feat(calendars): add NIP-52 feed foundation, DAL and relay subscription

Wires per-account calendar follow-list settings, two feed filters
(appointments 31922/31923 and collections 31924), and a relay
subscription assembler that pulls all four calendar kinds. Sorts
the appointment feed with upcoming events first, past events after,
so the calendar timeline behaves like a calendar rather than a chat
feed.

https://claude.ai/code/session_01CbyrA2GdM4EQh8T6nsst6U

amethyst/src/main/java/com/vitorpamplona/amethyst/LocalPreferences.kt

@@ -104,6 +104,7 @@ private object PrefKeys {
     const val DEFAULT_DISCOVERY_FOLLOW_LIST = "defaultDiscoveryFollowList"
     const val DEFAULT_POLLS_FOLLOW_LIST = "defaultPollsFollowList"
     const val DEFAULT_PICTURES_FOLLOW_LIST = "defaultPicturesFollowList"
+    const val DEFAULT_CALENDARS_FOLLOW_LIST = "defaultCalendarsFollowList"
     const val DEFAULT_PRODUCTS_FOLLOW_LIST = "defaultProductsFollowList"
     const val DEFAULT_SHORTS_FOLLOW_LIST = "defaultShortsFollowList"
     const val DEFAULT_PUBLIC_CHATS_FOLLOW_LIST = "defaultPublicChatsFollowList"
@@ -361,6 +362,7 @@ object LocalPreferences {
 
                     putString(PrefKeys.DEFAULT_POLLS_FOLLOW_LIST, JsonMapper.toJson(settings.defaultPollsFollowList.value))
                     putString(PrefKeys.DEFAULT_PICTURES_FOLLOW_LIST, JsonMapper.toJson(settings.defaultPicturesFollowList.value))
+                    putString(PrefKeys.DEFAULT_CALENDARS_FOLLOW_LIST, JsonMapper.toJson(settings.defaultCalendarsFollowList.value))
                     putString(PrefKeys.DEFAULT_PRODUCTS_FOLLOW_LIST, JsonMapper.toJson(settings.defaultProductsFollowList.value))
                     putString(PrefKeys.DEFAULT_SHORTS_FOLLOW_LIST, JsonMapper.toJson(settings.defaultShortsFollowList.value))
                     putString(PrefKeys.DEFAULT_PUBLIC_CHATS_FOLLOW_LIST, JsonMapper.toJson(settings.defaultPublicChatsFollowList.value))
@@ -641,6 +643,7 @@ object LocalPreferences {
                         defaultDiscoveryFollowList = MutableStateFlow(followListPrefs.discovery),
                         defaultPollsFollowList = MutableStateFlow(followListPrefs.polls),
                         defaultPicturesFollowList = MutableStateFlow(followListPrefs.pictures),
+                        defaultCalendarsFollowList = MutableStateFlow(followListPrefs.calendars),
                         defaultProductsFollowList = MutableStateFlow(followListPrefs.products),
                         defaultShortsFollowList = MutableStateFlow(followListPrefs.shorts),
                         defaultPublicChatsFollowList = MutableStateFlow(followListPrefs.publicChats),
@@ -712,6 +715,7 @@ object LocalPreferences {
         val discovery: TopFilter,
         val polls: TopFilter,
         val pictures: TopFilter,
+        val calendars: TopFilter,
         val products: TopFilter,
         val shorts: TopFilter,
         val publicChats: TopFilter,
@@ -733,6 +737,7 @@ object LocalPreferences {
             discovery = parseTopFilterOrDefault(getString(PrefKeys.DEFAULT_DISCOVERY_FOLLOW_LIST, null), TopFilter.Global),
             polls = parseTopFilterOrDefault(getString(PrefKeys.DEFAULT_POLLS_FOLLOW_LIST, null), TopFilter.Global),
             pictures = parseTopFilterOrDefault(getString(PrefKeys.DEFAULT_PICTURES_FOLLOW_LIST, null), TopFilter.Global),
+            calendars = parseTopFilterOrDefault(getString(PrefKeys.DEFAULT_CALENDARS_FOLLOW_LIST, null), TopFilter.Global),
             products = parseTopFilterOrDefault(getString(PrefKeys.DEFAULT_PRODUCTS_FOLLOW_LIST, null), TopFilter.AroundMe),
             shorts = parseTopFilterOrDefault(getString(PrefKeys.DEFAULT_SHORTS_FOLLOW_LIST, null), TopFilter.Global),
             publicChats = parseTopFilterOrDefault(getString(PrefKeys.DEFAULT_PUBLIC_CHATS_FOLLOW_LIST, null), TopFilter.Global),

