Re-sync suggestion popups when the composer text is set in code

When a suggestion popup is open and the app sets the composer text
itself, the popup stays up over the new text. The popups are updated
only from the field's text-change handler, which a code-driven change
does not run. PR #847 fixed this for the send path, the case #250
reported. While working on that fix, two more places with the same older
bug were found: tapping a nickname in the message list, which inserts
"@name " into the field, and switching private conversations, which
restores that conversation's draft.

Each site now calls updateCommandSuggestions and updateMentionSuggestions
with the text it just set, the same calls the text-change handler makes
while typing. The popup state then always matches the field content: an
inserted mention ends with a space, so an open popup hides, and a restored
draft that starts with "/" brings the command popup back the way typing it
would.

The iOS app already works this way: its composer drives autocomplete
from onChange(of: messageText), which runs for code-driven changes too,
so a mention insert or a restored draft re-syncs the popup there.

Tests in CommandProcessorTest pin the inserted-mention shape, the
trailing-space rule, and the draft-restore behavior. The unit tests do not
drive Compose, so they cover the functions the two sites call rather than
the sites themselves.

Full Android unit suite green; lint and the debug build pass.

app/src/main/java/com/bitchat/android/ui/ChatScreen.kt

@@ -100,11 +100,14 @@ fun ChatScreen(viewModel: ChatViewModel) {
     var isScrolledUp by remember { mutableStateOf(false) }
 
     LaunchedEffect(selectedPrivatePeer) {
-        messageText = TextFieldValue(
-            selectedPrivatePeer
-                ?.let(viewModel::conversationDraft)
-                .orEmpty()
-        )
+        val draft = selectedPrivatePeer
+            ?.let(viewModel::conversationDraft)
+            .orEmpty()
+        messageText = TextFieldValue(draft)
+        // Setting the field in code does not run onMessageTextChange, so the
+        // popups have to be re-synced with the restored draft here.
+        viewModel.updateCommandSuggestions(draft)
+        viewModel.updateMentionSuggestions(draft)
     }
 
     // Show password dialog when needed
@@ -342,6 +345,11 @@ fun ChatScreen(viewModel: ChatViewModel) {
                         text = newText,
                         selection = TextRange(newText.length)
                     )
+                    // Setting the field in code does not run onMessageTextChange, so
+                    // the popups have to be re-synced with the new text here. The
+                    // inserted mention ends with a space, which hides an open popup.
+                    viewModel.updateCommandSuggestions(newText)
+                    viewModel.updateMentionSuggestions(newText)
                 },
                 onMessageLongPress = { message ->
                     // Message long press - open user action sheet with message context

app/src/test/java/com/bitchat/android/ui/CommandProcessorTest.kt

@@ -188,4 +188,48 @@ class CommandProcessorTest() {
     assertFalse(chatState.getShowMentionSuggestionsValue())
     assertTrue(chatState.getMentionSuggestionsValue().isEmpty())
   }
+
+  @Test
+  fun `text set to an inserted mention hides both popups`() {
+    // A command popup is open while the user taps a nickname in the message list.
+    commandProcessor.updateCommandSuggestions("/")
+    assertTrue(chatState.getShowCommandSuggestionsValue())
+
+    // The composer re-syncs both popups with the inserted text, which ends in a
+    // space, so neither popup matches it.
+    commandProcessor.updateCommandSuggestions("/ @alice ")
+    commandProcessor.updateMentionSuggestions("/ @alice ", meshService, viewModel = null)
+    assertFalse(chatState.getShowCommandSuggestionsValue())
+    assertTrue(chatState.getCommandSuggestionsValue().isEmpty())
+    assertFalse(chatState.getShowMentionSuggestionsValue())
+    assertTrue(chatState.getMentionSuggestionsValue().isEmpty())
+  }
+
+  @Test
+  fun `a mention followed by a space no longer matches the mention popup`() {
+    whenever(meshService.myPeerID).thenReturn("me")
+    whenever(meshService.getPeerNicknames()).thenReturn(mapOf("peer-1" to "alice"))
+
+    commandProcessor.updateMentionSuggestions("@a", meshService, viewModel = null)
+    assertTrue(chatState.getShowMentionSuggestionsValue())
+
+    commandProcessor.updateMentionSuggestions("@alice ", meshService, viewModel = null)
+    assertFalse(chatState.getShowMentionSuggestionsValue())
+    assertTrue(chatState.getMentionSuggestionsValue().isEmpty())
+  }
+
+  @Test
+  fun `a restored command draft reopens the command popup`() {
+    // Switching conversations restores the draft in code; re-syncing with the
+    // restored text brings the popup back for a command draft.
+    commandProcessor.updateCommandSuggestions("/j")
+    assertTrue(chatState.getShowCommandSuggestionsValue())
+    assertTrue(chatState.getCommandSuggestionsValue().isNotEmpty())
+
+    // An empty restored draft leaves both popups hidden.
+    commandProcessor.updateCommandSuggestions("")
+    commandProcessor.updateMentionSuggestions("", meshService, viewModel = null)
+    assertFalse(chatState.getShowCommandSuggestionsValue())
+    assertFalse(chatState.getShowMentionSuggestionsValue())
+  }
 }