refactor(commons): move the marmot encrypted stores and the NIP-11 / online caches

Two clusters from the survey of what was left in amethyst/, both cases of code
that was shared-layer already and just happened to live in the app.

The four Marmot stores go to commons/jvmAndroid/marmot, next to the
EncryptedAppendLog they were already built on. Nothing in them was Android
despite the prefix: no android.* import, no Context, just
(rootDir: File, encryption: SecretEncryption) and the quartz interfaces. One
call site, AccountCacheState. The KDoc lines claiming "Android implementation"
and "AES/GCM via Android KeyStore" are reworded: SecretEncryption is
expect/actual, AndroidKeyStore on Android and a key file on desktop, so the old
wording is now only half true. Commons already referred to two of them by name
in its own KDoc; those references are updated.

They are Encrypted* rather than File*, and that is not cosmetic. cli/stores
already declares FileMlsGroupStateStore, FileMarmotMessageStore,
FileKeyPackageBundleStore and FilePublishObligationStore — deliberately
UNENCRYPTED test-harness stores, in a module that depends on commons. Two
same-named classes with opposite encryption semantics, one import away from each
other, is how MLS state ends up written in plaintext. Encrypted* is also what
these actually are, and reads correctly next to EncryptedAppendLog.

Nip11CachedRetriever + Nip11Retriever + RetrieveResult go to
commons/relays/nip11, and OnlineChecker to commons/service. RetrieveResult had
to travel: the cache is typed on it and commons cannot import from amethyst.
Nip11RetrieverTest travels too — it sat in the same package and used the class
with no import line. LoadRelayInfo and RelaySupportsNip stay behind; both reach
Amethyst.instance.

android.util.LruCache -> androidx.collection.LruCache is not the pure import
swap it looks like, and the compiler said so: androidx bounds V to Any, while
android.util.LruCache is a Java platform type that accepted
LruCache<NormalizedRelayUrl, RetrieveResult?>. Checked all four put() sites
first — every one stores a concrete RetrieveResult, so the nullable argument
never meant anything and get() still returns null on a miss, which is what the
readers already branch on. Dropping it is behaviour-preserving.

NotifyCoordinator does NOT move despite being grouped with the other two:
android.util.LruCache really is its only platform import, but it takes
accountForPubkey: (HexKey) -> Account?, and Account lives in amethyst/model. It
needs that abstraction, not an import swap.

17 new tests. OnlineChecker's predicates decide whether the UI shows a player or
an offline placeholder, so the five-minute TTL is pinned in both directions — a
stale online entry must stop reading online, and a stale offline one must stop
suppressing retries — along with resetIfOfflineToRetry dropping only failures,
since evicting good entries would refetch every URL that already worked. Its
suspend probe is left alone: it needs a real OkHttp round trip and commons has
no MockWebServer, so there is no honest way to drive it. Same reason
Nip11CachedRetriever gets nothing new here; its fetch and error-caching paths
are all network.

The Marmot tests cover what restart depends on: group state, sender ratchet and
message log surviving a new store over the same directory, deletes removing both
the state and the listing, and two account directories not seeing each other.
Writing them found validation I had not noticed reading the code — group ids
must be hex, which is a path-traversal guard — after a first pass using readable
labels failed every test on it. That guard is pinned now too: "../escape" and
friends are rejected rather than resolved to a path.

Verified: :commons:jvmTest (2549, 0 failures), :amethyst:testPlayDebugUnitTest,
:cli:compileKotlin, :commons:verifyKmpPurity,
:commons:compileCommonMainKotlinMetadata, :amethyst:compilePlayDebugKotlin.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AXvKXakvup4inNFfAhhr4L

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

@@ -55,6 +55,7 @@ import com.vitorpamplona.amethyst.commons.relayClient.event.EventFinderQueryStat
 import com.vitorpamplona.amethyst.commons.relayClient.speedLogger.RelaySpeedLogger
 import com.vitorpamplona.amethyst.commons.relayClient.user.UserFinderQueryState
 import com.vitorpamplona.amethyst.commons.relays.health.TorCircuitHealthTracker
+import com.vitorpamplona.amethyst.commons.relays.nip11.Nip11CachedRetriever
 import com.vitorpamplona.amethyst.commons.richtext.CachedAsciiDocToMarkdown
 import com.vitorpamplona.amethyst.commons.richtext.CachedRichTextParser
 import com.vitorpamplona.amethyst.commons.robohash.CachedRobohash
@@ -75,7 +76,6 @@ import com.vitorpamplona.amethyst.commons.state.UiSettingsState
 import com.vitorpamplona.amethyst.commons.tor.TorSettings
 import com.vitorpamplona.amethyst.model.Account
 import com.vitorpamplona.amethyst.model.accountsCache.AccountCacheState
-import com.vitorpamplona.amethyst.model.nip11RelayInfo.Nip11CachedRetriever
 import com.vitorpamplona.amethyst.model.nip60Cashu.CashuPreferences
 import com.vitorpamplona.amethyst.model.preferences.UiSharedPreferences
 import com.vitorpamplona.amethyst.model.privacyOptions.RoleBasedHttpClientBuilder

amethyst/src/main/java/com/vitorpamplona/amethyst/model/accountsCache/AccountCacheState.kt