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

@@ -489,6 +489,9 @@ class Account(
     val livePicturesFollowLists: StateFlow<IFeedTopNavFilter> = topNavFilterFlow(settings.defaultPicturesFollowList)
     val livePicturesFollowListsPerRelay = OutboxLoaderState(livePicturesFollowLists, cache, scope).flow
 
+    val liveCalendarsFollowLists: StateFlow<IFeedTopNavFilter> = topNavFilterFlow(settings.defaultCalendarsFollowList)
+    val liveCalendarsFollowListsPerRelay = OutboxLoaderState(liveCalendarsFollowLists, cache, scope).flow
+
     val liveProductsFollowLists: StateFlow<IFeedTopNavFilter> = topNavFilterFlow(settings.defaultProductsFollowList)
     val liveProductsFollowListsPerRelay = OutboxLoaderState(liveProductsFollowLists, cache, scope).flow
 

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

@@ -163,6 +163,7 @@ class AccountSettings(
     val defaultDiscoveryFollowList: MutableStateFlow<TopFilter> = MutableStateFlow(TopFilter.Global),
     val defaultPollsFollowList: MutableStateFlow<TopFilter> = MutableStateFlow(TopFilter.Global),
     val defaultPicturesFollowList: MutableStateFlow<TopFilter> = MutableStateFlow(TopFilter.Global),
+    val defaultCalendarsFollowList: MutableStateFlow<TopFilter> = MutableStateFlow(TopFilter.Global),
     val defaultProductsFollowList: MutableStateFlow<TopFilter> = MutableStateFlow(TopFilter.AroundMe),
     val defaultShortsFollowList: MutableStateFlow<TopFilter> = MutableStateFlow(TopFilter.Global),
     val defaultPublicChatsFollowList: MutableStateFlow<TopFilter> = MutableStateFlow(TopFilter.Global),
@@ -529,6 +530,17 @@ class AccountSettings(
         }
     }
 
+    fun changeDefaultCalendarsFollowList(name: FeedDefinition) {
+        changeDefaultCalendarsFollowList(name.code)
+    }
+
+    fun changeDefaultCalendarsFollowList(name: TopFilter) {
+        if (defaultCalendarsFollowList.value != name) {
+            defaultCalendarsFollowList.tryEmit(name)
+            saveAccountSettings()
+        }
+    }
+
     fun changeDefaultProductsFollowList(name: FeedDefinition) {
         changeDefaultProductsFollowList(name.code)
     }

amethyst/src/main/java/com/vitorpamplona/amethyst/service/relayClient/reqCommand/RelaySubscriptionsCoordinator.kt

@@ -31,6 +31,7 @@ import com.vitorpamplona.amethyst.service.relayClient.searchCommand.SearchFilter
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.articles.datasource.ArticlesFilterAssembler
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.badges.datasource.BadgesFilterAssembler
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.badges.profile.datasource.ProfileBadgesFilterAssembler
+import com.vitorpamplona.amethyst.ui.screen.loggedIn.calendars.datasource.CalendarsFilterAssembler
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.privateDM.datasource.ChatroomFilterAssembler
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.publicChannels.datasource.ChannelFilterAssembler
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.rooms.datasource.ChatroomListFilterAssembler
@@ -111,6 +112,7 @@ class RelaySubscriptionsCoordinator(
 
     val polls = PollsFilterAssembler(client)
     val pictures = PicturesFilterAssembler(client)
+    val calendars = CalendarsFilterAssembler(client)
     val products = ProductsFilterAssembler(client)
     val shorts = ShortsFilterAssembler(client)
     val publicChats = PublicChatsFilterAssembler(client)
@@ -141,6 +143,7 @@ class RelaySubscriptionsCoordinator(
             discovery,
             polls,
             pictures,
+            calendars,
             products,
             shorts,
             publicChats,

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

@@ -30,6 +30,8 @@ import com.vitorpamplona.amethyst.ui.feeds.ChannelFeedContentState
 import com.vitorpamplona.amethyst.ui.screen.TopNavFilterState
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.articles.dal.ArticlesFeedFilter
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.badges.dal.BadgesFeedFilter
+import com.vitorpamplona.amethyst.ui.screen.loggedIn.calendars.dal.CalendarCollectionsFeedFilter
+import com.vitorpamplona.amethyst.ui.screen.loggedIn.calendars.dal.CalendarsFeedFilter
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.rooms.dal.ChatroomListKnownFeedFilter
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.rooms.dal.ChatroomListNewFeedFilter
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.communities.list.dal.CommunitiesFeedFilter
@@ -99,6 +101,8 @@ class AccountFeedContentStates(
     val communitiesList = FeedContentState(CommunitiesFeedFilter(account), scope, LocalCache)
 
     val picturesFeed = FeedContentState(PictureFeedFilter(account), scope, LocalCache)
+    val calendarsFeed = FeedContentState(CalendarsFeedFilter(account), scope, LocalCache)
+    val calendarCollectionsFeed = FeedContentState(CalendarCollectionsFeedFilter(account), scope, LocalCache)
     val productsFeed = FeedContentState(ProductsFeedFilter(account), scope, LocalCache)
     val shortsFeed = FeedContentState(ShortsFeedFilter(account), scope, LocalCache)
     val publicChatsFeed = FeedContentState(PublicChatsFeedFilter(account), scope, LocalCache)

