Give the id to AvatarData to be able to compute initial properly.

libraries/designsystem/src/main/kotlin/io/element/android/libraries/designsystem/components/avatar/Avatar.kt

@@ -29,6 +29,7 @@ import androidx.compose.ui.graphics.Brush
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.layout.ContentScale
 import androidx.compose.ui.tooling.preview.Preview
+import androidx.compose.ui.tooling.preview.PreviewParameter
 import androidx.compose.ui.unit.sp
 import coil.compose.AsyncImage
 import io.element.android.libraries.designsystem.AvatarGradientEnd
@@ -90,7 +91,7 @@ private fun InitialsAvatar(
     ) {
         Text(
             modifier = Modifier.align(Alignment.Center),
-            text = avatarData.name.first().uppercase(),
+            text = avatarData.getInitial(),
             fontSize = (avatarData.size.value / 2).sp,
             color = Color.White,
         )
@@ -99,13 +100,15 @@ private fun InitialsAvatar(
 
 @Preview
 @Composable
-fun AvatarLightPreview() = ElementPreviewLight { ContentToPreview() }
+fun AvatarLightPreview(@PreviewParameter(AvatarDataPreviewParameterProvider::class) avatarData: AvatarData) =
+    ElementPreviewLight { ContentToPreview(avatarData) }
 
 @Preview
 @Composable
-fun AvatarDarkPreview() = ElementPreviewDark { ContentToPreview() }
+fun AvatarDarkPreview(@PreviewParameter(AvatarDataPreviewParameterProvider::class) avatarData: AvatarData) =
+    ElementPreviewDark { ContentToPreview(avatarData) }
 
 @Composable
-private fun ContentToPreview() {
-    Avatar(AvatarData(name = "A"))
+private fun ContentToPreview(avatarData: AvatarData) {
+    Avatar(avatarData)
 }

libraries/designsystem/src/main/kotlin/io/element/android/libraries/designsystem/components/avatar/AvatarData.kt

@@ -17,10 +17,31 @@
 package io.element.android.libraries.designsystem.components.avatar
 
 import androidx.compose.runtime.Immutable
+import androidx.compose.ui.tooling.preview.PreviewParameterProvider
 
 @Immutable
 data class AvatarData(
-    val name: String = "",
+    val id: String,
+    val name: String?,
     val url: String? = null,
     val size: AvatarSize = AvatarSize.MEDIUM
+) {
+    fun getInitial(): String {
+        val firstChar = name?.firstOrNull() ?: id.getOrNull(1) ?: '?'
+        return firstChar.uppercase()
+    }
+}
+
+open class AvatarDataPreviewParameterProvider : PreviewParameterProvider<AvatarData> {
+    override val values: Sequence<AvatarData>
+        get() = sequenceOf(
+            anAvatarData(),
+            anAvatarData().copy(name = null),
+        )
+}
+
+fun anAvatarData() = AvatarData(
+    // Let's the id not start with a 'a'.
+    id = "@id_of_alice:server.org",
+    name = "Alice",
 )

libraries/matrixui/src/main/kotlin/io/element/android/libraries/matrix/ui/MatrixItemHelper.kt

@@ -38,7 +38,8 @@ class MatrixItemHelper @Inject constructor(
             val userDisplayName = client.loadUserDisplayName().getOrNull()
             val avatarData =
                 AvatarData(
-                    userDisplayName ?: client.userId().value,
+                    client.userId().value,
+                    userDisplayName,
                     userAvatarUrl,
                     avatarSize
                 )

libraries/matrixui/src/main/kotlin/io/element/android/libraries/matrix/ui/components/MatrixUserPreviewParameterProvider.kt

@@ -17,22 +17,24 @@
 package io.element.android.libraries.matrix.ui.components
 
 import androidx.compose.ui.tooling.preview.PreviewParameterProvider
-import io.element.android.libraries.designsystem.components.avatar.AvatarData
+import io.element.android.libraries.designsystem.components.avatar.anAvatarData
 import io.element.android.libraries.matrix.core.UserId
 import io.element.android.libraries.matrix.ui.model.MatrixUser
 
 open class MatrixUserPreviewParameterProvider : PreviewParameterProvider<MatrixUser> {
     override val values: Sequence<MatrixUser>
         get() = sequenceOf(
+            aMatrixUser(),
             MatrixUser(
-                id = UserId("@alice:server.org"),
-                username = "Alice",
-                avatarData = AvatarData("Alice")
-            ),
-            MatrixUser(
-                id = UserId("@alice:server.org"),
+                id = UserId("@id_of_alice:server.org"),
                 username = null,
-                avatarData = AvatarData("Alice")
+                avatarData = anAvatarData().copy(name = null)
             ),
         )
 }
+
+fun aMatrixUser() = MatrixUser(
+    id = UserId("@id_of_alice:server.org"),
+    username = "Alice",
+    avatarData = anAvatarData()
+)

libraries/matrixui/src/main/kotlin/io/element/android/libraries/matrix/ui/model/MatrixUser.kt

@@ -24,7 +24,7 @@ import io.element.android.libraries.matrix.core.UserId
 data class MatrixUser(
     val id: UserId,
     val username: String? = null,
-    val avatarData: AvatarData = AvatarData(),
+    val avatarData: AvatarData = AvatarData(id.value, username),
 )
 
 fun MatrixUser.getBestName(): String {