@@ -26,6 +26,10 @@ import com.vitorpamplona.amethyst.commons.connectedApps.nip46.InMemoryNip46Clien
 import com.vitorpamplona.amethyst.commons.connectedApps.nip46.Nip46ClientStore
 import com.vitorpamplona.amethyst.commons.connectedApps.signers.InMemoryNostrSignerPermissionStore
 import com.vitorpamplona.amethyst.commons.connectedApps.signers.NostrSignerPermissionStore
+import com.vitorpamplona.amethyst.commons.marmot.EncryptedKeyPackageBundleStore
+import com.vitorpamplona.amethyst.commons.marmot.EncryptedMarmotMessageStore
+import com.vitorpamplona.amethyst.commons.marmot.EncryptedMlsGroupStateStore
+import com.vitorpamplona.amethyst.commons.marmot.EncryptedPublishObligationStore
 import com.vitorpamplona.amethyst.commons.marmot.InMemoryMlsGroupStateStore
 import com.vitorpamplona.amethyst.commons.model.cache.LocalCache
 import com.vitorpamplona.amethyst.commons.model.marmot.AndroidIngestDedupStore
@@ -36,10 +40,6 @@ import com.vitorpamplona.amethyst.commons.relayauth.DataStoreRelayAuthPermission
 import com.vitorpamplona.amethyst.commons.service.pow.PoWPublishQueue
 import com.vitorpamplona.amethyst.model.Account
 import com.vitorpamplona.amethyst.model.AccountSettings
-import com.vitorpamplona.amethyst.model.marmot.AndroidKeyPackageBundleStore
-import com.vitorpamplona.amethyst.model.marmot.AndroidMarmotMessageStore
-import com.vitorpamplona.amethyst.model.marmot.AndroidMlsGroupStateStore
-import com.vitorpamplona.amethyst.model.marmot.AndroidPublishObligationStore
 import com.vitorpamplona.amethyst.service.location.LocationState
 import com.vitorpamplona.quartz.nip01Core.core.HexKey
 import com.vitorpamplona.quartz.nip01Core.core.toHexKey
@@ -250,13 +250,13 @@ class AccountCacheState(
         val mlsStore =
             try {
                 Log.d("AccountCacheState") {
-                    "Initializing AndroidMlsGroupStateStore for ${signer.pubKey.take(8)}… at ${accountDir.absolutePath}"
+                    "Initializing EncryptedMlsGroupStateStore for ${signer.pubKey.take(8)}… at ${accountDir.absolutePath}"
                 }
-                AndroidMlsGroupStateStore(accountDir)
+                EncryptedMlsGroupStateStore(accountDir)
             } catch (e: Exception) {
                 Log.e(
                     "AccountCacheState",
-                    "Failed to initialize AndroidMlsGroupStateStore, falling back to in-memory store (Marmot groups will NOT persist across restarts)",
+                    "Failed to initialize EncryptedMlsGroupStateStore, falling back to in-memory store (Marmot groups will NOT persist across restarts)",
                     e,
                 )
                 InMemoryMlsGroupStateStore()
@@ -267,11 +267,11 @@ class AccountCacheState(
 
         val marmotMessageStore =
             try {
-                AndroidMarmotMessageStore(accountDir)
+                EncryptedMarmotMessageStore(accountDir)
             } catch (e: Exception) {
                 Log.e(
                     "AccountCacheState",
-                    "Failed to initialize AndroidMarmotMessageStore (Marmot messages will NOT persist across restarts)",
+                    "Failed to initialize EncryptedMarmotMessageStore (Marmot messages will NOT persist across restarts)",
                     e,
                 )
                 null
@@ -279,11 +279,11 @@ class AccountCacheState(
 
         val marmotKeyPackageStore =
             try {
-                AndroidKeyPackageBundleStore(accountDir)
+                EncryptedKeyPackageBundleStore(accountDir)
             } catch (e: Exception) {
                 Log.e(
                     "AccountCacheState",
-                    "Failed to initialize AndroidKeyPackageBundleStore (Marmot KeyPackages will NOT persist across restarts)",
+                    "Failed to initialize EncryptedKeyPackageBundleStore (Marmot KeyPackages will NOT persist across restarts)",
                     e,
                 )
                 null
@@ -291,11 +291,11 @@ class AccountCacheState(
 
         val marmotPublishObligationStore =
             try {
-                AndroidPublishObligationStore(accountDir)
+                EncryptedPublishObligationStore(accountDir)
             } catch (e: Exception) {
                 Log.e(
                     "AccountCacheState",
-                    "Failed to initialize AndroidPublishObligationStore " +
+                    "Failed to initialize EncryptedPublishObligationStore " +
                         "(a Marmot commit interrupted mid-publish will NOT be retried after a restart)",
                     e,
                 )

amethyst/src/main/java/com/vitorpamplona/amethyst/model/nip11RelayInfo/LoadRelayInfo.kt

@@ -25,6 +25,7 @@ import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.State
 import androidx.compose.runtime.produceState
 import com.vitorpamplona.amethyst.Amethyst
+import com.vitorpamplona.amethyst.commons.relays.nip11.Nip11CachedRetriever
 import com.vitorpamplona.quartz.nip01Core.relay.normalizer.NormalizedRelayUrl
 import com.vitorpamplona.quartz.nip11RelayInfo.Nip11RelayInformation
 import com.vitorpamplona.quartz.utils.Log

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

@@ -96,6 +96,7 @@ import com.vitorpamplona.amethyst.commons.resources.unauthorized_exception
 import com.vitorpamplona.amethyst.commons.resources.unauthorized_exception_description
 import com.vitorpamplona.amethyst.commons.resources.user_x_does_not_have_a_lightning_address_setup_to_receive_sats
 import com.vitorpamplona.amethyst.commons.resources.video_saved_to_the_gallery
+import com.vitorpamplona.amethyst.commons.service.OnlineChecker
 import com.vitorpamplona.amethyst.commons.service.broadcast.BroadcastTracker
 import com.vitorpamplona.amethyst.commons.service.http.EmptyRoleBasedHttpClientBuilder
 import com.vitorpamplona.amethyst.commons.service.http.IRoleBasedHttpClientBuilder
@@ -116,7 +117,6 @@ import com.vitorpamplona.amethyst.model.LatestKeyPackageOwner
 import com.vitorpamplona.amethyst.model.UrlCachedPreviewer
 import com.vitorpamplona.amethyst.model.privacyOptions.RoleBasedHttpClientBuilder
 import com.vitorpamplona.amethyst.service.ClinkDebitPayer
-import com.vitorpamplona.amethyst.service.OnlineChecker
 import com.vitorpamplona.amethyst.service.V4VPaymentHandler
 import com.vitorpamplona.amethyst.service.ZapPaymentHandler
 import com.vitorpamplona.amethyst.service.cashu.melt.MeltProcessor