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/calendars/dal/CalendarCollectionsFeedFilter.kt

@@ -0,0 +1,74 @@
+/*
+ * 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.ui.screen.loggedIn.calendars.dal
+
+import com.vitorpamplona.amethyst.model.Account
+import com.vitorpamplona.amethyst.model.LocalCache
+import com.vitorpamplona.amethyst.model.Note
+import com.vitorpamplona.amethyst.model.TopFilter
+import com.vitorpamplona.amethyst.ui.dal.AdditiveFeedFilter
+import com.vitorpamplona.amethyst.ui.dal.DefaultFeedOrder
+import com.vitorpamplona.amethyst.ui.dal.FilterByListParams
+import com.vitorpamplona.quartz.nip52Calendar.calendar.CalendarEvent
+
+class CalendarCollectionsFeedFilter(
+    val account: Account,
+) : AdditiveFeedFilter<Note>() {
+    override fun feedKey(): String = account.userProfile().pubkeyHex + "-collections-" + followList().code
+
+    override fun limit() = 200
+
+    fun followList(): TopFilter = account.settings.defaultCalendarsFollowList.value
+
+    private fun TopFilter.isMuteList() = this is TopFilter.MuteList
+
+    private fun TopFilter.isBlockList() = this is TopFilter.PeopleList && this.address == account.blockPeopleList.getBlockListAddress()
+
+    override fun showHiddenKey(): Boolean = followList().let { it.isMuteList() || it.isBlockList() }
+
+    override fun feed(): List<Note> {
+        val params = buildFilterParams(account)
+        val notes =
+            LocalCache.addressables.filterIntoSet { _, it ->
+                val e = it.event
+                e is CalendarEvent && params.match(e, it.relays)
+            }
+        return sort(notes)
+    }
+
+    override fun applyFilter(newItems: Set<Note>): Set<Note> = innerApplyFilter(newItems)
+
+    private fun buildFilterParams(account: Account): FilterByListParams =
+        FilterByListParams.create(
+            account.liveCalendarsFollowLists.value,
+            account.hiddenUsers.flow.value,
+        )
+
+    private fun innerApplyFilter(collection: Collection<Note>): Set<Note> {
+        val params = buildFilterParams(account)
+        return collection.filterTo(HashSet()) {
+            val e = it.event
+            e is CalendarEvent && params.match(e, it.relays)
+        }
+    }
+
+    override fun sort(items: Set<Note>): List<Note> = items.sortedWith(DefaultFeedOrder)
+}

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/calendars/dal/CalendarSortKeys.kt

