refactor: move edit-overlay resolvers off LocalCache onto Note

findLatestModificationForNote (and the Buzz resolver) were pure Note.edits
filters with no LocalCache state — they only lived there for historical
reasons (back when resolving edits meant scanning the whole cache). Now that
every edit is a hard-referenced child of its message, resolution is a cheap
in-memory fold that belongs on the note.

New NoteEditOverlays.kt collects all three as Note extensions, so every edit
kind resolves the same way and none touches LocalCache:
- Note.textNoteModifications() (1010, author-only + NIP-40, version list)
- Note.latestBuzzEdit() (40003, author-only, newest by created_at)
- Note.latestConcordEdit() (3302, author-only, newest by CORD-02 send time)

Callers updated: observeEdits, observeNoteModifications, observeBuzzEdit,
observeConcordEdit, and the Buzz test. observeConcordEdit also drops its
early-return-before-produceState guards (a conditional-hook hazard) since the
resolver returns null for a non-Concord note anyway. LocalCache no longer
carries any edit-filtering logic.

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

@@ -2775,7 +2775,7 @@ object LocalCache : ILocalCache, ICacheProvider {
             note.loadEvent(event, author, emptyList())
 
             // Anchor the modification to the note it edits, like every other edit kind — the read side
-            // ([findLatestModificationForNote]) then folds `edited.edits` instead of scanning the cache,
+            // (Note.textNoteModifications) then folds `edited.edits` instead of scanning the cache,
             // and addEdit invalidates the note's edits flow so the UI re-derives.
             event.editedNote()?.let {
                 checkGetOrCreateNote(it.eventId)?.addEdit(note)
@@ -3251,36 +3251,6 @@ object LocalCache : ILocalCache, ICacheProvider {
         return minTime
     }
 
-    /**
-     * The NIP-1010 edits of [note] to apply, oldest first — folded from the note's own
-     * [Note.edits] (where [consume] anchors each modification) rather than scanned from the
-     * whole cache. Only the original author's edits count, and expired (NIP-40) ones are
-     * dropped. Cheap (bounded by this note's edits), so it's safe to call from any thread.
-     */
-    fun findLatestModificationForNote(note: Note): List<Note> {
-        val noteAuthor = note.author ?: return emptyList()
-        val time = TimeUtils.now()
-
-        return note.edits
-            .filter { item ->
-                val noteEvent = item.event
-                noteEvent is TextNoteModificationEvent && noteAuthor == item.author && !noteEvent.isExpirationBefore(time)
-            }.sortedWith(compareBy({ it.createdAt() }, { it.idHex }))
-    }
-
-    /**
-     * The kind-40003 Buzz edit currently overlaying [note], or null when unedited. Like every other
-     * edit kind, only the ORIGINAL message author's edits count — the send side already gates Edit to
-     * your own messages, and the relay is not trusted to reject a cross-author edit, so a 40003 signed
-     * by anyone else can never rewrite your message. The newest by created_at wins (Buzz's rule).
-     */
-    fun findLatestBuzzEditForNote(note: Note): Note? {
-        val authorHex = note.author?.pubkeyHex ?: return null
-        return note.edits
-            .filter { it.event is StreamMessageEditEvent && it.author?.pubkeyHex == authorHex }
-            .maxByOrNull { it.createdAt() ?: 0L }
-    }
-
     fun cleanMemory() {
         Log.d("LargeCache") { "Notes cleanup started. Current size: ${notes.size()}" }
         notes.cleanUp()

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

@@ -0,0 +1,69 @@
+/*
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.amethyst.model
+
+import com.vitorpamplona.quartz.buzz.stream.StreamMessageEditEvent
+import com.vitorpamplona.quartz.concord.cord03Channels.ConcordChatEditEvent
+import com.vitorpamplona.quartz.experimental.edits.TextNoteModificationEvent
+import com.vitorpamplona.quartz.nip40Expiration.isExpirationBefore
+import com.vitorpamplona.quartz.utils.TimeUtils
+
+/*
+ * Per-kind resolution of a message's edit overlay from its own `Note.edits`. Every edit that
+ * targets a note is held there as a hard-referenced child (like a reaction), so these are cheap
+ * in-memory folds — no cache scan, no LocalCache state involved, which is why they live on the
+ * note rather than the cache.
+ *
+ * All three kinds apply ONLY edits authored by the edited note's own author: the send side gates
+ * editing to your own messages, and neither the relay (Buzz) nor an encrypted-plane peer (Concord)
+ * is trusted to enforce that, so a foreign-authored edit never rewrites your message.
+ */
+
+/**
+ * Every kind-1010 post modification of this note, oldest first (author-only, dropping NIP-40
+ * expired ones). A list because the post's EditState cycles through the original + each version.
+ */
+fun Note.textNoteModifications(): List<Note> {
+    val noteAuthor = author ?: return emptyList()
+    val now = TimeUtils.now()
+    return edits
+        .filter { item ->
+            val e = item.event
+            e is TextNoteModificationEvent && noteAuthor == item.author && !e.isExpirationBefore(now)
+        }.sortedWith(compareBy({ it.createdAt() }, { it.idHex }))
+}
+
+/** The kind-40003 Buzz edit overlaying this message, or null — author-only, newest by created_at. */
+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 }
+}
+
+/** The kind-3302 Concord edit overlaying this message, or null — author-only, newest by CORD-02 §4 send time. */
+fun Note.latestConcordEdit(): Note? {
+    val authorHex = author?.pubkeyHex ?: return null
+    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/service/relayClient/reqCommand/event/EventObservers.kt

