amountOnClose.toLong()
         val remoteBalance = msatFloorOf(channel.details.inboundCapacityMsat).toLong()
@@ -429,18 +439,20 @@ private fun ChannelDetailContent(
                     )
                 }
 
-                SectionRow(
-                    name = stringResource(R.string.lightning__channel_id),
-                    valueContent = {
-                        CaptionB(
-                            text = channel.details.channelId,
-                            maxLines = 1,
-                            overflow = TextOverflow.MiddleEllipsis,
-                            textAlign = TextAlign.End,
-                        )
-                    },
-                    onClick = { onCopyText(channel.details.channelId) }
-                )
+                displayShortChannelId?.let { scid ->
+                    SectionRow(
+                        name = stringResource(R.string.lightning__channel_id),
+                        valueContent = {
+                            CaptionB(
+                                text = scid,
+                                maxLines = 1,
+                                overflow = TextOverflow.MiddleEllipsis,
+                                textAlign = TextAlign.End,
+                            )
+                        },
+                        onClick = { onCopyText(scid) }
+                    )
+                }
 
                 channel.details.fundingTxo?.let { fundingTxo ->
                     val channelPoint = "${fundingTxo.txid}:${fundingTxo.vout}"

app/src/test/java/to/bitkit/ext/ShortChannelIdTest.kt

@@ -0,0 +1,61 @@
+package to.bitkit.ext
+
+import org.junit.Test
+import to.bitkit.test.BaseUnitTest
+import kotlin.test.assertEquals
+import kotlin.test.assertNull
+
+class ShortChannelIdTest : BaseUnitTest() {
+
+    @Test
+    fun `formattedAsShortChannelId formats lnd scid into cln form`() {
+        // The two formats the issue calls out (LND uint64 and CLN block x tx x output)
+        // are two encodings of the same channel.
+        assertEquals("777477x916x0", 854_845_001_888_432_128uL.formattedAsShortChannelId())
+    }
+
+    @Test
+    fun `formattedAsShortChannelId formats from components`() {
+        val scid = (700_000uL shl 40) or (1uL shl 16) or 2uL
+        assertEquals("700000x1x2", scid.formattedAsShortChannelId())
+    }
+
+    @Test
+    fun `formattedAsShortChannelId formats zero as all zeroes`() {
+        assertEquals("0x0x0", 0uL.formattedAsShortChannelId())
+    }
+
+    @Test
+    fun `formattedAsShortChannelId keeps max components in their fields`() {
+        val scid = (0xFFFFFFuL shl 40) or (0xFFFFFFuL shl 16) or 0xFFFFuL
+        assertEquals("16777215x16777215x65535", scid.formattedAsShortChannelId())
+    }
+
+    @Test
+    fun `resolveDisplayShortChannelId prefers channel scid for open channel`() {
+        val result = resolveDisplayShortChannelId(
+            channelScid = 854_845_001_888_432_128uL,
+            linkedOrderScid = "0",
+        )
+        assertEquals("777477x916x0", result)
+    }
+
+    @Test
+    fun `resolveDisplayShortChannelId falls back to linked order scid for closed channel`() {
+        val result = resolveDisplayShortChannelId(
+            channelScid = null,
+            linkedOrderScid = "854845001888432128",
+        )
+        assertEquals("777477x916x0", result)
+    }
+
+    @Test
+    fun `resolveDisplayShortChannelId returns null when both unavailable`() {
+        assertNull(resolveDisplayShortChannelId(channelScid = null, linkedOrderScid = null))
+    }
+
+    @Test
+    fun `resolveDisplayShortChannelId returns null for non-numeric order scid`() {
+        assertNull(resolveDisplayShortChannelId(channelScid = null, linkedOrderScid = "not-a-number"))
+    }
+}

changelog.d/next/1002.fixed.md

@@ -0,0 +1 @@
+Connection Details now shows the short channel ID for Lightning connections instead of the long internal channel ID.