@@ -0,0 +1,104 @@
+/*
+ * 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.ui.screen.loggedIn.calendars.dal
+
+import com.vitorpamplona.amethyst.model.Note
+import com.vitorpamplona.quartz.nip52Calendar.appt.day.CalendarDateSlotEvent
+import com.vitorpamplona.quartz.nip52Calendar.appt.time.CalendarTimeSlotEvent
+import com.vitorpamplona.quartz.utils.TimeUtils
+import java.text.SimpleDateFormat
+import java.util.Locale
+import java.util.TimeZone
+
+private val IsoDateParser =
+    SimpleDateFormat("yyyy-MM-dd", Locale.US).apply {
+        timeZone = TimeZone.getTimeZone("UTC")
+        isLenient = false
+    }
+
+/**
+ * Calendar 31922 carries an ISO date string. Parsed in UTC so day-only events compare
+ * predictably across viewers in different time zones.
+ */
+fun parseIsoDateToUnixSeconds(date: String?): Long? {
+    if (date.isNullOrBlank()) return null
+    return try {
+        IsoDateParser.parse(date)?.time?.div(1000)
+    } catch (_: Throwable) {
+        null
+    }
+}
+
+/**
+ * Unified start time as unix-seconds for any NIP-52 calendar appointment.
+ * Returns null when neither slot kind is present or the start cannot be parsed.
+ */
+fun Note.calendarStartSeconds(): Long? =
+    when (val e = event) {
+        is CalendarTimeSlotEvent -> e.start()
+        is CalendarDateSlotEvent -> parseIsoDateToUnixSeconds(e.start())
+        else -> null
+    }
+
+fun Note.calendarEndSeconds(): Long? =
+    when (val e = event) {
+        is CalendarTimeSlotEvent -> e.end() ?: e.start()
+        is CalendarDateSlotEvent -> parseIsoDateToUnixSeconds(e.end()) ?: parseIsoDateToUnixSeconds(e.start())
+        else -> null
+    }
+
+/**
+ * Sort by: upcoming events ascending (closest first), then past events descending (most-recent first).
+ * Falls back to createdAt + id when start is missing so the order remains stable.
+ */
+val UpcomingFirstCalendarOrder: Comparator<Note> =
+    Comparator { a, b ->
+        val now = TimeUtils.now()
+        val sa = a.calendarStartSeconds()
+        val sb = b.calendarStartSeconds()
+
+        when {
+            sa == null && sb == null -> compareCreatedAt(a, b)
+            sa == null -> 1
+            sb == null -> -1
+            else -> {
+                val aUpcoming = sa >= now
+                val bUpcoming = sb >= now
+                when {
+                    aUpcoming && !bUpcoming -> -1
+                    !aUpcoming && bUpcoming -> 1
+                    aUpcoming -> sa.compareTo(sb) // both future: nearest first
+                    else -> sb.compareTo(sa) // both past: most recent first
+                }
+            }
+        }.let { primary ->
+            if (primary != 0) primary else a.idHex.compareTo(b.idHex)
+        }
+    }
+
+private fun compareCreatedAt(
+    a: Note,
+    b: Note,
+): Int {
+    val ca = a.createdAt() ?: 0L
+    val cb = b.createdAt() ?: 0L
+    return cb.compareTo(ca)
+}

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/calendars/dal/CalendarsFeedFilter.kt

@@ -0,0 +1,76 @@
+/*
+ * 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.ui.screen.loggedIn.calendars.dal
+
+import com.vitorpamplona.amethyst.model.Account
+import com.vitorpamplona.amethyst.model.LocalCache
+import com.vitorpamplona.amethyst.model.Note
+import com.vitorpamplona.amethyst.model.TopFilter
+import com.vitorpamplona.amethyst.ui.dal.AdditiveFeedFilter
+import com.vitorpamplona.amethyst.ui.dal.FilterByListParams
+import com.vitorpamplona.quartz.nip52Calendar.appt.day.CalendarDateSlotEvent
+import com.vitorpamplona.quartz.nip52Calendar.appt.time.CalendarTimeSlotEvent
+
+class CalendarsFeedFilter(
+    val account: Account,
+) : AdditiveFeedFilter<Note>() {
+    override fun feedKey(): String = account.userProfile().pubkeyHex + "-" + followList().code
+
+    override fun limit() = 500
+
+    fun followList(): TopFilter = account.settings.defaultCalendarsFollowList.value
+
+    private fun TopFilter.isMuteList() = this is TopFilter.MuteList
+
+    private fun TopFilter.isBlockList() = this is TopFilter.PeopleList && this.address == account.blockPeopleList.getBlockListAddress()
+
+    private fun TopFilter.wantsToSeeNegativeStuff() = isMuteList() || isBlockList()
+
+    override fun showHiddenKey(): Boolean = followList().wantsToSeeNegativeStuff()
+
+    override fun feed(): List<Note> {
+        val params = buildFilterParams(account)
+        val notes =
+            LocalCache.notes.filterIntoSet { _, it ->
+                val e = it.event
+                (e is CalendarTimeSlotEvent || e is CalendarDateSlotEvent) && params.match(e, it.relays)
+            }
+        return sort(notes)
+    }
+
+    override fun applyFilter(newItems: Set<Note>): Set<Note> = innerApplyFilter(newItems)
+
+    private fun buildFilterParams(account: Account): FilterByListParams =
+        FilterByListParams.create(
+            account.liveCalendarsFollowLists.value,
+            account.hiddenUsers.flow.value,
+        )
+
+    private fun innerApplyFilter(collection: Collection<Note>): Set<Note> {
+        val params = buildFilterParams(account)
+        return collection.filterTo(HashSet()) {
+            val e = it.event
+            (e is CalendarTimeSlotEvent || e is CalendarDateSlotEvent) && params.match(e, it.relays)
+        }
+    }
+
+    override fun sort(items: Set<Note>): List<Note> = items.sortedWith(UpcomingFirstCalendarOrder)
+}

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/calendars/datasource/CalendarsFilterAssembler.kt