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/chats/publicChannels/nip53LiveActivities/LiveActivityChannelScreen.kt

@@ -27,8 +27,8 @@ import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.remember
 import androidx.compose.ui.Modifier
 import com.vitorpamplona.amethyst.commons.model.cache.LocalCache
+import com.vitorpamplona.amethyst.commons.service.OnlineChecker
 import com.vitorpamplona.amethyst.commons.ui.navigation.navs.INav
-import com.vitorpamplona.amethyst.service.OnlineChecker
 import com.vitorpamplona.amethyst.ui.layouts.DisappearingScaffold
 import com.vitorpamplona.amethyst.ui.note.LoadLiveActivityChannel
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.AccountViewModel

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/discover/nip53LiveActivities/DiscoverLiveFeedFilter.kt

@@ -32,8 +32,8 @@ import com.vitorpamplona.amethyst.commons.model.topNavFeeds.noteBased.author.Aut
 import com.vitorpamplona.amethyst.commons.model.topNavFeeds.noteBased.community.SingleCommunityTopNavFilter
 import com.vitorpamplona.amethyst.commons.model.topNavFeeds.noteBased.muted.MutedAuthorsByOutboxTopNavFilter
 import com.vitorpamplona.amethyst.commons.model.topNavFeeds.noteBased.muted.MutedAuthorsByProxyTopNavFilter
+import com.vitorpamplona.amethyst.commons.service.OnlineChecker
 import com.vitorpamplona.amethyst.model.Account
-import com.vitorpamplona.amethyst.service.OnlineChecker
 import com.vitorpamplona.amethyst.ui.dal.FilterByListParams
 import com.vitorpamplona.quartz.nip53LiveActivities.meetingSpaces.MeetingRoomEvent
 import com.vitorpamplona.quartz.nip53LiveActivities.meetingSpaces.MeetingSpaceEvent

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

@@ -74,6 +74,7 @@ import com.vitorpamplona.amethyst.commons.resources.feed_is_empty
 import com.vitorpamplona.amethyst.commons.resources.home_tab_everything
 import com.vitorpamplona.amethyst.commons.resources.new_threads
 import com.vitorpamplona.amethyst.commons.resources.refresh
+import com.vitorpamplona.amethyst.commons.service.OnlineChecker
 import com.vitorpamplona.amethyst.commons.ui.components.CrossfadeIfEnabled
 import com.vitorpamplona.amethyst.commons.ui.feeds.FeedError
 import com.vitorpamplona.amethyst.commons.ui.feeds.LoadingFeed
@@ -94,7 +95,6 @@ import com.vitorpamplona.amethyst.commons.ui.theme.Size5dp
 import com.vitorpamplona.amethyst.commons.ui.theme.StdVertSpacer
 import com.vitorpamplona.amethyst.commons.ui.theme.TabRowHeight
 import com.vitorpamplona.amethyst.commons.ui.theme.ThemeComparisonRow
-import com.vitorpamplona.amethyst.service.OnlineChecker
 import com.vitorpamplona.amethyst.service.location.LocationState
 import com.vitorpamplona.amethyst.ui.feeds.ChannelFeedContentState
 import com.vitorpamplona.amethyst.ui.feeds.ChannelFeedState

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/home/live/LiveStatusIndicator.kt

@@ -32,7 +32,7 @@ import com.vitorpamplona.amethyst.commons.model.Channel
 import com.vitorpamplona.amethyst.commons.model.cache.LocalCache
 import com.vitorpamplona.amethyst.commons.model.emphChat.EphemeralChatChannel
 import com.vitorpamplona.amethyst.commons.model.nip53LiveActivities.LiveActivitiesChannel
-import com.vitorpamplona.amethyst.service.OnlineChecker
+import com.vitorpamplona.amethyst.commons.service.OnlineChecker
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.AccountViewModel
 import com.vitorpamplona.quartz.nip53LiveActivities.meetingSpaces.MeetingSpaceEvent
 import com.vitorpamplona.quartz.utils.Log

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/livestreams/dal/LiveStreamsFeedFilter.kt

@@ -32,8 +32,8 @@ import com.vitorpamplona.amethyst.commons.model.topNavFeeds.noteBased.author.Aut
 import com.vitorpamplona.amethyst.commons.model.topNavFeeds.noteBased.community.SingleCommunityTopNavFilter
 import com.vitorpamplona.amethyst.commons.model.topNavFeeds.noteBased.muted.MutedAuthorsByOutboxTopNavFilter
 import com.vitorpamplona.amethyst.commons.model.topNavFeeds.noteBased.muted.MutedAuthorsByProxyTopNavFilter
+import com.vitorpamplona.amethyst.commons.service.OnlineChecker
 import com.vitorpamplona.amethyst.model.Account
-import com.vitorpamplona.amethyst.service.OnlineChecker
 import com.vitorpamplona.amethyst.ui.dal.FilterByListParams
 import com.vitorpamplona.quartz.nip53LiveActivities.meetingSpaces.MeetingRoomEvent
 import com.vitorpamplona.quartz.nip53LiveActivities.meetingSpaces.MeetingSpaceEvent

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/relays/common/BasicRelaySetupInfoClickableRow.kt

