diff --git a/amethyst/src/main/java/com/vitorpamplona/amethyst/model/Account.kt b/amethyst/src/main/java/com/vitorpamplona/amethyst/model/Account.kt
index 4cfab50126..458d7c7b64 100644
--- a/amethyst/src/main/java/com/vitorpamplona/amethyst/model/Account.kt
+++ b/amethyst/src/main/java/com/vitorpamplona/amethyst/model/Account.kt
@@ -147,6 +147,7 @@ import com.vitorpamplona.amethyst.service.location.LocationState
 import com.vitorpamplona.amethyst.service.relayClient.authCommand.model.InMemoryRelayAuthPermissionStore
 import com.vitorpamplona.amethyst.service.relayClient.authCommand.model.RelayAuthPermissionCache
 import com.vitorpamplona.amethyst.service.relayClient.authCommand.model.RelayAuthPermissionLedger
+import com.vitorpamplona.amethyst.service.relayClient.authCommand.model.RelayAuthVenues
 import com.vitorpamplona.amethyst.service.relayClient.chatDelivery.ChatDeliveryTracker
 import com.vitorpamplona.amethyst.service.relayClient.notifyCommand.model.NotifyRequestsCache
 import com.vitorpamplona.amethyst.service.relayClient.reqCommand.nwc.NWCPaymentFilterAssembler
@@ -424,11 +425,47 @@ class Account(
             isInMyRelayList = { relayUrl -> relayUrl.normalizeRelayUrlOrNull()?.let { it in trustedRelays.flow.value } ?: false },
             isBlocked = { relayUrl -> relayUrl.normalizeRelayUrlOrNull()?.let { it in blockedRelayList.flow.value } ?: false },
             isFollowed = { pubkey -> pubkey in allFollows.flow.value.authors },
-            isTrustedVenue = { venueId ->
+            isTrustedVenue = { relayUrl, venueId ->
                 venueId in publicChatList.flowSet.value ||
                     venueId in communityList.flowSet.value ||
+                    isJoinedRoomId(relayUrl, venueId) ||
                     Address.parse(venueId)?.pubKeyHex?.let { it in allFollows.flow.value.authors } == true
             },
+            isVenueHostRelay = { relayUrl -> relayUrl.normalizeRelayUrlOrNull()?.let { it in venueHostRelays() } ?: false },
+        )
+
+    /**
+     * Relays that exist here because *this account* joined a room on them: the host of every NIP-29
+     * relay group on its kind-10009 list, plus the relays of every Concord community on its
+     * kind-13302 list.
+     *
+     * Both are venues in the [RelayAuthCustomToggles.myRelaysAndVenues] sense but neither shows up in
+     * a NIP-65/DM/search list, so nothing else in the auth path can see them: a NIP-29 group's content
+     * is `#h`-scoped and never names the user, and a Concord plane is addressed to a derived stream
+     * key rather than to anyone's pubkey.
+     */
+    fun venueHostRelays(): Set<NormalizedRelayUrl> =
+        RelayAuthVenues.hostRelays(
+            joinedGroups = relayGroupList.liveRelayGroupIds.value,
+            joinedCommunities = concordChannelList.liveCommunities.value,
+        )
+
+    /**
+     * True when [venueId], served by [relayUrl], is a room this account joined that the venue *lists*
+     * above don't cover: a NIP-29 group id (from the kind-10009 list) or a Concord community id (from
+     * the kind-13302 list). Those are the ids the subscription assemblers declare on their filters, so
+     * this is what turns a `READ_VENUE`/`POST_VENUE` on a joined group or community into a trusted
+     * venue.
