fix(edits): unlink deleted edits from their message; one collector per row

Audit of the three edit paths (feed 1010 / Buzz 40003 / Concord 3302) found:

1. Bug (feed regression): a deleted edit kept overlaying its message. Edits
   anchor on the target's Note.edits with no `replyTo` back-link, and
   removeNote didn't cover `edits`, so unlinkAndRemove never dropped them — the
   old cache-scan resolver dropped deleted edits for free, Note.edits did not.
   Fix: removeNote now also removeEdit()s, and unlinkAndRemove resolves the
   edit's `e`-tag target and unlinks it there (editedTargetIdOf covers all
   three kinds). New test: deleting an edit un-overlays and unlinks it.

2. Perf: every chat row ran two edits-flow collectors (observeConcordEdit +
   observeBuzzEdit). A message is only ever one kind, so they're merged into a
   single observeChatEdit that resolves latestConcordEdit() ?: latestBuzzEdit()
   — one collector per row, dispatched by the winning edit's event type.

3. Nits: latestBuzzEdit now tie-breaks by idHex (deterministic on same-second
   edits, matching Concord); dropped a redundant takeIf in latestConcordEdit.

The author check stays at read time on purpose: an edit can be consumed before
its target loads (author unknown), so an attach-time gate would wrongly drop
early-arriving legit edits.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013HdLnAa4Pa1pFV9FTYVTB6

amethyst/src/main/java/com/vitorpamplona/amethyst/model/LocalCache.kt

@@ -3567,6 +3567,11 @@ object LocalCache : ILocalCache, ICacheProvider {
             getNoteIfExists(quotedId)?.removeBoost(note)
         }
 
+        // Edits (1010/3302/40003) are anchored on their target's Note.edits and carry no `replyTo`
+        // back-link, so the unlink above can't reach them — resolve the target by the edit's `e` tag
+        // and drop it there, or a deleted edit would keep overlaying its message.
+        editedTargetIdOf(noteEvent)?.let { getNoteIfExists(it)?.removeEdit(note) }
+
         if (noteEvent is ReportEvent) {
             noteEvent.reportedAuthor().forEach {
                 getUserIfExists(it.pubkey)?.reportsOrNull()?.let { reports ->
@@ -3605,6 +3610,15 @@ object LocalCache : ILocalCache, ICacheProvider {
         refreshDeletedNoteObservers(note)
     }
 
+    /** The id of the message/post an edit event targets (its `e` tag), across all three edit kinds. */
+    private fun editedTargetIdOf(event: Event?): HexKey? =
+        when (event) {
+            is TextNoteModificationEvent -> event.editedNote()?.eventId
+            is ConcordChatEditEvent -> event.editedMessageId()
+            is StreamMessageEditEvent -> event.editedMessage()
+            else -> null
+        }
+
     fun unlinkAndRemove(nextToBeRemoved: List<Note>) {
         nextToBeRemoved.forEach { note -> unlinkAndRemove(note) }
     }

amethyst/src/main/java/com/vitorpamplona/amethyst/model/NoteEditOverlays.kt

@@ -56,7 +56,8 @@ fun Note.latestBuzzEdit(): Note? {
     val authorHex = author?.pubkeyHex ?: return null
     return edits
         .filter { it.event is StreamMessageEditEvent && it.author?.pubkeyHex == authorHex }
-        .maxByOrNull { it.createdAt() ?: 0L }
+        // idHex tie-break so a same-second pair resolves identically on every client.
+        .maxWithOrNull(compareBy({ it.createdAt() ?: 0L }, { it.idHex }))
 }
 
 /** The kind-3302 Concord edit overlaying this message, or null — author-only, newest by CORD-02 §4 send time. */
@@ -65,5 +66,4 @@ fun Note.latestConcordEdit(): Note? {
     return edits
         .filter { it.author?.pubkeyHex == authorHex && it.event is ConcordChatEditEvent }
         .maxWithOrNull(compareBy({ (it.event as ConcordChatEditEvent).orderingMs() }, { it.idHex }))
-        ?.takeIf { it.event != null }
 }

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/chats/feed/ChatMessageCompose.kt

