android: polish fullscreen chats search interactions

android/CHANGELOG.md

@@ -592,3 +592,10 @@
 ### Step 92 - Search filter leak fix on exit
 - Fixed chats search state leak: leaving fullscreen search now resets local/global query.
 - Main chats list no longer stays filtered by previous search input after returning from search mode.
+
+### Step 93 - Fullscreen search UX polish
+- Added system back-handler for search mode with safe query reset.
+- Improved fullscreen search result sections:
+  - `Показать больше / Свернуть` toggle for global users,
+  - `Показать больше / Свернуть` toggle for message results.
+- Added explicit empty-state text when local/global/message search sections all have no results.

android/app/src/main/java/ru/daemonlord/messenger/ui/chats/ChatListScreen.kt

@@ -1,6 +1,7 @@
 package ru.daemonlord.messenger.ui.chats
 
 import android.widget.Toast
+import androidx.activity.compose.BackHandler
 import androidx.compose.foundation.clickable
 import androidx.compose.foundation.combinedClickable
 import androidx.compose.foundation.background
@@ -45,8 +46,8 @@ import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
-import androidx.compose.runtime.snapshotFlow
 import androidx.compose.runtime.setValue
+import androidx.compose.runtime.snapshotFlow
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.clip
@@ -176,6 +177,12 @@ fun ChatListScreen(
     var manageRoleText by remember { mutableStateOf("member") }
     val isTabletLayout = LocalConfiguration.current.screenWidthDp >= 840
     val listState = rememberLazyListState()
+    BackHandler(enabled = isSearchMode) {
+        isSearchMode = false
+        localSearchQuery = ""
+        onSearchChanged("")
+        onGlobalSearchChanged("")
+    }
 
     LaunchedEffect(Unit) {
         onMainBarVisibilityChanged(true)
@@ -712,6 +719,12 @@ private fun ChatSearchFullscreen(
     onOpenChat: (Long) -> Unit,
 ) {
     val trimmedQuery = searchQuery.trim()
+    var showMoreGlobalUsers by remember { mutableStateOf(false) }
+    var showMoreMessages by remember { mutableStateOf(false) }
+    LaunchedEffect(trimmedQuery) {
+        showMoreGlobalUsers = false
+        showMoreMessages = false
+    }
     val sectionChats = remember(state.chats, searchSection) {
         when (searchSection) {
             SearchSection.Chats -> state.chats
@@ -864,11 +877,13 @@ private fun ChatSearchFullscreen(
                 item(key = "global_header") {
                     SectionHeader(
                         title = "Глобальный поиск",
-                        action = "Показать больше",
+                        action = if (showMoreGlobalUsers) "Свернуть" else "Показать больше",
+                        onActionClick = { showMoreGlobalUsers = !showMoreGlobalUsers },
                     )
                 }
                 if (state.globalUsers.isNotEmpty()) {
-                    items(state.globalUsers.take(8), key = { "user_${it.id}" }) { user ->
+                    val users = if (showMoreGlobalUsers) state.globalUsers else state.globalUsers.take(5)
+                    items(users, key = { "user_${it.id}" }) { user ->
                         SearchUserRow(
                             title = user.name,
                             subtitle = buildString {
@@ -890,10 +905,12 @@ private fun ChatSearchFullscreen(
                 item(key = "messages_header") {
                     SectionHeader(
                         title = "Сообщения",
-                        action = "Из всех чатов",
+                        action = if (showMoreMessages) "Свернуть" else "Показать больше",
+                        onActionClick = { showMoreMessages = !showMoreMessages },
                     )
                 }
-                items(state.globalMessages.take(12), key = { "msg_${it.id}" }) { message ->
+                val messages = if (showMoreMessages) state.globalMessages else state.globalMessages.take(8)
+                items(messages, key = { "msg_${it.id}" }) { message ->
                     SearchMessageRow(
                         state = state,
                         messageText = message.text?.take(70).orEmpty().ifBlank { "[${message.type}]" },
@@ -905,6 +922,16 @@ private fun ChatSearchFullscreen(
                         chatId = message.chatId,
                     )
                 }
+                if (localQueryResults.isEmpty() && state.globalUsers.isEmpty() && state.globalMessages.isEmpty()) {
+                    item(key = "all_empty") {
+                        Text(
+                            text = "Ничего не найдено",
+                            style = MaterialTheme.typography.bodyLarge,
+                            color = MaterialTheme.colorScheme.onSurfaceVariant,
+                            modifier = Modifier.padding(horizontal = 8.dp, vertical = 12.dp),
+                        )
+                    }
+                }
             }
         }
     }
@@ -914,6 +941,7 @@ private fun ChatSearchFullscreen(
 private fun SectionHeader(
     title: String,
     action: String,
+    onActionClick: (() -> Unit)? = null,
 ) {
     Row(
         modifier = Modifier
@@ -931,6 +959,7 @@ private fun SectionHeader(
             text = action,
             style = MaterialTheme.typography.labelLarge,
             color = MaterialTheme.colorScheme.onSurfaceVariant,
+            modifier = if (onActionClick != null) Modifier.clickable(onClick = onActionClick) else Modifier,
         )
     }
 }