@@ -0,0 +1,50 @@
+/*
+ * 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.ui.screen.loggedIn.calendars.datasource
+
+import androidx.compose.runtime.Stable
+import com.vitorpamplona.amethyst.commons.relayClient.composeSubscriptionManagers.ComposeSubscriptionManager
+import com.vitorpamplona.amethyst.model.Account
+import com.vitorpamplona.amethyst.ui.screen.loggedIn.AccountFeedContentStates
+import com.vitorpamplona.quartz.nip01Core.relay.client.INostrClient
+import kotlinx.coroutines.CoroutineScope
+
+class CalendarsQueryState(
+    val account: Account,
+    val feedStates: AccountFeedContentStates,
+    val scope: CoroutineScope,
+)
+
+@Stable
+class CalendarsFilterAssembler(
+    client: INostrClient,
+) : ComposeSubscriptionManager<CalendarsQueryState>() {
+    val group =
+        listOf(
+            CalendarsSubAssembler(client, ::allKeys),
+        )
+
+    override fun invalidateKeys() = invalidateFilters()
+
+    override fun invalidateFilters() = group.forEach { it.invalidateFilters() }
+
+    override fun destroy() = group.forEach { it.destroy() }
+}

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/calendars/datasource/CalendarsFilterAssemblerSubscription.kt

@@ -0,0 +1,48 @@
+/*
+ * 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.ui.screen.loggedIn.calendars.datasource
+
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.remember
+import androidx.lifecycle.viewModelScope
+import com.vitorpamplona.amethyst.commons.relayClient.subscriptions.LifecycleAwareKeyDataSourceSubscription
+import com.vitorpamplona.amethyst.ui.screen.loggedIn.AccountViewModel
+
+@Composable
+fun CalendarsFilterAssemblerSubscription(accountViewModel: AccountViewModel) {
+    CalendarsFilterAssemblerSubscription(
+        accountViewModel.dataSources().calendars,
+        accountViewModel,
+    )
+}
+
+@Composable
+fun CalendarsFilterAssemblerSubscription(
+    dataSource: CalendarsFilterAssembler,
+    accountViewModel: AccountViewModel,
+) {
+    val state =
+        remember(accountViewModel.account) {
+            CalendarsQueryState(accountViewModel.account, accountViewModel.feedStates, accountViewModel.viewModelScope)
+        }
+
+    LifecycleAwareKeyDataSourceSubscription(state, dataSource)
+}

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/calendars/datasource/CalendarsSubAssembler.kt

@@ -0,0 +1,97 @@
+/*
+ * 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.ui.screen.loggedIn.calendars.datasource
+
+import com.vitorpamplona.amethyst.model.TopFilter
+import com.vitorpamplona.amethyst.model.User
+import com.vitorpamplona.amethyst.service.relayClient.eoseManagers.PerUserAndFollowListEoseManager
+import com.vitorpamplona.amethyst.service.relays.SincePerRelayMap
+import com.vitorpamplona.quartz.nip01Core.relay.client.INostrClient
+import com.vitorpamplona.quartz.nip01Core.relay.client.pool.RelayBasedFilter
+import com.vitorpamplona.quartz.nip01Core.relay.client.subscriptions.Subscription
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.FlowPreview
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.flow.collectLatest
+import kotlinx.coroutines.flow.sample
+import kotlinx.coroutines.launch
+
+class CalendarsSubAssembler(
+    client: INostrClient,
+    allKeys: () -> Set<CalendarsQueryState>,
+) : PerUserAndFollowListEoseManager<CalendarsQueryState, TopFilter>(client, allKeys) {
+    override fun updateFilter(
+        key: CalendarsQueryState,
+        since: SincePerRelayMap?,
+    ): List<RelayBasedFilter> {
+        val feedSettings = key.followsPerRelay()
+
+        return makeCalendarsFilter(feedSettings, since, key.feedStates.calendarsFeed.lastNoteCreatedAtIfFilled())
+    }
+
+    override fun user(key: CalendarsQueryState) = key.account.userProfile()
+
+    override fun list(key: CalendarsQueryState) = key.listName()
+
+    fun CalendarsQueryState.listNameFlow() = account.settings.defaultCalendarsFollowList
+
+    fun CalendarsQueryState.listName() = listNameFlow().value
+
+    fun CalendarsQueryState.followsPerRelayFlow() = account.liveCalendarsFollowListsPerRelay
+
+    fun CalendarsQueryState.followsPerRelay() = followsPerRelayFlow().value
+
+    val userJobMap = mutableMapOf<User, List<Job>>()
+
+    @OptIn(FlowPreview::class)
+    override fun newSub(key: CalendarsQueryState): Subscription {
+        val user = user(key)
+        userJobMap[user]?.forEach { it.cancel() }
+        userJobMap[user] =
+            listOf(
+                key.scope.launch(Dispatchers.IO) {
+                    key.listNameFlow().collectLatest {
+                        invalidateFilters()
+                    }
+                },
+                key.scope.launch(Dispatchers.IO) {
+                    key.followsPerRelayFlow().sample(500).collectLatest {
+                        invalidateFilters()
+                    }
+                },
+                key.account.scope.launch(Dispatchers.IO) {
+                    key.feedStates.calendarsFeed.lastNoteCreatedAtWhenFullyLoaded.sample(5000).collectLatest {
+                        invalidateFilters()
+                    }
+                },
+            )
+
+        return super.newSub(key)
+    }
+
+    override fun endSub(
+        key: User,
+        subId: String,
+    ) {
+        super.endSub(key, subId)
+        userJobMap[key]?.forEach { it.cancel() }
+    }
+}