@@ -41,6 +41,7 @@ import androidx.compose.ui.platform.LocalClipboard
 import androidx.compose.ui.unit.dp
 import com.vitorpamplona.amethyst.commons.icons.symbols.Icon
 import com.vitorpamplona.amethyst.commons.icons.symbols.MaterialSymbols
+import com.vitorpamplona.amethyst.commons.relays.nip11.Nip11CachedRetriever
 import com.vitorpamplona.amethyst.commons.relays.ui.RelayCountResult
 import com.vitorpamplona.amethyst.commons.relays.ui.RelayDragState
 import com.vitorpamplona.amethyst.commons.relays.ui.RelayEventCountRow
@@ -59,7 +60,6 @@ import com.vitorpamplona.amethyst.commons.ui.theme.Height25Modifier
 import com.vitorpamplona.amethyst.commons.ui.theme.LargeRelayIconModifier
 import com.vitorpamplona.amethyst.commons.ui.theme.ReactionRowHeightChatMaxWidth
 import com.vitorpamplona.amethyst.commons.ui.theme.Size25dp
-import com.vitorpamplona.amethyst.model.nip11RelayInfo.Nip11CachedRetriever
 import com.vitorpamplona.amethyst.model.nip11RelayInfo.loadRelayInfo
 import com.vitorpamplona.amethyst.ui.note.RenderRelayIcon
 import com.vitorpamplona.amethyst.ui.note.UserPicture

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/relays/common/BasicRelaySetupInfoDialog.kt

@@ -23,11 +23,11 @@ package com.vitorpamplona.amethyst.ui.screen.loggedIn.relays.common
 import androidx.compose.runtime.Composable
 import androidx.compose.ui.Modifier
 import com.vitorpamplona.amethyst.commons.model.navigation.Route
+import com.vitorpamplona.amethyst.commons.relays.nip11.Nip11CachedRetriever
 import com.vitorpamplona.amethyst.commons.relays.ui.RelayCountResult
 import com.vitorpamplona.amethyst.commons.relays.ui.RelayDragState
 import com.vitorpamplona.amethyst.commons.ui.navigation.navs.INav
 import com.vitorpamplona.amethyst.commons.ui.screen.LocalDisplaySettings
-import com.vitorpamplona.amethyst.model.nip11RelayInfo.Nip11CachedRetriever
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.AccountViewModel
 
 @Composable

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/relays/common/RelayUrlEditField.kt

@@ -45,6 +45,7 @@ import androidx.compose.ui.text.input.KeyboardType
 import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.dp
 import com.vitorpamplona.amethyst.Amethyst
+import com.vitorpamplona.amethyst.commons.relays.nip11.Nip11CachedRetriever
 import com.vitorpamplona.amethyst.commons.resources.Res
 import com.vitorpamplona.amethyst.commons.resources.add
 import com.vitorpamplona.amethyst.commons.resources.add_a_relay
@@ -58,7 +59,6 @@ import com.vitorpamplona.amethyst.commons.ui.theme.PopupUpEffect
 import com.vitorpamplona.amethyst.commons.ui.theme.StdEndPadding
 import com.vitorpamplona.amethyst.commons.ui.theme.ThemeComparisonColumn
 import com.vitorpamplona.amethyst.commons.ui.theme.placeholderText
-import com.vitorpamplona.amethyst.model.nip11RelayInfo.Nip11CachedRetriever
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.AccountViewModel
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.mockAccountViewModel
 import com.vitorpamplona.quartz.nip01Core.relay.client.stats.RelayStat

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/relays/common/ShowRelaySuggestionList.kt

@@ -26,11 +26,11 @@ import androidx.compose.runtime.Composable
 import androidx.compose.runtime.getValue
 import androidx.compose.ui.Modifier
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
+import com.vitorpamplona.amethyst.commons.relays.nip11.Nip11CachedRetriever
 import com.vitorpamplona.amethyst.commons.ui.navigation.navs.INav
 import com.vitorpamplona.amethyst.commons.ui.screen.LocalDisplaySettings
 import com.vitorpamplona.amethyst.commons.ui.theme.DividerThickness
 import com.vitorpamplona.amethyst.commons.ui.theme.HalfVertPadding
-import com.vitorpamplona.amethyst.model.nip11RelayInfo.Nip11CachedRetriever
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.AccountViewModel
 import com.vitorpamplona.quartz.nip01Core.relay.normalizer.NormalizedRelayUrl
 

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/relays/vanish/RequestToVanishScreen.kt

@@ -68,6 +68,7 @@ import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import com.vitorpamplona.amethyst.Amethyst
 import com.vitorpamplona.amethyst.commons.icons.symbols.Icon
 import com.vitorpamplona.amethyst.commons.icons.symbols.MaterialSymbols
+import com.vitorpamplona.amethyst.commons.relays.nip11.Nip11CachedRetriever
 import com.vitorpamplona.amethyst.commons.resources.Res
 import com.vitorpamplona.amethyst.commons.resources.cancel
 import com.vitorpamplona.amethyst.commons.resources.confirm
@@ -96,7 +97,6 @@ import com.vitorpamplona.amethyst.commons.ui.stringRes
 import com.vitorpamplona.amethyst.commons.ui.theme.DividerThickness
 import com.vitorpamplona.amethyst.commons.ui.theme.HorzHalfVertPadding
 import com.vitorpamplona.amethyst.commons.ui.theme.ThemeComparisonColumn
-import com.vitorpamplona.amethyst.model.nip11RelayInfo.Nip11CachedRetriever
 import com.vitorpamplona.amethyst.ui.note.formatMediumDateTime
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.AccountViewModel
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.mockAccountViewModel

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/marmot/InMemoryMlsGroupStateStore.kt

@@ -26,7 +26,7 @@ import com.vitorpamplona.quartz.utils.concurrent.ConcurrentMap
 /**
  * In-memory fallback implementation of [MlsGroupStateStore].
  *
- * Used only when [AndroidMlsGroupStateStore] cannot be initialized (e.g., when the
+ * Used only when [EncryptedMlsGroupStateStore] cannot be initialized (e.g., when the
  * Android KeyStore is unavailable). State is lost on app restart, but this lets
  * Marmot group operations at least work within a single session instead of failing
  * with "Marmot not initialized".