@@ -46,6 +46,8 @@ import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.unit.dp
 import com.vitorpamplona.amethyst.model.Note
+import com.vitorpamplona.amethyst.model.latestBuzzEdit
+import com.vitorpamplona.amethyst.model.latestConcordEdit
 import com.vitorpamplona.amethyst.ui.components.LocalInlineQuoteRenderer
 import com.vitorpamplona.amethyst.ui.navigation.navs.INav
 import com.vitorpamplona.amethyst.ui.navigation.routes.routeFor
@@ -72,13 +74,13 @@ import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.feed.types.RenderMarm
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.feed.types.RenderRegularTextNote
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.feed.types.hasMip04Media
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.feed.types.isBuzzActivityRow
-import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.feed.types.observeBuzzEdit
-import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.feed.types.observeConcordEdit
 import com.vitorpamplona.amethyst.ui.theme.ReactionRowZapraiser
 import com.vitorpamplona.amethyst.ui.theme.StdVertSpacer
 import com.vitorpamplona.quartz.buzz.forum.ForumVoteEvent
 import com.vitorpamplona.quartz.buzz.stream.StreamMessageDiffEvent
+import com.vitorpamplona.quartz.buzz.stream.StreamMessageEditEvent
 import com.vitorpamplona.quartz.buzz.stream.SystemMessageEvent
+import com.vitorpamplona.quartz.concord.cord03Channels.ConcordChatEditEvent
 import com.vitorpamplona.quartz.nip01Core.core.HexKey
 import com.vitorpamplona.quartz.nip04Dm.messages.PrivateDmEvent
 import com.vitorpamplona.quartz.nip10Notes.BaseNoteEvent
@@ -615,17 +617,33 @@ fun NoteRow(
             note.event is ChatMessageEncryptedFileHeaderEvent -> RenderEncryptedFile(note, bgColor, accountViewModel, nav)
             hasMip04Media(note.event) -> RenderMarmotEncryptedMedia(note, bgColor, accountViewModel, nav)
             else -> {
-                // Concord and Buzz channels overlay edits on their messages (kind-1010 and
-                // kind-40003 respectively): when one exists, render the newest edit's content
-                // instead of the stale original. Both are null for every other chat surface.
-                val concordEdit = observeConcordEdit(note)
-                val buzzEdit = observeBuzzEdit(note)
-                when {
-                    concordEdit != null -> RenderConcordEditedNote(note, concordEdit, canPreview, innerQuote, bgColor, accountViewModel, nav)
-                    buzzEdit != null -> RenderBuzzEditedNote(note, buzzEdit, canPreview, innerQuote, bgColor, accountViewModel, nav)
+                // Concord and Buzz channels overlay edits on their messages (kind-3302 and
+                // kind-40003): when one exists, render the newest edit's content instead of the
+                // stale original. One observer for both — a message is only ever one kind, so a
+                // single edits-flow collector per row covers both (and is null for other surfaces).
+                val edit = observeChatEdit(note)
+                when (edit?.event) {
+                    is ConcordChatEditEvent -> RenderConcordEditedNote(note, edit, canPreview, innerQuote, bgColor, accountViewModel, nav)
+                    is StreamMessageEditEvent -> RenderBuzzEditedNote(note, edit, canPreview, innerQuote, bgColor, accountViewModel, nav)
                     else -> RenderRegularTextNote(note, canPreview, innerQuote, bgColor, accountViewModel, nav)
                 }
             }
         }
     }
 }
+
+/**
+ * The newest edit overlaying a chat message [note] (Concord kind-3302 or Buzz kind-40003), or null
+ * when unedited. A message is only ever one kind, so both resolve off the same [Note.edits] and one
+ * collector on the note's edits flow serves both — recomposing whenever an edit is added or removed.
+ */
+@Composable
+fun observeChatEdit(note: Note): Note? {
+    val latest by
+        produceState<Note?>(initialValue = null, note.idHex) {
+            note.flow().edits.stateFlow.collect {
+                value = note.latestConcordEdit() ?: note.latestBuzzEdit()
+            }
+        }
+    return latest
+}

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/chats/feed/types/RenderBuzzNotes.kt

@@ -30,8 +30,6 @@ import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.MutableState
-import androidx.compose.runtime.getValue
-import androidx.compose.runtime.produceState
 import androidx.compose.runtime.remember
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.Color
@@ -43,7 +41,6 @@ import com.vitorpamplona.amethyst.R
 import com.vitorpamplona.amethyst.commons.model.EmptyTagList
 import com.vitorpamplona.amethyst.commons.model.toImmutableListOfLists
 import com.vitorpamplona.amethyst.model.Note
-import com.vitorpamplona.amethyst.model.latestBuzzEdit
 import com.vitorpamplona.amethyst.ui.components.TranslatableRichTextViewer
 import com.vitorpamplona.amethyst.ui.navigation.navs.INav
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.AccountViewModel
@@ -64,26 +61,6 @@ import com.vitorpamplona.quartz.buzz.stream.StreamMessageDiffEvent
 import com.vitorpamplona.quartz.buzz.stream.SystemMessageEvent
 import com.vitorpamplona.quartz.nip01Core.core.Event
 
-/**
- * Observes the newest kind-40003 edit overlaying [note], recomposing when new edits
- * arrive. Returns null when the message is unedited.
- *
- * Each edit is anchored on the message it edits ([Note.edits], where LocalCache consumes it),
- * so it is held for as long as its message and read straight off the note — no channel-keyed side
- * store. [Note.latestBuzzEdit] applies only the original author's newest edit; [addEdit]
- * invalidates the note's edits flow, so collecting it re-runs the fold.
- */
-@Composable
-fun observeBuzzEdit(note: Note): Note? {
-    val latest by
-        produceState<Note?>(initialValue = null, note.idHex) {
-            note.flow().edits.stateFlow.collect {
-                value = note.latestBuzzEdit()
-            }
-        }
-    return latest
-}
-
 /**
  * A Buzz stream message whose content has been superseded by a kind-40003 edit:
  * renders the NEWEST edit's content (never the stale original) plus an "(edited)"

