refactor(dm): centralize the DM history-window boundary + log prune rewinds

The "where the live tail ends and paged history begins" boundary (one week)
was copy-pasted across the gift-wrap + NIP-04 live tails, the backward history
pager floor, and the prune's recent/old split — easy to drift out of lockstep
(overlap = double-load, gap = missed messages).

- Add DmHistoryTuning: one place for liveTailSeconds + recentKeepCount, read by
  AccountGiftWrapsEoseManager, both NIP-04 SubAssemblers, BackwardRelayPager,
  and Chatroom.pruneMessagesToTheLatestOnly. Drops the duplicated
  LIVE_TAIL_SECONDS / DEFAULT_LIVE_TAIL_SECONDS constants.
- Log the prune-time window realignment under DMPagination, per scope
  ([giftwrap] / [rooms.nip04] / [convo.nip04]): relay count + newest pruned
  timestamp, so the rewind is observable in logcat.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

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

@@ -2693,9 +2693,18 @@ object LocalCache : ILocalCache, ICacheProvider {
 
                 // Realign the windows so a relay that already paged past (or `done` below) the dropped band
                 // re-requests it on the next demand-advance instead of skipping the hole.
-                if (giftWrapPruned.isNotEmpty()) room.giftWrapHistory.rewindTo(giftWrapPruned)
-                if (accountNip04Pruned.isNotEmpty()) room.nip04History.rewindTo(accountNip04Pruned)
-                if (roomNip04Pruned.isNotEmpty()) chatroom.nip04History.rewindTo(roomNip04Pruned)
+                if (giftWrapPruned.isNotEmpty()) {
+                    room.giftWrapHistory.rewindTo(giftWrapPruned)
+                    Log.d("DMPagination") { "[giftwrap] window rewound after prune: ${giftWrapPruned.size} relay(s), newest pruned wrap @${giftWrapPruned.values.max()}" }
+                }
+                if (accountNip04Pruned.isNotEmpty()) {
+                    room.nip04History.rewindTo(accountNip04Pruned)
+                    Log.d("DMPagination") { "[rooms.nip04] window rewound after prune: ${accountNip04Pruned.size} relay(s), newest pruned @${accountNip04Pruned.values.max()}" }
+                }
+                if (roomNip04Pruned.isNotEmpty()) {
+                    chatroom.nip04History.rewindTo(roomNip04Pruned)
+                    Log.d("DMPagination") { "[convo.nip04] window rewound after prune of ${key.users.joinToString()}: ${roomNip04Pruned.size} relay(s), newest pruned @${roomNip04Pruned.values.max()}" }
+                }
 
                 if (toBeRemoved.size > 1) {
                     println(

amethyst/src/main/java/com/vitorpamplona/amethyst/service/relayClient/reqCommand/account/nip59GiftWraps/AccountGiftWrapsEoseManager.kt

@@ -20,6 +20,7 @@
  */
 package com.vitorpamplona.amethyst.service.relayClient.reqCommand.account.nip59GiftWraps
 
+import com.vitorpamplona.amethyst.commons.model.privateChats.DmHistoryTuning
 import com.vitorpamplona.amethyst.commons.relayClient.nip17Dm.filterGiftWrapsToPubkey
 import com.vitorpamplona.amethyst.commons.relayClient.paging.WindowLoadTracker
 import com.vitorpamplona.amethyst.commons.relayClient.paging.trackingListener
@@ -68,9 +69,9 @@ class AccountGiftWrapsEoseManager(
         }
         val relays = key.account.dmRelays.flow.value
         windowLoad.setExpectedRelays(relays.toSet())
-        val sinceTime = TimeUtils.now() - LIVE_TAIL_SECONDS
+        val sinceTime = DmHistoryTuning.recentBoundary()
         DmRelayLog.log("giftwrap.live", key.account)
-        Log.d(TAG) { "[giftwrap.live] REQ since=$sinceTime (7d, no until) on ${relays.size} relay(s): ${relays.map { it.url }}" }
+        Log.d(TAG) { "[giftwrap.live] REQ since=$sinceTime (no until) on ${relays.size} relay(s): ${relays.map { it.url }}" }
         return relays.flatMap { relay ->
             filterGiftWrapsToPubkey(relay = relay, pubkey = user(key).pubkeyHex, since = sinceTime)
         }
@@ -106,8 +107,5 @@ class AccountGiftWrapsEoseManager(
 
     companion object {
         private const val TAG = "DMPagination"
-
-        // The live tail's fixed lower bound: one week of recent history, always open at the top.
-        val LIVE_TAIL_SECONDS = 7L * TimeUtils.ONE_DAY
     }
 }

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/chats/privateDM/datasource/ChatroomNip04SubAssembler.kt

@@ -20,11 +20,11 @@
  */
 package com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.privateDM.datasource
 
