fix(audio-rooms): UX rough edges from the screen walk (audit walk #5-8)

Four user-visible quirks the walkthrough surfaced:

  5. EditAudioRoomSheet's "Close room" button was one tap with no
     confirm. A misclick destroyed the room. Added an AlertDialog
     gate ("All attendees will be disconnected. The room will
     show as CLOSED in the feed.") with a destructive primary
     action and a Cancel.

  6. Silent ActivityNotFoundException in ParticipantHostActionsSheet
     (View Profile) and MeetingSpace.kt (Listen to Recording).
     Both were `runCatching { startActivity(...) }` with no toast
     on failure — user taps, nothing happens, no feedback. Now
     they toast "No app installed to open this link." through
     the standard toastManager.

  7. ScheduleStartPicker dismiss didn't revert in-dialog state.
     User picks Dec 13, taps Cancel, reopens the dialog → still
     pre-selected to Dec 13 (the cancelled choice) instead of the
     committed value. Added `resetPickersToCommitted()` that
     rewinds both picker states to the committed unixSeconds on
     every dismiss / cancel path.

  8. CreateAudioRoomViewModel.publishAndBuildLaunchInfo accepted
     past start times. Added a `scheduledStartUnix < now` guard so
     the host gets "Pick a future start time." instead of publishing
     a kind-30312 with `status=planned` + a backdated `starts` tag.

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/note/types/MeetingSpace.kt

@@ -172,7 +172,7 @@ fun RenderMeetingSpaceEventInner(
     ) {
         if (status == MeetingSpaceStatusTag.STATUS.CLOSED) {
             recording?.let {
-                ListenToRecordingButton(url = it)
+                ListenToRecordingButton(url = it, accountViewModel = accountViewModel)
             }
         } else {
             com.vitorpamplona.amethyst.ui.screen.loggedIn.audiorooms.room.JoinAudioRoomButton(
@@ -191,15 +191,27 @@ fun RenderMeetingSpaceEventInner(
  * purpose — Amethyst doesn't ship its own audio player surface.
  */
 @Composable
-private fun ListenToRecordingButton(url: String) {
+private fun ListenToRecordingButton(
+    url: String,
+    accountViewModel: AccountViewModel,
+) {
     val context = androidx.compose.ui.platform.LocalContext.current
+    val noAppMessage = stringRes(R.string.audio_room_no_app_to_open_link)
     androidx.compose.material3.OutlinedButton(onClick = {
+        val launched =
             runCatching {
                 context.startActivity(
                     android.content
                         .Intent(android.content.Intent.ACTION_VIEW, android.net.Uri.parse(url))
                         .addFlags(android.content.Intent.FLAG_ACTIVITY_NEW_TASK),
                 )
+            }.isSuccess
+        if (!launched) {
+            accountViewModel.toastManager.toast(
+                R.string.audio_room_chat_send_failed_title,
+                noAppMessage,
+                user = null,
+            )
         }
     }) {
         Text(stringRes(R.string.audio_room_listen_to_recording))

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/audiorooms/create/CreateAudioRoomSheet.kt

@@ -253,6 +253,10 @@ private fun ScheduleStartPicker(
             .atZone(java.time.ZoneId.systemDefault())
             .toLocalDateTime()
 
+    // Re-key the picker state on `unixSeconds` so the dialog opens
+    // pre-populated with the COMMITTED value. Without this key, a
+    // mid-edit Cancel would leave the in-dialog state reflecting
+    // the half-typed cancelled choice on the next reopen.
     val datePickerState =
         androidx.compose.material3.rememberDatePickerState(
             initialSelectedDateMillis = initialMillis,
@@ -264,6 +268,16 @@ private fun ScheduleStartPicker(
             is24Hour = false,
         )
 
+    // On dismiss (Cancel or back-press), restore the picker states
+    // to the committed `unixSeconds`. rememberDatePickerState /
+    // TimePickerState are reference-stable across recompositions
+    // and survive `cancel`, so we have to rewind them by hand.
+    fun resetPickersToCommitted() {
+        datePickerState.selectedDateMillis = initialMillis
+        timePickerState.hour = initialLocal.hour
+        timePickerState.minute = initialLocal.minute
+    }
+
     androidx.compose.material3.OutlinedButton(
         onClick = { showDate = true },
         modifier = Modifier.fillMaxWidth(),
@@ -273,7 +287,10 @@ private fun ScheduleStartPicker(
 
     if (showDate) {
         androidx.compose.material3.DatePickerDialog(
-            onDismissRequest = { showDate = false },
+            onDismissRequest = {
+                resetPickersToCommitted()
+                showDate = false
+            },
             confirmButton = {
                 TextButton(onClick = {
                     showDate = false
@@ -281,7 +298,10 @@ private fun ScheduleStartPicker(
                 }) { Text(stringRes(R.string.next)) }
             },
             dismissButton = {
-                TextButton(onClick = { showDate = false }) {
+                TextButton(onClick = {
+                    resetPickersToCommitted()
+                    showDate = false
+                }) {
                     Text(stringRes(R.string.audio_room_create_cancel))
                 }
             },
@@ -293,7 +313,10 @@ private fun ScheduleStartPicker(
     if (showTime) {
         androidx.compose.material3.TimePickerDialog(
             title = { Text(stringRes(R.string.audio_room_create_when)) },
-            onDismissRequest = { showTime = false },
+            onDismissRequest = {
+                resetPickersToCommitted()
+                showTime = false
+            },
             confirmButton = {
                 TextButton(onClick = {
                     val dayMillisUtc = datePickerState.selectedDateMillis
@@ -320,7 +343,10 @@ private fun ScheduleStartPicker(
                 }) { Text(stringRes(R.string.audio_room_create_submit)) }
             },
             dismissButton = {
-                TextButton(onClick = { showTime = false }) {
+                TextButton(onClick = {
+                    resetPickersToCommitted()
+                    showTime = false
+                }) {
                     Text(stringRes(R.string.audio_room_create_cancel))
                 }
             },

