feat(napplet): relay subscription to discover napplet manifests

NappletsScreen previously showed only what was already cached. Adds a lightweight
discovery subscription so the list actually populates:

- NappletsFilterAssembler / NappletsFilterSubAssembler (SingleSubEoseManager):
  one REQ per read relay for kinds 15129/35129, deduped to a single subscription
  per account. No follow-list/feed-state machinery — the screen reads LocalCache
  directly, so the query state carries only the account + scope.
- Registered as an app-lifetime singleton in RelaySubscriptionsCoordinator (the
  EOSE manager opens its relay sub at construction, so it can't be per-screen).
- NappletsScreen invokes NappletsFilterAssemblerSubscription, which subscribes
  on STARTED and tears down after the lifecycle grace window.

:amethyst:compileFdroidDebugKotlin passes; spotless clean.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016ncMHuBBVHEf7spAoSssde

amethyst/plans/2026-06-19-napplet-sandbox-host.md

@@ -225,9 +225,9 @@ Deferred to v2; v1 nails the single-applet boundary first.
 - ✅ **Privacy:** the host routes blob fetches through the user's Tor SOCKS proxy
   when active; the port is passed in by the launcher (main process) so the sandbox
   process never touches the account-bound HTTP stack.
-- **Relay discovery:** `NappletsScreen` reads only what's already in `LocalCache` —
-  no dedicated subscription fetches napplet manifests yet, so the list is empty
-  until one arrives via another feed. A `NappletsFilterAssemblerSubscription` is the
-  next step.
+- ✅ **Relay discovery:** `NappletsFilterAssembler` (registered in
+  `RelaySubscriptionsCoordinator`, invoked by `NappletsScreen`) REQs kinds
+  15129/35129 from the user's read relays while the screen is open, so manifests
+  flow into `LocalCache` for the list to render.
 - **Consent UX:** reuse `commons/.../ui/signing` styling; show the manifest title
   and a per-capability rationale; batch-grant on first run.

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

@@ -53,6 +53,7 @@ import com.vitorpamplona.amethyst.ui.screen.loggedIn.livestreams.datasource.Live
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.longs.datasource.LongsFilterAssembler
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.music.datasource.MusicPlaylistsFilterAssembler
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.music.datasource.MusicTracksFilterAssembler
+import com.vitorpamplona.amethyst.ui.screen.loggedIn.napplets.datasource.NappletsFilterAssembler
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.nests.datasource.NestRoomFilterAssembler
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.nests.datasource.NestRoomLivenessAssembler
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.nests.datasource.NestsFilterAssembler
@@ -139,6 +140,7 @@ class RelaySubscriptionsCoordinator(
     val podcasts = PodcastsFilterAssembler(client)
     val onePodcast = OnePodcastFilterAssembler(client)
     val softwareApps = SoftwareAppsFilterAssembler(client)
+    val napplets = NappletsFilterAssembler(client)
     val badges = BadgesFilterAssembler(client)
     val profileBadges = ProfileBadgesFilterAssembler(client)
     val profileAppRecommendations = ProfileAppRecommendationsFilterAssembler(client)

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

@@ -49,6 +49,7 @@ import com.vitorpamplona.amethyst.napplet.NappletLauncher
 import com.vitorpamplona.amethyst.ui.navigation.navs.INav
 import com.vitorpamplona.amethyst.ui.navigation.topbars.TopBarWithBackButton
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.AccountViewModel
+import com.vitorpamplona.amethyst.ui.screen.loggedIn.napplets.datasource.NappletsFilterAssemblerSubscription
 import com.vitorpamplona.quartz.nip01Core.core.Event
 import com.vitorpamplona.quartz.nip01Core.relay.filters.Filter
 import com.vitorpamplona.quartz.nip5dNapplets.NamedNappletEvent
@@ -66,6 +67,10 @@ fun NappletsScreen(
     nav: INav,
 ) {
     val context = LocalContext.current
+
+    // Pull napplet manifests from the user's relays into LocalCache while this screen is open.
+    NappletsFilterAssemblerSubscription(accountViewModel)
+
     val napplets by remember {
         Amethyst.instance.cache.observeEvents<Event>(
             Filter(kinds = listOf(RootNappletEvent.KIND, NamedNappletEvent.KIND)),