+     */
+    private fun isJoinedRoomId(
+        relayUrl: String,
+        venueId: String,
+    ): Boolean =
+        RelayAuthVenues.isJoinedRoom(
+            venueId = venueId,
+            relayUrl = relayUrl.normalizeRelayUrlOrNull(),
+            joinedGroups = relayGroupList.liveRelayGroupIds.value,
+            joinedCommunities = concordChannelList.liveCommunities.value,
         )
 
     // Per-account relay NOTIFY (payment-prompt) cache. NotifyCoordinator attributes each incoming
diff --git a/amethyst/src/main/java/com/vitorpamplona/amethyst/model/LocalCache.kt b/amethyst/src/main/java/com/vitorpamplona/amethyst/model/LocalCache.kt
index 14bb1531d4..7254304b16 100644
--- a/amethyst/src/main/java/com/vitorpamplona/amethyst/model/LocalCache.kt
+++ b/amethyst/src/main/java/com/vitorpamplona/amethyst/model/LocalCache.kt
@@ -846,6 +846,15 @@ object LocalCache : ILocalCache, ICacheProvider, Dao {
 
     fun getOrCreateConcordChannel(key: ConcordChannelId): ConcordChannel = concordChannels.getOrCreate(key) { ConcordChannel(key) }
 
+    /**
+     * Any known channel of Concord community [communityId], or null when we hold none.
+     *
+     * A community is not itself a cached object — it has no metadata event, only a folded Control
+     * Plane — so its display fields (`communityName`, icon, relays) are carried on every one of its
+     * channels. Callers that need to *name* a community therefore ask for whichever channel we have.
+     */
+    fun getAnyConcordChannelOfCommunity(communityId: HexKey): ConcordChannel? = concordChannels.filter { key, _ -> key.communityId == communityId }.firstOrNull()
+
     /**
      * Lands a decrypted Concord chat rumor in the cache as a real Note and, for
      * message-like kinds, attaches it to its channel so the shared chat feed and
diff --git a/amethyst/src/main/java/com/vitorpamplona/amethyst/service/relayClient/authCommand/compose/RelayAuthPromptHost.kt b/amethyst/src/main/java/com/vitorpamplona/amethyst/service/relayClient/authCommand/compose/RelayAuthPromptHost.kt
index 999860ab29..34e23d91da 100644
--- a/amethyst/src/main/java/com/vitorpamplona/amethyst/service/relayClient/authCommand/compose/RelayAuthPromptHost.kt
+++ b/amethyst/src/main/java/com/vitorpamplona/amethyst/service/relayClient/authCommand/compose/RelayAuthPromptHost.kt
@@ -82,7 +82,9 @@ import com.vitorpamplona.amethyst.ui.stringRes
 import com.vitorpamplona.amethyst.ui.theme.RelayIconFilter
 import com.vitorpamplona.quartz.nip01Core.core.Address
 import com.vitorpamplona.quartz.nip01Core.core.HexKey
+import com.vitorpamplona.quartz.nip01Core.relay.normalizer.NormalizedRelayUrl
 import com.vitorpamplona.quartz.nip01Core.relay.normalizer.displayUrl
+import com.vitorpamplona.quartz.nip29RelayGroups.GroupId
 
 /** Avatars shown in the facepile before the "+N" overflow badge. */
 private const val FACEPILE_MAX = 5
@@ -177,7 +179,7 @@ private fun RelayAuthPromptDialog(
     val who =
         when (primary?.kind) {
             AuthPurposeKind.POST_VENUE, AuthPurposeKind.READ_VENUE ->
-                primary.venues.firstOrNull()?.let { rememberVenueLabel(it, primary.kind, accountViewModel) }
+                primary.venues.firstOrNull()?.let { rememberVenueLabel(it, primary.kind, prompt.relayUrl, accountViewModel) }
             else -> counterpartyLabel(faces, accountViewModel)
         }
 
@@ -478,33 +480,48 @@ private fun rememberCounterpartyName(
 }
 
 /**
- * A display name for a venue id — a public chat channel (64-hex event id), a NIP-53 live activity,
- * or a NIP-72 community.
