feat: editable Notify block — pick receivers for private posts

Phase 3 of the private-notes plan: the composer's Notify row gains an
'+ Add' chip backed by the existing user-suggestion search, so users can
p-tag people who aren't cited in the text — for any post, public or
private. While the private toggle is ON the row is always visible,
relabeled 'Visible to' (the p-tags ARE the audience of the wrap), and an
empty list shows a 'only you will see this' hint for self-only notes.

https://claude.ai/code/session_01B39MQmrT3dz137nfpXABvo

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/note/creators/notify/Notifying.kt

@@ -52,20 +52,23 @@ import kotlinx.collections.immutable.ImmutableList
 fun Notifying(
     baseMentions: ImmutableList<User>?,
     accountViewModel: AccountViewModel,
+    label: String? = null,
+    showWhenEmpty: Boolean = false,
+    onAddUser: (() -> Unit)? = null,
     onClick: (User) -> Unit,
 ) {
     val mentions = baseMentions?.toSet()
 
     FlowRow(horizontalArrangement = Arrangement.spacedBy(5.dp)) {
-        if (!mentions.isNullOrEmpty()) {
+        if (!mentions.isNullOrEmpty() || showWhenEmpty) {
             Text(
-                stringRes(R.string.reply_notify),
+                label ?: stringRes(R.string.reply_notify),
                 fontWeight = FontWeight.Bold,
                 color = MaterialTheme.colorScheme.placeholderText,
                 modifier = Modifier.align(CenterVertically),
             )
 
-            mentions.forEachIndexed { _, user ->
+            mentions?.forEachIndexed { _, user ->
                 Button(
                     shape = ButtonBorder,
                     colors =
@@ -77,6 +80,23 @@ fun Notifying(
                     DisplayUserNameWithDeleteMark(user, accountViewModel)
                 }
             }
+
+            if (onAddUser != null) {
+                Button(
+                    shape = ButtonBorder,
+                    colors =
+                        ButtonDefaults.buttonColors(
+                            containerColor = MaterialTheme.colorScheme.mediumImportanceLink,
+                        ),
+                    onClick = onAddUser,
+                ) {
+                    Text(
+                        text = stringRes(R.string.notify_add_user),
+                        color = Color.White,
+                        textAlign = TextAlign.Center,
+                    )
+                }
+            }
         }
     }
 }

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/home/ShortNotePostScreen.kt

@@ -84,6 +84,7 @@ import com.vitorpamplona.amethyst.ui.actions.uploads.TakeVideoButton
 import com.vitorpamplona.amethyst.ui.actions.uploads.UploadProgressIndicator
 import com.vitorpamplona.amethyst.ui.actions.uploads.VoiceAnonymizationSection
 import com.vitorpamplona.amethyst.ui.actions.uploads.VoiceMessagePreview
+import com.vitorpamplona.amethyst.ui.components.OutlinedThinPaddingTextField
 import com.vitorpamplona.amethyst.ui.components.getActivity
 import com.vitorpamplona.amethyst.ui.navigation.navs.Nav
 import com.vitorpamplona.amethyst.ui.navigation.routes.Route
@@ -128,6 +129,7 @@ import com.vitorpamplona.amethyst.ui.theme.Size35dp
 import com.vitorpamplona.amethyst.ui.theme.StdVertSpacer
 import com.vitorpamplona.amethyst.ui.theme.SuggestionListDefaultHeightPage
 import com.vitorpamplona.amethyst.ui.theme.ThemeComparisonColumn
+import com.vitorpamplona.amethyst.ui.theme.placeholderText
 import com.vitorpamplona.amethyst.ui.theme.replyModifier
 import com.vitorpamplona.quartz.nip01Core.core.HexKey
 import kotlinx.collections.immutable.persistentListOf
@@ -306,11 +308,41 @@ private fun NewPostScreenBody(
                 }
 
                 Row {
-                    Notifying(postViewModel.pTags?.toImmutableList(), accountViewModel) {
+                    Notifying(
+                        baseMentions = postViewModel.pTags?.toImmutableList(),
+                        accountViewModel = accountViewModel,
+                        label = if (postViewModel.wantsPrivateNote) stringRes(R.string.private_note_visible_to) else null,
+                        showWhenEmpty = postViewModel.wantsPrivateNote,
+                        onAddUser = { postViewModel.wantsToAddNotifyUser = !postViewModel.wantsToAddNotifyUser },
+                    ) {
                         postViewModel.removeFromReplyList(it)
                     }
                 }
 