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/calendars/datasource/SubAssemblyHelper.kt

@@ -0,0 +1,52 @@
+/*
+ * 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.ui.screen.loggedIn.calendars.datasource
+
+import com.vitorpamplona.amethyst.model.topNavFeeds.IFeedTopNavPerRelayFilterSet
+import com.vitorpamplona.amethyst.model.topNavFeeds.allFollows.AllFollowsTopNavPerRelayFilterSet
+import com.vitorpamplona.amethyst.model.topNavFeeds.aroundMe.LocationTopNavPerRelayFilterSet
+import com.vitorpamplona.amethyst.model.topNavFeeds.global.GlobalTopNavPerRelayFilterSet
+import com.vitorpamplona.amethyst.model.topNavFeeds.hashtag.HashtagTopNavPerRelayFilterSet
+import com.vitorpamplona.amethyst.model.topNavFeeds.noteBased.author.AuthorsTopNavPerRelayFilterSet
+import com.vitorpamplona.amethyst.model.topNavFeeds.noteBased.muted.MutedAuthorsTopNavPerRelayFilterSet
+import com.vitorpamplona.amethyst.service.relays.SincePerRelayMap
+import com.vitorpamplona.amethyst.ui.screen.loggedIn.calendars.datasource.subassemblies.filterCalendarsByAuthors
+import com.vitorpamplona.amethyst.ui.screen.loggedIn.calendars.datasource.subassemblies.filterCalendarsByFollows
+import com.vitorpamplona.amethyst.ui.screen.loggedIn.calendars.datasource.subassemblies.filterCalendarsByGeohashes
+import com.vitorpamplona.amethyst.ui.screen.loggedIn.calendars.datasource.subassemblies.filterCalendarsByHashtag
+import com.vitorpamplona.amethyst.ui.screen.loggedIn.calendars.datasource.subassemblies.filterCalendarsByMutedAuthors
+import com.vitorpamplona.amethyst.ui.screen.loggedIn.calendars.datasource.subassemblies.filterCalendarsGlobal
+import com.vitorpamplona.quartz.nip01Core.relay.client.pool.RelayBasedFilter
+
+fun makeCalendarsFilter(
+    feedSettings: IFeedTopNavPerRelayFilterSet,
+    since: SincePerRelayMap?,
+    defaultSince: Long? = null,
+): List<RelayBasedFilter> =
+    when (feedSettings) {
+        is AllFollowsTopNavPerRelayFilterSet -> filterCalendarsByFollows(feedSettings, since, defaultSince)
+        is AuthorsTopNavPerRelayFilterSet -> filterCalendarsByAuthors(feedSettings, since, defaultSince)
+        is GlobalTopNavPerRelayFilterSet -> filterCalendarsGlobal(feedSettings, since, defaultSince)
+        is HashtagTopNavPerRelayFilterSet -> filterCalendarsByHashtag(feedSettings, since, defaultSince)
+        is LocationTopNavPerRelayFilterSet -> filterCalendarsByGeohashes(feedSettings, since, defaultSince)
+        is MutedAuthorsTopNavPerRelayFilterSet -> filterCalendarsByMutedAuthors(feedSettings, since, defaultSince)
+        else -> emptyList()
+    }

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/calendars/datasource/subassemblies/CalendarKinds.kt

@@ -0,0 +1,39 @@
+/*
+ * 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.ui.screen.loggedIn.calendars.datasource.subassemblies
+
+import com.vitorpamplona.quartz.nip52Calendar.appt.day.CalendarDateSlotEvent
+import com.vitorpamplona.quartz.nip52Calendar.appt.time.CalendarTimeSlotEvent
+import com.vitorpamplona.quartz.nip52Calendar.calendar.CalendarEvent
+import com.vitorpamplona.quartz.nip52Calendar.rsvp.CalendarRSVPEvent
+
+// Appointments are the only kinds shown in the main calendar feed/views. RSVPs and
+// collections come along on the same subscription so detail screens can render without
+// a second round-trip, but they don't drive the timeline DAL.
+val CalendarAppointmentKinds = listOf(CalendarTimeSlotEvent.KIND, CalendarDateSlotEvent.KIND)
+
+val AllCalendarKinds =
+    listOf(
+        CalendarTimeSlotEvent.KIND,
+        CalendarDateSlotEvent.KIND,
+        CalendarEvent.KIND,
+        CalendarRSVPEvent.KIND,
+    )