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/chats/feed/types/RenderConcordEdits.kt

@@ -25,8 +25,6 @@ import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.MutableState
-import androidx.compose.runtime.getValue
-import androidx.compose.runtime.produceState
 import androidx.compose.runtime.remember
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.Color
@@ -34,41 +32,12 @@ import androidx.compose.ui.unit.sp
 import com.vitorpamplona.amethyst.R
 import com.vitorpamplona.amethyst.commons.model.EmptyTagList
 import com.vitorpamplona.amethyst.commons.model.toImmutableListOfLists
-import com.vitorpamplona.amethyst.model.LocalCache
 import com.vitorpamplona.amethyst.model.Note
-import com.vitorpamplona.amethyst.model.latestConcordEdit
 import com.vitorpamplona.amethyst.ui.components.TranslatableRichTextViewer
 import com.vitorpamplona.amethyst.ui.navigation.navs.INav
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.AccountViewModel
 import com.vitorpamplona.amethyst.ui.stringRes
 
-/**
- * Observes the newest kind-3302 Concord edit overlaying a Concord chat message [note],
- * recomposing when a new edit lands. Returns null for non-Concord messages or an
- * unedited one.
- *
- * Concord edits ride the encrypted channel plane (unlike public feed edits, there is no
- * relay subscription to start — the session decrypts the wrap and lands the kind-3302
- * rumor in [LocalCache] itself). Each edit is attached to the message it edits ([Note.edits],
- * like a reaction to its target), so it is held for exactly as long as the channel-retained
- * message — a Concord rumor is decrypted once per session and can't be re-downloaded, so it
- * must not be left orphaned in the soft cache. We recompute from that list whenever it changes.
- * Only edits authored by the original message's author are applied — so a member can't rewrite
- * someone else's message — and the latest by CORD-02 §4 send time wins.
- */
-@Composable
-fun observeConcordEdit(note: Note): Note? {
-    // `addEdit` invalidates this flow, so collecting it re-runs the fold on each new edit. A non-Concord
-    // message simply has no kind-3302 edits, so [Note.latestConcordEdit] returns null for it.
-    val latest by
-        produceState<Note?>(initialValue = null, note.idHex) {
-            note.flow().edits.stateFlow.collect {
-                value = note.latestConcordEdit()
-            }
-        }
-    return latest
-}
-
 /**
  * A Concord chat message whose content has been superseded by a kind-3302 edit:
  * renders the NEWEST edit's content (never the stale original) plus an "(edited)"

amethyst/src/test/java/com/vitorpamplona/amethyst/model/BuzzWorkspaceChannelTest.kt

@@ -29,6 +29,7 @@ import com.vitorpamplona.quartz.buzz.stream.StreamMessageV2Event
 import com.vitorpamplona.quartz.nip01Core.crypto.KeyPair
 import com.vitorpamplona.quartz.nip01Core.relay.normalizer.RelayUrlNormalizer
 import com.vitorpamplona.quartz.nip01Core.signers.NostrSignerInternal
+import com.vitorpamplona.quartz.nip09Deletions.DeletionEvent
 import com.vitorpamplona.quartz.nip29RelayGroups.GroupId
 import io.mockk.every
 import io.mockk.mockk
@@ -208,6 +209,27 @@ class BuzzWorkspaceChannelTest {
             assertEquals("the fix", target.latestBuzzEdit()?.event?.content)
         }
 
+    @Test
+    fun deletingAnEditUnlinksItFromTheMessage() =
+        runBlocking {
+            val channelId = newChannelId()
+            val original = streamMessage(channelId, "typo")
+            LocalCache.checkDeletionAndConsume(original, buzzRelay, false)
+            val edit = signer.sign(StreamMessageEditEvent.build(channelId, original.id, "fixed", createdAt = original.createdAt + 5))
+            LocalCache.checkDeletionAndConsume(edit, buzzRelay, false)
+
+            val target = LocalCache.getNoteIfExists(original.id)!!
+            assertEquals("fixed", target.latestBuzzEdit()?.event?.content)
+
+            // The author deletes their own edit (NIP-09). It must stop overlaying the message and
+            // be unlinked from Note.edits, not linger as a stale overlay.
+            val deletion = signer.sign(DeletionEvent.build(listOf(edit)))
+            LocalCache.checkDeletionAndConsume(deletion, buzzRelay, false)
+
+            assertNull("a deleted edit must no longer overlay its message", target.latestBuzzEdit())
+            assertTrue("the deleted edit is unlinked from the message", target.edits.none { it.idHex == edit.id })
+        }
+
     @Test
     fun pruningAMessageReleasesItsEdits() =
         runBlocking {

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/model/Note.kt

@@ -163,6 +163,7 @@ open class Note(
         removeReply(note)
         removeBoost(note)
         removeReaction(note)
+        removeEdit(note)
         removeZap(note)
         removeZapPayment(note)
         removeReport(note)