+ * A display name for a venue id — a public chat channel (64-hex event id), a NIP-53 live activity, a
+ * NIP-72 community, a NIP-29 relay group, or a Concord community.
  *
  * Only a [AuthPurposeKind.POST_VENUE] id is *known* to be a channel (it is the root of a channel
  * message we are sending). A READ id may have come from the tag-shape fallback, where a bare `#e`
  * list is as likely to be note ids on a thread as channel roots — so we only ever *look up* an
  * existing channel there. Get-or-creating on read is what used to mint phantom public chats in
  * [LocalCache] for ordinary notes, complete with a metadata subscription for a room that never was.
+ *
+ * Both joined-room shapes are resolved **before** any of that, because the rules above would not just
+ * mislabel them, they would act on them. A NIP-29 group id is only meaningful together with its host
+ * relay ([relayUrl], the relay doing the asking). A Concord community id is a bare 64-hex string, so
+ * the public-chat branch would take it: on a `POST_VENUE` — which is exactly what a pending plane wrap
+ * now derives — that get-or-create mints the phantom channel this function was rewritten to stop
+ * minting, and then names the room after its own nevent.
  */
 @Composable
 private fun rememberVenueLabel(
     venueId: String,
     kind: AuthPurposeKind,
+    relayUrl: NormalizedRelayUrl,
     accountViewModel: AccountViewModel,
 ): String {
+    // Resolved off LocalCache first and the active account's list second: a prompt is raised per
+    // account, so the account on screen is not necessarily the one being asked about — the cache is
+    // shared by all of them, the list is not.
+    val concordName = remember(venueId) { concordCommunityLabel(venueId, accountViewModel) }
+    if (concordName != null) return concordName
+
     val channel: Channel? =
-        remember(venueId, kind) {
-            when {
-                venueId.length == 64 ->
-                    if (kind == AuthPurposeKind.POST_VENUE) {
-                        accountViewModel.checkGetOrCreatePublicChatChannel(venueId)
-                    } else {
-                        LocalCache.getPublicChatChannelIfExists(venueId)
-                    }
-                venueId.startsWith("30311:") -> Address.parse(venueId)?.let { accountViewModel.checkGetOrCreateLiveActivityChannel(it) }
-                else -> null
-            }
+        remember(venueId, kind, relayUrl) {
+            LocalCache.getRelayGroupChannelIfExists(GroupId(venueId, relayUrl))
+                ?: when {
+                    venueId.length == 64 ->
+                        if (kind == AuthPurposeKind.POST_VENUE) {
+                            accountViewModel.checkGetOrCreatePublicChatChannel(venueId)
+                        } else {
+                            LocalCache.getPublicChatChannelIfExists(venueId)
+                        }
+                    venueId.startsWith("30311:") -> Address.parse(venueId)?.let { accountViewModel.checkGetOrCreateLiveActivityChannel(it) }
+                    else -> null
+                }
         }
 
     if (channel != null) {
@@ -518,6 +535,30 @@ private fun rememberVenueLabel(
     return venueId.substringAfterLast(':').ifEmpty { venueId.take(8) }
 }
 
+/**
+ * The label for a Concord community id, or null when [venueId] is not a community we know of — which
+ * is what tells the caller to go on treating the id as a channel root.
+ *
+ * A community has no metadata event to look up: its name comes from the folded Control Plane, held on
+ * the `ConcordChannel`s in [LocalCache] (shared by every logged-in account, so this still resolves a
+ * prompt raised for a different one), and failing that from the active account's joined list. A
+ * community we can place but cannot name still returns a label, so the caller never falls through to
+ * the channel branches with an id it would get-or-create.