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/napplets/datasource/NappletsFilterAssembler.kt

@@ -0,0 +1,60 @@
+/*
+ * 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.napplets.datasource
+
+import androidx.compose.runtime.Stable
+import com.vitorpamplona.amethyst.commons.relayClient.composeSubscriptionManagers.ComposeSubscriptionManager
+import com.vitorpamplona.amethyst.model.Account
+import com.vitorpamplona.quartz.nip01Core.relay.client.INostrClient
+import kotlinx.coroutines.CoroutineScope
+
+/**
+ * Keyspace for the napplet-discovery subscription. Unlike a feed datasource it carries no
+ * `FeedContentState` — [com.vitorpamplona.amethyst.ui.screen.loggedIn.napplets.NappletsScreen]
+ * reads the manifests straight out of `LocalCache`, so this only needs the account (for relay
+ * selection) and a scope.
+ */
+class NappletsQueryState(
+    val account: Account,
+    val scope: CoroutineScope,
+)
+
+/**
+ * Subscribes to NIP-5D napplet manifests (kinds 15129/35129) on the user's read relays while a
+ * napplet screen is open, dumping them into `LocalCache` for the screen to observe. Registered as
+ * an app-lifetime singleton in `RelaySubscriptionsCoordinator` (the underlying EOSE manager opens
+ * its relay subscription at construction, so it must not be created per screen).
+ */
+@Stable
+class NappletsFilterAssembler(
+    client: INostrClient,
+) : ComposeSubscriptionManager<NappletsQueryState>() {
+    val group =
+        listOf(
+            NappletsFilterSubAssembler(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/napplets/datasource/NappletsFilterAssemblerSubscription.kt

@@ -0,0 +1,37 @@
+/*
+ * 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.napplets.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 NappletsFilterAssemblerSubscription(accountViewModel: AccountViewModel) {
+    val state =
+        remember(accountViewModel.account) {
+            NappletsQueryState(accountViewModel.account, accountViewModel.viewModelScope)
+        }
+
+    LifecycleAwareKeyDataSourceSubscription(state, accountViewModel.dataSources().napplets)
+}

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/napplets/datasource/NappletsFilterSubAssembler.kt

@@ -0,0 +1,64 @@
+/*
+ * 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.napplets.datasource
+
+import com.vitorpamplona.amethyst.commons.relayClient.eoseManagers.SingleSubEoseManager
+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.filters.Filter
+import com.vitorpamplona.quartz.nip5dNapplets.NamedNappletEvent
+import com.vitorpamplona.quartz.nip5dNapplets.RootNappletEvent
+
+private const val NAPPLET_PAGE_LIMIT = 200
+
+/**
+ * Emits one REQ per read relay for both napplet manifest kinds. A single subscription per account
+ * (deduped by [distinct]) is enough — the screen wants "what napplets exist", not a per-author
+ * feed — so this stays far lighter than the follow-list feed assemblers.
+ */
+class NappletsFilterSubAssembler(
+    client: INostrClient,
+    allKeys: () -> Set<NappletsQueryState>,
+) : SingleSubEoseManager<NappletsQueryState>(client, allKeys) {
+    override fun updateFilter(
+        keys: List<NappletsQueryState>,
+        since: SincePerRelayMap?,
+    ): List<RelayBasedFilter> {
+        if (keys.isEmpty()) return emptyList()
+
+        return keys.flatMap { key ->
+            key.account.homeRelays.flow.value.map { relay ->
+                RelayBasedFilter(
+                    relay = relay,
+                    filter =
+                        Filter(
+                            kinds = listOf(RootNappletEvent.KIND, NamedNappletEvent.KIND),
+                            limit = NAPPLET_PAGE_LIMIT,
+                            since = since?.get(relay)?.time,
+                        ),
+                )
+            }
+        }
+    }
+
+    override fun distinct(key: NappletsQueryState) = key.account.signer.pubKey
+}