+                if (postViewModel.wantsToAddNotifyUser) {
+                    OutlinedThinPaddingTextField(
+                        state = postViewModel.notifyUserSearchText,
+                        onTextChanged = postViewModel::onNotifyUserSearchTextChanged,
+                        label = { Text(text = stringRes(R.string.notify_search_and_add_user)) },
+                        modifier = Modifier.fillMaxWidth(),
+                        placeholder = {
+                            Text(
+                                text = stringRes(R.string.zap_split_search_and_add_user_placeholder),
+                                color = MaterialTheme.colorScheme.placeholderText,
+                            )
+                        },
+                        singleLine = true,
+                    )
+                }
+
+                if (postViewModel.wantsPrivateNote && postViewModel.pTags.isNullOrEmpty()) {
+                    Text(
+                        text = stringRes(R.string.private_note_no_receivers),
+                        style = MaterialTheme.typography.bodySmall,
+                        color = MaterialTheme.colorScheme.placeholderText,
+                    )
+                }
+
                 // Only show text input if no voice message is being posted
                 if (postViewModel.voiceMetadata == null && postViewModel.voiceRecording == null) {
                     Row(

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/home/ShortNotePostViewModel.kt

@@ -167,6 +167,7 @@ enum class UserSuggestionAnchor {
     MAIN_MESSAGE,
     FORWARD_ZAPS,
     TO_USERS,
+    NOTIFY,
 }
 
 @Stable
@@ -322,6 +323,26 @@ open class ShortNotePostViewModel :
         wantsPrivateNote = !wantsPrivateNote
     }
 
+    // Notify / Visible-to editor: lets the user p-tag people who aren't
+    // cited in the message. For private notes the Notify list IS the
+    // audience, so this is how receivers are picked.
+    var wantsToAddNotifyUser by mutableStateOf(false)
+    val notifyUserSearchText = TextFieldState()
+
+    fun onNotifyUserSearchTextChanged() {
+        if (notifyUserSearchText.selection.collapsed) {
+            val lastWord = notifyUserSearchText.text.toString()
+            userSuggestionsMainMessage = UserSuggestionAnchor.NOTIFY
+            userSuggestions?.processCurrentWord(lastWord)
+        }
+    }
+
+    fun addToReplyList(user: User) {
+        if (pTags?.contains(user) != true) {
+            pTags = (pTags ?: emptyList()).plus(user)
+        }
+    }
+
     // A single ephemeral signer reused for the whole compose session so that media
     // uploads (Blossom/NIP-96 auth events) and the final anonymous post are all signed
     // by the same throwaway key, instead of leaking the real account's pubkey into the
@@ -1286,6 +1307,8 @@ open class ShortNotePostViewModel :
         scheduledForSec = null
         wantsPrivateNote = false
         privateNoteLocked = false
+        wantsToAddNotifyUser = false
+        notifyUserSearchText.clearText()
 
         forwardZapTo.value = SplitBuilder()
         forwardZapToEditting.clearText()
@@ -1350,6 +1373,10 @@ open class ShortNotePostViewModel :
             } else if (userSuggestionsMainMessage == UserSuggestionAnchor.FORWARD_ZAPS) {
                 forwardZapTo.value.addItem(item)
                 forwardZapToEditting.clearText()
+            } else if (userSuggestionsMainMessage == UserSuggestionAnchor.NOTIFY) {
+                addToReplyList(item)
+                notifyUserSearchText.clearText()
+                wantsToAddNotifyUser = false
             }
 
             userSuggestionsMainMessage = null

amethyst/src/main/res/values/strings.xml

@@ -873,6 +873,10 @@
     <string name="private_note">Make private: gift-wrap the note to the notified users only</string>
     <string name="disable_private_note">Make public</string>
     <string name="private_note_locked">Replies to a private note always stay private</string>
+    <string name="private_note_visible_to">Visible to</string>
+    <string name="private_note_no_receivers">No receivers yet: only you will be able to see this note. Add people to share it with.</string>
+    <string name="notify_add_user">+ Add</string>
+    <string name="notify_search_and_add_user">Search and add a user to notify</string>
     <string name="bookmark_absence_indicator">is not a bookmark here</string>
     <string name="bookmark_remove_action_desc">Remove bookmark from list</string>
     <string name="bookmark_add_action_desc">Add bookmark to list</string>