+ */
+private fun concordCommunityLabel(
+    venueId: String,
+    accountViewModel: AccountViewModel,
+): String? {
+    val folded = LocalCache.getAnyConcordChannelOfCommunity(venueId)
+    val joined =
+        accountViewModel.account.concordChannelList.liveCommunities.value
+            .firstOrNull { it.id == venueId }
+    if (folded == null && joined == null) return null
+    return folded?.communityName?.takeIf { it.isNotBlank() }
+        ?: joined?.name?.takeIf { it.isNotBlank() }
+        ?: venueId.take(8)
+}
+
 /**
  * The best display name for [pubkey], reactive to metadata arriving from relays. Falls back to a
  * generic "someone you haven't loaded yet" rather than a hex prefix dressed up as a person's name.
diff --git a/amethyst/src/main/java/com/vitorpamplona/amethyst/service/relayClient/authCommand/model/AuthCoordinator.kt b/amethyst/src/main/java/com/vitorpamplona/amethyst/service/relayClient/authCommand/model/AuthCoordinator.kt
index 4865be0594..7ff6533dc3 100644
--- a/amethyst/src/main/java/com/vitorpamplona/amethyst/service/relayClient/authCommand/model/AuthCoordinator.kt
+++ b/amethyst/src/main/java/com/vitorpamplona/amethyst/service/relayClient/authCommand/model/AuthCoordinator.kt
@@ -76,6 +76,10 @@ class AuthCoordinator(
                                 RelayAuthPurposeDeriver.derive(
                                     pendingEvents = client.activeOutboxEvents(relayUrl),
                                     activeFilters = client.activeRequests(relayUrl),
+                                    // The context describes the shared socket, not one account, so a
+                                    // plane is looked up across every watched account — same as the
+                                    // stream-key AUTHs above.
+                                    venueForPlaneAuthor = ::concordCommunityForPlane,
                                 ),
                         )
                     }
@@ -165,6 +169,13 @@ class AuthCoordinator(
             },
         )
 
+    /**
+     * The joined Concord community whose plane [planeAddress] is, across every watched account, or
+     * null when the pubkey isn't a plane of ours. Feeds [RelayAuthPurposeDeriver] so a pending plane
+     * wrap reads as a post into that community rather than as a DM to the throwaway key it `p`-tags.
+     */
+    private fun concordCommunityForPlane(planeAddress: HexKey): HexKey? = authWithAccounts.distinct().firstNotNullOfOrNull { it.concordSessions.communityIdForPlane(planeAddress) }
+
     /**
      * Signs one kind-22242 AUTH per Concord plane stream key hosted on [relayUrl], across every
      * watched account. Signed locally from the derived stream secret (a raw [KeyPair] via
@@ -237,13 +248,12 @@ class AuthCoordinator(
                 relayUrl = relayUrl,
                 pendingEvents = client.activeOutboxEvents(relayUrl),
                 myRelays = account.trustedRelays.flow.value,
-                // A NIP-29 relay group the user explicitly joined (kind-10009) is a first-party reason
-                // to authenticate with its host relay: private/closed group content is `#h`-scoped and
-                // never names the user, so it fails the pubkey checks above — without this, a joined
-                // private group's messages are refused with `auth-required` and the group stays empty.
-                myGroupRelays =
-                    account.relayGroupList.liveRelayGroupIds.value
-                        .mapTo(mutableSetOf()) { it.relayUrl },
+                // A room the user explicitly joined — a NIP-29 relay group (kind-10009) or a Concord
+                // community (kind-13302) — makes its host relay first-party. Neither room's traffic
+                // names the user: NIP-29 content is `#h`-scoped and Concord planes ride derived stream
+                // keys, so both fail the pubkey checks above. Without this, a joined private group's
+                // messages are refused with `auth-required` and the room stays empty.
