Edit : fallback to room.edit when timeline item is not found.

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/room/MatrixRoom.kt

@@ -126,6 +126,8 @@ interface MatrixRoom : Closeable {
 
     suspend fun sendMessage(body: String, htmlBody: String?, mentions: List<Mention>): Result<Unit>
 
+    suspend fun editMessage(eventId: EventId, body: String, htmlBody: String?, mentions: List<Mention>): Result<Unit>
+
     suspend fun sendImage(
         file: File,
         thumbnailFile: File?,

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/timeline/TimelineException.kt

@@ -18,4 +18,5 @@ package io.element.android.libraries.matrix.api.timeline
 
 sealed class TimelineException : Exception() {
     data object CannotPaginate : TimelineException()
+    data object EventNotFound : TimelineException()
 }