commons/src/jvmAndroid/kotlin/com/vitorpamplona/amethyst/commons/marmot/EncryptedAppendLog.kt

@@ -58,7 +58,7 @@ import java.io.RandomAccessFile
  *
  * **Not thread-safe.** Entries are cached in memory so an append never has to
  * read the log back, and that cache assumes one owner. Callers hold their own
- * lock around every method (see `AndroidMarmotMessageStore`), and one instance
+ * lock around every method (see `EncryptedMarmotMessageStore`), and one instance
  * must own any given file.
  *
  * @param encrypt must produce a self-describing blob — it carries its own IV /

commons/src/jvmAndroid/kotlin/com/vitorpamplona/amethyst/commons/marmot/EncryptedKeyPackageBundleStore.kt

@@ -18,7 +18,7 @@
  * 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.marmot
+package com.vitorpamplona.amethyst.commons.marmot
 
 import com.vitorpamplona.amethyst.commons.model.preferences.SecretEncryption
 import com.vitorpamplona.quartz.marmot.mip00KeyPackages.KeyPackageBundleStore
@@ -30,7 +30,7 @@ import kotlinx.coroutines.withContext
 import java.io.File
 
 /**
- * Android implementation of [KeyPackageBundleStore] using file-based encrypted storage.
+ * File-backed [KeyPackageBundleStore], encrypted at rest.
  *
  * Storage layout:
  * ```
@@ -40,10 +40,10 @@ import java.io.File
  * The blob contains private key material — init keys, encryption keys,
  * signature keys — that the MLS engine needs to process Welcome events
  * received days or weeks after the corresponding KeyPackage was published.
- * It is encrypted at rest with [SecretEncryption] (AES/GCM via Android
+ * It is encrypted at rest with [SecretEncryption] (AES-256-GCM, keyed by the platform's
- * KeyStore), the same primitive used by [AndroidMlsGroupStateStore].
+ * keystore), the same primitive used by [EncryptedMlsGroupStateStore].
  */
-class AndroidKeyPackageBundleStore(
+class EncryptedKeyPackageBundleStore(
     private val rootDir: File,
     private val encryption: SecretEncryption = SecretEncryption(),
 ) : KeyPackageBundleStore {
@@ -51,7 +51,7 @@ class AndroidKeyPackageBundleStore(
 
     init {
         Log.d(TAG) {
-            "Initialized AndroidKeyPackageBundleStore: rootDir=${rootDir.absolutePath}"
+            "Initialized EncryptedKeyPackageBundleStore: rootDir=${rootDir.absolutePath}"
         }
     }
 
@@ -121,6 +121,6 @@ class AndroidKeyPackageBundleStore(
     }
 
     companion object {
-        private const val TAG = "AndroidKeyPackageBundleStore"
+        private const val TAG = "EncryptedKeyPackageBundleStore"
     }
 }

commons/src/jvmAndroid/kotlin/com/vitorpamplona/amethyst/commons/marmot/EncryptedMarmotMessageStore.kt

@@ -18,7 +18,7 @@
  * 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.marmot
+package com.vitorpamplona.amethyst.commons.marmot
 
 import com.vitorpamplona.amethyst.commons.marmot.EncryptedAppendLog
 import com.vitorpamplona.amethyst.commons.model.preferences.SecretEncryption
@@ -32,9 +32,9 @@ import kotlinx.coroutines.withContext
 import java.io.File
 
 /**
- * Android implementation of [MarmotMessageStore] using file-based encrypted storage.
+ * File-backed [MarmotMessageStore], encrypted at rest.
  *
- * Stored alongside the [AndroidMlsGroupStateStore] data:
+ * Stored alongside the [EncryptedMlsGroupStateStore] data:
  * ```
  * <rootDir>/mls_groups/<nostrGroupId>/messages    — encrypted message log
  * ```
@@ -44,7 +44,7 @@ import java.io.File
  * small encrypted segment instead of rewriting the conversation, which is what
  * keeps the cost of a send flat as the history grows.
  */
-class AndroidMarmotMessageStore(
+class EncryptedMarmotMessageStore(
     private val rootDir: File,
     private val encryption: SecretEncryption = SecretEncryption(),
 ) : MarmotMessageStore {
@@ -52,7 +52,7 @@ class AndroidMarmotMessageStore(
 
     init {
         Log.d(TAG) {
-            "Initialized AndroidMarmotMessageStore: rootDir=${rootDir.absolutePath}"
+            "Initialized EncryptedMarmotMessageStore: rootDir=${rootDir.absolutePath}"
         }
     }
 
@@ -353,7 +353,7 @@ class AndroidMarmotMessageStore(
     ) = log.rewrite(file, messages)
 
     companion object {
-        private const val TAG = "AndroidMarmotMessageStore"
+        private const val TAG = "EncryptedMarmotMessageStore"
         private val HEX_PATTERN = Regex("^[0-9a-fA-F]+$")
     }
 }

commons/src/jvmAndroid/kotlin/com/vitorpamplona/amethyst/commons/marmot/EncryptedMlsGroupStateStore.kt

@@ -18,7 +18,7 @@
  * 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.marmot
+package com.vitorpamplona.amethyst.commons.marmot
 
 import com.vitorpamplona.amethyst.commons.model.preferences.SecretEncryption
 import com.vitorpamplona.quartz.marmot.mls.group.MlsGroupStateStore
@@ -29,10 +29,10 @@ import java.io.File
 import java.io.FileOutputStream
 
 /**
- * Android implementation of [MlsGroupStateStore] using file-based encrypted storage.
+ * File-backed [MlsGroupStateStore], encrypted at rest.
  *
  * All MLS group state (containing private keys and epoch secrets) is encrypted
- * at rest using [SecretEncryption] (AES/GCM backed by Android KeyStore).
+ * at rest using [SecretEncryption] (AES-256-GCM, keyed by the platform's keystore).
  *
  * Storage layout:
  * ```
@@ -41,13 +41,13 @@ import java.io.FileOutputStream
  * <rootDir>/mls_groups/<nostrGroupId>/ratchet   — encrypted OwnSenderRatchet
  * ```
  */
-class AndroidMlsGroupStateStore(
+class EncryptedMlsGroupStateStore(
     private val rootDir: File,
     private val encryption: SecretEncryption = SecretEncryption(),
 ) : MlsGroupStateStore {
     init {
         Log.d(TAG) {
-            "Initialized AndroidMlsGroupStateStore: rootDir=${rootDir.absolutePath}, " +
+            "Initialized EncryptedMlsGroupStateStore: rootDir=${rootDir.absolutePath}, " +
                 "mls_groups exists=${File(rootDir, "mls_groups").exists()}"
         }
     }
@@ -61,7 +61,7 @@ class AndroidMlsGroupStateStore(
     }
 
     companion object {
-        private const val TAG = "AndroidMlsGroupStateStore"
+        private const val TAG = "EncryptedMlsGroupStateStore"
         private val HEX_PATTERN = Regex("^[0-9a-fA-F]+$")
     }
 
@@ -274,7 +274,7 @@ class AndroidMlsGroupStateStore(
             // Fallback: if rename fails (e.g., cross-filesystem), copy and delete
             tempFile.copyTo(target, overwrite = true)
             if (!tempFile.delete()) {
-                Log.w("AndroidMlsGroupStateStore") { "Failed to delete temp file after copy fallback: ${tempFile.absolutePath}" }
+                Log.w("EncryptedMlsGroupStateStore") { "Failed to delete temp file after copy fallback: ${tempFile.absolutePath}" }
             }
         }
     }

commons/src/jvmAndroid/kotlin/com/vitorpamplona/amethyst/commons/marmot/EncryptedPublishObligationStore.kt

@@ -18,7 +18,7 @@
  * 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.marmot
+package com.vitorpamplona.amethyst.commons.marmot
 
 import com.vitorpamplona.amethyst.commons.model.preferences.SecretEncryption
 import com.vitorpamplona.quartz.marmot.protocolCore.MarmotPublishObligationStore
@@ -31,7 +31,7 @@ import kotlinx.coroutines.withContext
 import java.io.File
 
 /**
- * Android implementation of [MarmotPublishObligationStore], encrypted at rest
+ * File-backed [MarmotPublishObligationStore], encrypted at rest
  * with [SecretEncryption] like the group-state and KeyPackage stores.
  *
  * ```
@@ -49,7 +49,7 @@ import java.io.File
  * concurrently and resolve out of order, so removing one record must not
  * rewrite another's.
  */
-class AndroidPublishObligationStore(
+class EncryptedPublishObligationStore(
     private val rootDir: File,
     private val encryption: SecretEncryption = SecretEncryption(),
 ) : MarmotPublishObligationStore {
@@ -184,6 +184,6 @@ class AndroidPublishObligationStore(
         }
 