+                myVenueRelays = account.venueHostRelays(),
             )
 
     fun destroy() {
diff --git a/amethyst/src/main/java/com/vitorpamplona/amethyst/service/relayClient/authCommand/model/RelayAuthFirstParty.kt b/amethyst/src/main/java/com/vitorpamplona/amethyst/service/relayClient/authCommand/model/RelayAuthFirstParty.kt
index c44c506364..68009ebc7b 100644
--- a/amethyst/src/main/java/com/vitorpamplona/amethyst/service/relayClient/authCommand/model/RelayAuthFirstParty.kt
+++ b/amethyst/src/main/java/com/vitorpamplona/amethyst/service/relayClient/authCommand/model/RelayAuthFirstParty.kt
@@ -35,13 +35,15 @@ import com.vitorpamplona.quartz.nip01Core.relay.normalizer.NormalizedRelayUrl
  *    the recipient's inbox relay), or
  *  - the relay is one it configured itself ([myRelays] — its NIP-65 / DM / search / … lists, which
  *    is where its own inbox/outbox reads are routed anyway), or
- *  - the relay hosts a NIP-29 relay group the account explicitly joined ([myGroupRelays], from its
- *    kind-10009 list). A private/closed group's content (kind-9 chat, kind-11 threads, …) is
- *    `#h`-scoped and served only to authenticated members; that read never names the user, so it
- *    can't qualify via [pendingEvents], and a group host relay is not one of the account's own
- *    NIP-65/DM/… lists, so it can't qualify via [myRelays] either. Without this, a joined private
- *    group is refused with `auth-required` and renders empty — the group's own metadata (39000) is
- *    public and still loads, so the group appears but shows no messages.
+ *  - the relay hosts a room the account explicitly joined ([myVenueRelays]): a NIP-29 relay group
+ *    from its kind-10009 list, or a Concord community from its kind-13302 list. Neither kind of room
+ *    can qualify by the two rules above. A private/closed NIP-29 group's content (kind-9 chat,
+ *    kind-11 threads, …) is `#h`-scoped and served only to authenticated members, so the read never
+ *    names the user; a Concord plane is authored by — and addressed to — a derived stream key, so
+ *    even the wraps the account *publishes* there carry someone else's pubkey. And neither host relay
+ *    is in the account's own NIP-65/DM/… lists, so [myRelays] doesn't see them either. Without this,
+ *    a joined private group is refused with `auth-required` and renders empty — the group's own
+ *    metadata (39000) is public and still loads, so the group appears but shows no messages.
  *
  * Crucially, an active subscription merely *naming* the account (a `#p` tag or `authors` entry) is
  * NOT a first-party reason: the app packs several accounts' pubkeys into one merged filter and fans
@@ -56,10 +58,10 @@ object RelayAuthFirstParty {
         relayUrl: NormalizedRelayUrl,
         pendingEvents: List<Event>,
         myRelays: Set<NormalizedRelayUrl>,
-        myGroupRelays: Set<NormalizedRelayUrl> = emptySet(),
+        myVenueRelays: Set<NormalizedRelayUrl> = emptySet(),
     ): Boolean {
         if (pendingEvents.any { it.pubKey == me }) return true
         if (relayUrl in myRelays) return true
-        return relayUrl in myGroupRelays
+        return relayUrl in myVenueRelays
     }
 }
diff --git a/amethyst/src/main/java/com/vitorpamplona/amethyst/service/relayClient/authCommand/model/RelayAuthPermissionLedger.kt b/amethyst/src/main/java/com/vitorpamplona/amethyst/service/relayClient/authCommand/model/RelayAuthPermissionLedger.kt
index 6181fa1807..a4170280f8 100644
--- a/amethyst/src/main/java/com/vitorpamplona/amethyst/service/relayClient/authCommand/model/RelayAuthPermissionLedger.kt
+++ b/amethyst/src/main/java/com/vitorpamplona/amethyst/service/relayClient/authCommand/model/RelayAuthPermissionLedger.kt
@@ -37,6 +37,14 @@ import com.vitorpamplona.amethyst.commons.relayauth.RelayAuthVerdict
  * [globalPolicy] → prompt-if-attributable-else-deny. Under [RelayAuthPolicy.CUSTOM] the
  * [customToggles] gate each category, using [isFollowed] to split the counterparties carried in the
  * [RelayAuthContext] into followed vs. stranger.
