fix(ime): stop the soft keyboard state from getting stuck open

Leaving a chat with the keyboard up via a back gesture left a large IME
padding stranded at the bottom — and, because WindowInsets.ime is a single
app-wide holder, on every other screen too — until some later inset pass
happened to rebalance it. It only reproduced on release builds.

Root cause: the chat composers install a BackHandler that flushes the draft
and pops the screen. When that pop runs while the keyboard is still visible,
the predictive-back window animation races the IME's close animation. On an
optimized release build the window animation wins, and the IME
WindowInsetsAnimation is cancelled before its terminal (zero) frame reaches
Compose, so the shared insets holder stays "animating" and every
imePadding() in the app freezes at the keyboard height. Debug and benchmark
builds are slow enough that the IME animation completes first, which is why
they were unaffected.

Fixes:
- New KeyboardAwareBackHandler: while the keyboard is on screen it does not
  consume back, so the system dismisses the keyboard first (its animation
  completes cleanly); the next back runs the original handler. The top-bar
  back arrow remains an always-available exit. Adopted in the DM, public-chat
  and new-group-DM composers.
- Rederive keyboardAsState() from WindowInsets.ime instead of the
  pre-edge-to-edge getWindowVisibleDisplayFrame/OnGlobalLayout heuristic,
  which under enableEdgeToEdge() could itself latch Opened after the keyboard
  closed. Now it tracks the same inset that drives imePadding().
- Concord channel chat and the minichat thread view used a bare Material3
  Scaffold whose content insets ignore the IME; add imePadding() so the
  composer rides above the keyboard while typing.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012dT2RLbPZzan2hULL2cmc6

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/navigation/bottombars/KeyboardState.kt

@@ -20,52 +20,67 @@
  */
 package com.vitorpamplona.amethyst.ui.navigation.bottombars
 
-import android.graphics.Rect
-import android.view.View
-import android.view.ViewTreeObserver
+import androidx.activity.compose.BackHandler
+import androidx.compose.foundation.layout.WindowInsets
+import androidx.compose.foundation.layout.ime
 import androidx.compose.runtime.Composable
-import androidx.compose.runtime.DisposableEffect
 import androidx.compose.runtime.State
-import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.derivedStateOf
+import androidx.compose.runtime.getValue
 import androidx.compose.runtime.remember
-import androidx.compose.ui.platform.LocalView
+import androidx.compose.ui.platform.LocalDensity
 