@@ -25,10 +25,10 @@ import androidx.compose.runtime.State
 import androidx.compose.runtime.produceState
 import androidx.compose.runtime.remember
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
-import com.vitorpamplona.amethyst.model.LocalCache
 import com.vitorpamplona.amethyst.model.Note
 import com.vitorpamplona.amethyst.model.NoteState
 import com.vitorpamplona.amethyst.model.User
+import com.vitorpamplona.amethyst.model.textNoteModifications
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.AccountViewModel
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.isMinichatReply
 import com.vitorpamplona.quartz.nip01Core.core.Event
@@ -418,7 +418,7 @@ fun observeNoteModifications(
             .edits
             .stateFlow
             .sample(500)
-            .mapLatest { LocalCache.findLatestModificationForNote(note) }
+            .mapLatest { note.textNoteModifications() }
             .distinctUntilChanged()
             .flowOn(Dispatchers.IO)
             .collect { value = it }

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/note/NoteCompose.kt

@@ -71,6 +71,7 @@ import com.vitorpamplona.amethyst.commons.ui.state.produceCachedStateAsync
 import com.vitorpamplona.amethyst.model.AddressableNote
 import com.vitorpamplona.amethyst.model.LocalCache
 import com.vitorpamplona.amethyst.model.Note
+import com.vitorpamplona.amethyst.model.textNoteModifications
 import com.vitorpamplona.amethyst.service.relayClient.reqCommand.channel.observeChannelPicture
 import com.vitorpamplona.amethyst.service.relayClient.reqCommand.event.observeCommunityApprovalNeedStatus
 import com.vitorpamplona.amethyst.service.relayClient.reqCommand.event.observeNoteEvent
@@ -2062,7 +2063,7 @@ fun observeEdits(
         remember(baseNote.idHex) {
             // Edits are anchored on the note (Note.edits), so the current set is readable synchronously
             // (no cache scan) — start Empty or Loaded, never Loading.
-            val cached = LocalCache.findLatestModificationForNote(baseNote)
+            val cached = baseNote.textNoteModifications()
             mutableStateOf(
                 if (cached.isEmpty()) {
                     GenericLoadable.Empty()

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

@@ -42,8 +42,8 @@ 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.latestBuzzEdit
 import com.vitorpamplona.amethyst.ui.components.TranslatableRichTextViewer
 import com.vitorpamplona.amethyst.ui.navigation.navs.INav
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.AccountViewModel
@@ -68,17 +68,17 @@ 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),
+ * 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. [LocalCache.findLatestBuzzEditForNote] applies only the original author's newest edit;
- * [addEdit] invalidates the note's edits flow, so collecting it re-runs the fold.
+ * 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 = LocalCache.findLatestBuzzEditForNote(note)
+                value = note.latestBuzzEdit()
             }
         }
     return latest

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

@@ -33,15 +33,14 @@ import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.unit.sp
 import com.vitorpamplona.amethyst.R
 import com.vitorpamplona.amethyst.commons.model.EmptyTagList
-import com.vitorpamplona.amethyst.commons.model.concord.ConcordChannel
 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
-import com.vitorpamplona.quartz.concord.cord03Channels.ConcordChatEditEvent
 
 /**
  * Observes the newest kind-3302 Concord edit overlaying a Concord chat message [note],
@@ -59,21 +58,12 @@ import com.vitorpamplona.quartz.concord.cord03Channels.ConcordChatEditEvent
  */
 @Composable
 fun observeConcordEdit(note: Note): Note? {
-    // Key on note.event, not note: LocalCache mutates a Note in place, so keying on the Note instance
-    // would cache a null gatherer taken before the event populated and never recompute for that row.
-    val isConcord = remember(note.event) { note.inGatherers?.any { it is ConcordChannel } == true }
-    if (!isConcord) return null
-    val authorHex = note.author?.pubkeyHex ?: return null
-
-    // `addEdit` invalidates this flow, so collecting it re-runs the fold below on each new edit.
+    // `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.edits
-                        .filter { it.author?.pubkeyHex == authorHex && it.event is ConcordChatEditEvent }
-                        .maxWithOrNull(compareBy({ (it.event as ConcordChatEditEvent).orderingMs() }, { it.idHex }))
-                        ?.takeIf { it.event != null }
+                value = note.latestConcordEdit()
             }
         }
     return latest

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

@@ -199,13 +199,13 @@ class BuzzWorkspaceChannelTest {
             // …but the overlay only applies the ORIGINAL author's edits, so it is ignored.
             assertNull(
                 "an edit by a different author must never override the message",
-                LocalCache.findLatestBuzzEditForNote(target),
+                target.latestBuzzEdit(),
             )
 
             // The real author's own later edit does apply.
             val real = signer.sign(StreamMessageEditEvent.build(channelId, original.id, "the fix", createdAt = original.createdAt + 200))
             LocalCache.checkDeletionAndConsume(real, buzzRelay, false)
-            assertEquals("the fix", LocalCache.findLatestBuzzEditForNote(target)?.event?.content)
+            assertEquals("the fix", target.latestBuzzEdit()?.event?.content)
         }
 
     @Test