+ *
+ * Venues come in two shapes and both count as "a room I joined" for the
+ * [RelayAuthCustomToggles.myRelaysAndVenues] toggle: [isTrustedVenue] recognizes a venue *id* named
+ * by a purpose (a NIP-28 chat, a NIP-72 community, a NIP-53 stream, a NIP-29 group id, a Concord
+ * community id), while [isVenueHostRelay] recognizes the relay that *hosts* one — the only signal
+ * available for a room whose traffic never names it in a way the deriver can see, or whose challenge
+ * arrives before its subscription does. [isTrustedVenue] is asked about the (relay, venue) pair
+ * rather than the id alone because a NIP-29 group id means nothing without its host relay.
  */
 class RelayAuthPermissionLedger(
     val store: RelayAuthPermissionStore,
@@ -45,7 +53,8 @@ class RelayAuthPermissionLedger(
     val isInMyRelayList: (String) -> Boolean = { false },
     val isBlocked: (String) -> Boolean = { false },
     val isFollowed: (String) -> Boolean = { false },
-    val isTrustedVenue: (String) -> Boolean = { false },
+    val isTrustedVenue: (relayUrl: String, venueId: String) -> Boolean = { _, _ -> false },
+    val isVenueHostRelay: (String) -> Boolean = { false },
 ) {
     /**
      * The authorization verdict for [ctx], taking the challenge's purpose into account.
@@ -59,6 +68,15 @@ class RelayAuthPermissionLedger(
         isFirstParty: Boolean = true,
     ): RelayAuthVerdict {
         fun isWrite(kind: AuthPurposeKind) = kind == AuthPurposeKind.SEND_DM || kind == AuthPurposeKind.NOTIFY_INBOX
+
+        // The relay itself hosts a room this account joined — a NIP-29 relay group or a Concord
+        // community. Computed apart from the purposes because those rooms are the relay's whole
+        // reason to be here: their traffic is `#h`-scoped (NIP-29) or addressed to derived stream
+        // keys (Concord), so an AUTH challenge that lands before the room's subscription is
+        // assembled carries no venue to match — and the joined room would sit empty behind a
+        // question the user already answered by joining it.
+        val hostsMyVenue = isVenueHostRelay(ctx.relayUrl)
+
         val inputs =
             RelayAuthInputs(
                 storedOverride = store.loadDecision(ctx.relayUrl),
@@ -67,10 +85,11 @@ class RelayAuthPermissionLedger(
                 toggles = customToggles(),
                 isInMyRelayList = isInMyRelayList(ctx.relayUrl),
                 servesTrustedVenue =
-                    ctx.purposes.any { p ->
-                        (p.kind == AuthPurposeKind.POST_VENUE || p.kind == AuthPurposeKind.READ_VENUE) &&
-                            p.venues.any(isTrustedVenue)
-                    },
+                    hostsMyVenue ||
+                        ctx.purposes.any { p ->
+                            (p.kind == AuthPurposeKind.POST_VENUE || p.kind == AuthPurposeKind.READ_VENUE) &&
+                                p.venues.any { isTrustedVenue(ctx.relayUrl, it) }
+                        },
                 // Reading a followed author's outbox.
                 servesFollowedReadCounterparty =
                     ctx.purposes.any { p ->
@@ -82,18 +101,22 @@ class RelayAuthPermissionLedger(
                 // Messaging a non-followed user's inbox.
                 servesStrangerWriteCounterparty =
                     ctx.purposes.any { p -> isWrite(p.kind) && p.counterparties.any { !isFollowed(it) } },
+                // Hosting a joined room is itself an explanation, and the only one available when the
+                // challenge arrives before any of that room's filters do. Without it, a user on
+                // "decide per relay" (or with the venue toggle off) would get a silent denial for a
+                // room they joined instead of the question. MY_INBOX and THREAD likewise name no
+                // counterparty by design — the relay is holding back the user's *own* inbox or the
+                // conversation on screen — and are fully explainable, so they too must reach ASK.
                 hasAttributablePurpose =
-                    ctx.purposes.any {
-                        // MY_INBOX and THREAD name no counterparty by design — the relay is holding
-                        // back the user's *own* inbox or the conversation on screen. They are still
-                        // fully explainable, so they must reach ASK rather than a silent DENY.