     companion object {
-        private const val TAG = "AndroidPublishObligationStore"
+        private const val TAG = "EncryptedPublishObligationStore"
     }
 }

commons/src/jvmAndroid/kotlin/com/vitorpamplona/amethyst/commons/relays/nip11/Nip11CachedRetriever.kt

@@ -18,9 +18,9 @@
  * 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.nip11RelayInfo
+package com.vitorpamplona.amethyst.commons.relays.nip11
 
-import android.util.LruCache
+import androidx.collection.LruCache
 import androidx.compose.runtime.Stable
 import com.vitorpamplona.quartz.nip01Core.relay.normalizer.NormalizedRelayUrl
 import com.vitorpamplona.quartz.nip01Core.relay.normalizer.displayUrl
@@ -33,7 +33,12 @@ class Nip11CachedRetriever(
     val okHttpClient: (NormalizedRelayUrl) -> OkHttpClient,
 ) {
     private val relayInformationEmptyCache = LruCache<NormalizedRelayUrl, Nip11RelayInformation>(1000)
-    private val relayInformationDocumentCache = LruCache<NormalizedRelayUrl, RetrieveResult?>(1000)
+
+    // Value type is non-null: androidx.collection.LruCache bounds V to Any, and every put here
+    // stores a concrete RetrieveResult. The old android.util.LruCache was a Java platform type, so
+    // the nullable argument compiled but never meant anything — get() returns null on a miss either
+    // way, which is what the readers below already branch on.
+    private val relayInformationDocumentCache = LruCache<NormalizedRelayUrl, RetrieveResult>(1000)
     private val retriever = Nip11Retriever(okHttpClient)
 
     /**

commons/src/jvmAndroid/kotlin/com/vitorpamplona/amethyst/commons/relays/nip11/Nip11Retriever.kt

@@ -18,7 +18,7 @@
  * 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.nip11RelayInfo
+package com.vitorpamplona.amethyst.commons.relays.nip11
 
 import com.vitorpamplona.quartz.nip01Core.relay.normalizer.NormalizedRelayUrl
 import com.vitorpamplona.quartz.nip01Core.relay.normalizer.toHttp

commons/src/jvmAndroid/kotlin/com/vitorpamplona/amethyst/commons/relays/nip11/RetrieveResult.kt

@@ -18,7 +18,7 @@
  * 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.nip11RelayInfo
+package com.vitorpamplona.amethyst.commons.relays.nip11
 
 import com.vitorpamplona.quartz.nip11RelayInfo.Nip11RelayInformation
 import com.vitorpamplona.quartz.utils.TimeUtils

commons/src/jvmAndroid/kotlin/com/vitorpamplona/amethyst/commons/service/OnlineCheck.kt

@@ -18,9 +18,9 @@
  * 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.service
+package com.vitorpamplona.amethyst.commons.service
 