+import com.vitorpamplona.amethyst.commons.model.privateChats.DmHistoryTuning
 import com.vitorpamplona.amethyst.commons.relayClient.paging.WindowLoadTracker
 import com.vitorpamplona.amethyst.commons.relayClient.paging.trackingListener
 import com.vitorpamplona.amethyst.service.relayClient.eoseManagers.DmRelayLog
 import com.vitorpamplona.amethyst.service.relayClient.eoseManagers.PerUserAndFollowListEoseManager
-import com.vitorpamplona.amethyst.service.relayClient.reqCommand.account.nip59GiftWraps.AccountGiftWrapsEoseManager
 import com.vitorpamplona.amethyst.service.relays.SincePerRelayMap
 import com.vitorpamplona.quartz.nip01Core.relay.client.INostrClient
 import com.vitorpamplona.quartz.nip01Core.relay.client.pool.RelayBasedFilter
@@ -50,11 +50,11 @@ class ChatroomNip04SubAssembler(
         since: SincePerRelayMap?,
     ): List<RelayBasedFilter>? =
         if (key.account.isWriteable()) {
-            val sinceTime = TimeUtils.now() - AccountGiftWrapsEoseManager.LIVE_TAIL_SECONDS
+            val sinceTime = DmHistoryTuning.recentBoundary()
             val filters = filterNip04DMs(key.room.users, key.account, sinceTime)
             windowLoad.setExpectedRelays(filters?.mapTo(mutableSetOf()) { it.relay } ?: emptySet())
             DmRelayLog.log("convo.nip04.live", key.account)
-            Log.d("DMPagination") { "[convo.nip04.live] REQ since=$sinceTime (7d, no until) on ${filters?.size ?: 0} relay-filter(s): ${filters?.map { it.relay.url }?.distinct()}" }
+            Log.d("DMPagination") { "[convo.nip04.live] REQ since=$sinceTime (no until) on ${filters?.size ?: 0} relay-filter(s): ${filters?.map { it.relay.url }?.distinct()}" }
             filters
         } else {
             windowLoad.setExpectedRelays(emptySet())

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/chats/rooms/datasource/ChatroomListNip04SubAssembler.kt

@@ -20,12 +20,12 @@
  */
 package com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.rooms.datasource
 
+import com.vitorpamplona.amethyst.commons.model.privateChats.DmHistoryTuning
 import com.vitorpamplona.amethyst.commons.relayClient.paging.WindowLoadTracker
 import com.vitorpamplona.amethyst.commons.relayClient.paging.trackingListener
 import com.vitorpamplona.amethyst.model.User
 import com.vitorpamplona.amethyst.service.relayClient.eoseManagers.DmRelayLog
 import com.vitorpamplona.amethyst.service.relayClient.eoseManagers.PerUserEoseManager
-import com.vitorpamplona.amethyst.service.relayClient.reqCommand.account.nip59GiftWraps.AccountGiftWrapsEoseManager
 import com.vitorpamplona.amethyst.service.relays.SincePerRelayMap
 import com.vitorpamplona.quartz.nip01Core.relay.client.INostrClient
 import com.vitorpamplona.quartz.nip01Core.relay.client.pool.RelayBasedFilter
@@ -59,9 +59,9 @@ class ChatroomListNip04SubAssembler(
             val homeRelays = key.account.homeRelays.flow.value
             val dmRelays = key.account.dmRelays.flow.value
             windowLoad.setExpectedRelays((homeRelays + dmRelays).toSet())
-            val sinceTime = TimeUtils.now() - AccountGiftWrapsEoseManager.LIVE_TAIL_SECONDS
+            val sinceTime = DmHistoryTuning.recentBoundary()
             DmRelayLog.log("rooms.nip04.live", key.account)
-            Log.d("DMPagination") { "[rooms.nip04.live] REQ since=$sinceTime (7d, no until) fromMe(outbox)=${homeRelays.map { it.url }} toMe(inbox)=${dmRelays.map { it.url }}" }
+            Log.d("DMPagination") { "[rooms.nip04.live] REQ since=$sinceTime (no until) fromMe(outbox)=${homeRelays.map { it.url }} toMe(inbox)=${dmRelays.map { it.url }}" }
             homeRelays.map { filterNip04DMsFromMe(key.account.userProfile(), it, sinceTime) } +
                 dmRelays.map { filterNip04DMsToMe(key.account.userProfile(), it, sinceTime) }
         } else {

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/model/privateChats/Chatroom.kt