 enum class KeyboardState {
     Opened,
     Closed,
 }
 
+/**
+ * Whether the soft keyboard is currently on screen, derived from [WindowInsets.ime].
+ *
+ * This intentionally reads the same animated IME inset that drives `Modifier.imePadding()`
+ * everywhere else in the app, so the two can never disagree. The previous implementation
+ * measured `View.getWindowVisibleDisplayFrame` from a `ViewTreeObserver` global-layout
+ * listener — a pre-edge-to-edge heuristic. Under `enableEdgeToEdge()`
+ * (`decorFitsSystemWindows = false`) the window content no longer resizes for the IME, so
+ * that listener fired when the keyboard appeared but frequently never fired again when it
+ * closed, latching the state at [Opened] even though the keyboard was gone (leaving the
+ * bottom navigation bar hidden and a stranded gap at the bottom). The IME inset always
+ * animates back to zero on the persistent root view, so this reading can't get stuck.
+ */
 @Composable
 fun keyboardAsState(): State<KeyboardState> {
-    val view = LocalView.current
-
-    val keyboardState = remember(view) { mutableStateOf(isKeyboardOpen(view)) }
-
-    DisposableEffect(view) {
-        val onGlobalListener =
-            ViewTreeObserver.OnGlobalLayoutListener {
-                val newKeyboardValue = isKeyboardOpen(view)
-
-                if (newKeyboardValue != keyboardState.value) {
-                    keyboardState.value = newKeyboardValue
-                }
-            }
-        view.viewTreeObserver.addOnGlobalLayoutListener(onGlobalListener)
-        onDispose { view.viewTreeObserver.removeOnGlobalLayoutListener(onGlobalListener) }
-    }
-
-    return keyboardState
-}
-
-fun isKeyboardOpen(view: View): KeyboardState {
-    val rect = Rect()
-    view.getWindowVisibleDisplayFrame(rect)
-    val screenHeight = view.rootView.height
-    val keypadHeight = screenHeight - rect.bottom
-
-    return if (keypadHeight > screenHeight * 0.15) {
-        KeyboardState.Opened
-    } else {
-        KeyboardState.Closed
+    val density = LocalDensity.current
+    val imeInsets = WindowInsets.ime
+    return remember(density, imeInsets) {
+        derivedStateOf {
+            if (imeInsets.getBottom(density) > 0) KeyboardState.Opened else KeyboardState.Closed
+        }
     }
 }
+
+/**
+ * A [BackHandler] that steps aside while the soft keyboard is on screen.
+ *
+ * Chat composers (and draft-saving editors) intercept back to flush a draft and pop the screen.
+ * When that pop happens while the keyboard is still up, it races the predictive-back window
+ * animation against the IME's close animation. On release builds — fast enough that the window
+ * animation wins — the IME [WindowInsetsAnimationCompat][androidx.core.view.WindowInsetsAnimationCompat]
+ * is cancelled before its terminal (zero) frame reaches Compose, so the shared `WindowInsets.ime`
+ * holder stays "animating" and every `Modifier.imePadding()` in the app freezes at the keyboard
+ * height until a later inset pass rebalances it (the "stuck IME padding" that survives leaving the
+ * screen).
+ *
+ * Gating on [keyboardAsState] fixes it: while the keyboard is visible we do NOT consume back, so the
+ * system dismisses the keyboard first with its own animation (which completes cleanly). The next
+ * back — keyboard already down — runs [onBack] as before. The top bar's back arrow stays an
+ * always-available exit, so this can never trap the user even if the inset reading were itself stale.
+ */
+@Composable
+fun KeyboardAwareBackHandler(
+    enabled: Boolean = true,
+    onBack: () -> Unit,
+) {
+    val keyboardState by keyboardAsState()
+    BackHandler(enabled = enabled && keyboardState == KeyboardState.Closed, onBack = onBack)
+}

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/chats/minichat/MinichatScreen.kt

@@ -25,6 +25,7 @@ import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.fillMaxHeight
 import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.imePadding
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.lazy.LazyColumn
 import androidx.compose.foundation.lazy.items
@@ -174,7 +175,9 @@ fun MinichatScreen(
             )
         },
     ) { padding ->
-        Column(Modifier.fillMaxHeight().padding(padding)) {
+        // imePadding so the reply composer rides above the soft keyboard — the bare Material3
+        // Scaffold's content insets cover the system bars but not the IME.
+        Column(Modifier.fillMaxHeight().imePadding().padding(padding)) {
             // Every reply here is rooted at [rootNote], which is already pinned at the top — so
             // suppress the redundant reply-to-root preview each reply would otherwise render.
             CompositionLocalProvider(LocalSuppressReplyToNoteId provides rootId) {

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/chats/privateDM/send/NewGroupDMScreen.kt

@@ -21,7 +21,6 @@
 package com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.privateDM.send
 
 import android.net.Uri
-import androidx.activity.compose.BackHandler
 import androidx.compose.foundation.horizontalScroll
 import androidx.compose.foundation.layout.Arrangement.Absolute.spacedBy
 import androidx.compose.foundation.layout.Box
@@ -87,6 +86,7 @@ import com.vitorpamplona.amethyst.ui.actions.uploads.TakePictureButton
 import com.vitorpamplona.amethyst.ui.actions.uploads.TakeVideoButton
 import com.vitorpamplona.amethyst.ui.components.ThinPaddingTextField
 import com.vitorpamplona.amethyst.ui.components.ZoomableContentView
+import com.vitorpamplona.amethyst.ui.navigation.bottombars.KeyboardAwareBackHandler
 import com.vitorpamplona.amethyst.ui.navigation.navs.INav
 import com.vitorpamplona.amethyst.ui.navigation.navs.Nav
 import com.vitorpamplona.amethyst.ui.navigation.routes.routeToMessage
@@ -169,7 +169,7 @@ fun NewGroupDMScreen(
 