-import android.util.LruCache
+import androidx.collection.LruCache
 import androidx.compose.runtime.Immutable
 import com.vitorpamplona.quartz.utils.Log
 import com.vitorpamplona.quartz.utils.RandomInstance

commons/src/jvmTest/kotlin/com/vitorpamplona/amethyst/commons/marmot/EncryptedMarmotStoresTest.kt

@@ -0,0 +1,184 @@
+/*
+ * 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.marmot
+
+import com.vitorpamplona.amethyst.commons.model.preferences.SecretEncryption
+import kotlinx.coroutines.test.runTest
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertNull
+import org.junit.Assert.assertTrue
+import org.junit.Rule
+import org.junit.Test
+import org.junit.rules.TemporaryFolder
+import java.io.File
+
+/**
+ * Round trips for the file-backed Marmot stores, which had no coverage while they sat in `amethyst/`
+ * behind an `Android` prefix they never earned.
+ *
+ * What matters here is that the bytes survive a restart: these hold MLS group state and the message
+ * log, so a store that writes but cannot read back loses a group's history and its ratchet — and MLS
+ * state that cannot be reloaded is not recoverable from the relays.
+ */
+class EncryptedMarmotStoresTest {
+    @get:Rule
+    val folder = TemporaryFolder()
+
+    private var seq = 0
+
+    /** A fresh account directory plus its own key file, so tests cannot read each other's data. */
+    private fun accountDir(): Pair<File, SecretEncryption> {
+        val n = seq++
+        val dir = folder.newFolder("account_$n")
+        return dir to SecretEncryption(File(folder.root, "secret_$n.key"))
+    }
+
+    // Group ids must be hex: both stores validate, which is what stops a crafted id escaping the
+    // account directory. Using a realistic 64-char id rather than a label keeps the tests honest.
+    private val groupId = "a".repeat(63) + "1"
+    private val otherGroupId = "b".repeat(63) + "2"
+
+    @Test
+    fun groupStateSurvivesANewStoreOverTheSameDirectory() =
+        runTest {
+            val (dir, encryption) = accountDir()
+            val payload = byteArrayOf(1, 2, 3, 4, 5)
+
+            EncryptedMlsGroupStateStore(dir, encryption).save(groupId, payload)
+
+            val reopened = EncryptedMlsGroupStateStore(dir, encryption).load(groupId)
+            assertEquals("the same bytes come back", payload.toList(), reopened?.toList())
+        }
+
+    @Test
+    fun anUnknownGroupLoadsAsNull() =
+        runTest {
+            val (dir, encryption) = accountDir()
+
+            assertNull(EncryptedMlsGroupStateStore(dir, encryption).load("c".repeat(63) + "3"))
+        }
+
+    @Test
+    fun deletingAGroupRemovesItFromTheListing() =
+        runTest {
+            val (dir, encryption) = accountDir()
+            val store = EncryptedMlsGroupStateStore(dir, encryption)
+            store.save(groupId, byteArrayOf(9))
+            store.save(otherGroupId, byteArrayOf(8))
+
+            store.delete(groupId)
+
+            assertEquals("only the other group is left", listOf(otherGroupId), store.listGroups())
+            assertNull("and its state is gone", store.load(groupId))
+        }
+
+    /** The sender ratchet is stored separately from the group blob; losing it breaks decryption. */
+    @Test
+    fun theSenderRatchetRoundTripsIndependentlyOfTheGroupState() =
+        runTest {
+            val (dir, encryption) = accountDir()
+            val store = EncryptedMlsGroupStateStore(dir, encryption)
+
+            store.save(groupId, byteArrayOf(1))
+            store.saveSenderRatchet(groupId, byteArrayOf(7, 7, 7))
+
+            val reopened = EncryptedMlsGroupStateStore(dir, encryption)
+            assertEquals("ratchet preserved", listOf<Byte>(7, 7, 7), reopened.loadSenderRatchet(groupId)?.toList())
+            assertEquals("and the group blob is untouched", listOf<Byte>(1), reopened.load(groupId)?.toList())
+        }
+
+    @Test
+    fun appendedMessagesComeBackInOrderAfterAReopen() =
+        runTest {
+            val (dir, encryption) = accountDir()
+            val store = EncryptedMarmotMessageStore(dir, encryption)
+
+            store.appendMessage(groupId, """{"id":"one"}""")
+            store.appendMessage(groupId, """{"id":"two"}""")
+
+            val reopened = EncryptedMarmotMessageStore(dir, encryption).loadMessages(groupId)
+            assertEquals("both, in append order", listOf("""{"id":"one"}""", """{"id":"two"}"""), reopened)
+        }
+
+    @Test
+    fun aGroupWithNoMessagesLoadsEmptyRatherThanFailing() =
+        runTest {
+            val (dir, encryption) = accountDir()
+
+            assertTrue(EncryptedMarmotMessageStore(dir, encryption).loadMessages("d".repeat(63) + "4").isEmpty())
+        }
+
+    @Test
+    fun deletingAGroupDropsItsMessageLog() =
+        runTest {
+            val (dir, encryption) = accountDir()
+            val store = EncryptedMarmotMessageStore(dir, encryption)
+            store.appendMessage(groupId, """{"id":"one"}""")
+
+            store.delete(groupId)
+
+            assertTrue(EncryptedMarmotMessageStore(dir, encryption).loadMessages(groupId).isEmpty())
+        }
+
+    /** The group snapshot is what a cold start restores from before replaying the log. */
+    @Test
+    fun theGroupSnapshotRoundTrips() =
+        runTest {
+            val (dir, encryption) = accountDir()
+            val store = EncryptedMarmotMessageStore(dir, encryption)
+
+            store.recordGroupSnapshot(groupId, """{"epoch":4}""")
+
+            assertEquals("""{"epoch":4}""", EncryptedMarmotMessageStore(dir, encryption).loadGroupSnapshot(groupId))
+        }
+
+    /** Two accounts are two directories: one must never read the other's groups. */
+    @Test
+    fun twoAccountDirectoriesDoNotSeeEachOther() =
+        runTest {
+            val (dirA, encA) = accountDir()
+            val (dirB, encB) = accountDir()
+
+            EncryptedMlsGroupStateStore(dirA, encA).save(groupId, byteArrayOf(1))
+
+            assertNull("B cannot see A's group", EncryptedMlsGroupStateStore(dirB, encB).load(groupId))
+            assertTrue("nor list it", EncryptedMlsGroupStateStore(dirB, encB).listGroups().isEmpty())
+        }
+
+    /** The hex check is a path-traversal guard: a crafted id must not be able to leave the account dir. */
+    @Test
+    fun aNonHexGroupIdIsRejected() =
+        runTest {
+            val (dir, encryption) = accountDir()
+            val store = EncryptedMlsGroupStateStore(dir, encryption)
+
+            listOf("../escape", "not hex", "abc/def", "").forEach { bad ->
+                val thrown =
+                    try {
+                        store.load(bad)
+                        false
+                    } catch (e: IllegalArgumentException) {
+                        true
+                    }
+                assertTrue("\"$bad\" must be rejected, not resolved to a path", thrown)
+            }
+        }
+}