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/calendars/datasource/subassemblies/FilterCalendarsByAuthors.kt

@@ -0,0 +1,91 @@
+/*
+ * 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.ui.screen.loggedIn.calendars.datasource.subassemblies
+
+import com.vitorpamplona.amethyst.model.topNavFeeds.noteBased.author.AuthorsTopNavPerRelayFilterSet
+import com.vitorpamplona.amethyst.model.topNavFeeds.noteBased.muted.MutedAuthorsTopNavPerRelayFilterSet
+import com.vitorpamplona.amethyst.service.relays.SincePerRelayMap
+import com.vitorpamplona.quartz.nip01Core.core.HexKey
+import com.vitorpamplona.quartz.nip01Core.relay.client.pool.RelayBasedFilter
+import com.vitorpamplona.quartz.nip01Core.relay.filters.Filter
+import com.vitorpamplona.quartz.nip01Core.relay.normalizer.NormalizedRelayUrl
+
+fun filterCalendarsByAuthors(
+    relay: NormalizedRelayUrl,
+    authors: Set<HexKey>,
+    since: Long? = null,
+): List<RelayBasedFilter> {
+    val authorList = authors.sorted()
+    return listOf(
+        RelayBasedFilter(
+            relay = relay,
+            filter =
+                Filter(
+                    authors = authorList,
+                    kinds = AllCalendarKinds,
+                    limit = 500,
+                    since = since,
+                ),
+        ),
+    )
+}
+
+fun filterCalendarsByAuthors(
+    authorSet: AuthorsTopNavPerRelayFilterSet,
+    since: SincePerRelayMap?,
+    defaultSince: Long? = null,
+): List<RelayBasedFilter> {
+    if (authorSet.set.isEmpty()) return emptyList()
+
+    return authorSet.set
+        .mapNotNull {
+            if (it.value.authors.isEmpty()) {
+                null
+            } else {
+                filterCalendarsByAuthors(
+                    relay = it.key,
+                    authors = it.value.authors,
+                    since = since?.get(it.key)?.time ?: defaultSince,
+                )
+            }
+        }.flatten()
+}
+
+fun filterCalendarsByMutedAuthors(
+    authorSet: MutedAuthorsTopNavPerRelayFilterSet,
+    since: SincePerRelayMap?,
+    defaultSince: Long? = null,
+): List<RelayBasedFilter> {
+    if (authorSet.set.isEmpty()) return emptyList()
+
+    return authorSet.set
+        .mapNotNull {
+            if (it.value.authors.isEmpty()) {
+                null
+            } else {
+                filterCalendarsByAuthors(
+                    relay = it.key,
+                    authors = it.value.authors,
+                    since = since?.get(it.key)?.time ?: defaultSince,
+                )
+            }
+        }.flatten()
+}

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/calendars/datasource/subassemblies/FilterCalendarsByFollows.kt

@@ -0,0 +1,44 @@
+/*
+ * 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.ui.screen.loggedIn.calendars.datasource.subassemblies
+
+import com.vitorpamplona.amethyst.model.topNavFeeds.allFollows.AllFollowsTopNavPerRelayFilterSet
+import com.vitorpamplona.amethyst.service.relays.SincePerRelayMap
+import com.vitorpamplona.quartz.nip01Core.relay.client.pool.RelayBasedFilter
+
+fun filterCalendarsByFollows(
+    followsSet: AllFollowsTopNavPerRelayFilterSet,
+    since: SincePerRelayMap?,
+    defaultSince: Long? = null,
+): List<RelayBasedFilter> {
+    if (followsSet.set.isEmpty()) return emptyList()
+
+    return followsSet.set.flatMap {
+        val sinceForRelay = since?.get(it.key)?.time ?: defaultSince
+        val relay = it.key
+
+        listOfNotNull(
+            it.value.authors?.let { authors ->
+                filterCalendarsByAuthors(relay, authors, sinceForRelay)
+            },
+        ).flatten()
+    }
+}

