Show the alias or the direct message user's Matrix ID in the room picker

The forward and share room picker showed only a display name, so several
direct messages or rooms sharing a name were indistinguishable.

Render a secondary line: the canonical alias when the room has one, otherwise
the other person's Matrix ID for a direct message. No model change was needed,
because heroes is populated only for a direct message with exactly one hero,
so heroes.singleOrNull() is the peer.

libraries/roomselect/impl/src/main/kotlin/io/element/android/libraries/roomselect/impl/RoomSelectStateProvider.kt

@@ -13,6 +13,7 @@ import androidx.compose.ui.tooling.preview.PreviewParameterProvider
 import io.element.android.libraries.designsystem.theme.components.SearchBarResultState
 import io.element.android.libraries.matrix.api.core.RoomAlias
 import io.element.android.libraries.matrix.api.core.RoomId
+import io.element.android.libraries.matrix.ui.components.aMatrixUser
 import io.element.android.libraries.matrix.ui.components.aSelectRoomInfo
 import io.element.android.libraries.matrix.ui.model.SelectRoomInfo
 import io.element.android.libraries.roomselect.api.RoomSelectMode
@@ -79,5 +80,12 @@ internal fun aRoomSelectRoomList() = persistentListOf(
     ),
     aSelectRoomInfo(
         roomId = RoomId("!room3:domain"),
+        name = "Alice",
+        heroes = persistentListOf(
+            aMatrixUser(id = "@alice:example.org", displayName = "Alice"),
+        ),
+    ),
+    aSelectRoomInfo(
+        roomId = RoomId("!room4:domain"),
     ),
 )

libraries/roomselect/impl/src/main/kotlin/io/element/android/libraries/roomselect/impl/RoomSelectView.kt

@@ -260,10 +260,10 @@ private fun RoomSummaryView(
                 maxLines = 1,
                 overflow = TextOverflow.Ellipsis
             )
-            // Alias
+            val subtitle = roomInfo.canonicalAlias?.value ?: roomInfo.heroes.singleOrNull()?.userId?.value
-            roomInfo.canonicalAlias?.let { alias ->
+            if (subtitle != null) {
                 Text(
-                    text = alias.value,
+                    text = subtitle,
                     color = ElementTheme.colors.textSecondary,
                     style = ElementTheme.typography.fontBodySmRegular,
                     maxLines = 1,

libraries/roomselect/impl/src/test/kotlin/io/element/android/libraries/roomselect/impl/RoomSelectViewTest.kt

@@ -0,0 +1,64 @@
+/*
+ * Copyright (c) 2026 Element Creations Ltd.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
+ * Please see LICENSE files in the repository root for full details.
+ */
+
+@file:OptIn(ExperimentalTestApi::class)
+
+package io.element.android.libraries.roomselect.impl
+
+import androidx.activity.ComponentActivity
+import androidx.compose.ui.test.AndroidComposeUiTest
+import androidx.compose.ui.test.ExperimentalTestApi
+import androidx.compose.ui.test.assertIsDisplayed
+import androidx.compose.ui.test.onNodeWithText
+import androidx.compose.ui.test.v2.runAndroidComposeUiTest
+import io.element.android.libraries.designsystem.theme.components.SearchBarResultState
+import io.element.android.libraries.matrix.api.core.RoomId
+import io.element.android.tests.testutils.EnsureNeverCalled
+import io.element.android.tests.testutils.EnsureNeverCalledWithParam
+import io.element.android.tests.testutils.robolectric.RobolectricTest
+import org.junit.Test
+import org.robolectric.annotation.Config
+
+class RoomSelectViewTest : RobolectricTest() {
+    @Config(qualifiers = "h1024dp")
+    @Test
+    fun `a room with a canonical alias renders the alias`() = runAndroidComposeUiTest {
+        setRoomSelectView(
+            aRoomSelectState(
+                resultState = SearchBarResultState.Results(aRoomSelectRoomList()),
+            ),
+        )
+        onNodeWithText("Room with alias").assertIsDisplayed()
+        onNodeWithText("#alias:example.org").assertIsDisplayed()
+    }
+
+    @Config(qualifiers = "h1024dp")
+    @Test
+    fun `a direct message without alias renders the matrix id of the other user`() = runAndroidComposeUiTest {
+        setRoomSelectView(
+            aRoomSelectState(
+                resultState = SearchBarResultState.Results(aRoomSelectRoomList()),
+            ),
+        )
+        onNodeWithText("Alice").assertIsDisplayed()
+        onNodeWithText("@alice:example.org").assertIsDisplayed()
+    }
+}
+
+private fun AndroidComposeUiTest<ComponentActivity>.setRoomSelectView(
+    state: RoomSelectState,
+    onDismiss: () -> Unit = EnsureNeverCalled(),
+    onSubmit: (List<RoomId>) -> Unit = EnsureNeverCalledWithParam(),
+) {
+    setContent {
+        RoomSelectView(
+            state = state,
+            onDismiss = onDismiss,
+            onSubmit = onSubmit,
+        )
+    }
+}