commons/src/jvmTest/kotlin/com/vitorpamplona/amethyst/commons/relays/nip11/Nip11RetrieverTest.kt

@@ -18,7 +18,7 @@
  * 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.nip11RelayInfo
+package com.vitorpamplona.amethyst.commons.relays.nip11
 
 import com.vitorpamplona.quartz.nip01Core.relay.normalizer.NormalizedRelayUrl
 import kotlinx.coroutines.runBlocking

commons/src/jvmTest/kotlin/com/vitorpamplona/amethyst/commons/service/OnlineCheckerTest.kt

@@ -0,0 +1,117 @@
+/*
+ * 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.service
+
+import com.vitorpamplona.quartz.utils.TimeUtils
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertTrue
+import org.junit.Before
+import org.junit.Test
+
+/**
+ * [OnlineChecker]'s cache predicates — the part that decides, without touching the network, whether a
+ * media URL is known-good, known-bad, or unknown.
+ *
+ * These decide whether the UI shows a player or a "this is offline" placeholder, and a stale entry
+ * being trusted is the difference between a video that plays and one that never gets retried. Nothing
+ * here had coverage while the object sat in `amethyst/`.
+ *
+ * The suspend `isOnline` probe is deliberately not exercised: it needs a real OkHttp round trip and
+ * `commons` has no MockWebServer, so there is no honest way to drive it from here.
+ */
+class OnlineCheckerTest {
+    private val url = "https://example.com/video.mp4"
+
+    @Before
+    fun clearSharedCache() {
+        // OnlineChecker is an object, so its LruCache outlives each test.
+        OnlineChecker.checkOnlineCache.evictAll()
+    }
+
+    private fun seed(
+        online: Boolean,
+        ageSeconds: Long,
+    ) {
+        OnlineChecker.checkOnlineCache.put(url, OnlineCheckResult(TimeUtils.now() - ageSeconds, online))
+    }
+
+    @Test
+    fun anUnknownUrlIsNeitherOnlineNorKnownOffline() {
+        assertFalse("nothing cached, so not known online", OnlineChecker.isOnlineCached(url))
+        assertFalse("and not known offline either", OnlineChecker.isCachedAndOffline(url))
+    }
+
+    @Test
+    fun aFreshOnlineEntryReadsOnline() {
+        seed(online = true, ageSeconds = 10)
+
+        assertTrue(OnlineChecker.isOnlineCached(url))
+        assertFalse("an online entry is not 'cached and offline'", OnlineChecker.isCachedAndOffline(url))
+    }
+
+    @Test
+    fun aFreshOfflineEntryReadsOffline() {
+        seed(online = false, ageSeconds = 10)
+
+        assertTrue(OnlineChecker.isCachedAndOffline(url))
+        assertFalse("and must not read as online", OnlineChecker.isOnlineCached(url))
+    }
+
+    /**
+     * The five-minute TTL in both directions. Trusting a stale *online* entry shows a player for
+     * something that has since gone; trusting a stale *offline* one never retries a URL that came back.
+     */
+    @Test
+    fun anEntryOlderThanFiveMinutesIsTrustedForNothing() {
+        seed(online = true, ageSeconds = 301)
+        assertFalse("a stale online entry is no longer online", OnlineChecker.isOnlineCached(url))
+
+        seed(online = false, ageSeconds = 301)
+        assertFalse("and a stale offline entry no longer counts as known-offline", OnlineChecker.isCachedAndOffline(url))
+    }
+
+    @Test
+    fun anEntryJustInsideFiveMinutesIsStillTrusted() {
+        seed(online = true, ageSeconds = 290)
+
+        assertTrue(OnlineChecker.isOnlineCached(url))
+    }
+
+    /** Retry is for failures only: dropping a good entry would refetch every URL that already worked. */
+    @Test
+    fun resetIfOfflineToRetryDropsOnlyTheOfflineEntries() {
+        seed(online = false, ageSeconds = 10)
+        OnlineChecker.resetIfOfflineToRetry(url)
+        assertFalse("the offline entry is gone, so the next check refetches", OnlineChecker.isCachedAndOffline(url))
+
+        seed(online = true, ageSeconds = 10)
+        OnlineChecker.resetIfOfflineToRetry(url)
+        assertTrue("the online entry survived", OnlineChecker.isOnlineCached(url))
+    }
+
+    @Test
+    fun aBlankOrNullUrlIsNeverOnline() {
+        assertFalse(OnlineChecker.isOnlineCached(null))
+        assertFalse(OnlineChecker.isOnlineCached("   "))
+        assertFalse(OnlineChecker.isCachedAndOffline(null))
+        assertFalse(OnlineChecker.isCachedAndOffline("   "))
+    }
+}