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/audiorooms/create/CreateAudioRoomViewModel.kt

@@ -121,6 +121,20 @@ class CreateAudioRoomViewModel : ViewModel() {
             _state.update { it.copy(error = "Pick a start time for the scheduled room.") }
             return null
         }
+        // The host may want to backdate a "scheduled" announcement
+        // for a room that already started elsewhere — but more often
+        // a past timestamp means the picker landed on the wrong day
+        // and the host didn't notice. Guard against the misfire.
+        // (Audience-side render is already past-aware: SCHEDULED
+        // chips suppress the "Starts <date>" subline once `now` >
+        // starts.)
+        val nowSec =
+            com.vitorpamplona.quartz.utils.TimeUtils
+                .now()
+        if (current.scheduled && current.scheduledStartUnix < nowSec) {
+            _state.update { it.copy(error = "Pick a future start time.") }
+            return null
+        }
 
         _state.update { it.copy(isPublishing = true, error = null) }
         val accountModel = account.account

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/audiorooms/room/EditAudioRoomSheet.kt

@@ -43,8 +43,10 @@ import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.collectAsState
 import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.rememberCoroutineScope
+import androidx.compose.runtime.setValue
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.unit.dp
 import androidx.lifecycle.viewmodel.compose.viewModel
@@ -79,6 +81,32 @@ fun EditAudioRoomSheet(
     val sheetState = rememberModalBottomSheetState(skipPartiallyExpanded = true)
     val scope = rememberCoroutineScope()
 
+    var confirmCloseOpen by remember { mutableStateOf(false) }
+    if (confirmCloseOpen) {
+        androidx.compose.material3.AlertDialog(
+            onDismissRequest = { confirmCloseOpen = false },
+            title = { Text(stringRes(R.string.audio_room_close_room_confirm_title)) },
+            text = { Text(stringRes(R.string.audio_room_close_room_confirm_body)) },
+            confirmButton = {
+                TextButton(
+                    colors = ButtonDefaults.textButtonColors(contentColor = MaterialTheme.colorScheme.error),
+                    onClick = {
+                        confirmCloseOpen = false
+                        scope.launch {
+                            if (viewModel.closeRoom()) onDismiss()
+                        }
+                    },
+                ) {
+                    Text(stringRes(R.string.audio_room_close_room_confirm_action))
+                }
+            },
+            dismissButton = {
+                TextButton(onClick = { confirmCloseOpen = false }) {
+                    Text(stringRes(R.string.audio_room_create_cancel))
+                }
+            },
+        )
+    }
     ModalBottomSheet(onDismissRequest = onDismiss, sheetState = sheetState) {
         Column(
             modifier = Modifier.fillMaxWidth().padding(horizontal = 16.dp, vertical = 8.dp),
@@ -135,15 +163,13 @@ fun EditAudioRoomSheet(
             Spacer(Modifier.height(4.dp))
             Row(modifier = Modifier.fillMaxWidth(), horizontalArrangement = Arrangement.SpaceBetween) {
                 // Destructive — flips status to CLOSED with the same d-tag
-                // so subscribers see the room go dark.
+                // so subscribers see the room go dark. Confirm prompt
+                // gates the actual publish so a misclick on the
+                // edit-sheet's bottom row doesn't kill the room.
                 TextButton(
                     enabled = !state.isPublishing,
                     colors = ButtonDefaults.textButtonColors(contentColor = MaterialTheme.colorScheme.error),
-                    onClick = {
+                    onClick = { confirmCloseOpen = true },
-                        scope.launch {
-                            if (viewModel.closeRoom()) onDismiss()
-                        }
-                    },
                 ) {
                     Text(stringRes(R.string.audio_room_close_action))
                 }

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/audiorooms/room/ParticipantHostActionsSheet.kt

@@ -145,8 +145,10 @@ internal fun ParticipantHostActionsSheet(
             // audio-room foreground service keeps audio alive while
             // the user is on the profile screen.
             val context = LocalContext.current
+            val noAppMessage = stringRes(R.string.audio_room_no_app_to_open_link)
             ActionRow(stringRes(R.string.audio_room_participant_view_profile)) {
                 val npub = NPub.create(target)
+                val launched =
                     runCatching {
                         context.startActivity(
                             android.content
@@ -160,6 +162,13 @@ internal fun ParticipantHostActionsSheet(
                                     )
                                 },
                         )
+                    }.isSuccess
+                if (!launched) {
+                    accountViewModel.toastManager.toast(
+                        R.string.audio_room_chat_send_failed_title,
+                        noAppMessage,
+                        user = null,
+                    )
                 }
                 onDismiss()
             }