@@ -34,7 +34,6 @@ import com.vitorpamplona.quartz.nip01Core.relay.client.paging.RelayLoadingCursor
 import com.vitorpamplona.quartz.nip04Dm.messages.PrivateDmEvent
 import com.vitorpamplona.quartz.nip14Subject.subject
 import com.vitorpamplona.quartz.nip59Giftwrap.WrappedEvent
-import com.vitorpamplona.quartz.utils.TimeUtils
 import kotlinx.coroutines.channels.BufferOverflow
 import kotlinx.coroutines.flow.MutableSharedFlow
 import kotlinx.coroutines.flow.MutableStateFlow
@@ -140,11 +139,11 @@ class Chatroom : NotesGatherer {
         val sorted = messages.sortedWith(DefaultFeedOrder)
 
         val toKeep =
-            if ((sorted.firstOrNull()?.createdAt() ?: 0L) > TimeUtils.oneWeekAgo()) {
-                // Recent messages, keep last 100
-                sorted.take(100).toSet()
+            if ((sorted.firstOrNull()?.createdAt() ?: 0L) > DmHistoryTuning.recentBoundary()) {
+                // Recent conversation, keep its newest N
+                sorted.take(DmHistoryTuning.recentKeepCount).toSet()
             } else {
-                // Old messages, keep the last one.
+                // Old conversation, keep the last one.
                 sorted.take(1).toSet()
             } + sorted.filter { it.flowSet?.isInUse() ?: false } + sorted.filter { it.event !is PrivateDmEvent && it.event !is WrappedEvent }
         // Both DM protocols are pruned by the recency rule above: NIP-04 (PrivateDmEvent) and NIP-17

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/model/privateChats/DmHistoryTuning.kt

@@ -0,0 +1,49 @@
+/*
+ * 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.commons.model.privateChats
+
+import com.vitorpamplona.quartz.utils.TimeUtils
+import kotlin.concurrent.Volatile
+
+/**
+ * One shared boundary for the DM history window, so the three things that must agree on "where the
+ * live tail ends and paged history begins" actually read the same number:
+ *  - the live-tail subscriptions' `since` floor (e.g. `AccountGiftWrapsEoseManager`),
+ *  - the backward history pager's pinned floor (`BackwardRelayPager`),
+ *  - the memory prune's recent/old split + retention cap (`Chatroom.pruneMessagesToTheLatestOnly`).
+ *
+ * Keeping them in one place avoids the live tail and history overlapping (double-loading) or leaving a
+ * gap when the boundary is tuned. The knobs are plain `@Volatile` vars (overridable once at startup —
+ * e.g. shrinking the window in a test to exercise pruning + the per-relay download-window realignment
+ * without needing week-old threads); they are not meant to change mid-session.
+ */
+object DmHistoryTuning {
+    /** Seconds below "now" where the live tail ends and paged history begins. Production: one week. */
+    @Volatile
+    var liveTailSeconds: Long = 7L * TimeUtils.ONE_DAY
+
+    /** How many newest messages a still-recent conversation keeps on a prune. Production: 100. */
+    @Volatile
+    var recentKeepCount: Int = 100
+
+    /** The epoch-seconds boundary `now − [liveTailSeconds]` (recomputed each call against the clock). */
+    fun recentBoundary(): Long = TimeUtils.now() - liveTailSeconds
+}

commons/src/jvmAndroid/kotlin/com/vitorpamplona/amethyst/commons/relayClient/paging/BackwardRelayPager.kt

@@ -20,6 +20,7 @@
  */
 package com.vitorpamplona.amethyst.commons.relayClient.paging
 
+import com.vitorpamplona.amethyst.commons.model.privateChats.DmHistoryTuning
 import com.vitorpamplona.quartz.nip01Core.relay.client.paging.RelayLoadingCursors
 import com.vitorpamplona.quartz.nip01Core.relay.client.paging.RelayPagingProgress
 import com.vitorpamplona.quartz.nip01Core.relay.normalizer.NormalizedRelayUrl
@@ -74,8 +75,8 @@ class BackwardRelayPager(
     // volume. A relay returning fewer is its own cap, NOT exhaustion — only an empty page ends a relay.
     val pageLimit: Int = DEFAULT_PAGE_LIMIT,
     // How far below "now" the history floor sits — paging starts here and walks backward. Defaults to
-    // the one-week live-tail boundary: everything newer is the always-on tail's job.
-    private val liveTailSeconds: Long = DEFAULT_LIVE_TAIL_SECONDS,
+    // the shared live-tail boundary ([DmHistoryTuning]): everything newer is the always-on tail's job.
+    private val liveTailSeconds: Long = DmHistoryTuning.liveTailSeconds,
 ) {
     private val loadTracker = PerRelayLoadTracker(name, onSilenced = ::onSilenced)
 
@@ -300,8 +301,5 @@ class BackwardRelayPager(
         private const val TAG = "DMPagination"
 
         const val DEFAULT_PAGE_LIMIT = 10000
-
-        // One week — matches the DM live-tail floor (everything newer is the always-on tail's job).
-        const val DEFAULT_LIVE_TAIL_SECONDS = 7L * TimeUtils.ONE_DAY
     }
 }