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/calendars/datasource/subassemblies/FilterCalendarsByGeohashes.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.ui.screen.loggedIn.calendars.datasource.subassemblies
+
+import com.vitorpamplona.amethyst.model.topNavFeeds.aroundMe.LocationTopNavPerRelayFilterSet
+import com.vitorpamplona.amethyst.service.relays.SincePerRelayMap
+import com.vitorpamplona.quartz.nip01Core.relay.client.pool.RelayBasedFilter
+import com.vitorpamplona.quartz.nip01Core.relay.filters.Filter
+import com.vitorpamplona.quartz.nip01Core.relay.normalizer.NormalizedRelayUrl
+
+fun filterCalendarsByGeohashes(
+    relay: NormalizedRelayUrl,
+    geotags: Set<String>,
+    since: Long?,
+): List<RelayBasedFilter> {
+    if (geotags.isEmpty()) return emptyList()
+
+    return listOf(
+        RelayBasedFilter(
+            relay = relay,
+            filter =
+                Filter(
+                    kinds = CalendarAppointmentKinds,
+                    tags = mapOf("g" to geotags.sorted()),
+                    limit = 200,
+                    since = since,
+                ),
+        ),
+    )
+}
+
+fun filterCalendarsByGeohashes(
+    geoSet: LocationTopNavPerRelayFilterSet,
+    since: SincePerRelayMap?,
+    defaultSince: Long?,
+): List<RelayBasedFilter> {
+    if (geoSet.set.isEmpty()) return emptyList()
+
+    return geoSet.set
+        .mapNotNull {
+            if (it.value.geotags.isEmpty()) {
+                null
+            } else {
+                filterCalendarsByGeohashes(
+                    relay = it.key,
+                    geotags = it.value.geotags,
+                    since = since?.get(it.key)?.time ?: defaultSince,
+                )
+            }
+        }.flatten()
+}

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/calendars/datasource/subassemblies/FilterCalendarsByHashtag.kt

@@ -0,0 +1,66 @@
+/*
+ * 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.ui.screen.loggedIn.calendars.datasource.subassemblies
+
+import com.vitorpamplona.amethyst.model.topNavFeeds.hashtag.HashtagTopNavPerRelayFilterSet
+import com.vitorpamplona.amethyst.service.relays.SincePerRelayMap
+import com.vitorpamplona.quartz.nip01Core.relay.client.pool.RelayBasedFilter
+import com.vitorpamplona.quartz.nip01Core.relay.filters.Filter
+import com.vitorpamplona.quartz.nip01Core.relay.normalizer.NormalizedRelayUrl
+
+fun filterCalendarsByHashtag(
+    relay: NormalizedRelayUrl,
+    hashtags: Set<String>,
+    since: Long? = null,
+): List<RelayBasedFilter> =
+    listOf(
+        RelayBasedFilter(
+            relay = relay,
+            filter =
+                Filter(
+                    kinds = CalendarAppointmentKinds,
+                    tags = mapOf("t" to hashtags.toList()),
+                    limit = 200,
+                    since = since,
+                ),
+        ),
+    )
+
+fun filterCalendarsByHashtag(
+    hashtagSet: HashtagTopNavPerRelayFilterSet,
+    since: SincePerRelayMap?,
+    defaultSince: Long? = null,
+): List<RelayBasedFilter> {
+    if (hashtagSet.set.isEmpty()) return emptyList()
+
+    return hashtagSet.set
+        .mapNotNull { relayHashSet ->
+            if (relayHashSet.value.hashtags.isEmpty()) {
+                null
+            } else {
+                filterCalendarsByHashtag(
+                    relay = relayHashSet.key,
+                    hashtags = relayHashSet.value.hashtags,
+                    since = since?.get(relayHashSet.key)?.time ?: defaultSince,
+                )
+            }
+        }.flatten()
+}

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/calendars/datasource/subassemblies/FilterCalendarsGlobal.kt

@@ -0,0 +1,48 @@
+/*
+ * 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.ui.screen.loggedIn.calendars.datasource.subassemblies
+
+import com.vitorpamplona.amethyst.model.topNavFeeds.global.GlobalTopNavPerRelayFilterSet
+import com.vitorpamplona.amethyst.service.relays.SincePerRelayMap
+import com.vitorpamplona.quartz.nip01Core.relay.client.pool.RelayBasedFilter
+import com.vitorpamplona.quartz.nip01Core.relay.filters.Filter
+import com.vitorpamplona.quartz.utils.TimeUtils
+
+fun filterCalendarsGlobal(
+    relays: GlobalTopNavPerRelayFilterSet,
+    since: SincePerRelayMap?,
+    defaultSince: Long? = null,
+): List<RelayBasedFilter> {
+    if (relays.set.isEmpty()) return emptyList()
+
+    return relays.set.map {
+        val sinceForRelay = since?.get(it.key)?.time ?: defaultSince ?: TimeUtils.oneMonthAgo()
+        RelayBasedFilter(
+            relay = it.key,
+            filter =
+                Filter(
+                    kinds = AllCalendarKinds,
+                    limit = 500,
+                    since = sinceForRelay,
+                ),
+        )
+    }
+}