refactor(chat): rename closeBacklog to tryCloseBacklog

  closeBacklog can fall back to fetching the newest messages instead of
  actually closing the gap once MAX_BACKLOG_ROUNDS is exceeded, leaving
  the remaining range genuinely open for later. The name promised full
  closure with no such caveat. Rename it and its OfflineFirstChatRepository
  wrapper (closeBacklogFromNewestOfflineMessage) to make the best-effort
  nature explicit, and update call sites, comments, and test names to
  match.

Assisted-by: Claude Sonnet 5 <noreply@anthropic.com>
Signed-off-by: Marcel Hibbe <dev@mhibbe.de>

Author: mahibi

app/src/main/java/com/nextcloud/talk/chat/data/network/ChatMessageSyncer.kt

@@ -308,7 +308,7 @@ class ChatMessageSyncer @Inject constructor(
             chatBlocksDao.getNewestMessageIdFromChatBlocks(target.internalConversationId, target.threadId)
 
         val outcome = if (newestMessageIdFromDb > 0) {
-            closeBacklog(
+            tryCloseBacklog(
                 target = target,
                 fromMessageId = newestMessageIdFromDb,
                 limit = limit,
@@ -344,7 +344,8 @@ class ChatMessageSyncer @Inject constructor(
     }
 
     /**
-     * Fetches the messages newer than [fromMessageId] until the backlog is fully closed.
+     * Tries to fetch the messages newer than [fromMessageId] until the backlog is fully closed —
+     * there is no guarantee it will be: see the [MAX_BACKLOG_ROUNDS] fallback below.
      *
      * A single fetch is capped by [limit], so one request only narrows a backlog larger than
      * that — and on chat-relay servers the remaining gap would become permanent as soon as a
@@ -355,8 +356,8 @@ class ChatMessageSyncer @Inject constructor(
      * stays visible in the block structure (closable by scrolling up) rather than a block
      * claiming ranges that were never fetched.
      */
-    @Suppress("LongParameterList")
-    suspend fun closeBacklog(
+    @Suppress("LongParameterList", "LongMethod")
+    suspend fun tryCloseBacklog(
         target: SyncTarget,
         fromMessageId: Long,
         limit: Int = DEFAULT_MESSAGES_LIMIT,

app/src/main/java/com/nextcloud/talk/chat/data/network/OfflineFirstChatRepository.kt

@@ -193,7 +193,7 @@ class OfflineFirstChatRepository @Inject constructor(
         Log.d(TAG, "weLikelyOnlyHaveASmallBacklog:$weLikelyOnlyHaveASmallBacklog")
 
         if (weLikelyOnlyHaveASmallBacklog) {
-            closeBacklogFromNewestOfflineMessage(newestMessageIdFromDb)
+            tryCloseBacklogFromNewestOfflineMessage(newestMessageIdFromDb)
         } else {
             fetchNewestMessagesForInitialLoad(
                 withNetworkParams,
@@ -206,10 +206,10 @@ class OfflineFirstChatRepository @Inject constructor(
     /**
      * Tries to close the backlog since the newest offline message.
      */
-    private suspend fun closeBacklogFromNewestOfflineMessage(newestMessageIdFromDb: Long) {
-        Log.d(TAG, "Closing the backlog from the newest offline message for initial loading")
+    private suspend fun tryCloseBacklogFromNewestOfflineMessage(newestMessageIdFromDb: Long) {
+        Log.d(TAG, "Try to close the backlog from the newest offline message for initial loading")
 
-        syncer.closeBacklog(
+        syncer.tryCloseBacklog(
             target = syncTarget,
             fromMessageId = newestMessageIdFromDb,
             lastCommonRead = newXChatLastCommonRead,
@@ -338,10 +338,10 @@ class OfflineFirstChatRepository @Inject constructor(
 
         val lastHttpSyncedMessageId = syncer.lastHttpSyncedMessageId(internalConversationId, threadId) ?: 0L
 
-        // closeBacklog loops until the backlog is fully closed, so a backlog larger than the
+        // tryCloseBacklog loops until the backlog is fully closed, so a backlog larger than the
         // request limit is caught up within one insurance cycle instead of narrowing it by one
         // page every cycle.
-        val outcome = syncer.closeBacklog(
+        val outcome = syncer.tryCloseBacklog(
             target = syncTarget,
             fromMessageId = lastHttpSyncedMessageId,
             limit = 200,

app/src/test/java/com/nextcloud/talk/chat/data/network/ChatMessageSyncerTest.kt

@@ -293,7 +293,7 @@ class ChatMessageSyncerTest {
         }
 
     @Test
-    fun `closeBacklog loops until the server returns fewer messages than the limit`() =
+    fun `tryCloseBacklog loops until the server returns fewer messages than the limit`() =
         runTest {
             val existingBlock = block(oldest = 10, newest = 42)
             whenever(chatBlocksDao.getChatBlocksContainingMessageId(eq(INTERNAL_CONVERSATION_ID), eq(null), any()))
@@ -306,7 +306,7 @@ class ChatMessageSyncerTest {
                     Response.success(overall(message(45)))
                 )
 
-            val outcome = syncer.closeBacklog(target(), fromMessageId = 42, limit = 2)
+            val outcome = syncer.tryCloseBacklog(target(), fromMessageId = 42, limit = 2)
 
             assertTrue(outcome.persistedNewMessages)
             assertEquals(3, outcome.persistedMessageCount)
@@ -320,7 +320,7 @@ class ChatMessageSyncerTest {
         }
 
     @Test
-    fun `closeBacklog falls back to the newest messages when the backlog persists`() =
+    fun `tryCloseBacklog falls back to the newest messages when the backlog persists`() =
         runTest {
             val existingBlock = block(oldest = 10, newest = 42)
             whenever(chatBlocksDao.getChatBlocksContainingMessageId(eq(INTERNAL_CONVERSATION_ID), eq(null), any()))
@@ -337,7 +337,7 @@ class ChatMessageSyncerTest {
                     Response.success(overall(message(100)))
                 )
 
-            val outcome = syncer.closeBacklog(target(), fromMessageId = 42, limit = 1)
+            val outcome = syncer.tryCloseBacklog(target(), fromMessageId = 42, limit = 1)
 
             // the reported range is the fallback's own — it must not be merged with the backlog
             // rounds' range, since the fallback lands in a separate, disconnected chat block