     WatchAndLoadMyEmojiList(accountViewModel)
 
-    BackHandler {
+    KeyboardAwareBackHandler {
         accountViewModel.launchSigner {
             postViewModel.sendDraftSync()
             postViewModel.cancel()

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/chats/privateDM/send/PrivateMessageEditFieldRow.kt

@@ -20,7 +20,6 @@
  */
 package com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.privateDM.send
 
-import androidx.activity.compose.BackHandler
 import androidx.compose.foundation.background
 import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Box
@@ -60,6 +59,7 @@ import com.vitorpamplona.amethyst.ui.actions.UrlUserTagOutputTransformation
 import com.vitorpamplona.amethyst.ui.actions.uploads.SelectFromGallery
 import com.vitorpamplona.amethyst.ui.actions.uploads.SelectedMedia
 import com.vitorpamplona.amethyst.ui.components.ThinPaddingTextField
+import com.vitorpamplona.amethyst.ui.navigation.bottombars.KeyboardAwareBackHandler
 import com.vitorpamplona.amethyst.ui.navigation.navs.EmptyNav
 import com.vitorpamplona.amethyst.ui.navigation.navs.INav
 import com.vitorpamplona.amethyst.ui.navigation.routes.routeFor
@@ -110,7 +110,7 @@ fun PrivateMessageEditFieldRow(
     onSendNewMessage: () -> Unit,
     nav: INav,
 ) {
-    BackHandler {
+    KeyboardAwareBackHandler {
         if (channelScreenModel.message.text.isNotBlank()) {
             accountViewModel.launchSigner {
                 channelScreenModel.sendDraftSync()

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/chats/publicChannels/concord/ConcordChannelScreen.kt

@@ -26,6 +26,7 @@ import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.Spacer
 import androidx.compose.foundation.layout.fillMaxHeight
 import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.imePadding
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.size
 import androidx.compose.material3.ExperimentalMaterial3Api
@@ -185,7 +186,10 @@ fun ConcordChannelScreen(
             )
         },
     ) { padding ->
-        Column(Modifier.fillMaxHeight().padding(padding)) {
+        // imePadding so the composer rides above the soft keyboard. The bare Material3 Scaffold's
+        // content insets cover the system bars but not the IME, so without this the message field
+        // sat behind the keyboard while typing.
+        Column(Modifier.fillMaxHeight().imePadding().padding(padding)) {
             Column(Modifier.fillMaxHeight().weight(1f, true)) {
                 RefreshingChatroomFeedView(
                     feedContentState = feedViewModel.feedState,

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/chats/publicChannels/send/EditFieldRow.kt

@@ -20,7 +20,6 @@
  */
 package com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.publicChannels.send
 
-import androidx.activity.compose.BackHandler
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.fillMaxWidth
@@ -54,6 +53,7 @@ import com.vitorpamplona.amethyst.ui.actions.UrlUserTagOutputTransformation
 import com.vitorpamplona.amethyst.ui.actions.uploads.SelectFromGallery
 import com.vitorpamplona.amethyst.ui.actions.uploads.SelectedMedia
 import com.vitorpamplona.amethyst.ui.components.ThinPaddingTextField
+import com.vitorpamplona.amethyst.ui.navigation.bottombars.KeyboardAwareBackHandler
 import com.vitorpamplona.amethyst.ui.navigation.navs.INav
 import com.vitorpamplona.amethyst.ui.note.creators.userSuggestions.ShowUserSuggestionList
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.AccountViewModel
@@ -78,7 +78,7 @@ fun EditFieldRow(
     onSendNewMessage: suspend () -> Unit,
     nav: INav,
 ) {
-    BackHandler {
+    KeyboardAwareBackHandler {
         accountViewModel.launchSigner {
             channelScreenModel.sendDraftSync()
             channelScreenModel.cancel()