-                        it.kind == AuthPurposeKind.MY_OWN_RELAY ||
-                            it.kind == AuthPurposeKind.OTHER ||
-                            it.kind == AuthPurposeKind.MY_INBOX ||
-                            it.kind == AuthPurposeKind.THREAD ||
-                            it.counterparties.isNotEmpty() ||
-                            it.venues.isNotEmpty()
-                    },
+                    hostsMyVenue ||
+                        ctx.purposes.any {
+                            it.kind == AuthPurposeKind.MY_OWN_RELAY ||
+                                it.kind == AuthPurposeKind.OTHER ||
+                                it.kind == AuthPurposeKind.MY_INBOX ||
+                                it.kind == AuthPurposeKind.THREAD ||
+                                it.counterparties.isNotEmpty() ||
+                                it.venues.isNotEmpty()
+                        },
                 isFirstParty = isFirstParty,
             )
         return RelayAuthResolver.resolve(inputs)
diff --git a/amethyst/src/main/java/com/vitorpamplona/amethyst/service/relayClient/authCommand/model/RelayAuthPurposeDeriver.kt b/amethyst/src/main/java/com/vitorpamplona/amethyst/service/relayClient/authCommand/model/RelayAuthPurposeDeriver.kt
index d6bad70abc..cec6d600c2 100644
--- a/amethyst/src/main/java/com/vitorpamplona/amethyst/service/relayClient/authCommand/model/RelayAuthPurposeDeriver.kt
+++ b/amethyst/src/main/java/com/vitorpamplona/amethyst/service/relayClient/authCommand/model/RelayAuthPurposeDeriver.kt
@@ -24,6 +24,9 @@ import com.vitorpamplona.amethyst.commons.relayClient.subscriptions.ExplainedFil
 import com.vitorpamplona.amethyst.commons.relayauth.AuthPurpose
 import com.vitorpamplona.amethyst.commons.relayauth.AuthPurposeKind
 import com.vitorpamplona.amethyst.commons.relayauth.toAuthPurposeKind
+import com.vitorpamplona.quartz.concord.envelope.ConcordStreamEnvelope
+import com.vitorpamplona.quartz.marmot.mip02Welcome.WelcomeEvent
+import com.vitorpamplona.quartz.marmot.mip03GroupMessages.GroupEvent
 import com.vitorpamplona.quartz.nip01Core.core.Address
 import com.vitorpamplona.quartz.nip01Core.core.Event
 import com.vitorpamplona.quartz.nip01Core.core.HexKey
@@ -33,6 +36,7 @@ import com.vitorpamplona.quartz.nip01Core.tags.events.ETag
 import com.vitorpamplona.quartz.nip01Core.tags.people.PTag
 import com.vitorpamplona.quartz.nip10Notes.tags.MarkedETag
 import com.vitorpamplona.quartz.nip28PublicChat.message.ChannelMessageEvent
+import com.vitorpamplona.quartz.nip29RelayGroups.tags.GroupIdTag
 import com.vitorpamplona.quartz.nip53LiveActivities.streaming.LiveActivitiesEvent
 import com.vitorpamplona.quartz.nip59Giftwrap.wraps.GiftWrapEvent
 import com.vitorpamplona.quartz.nip72ModCommunities.definition.CommunityDefinitionEvent
@@ -41,6 +45,18 @@ import com.vitorpamplona.quartz.nip72ModCommunities.definition.CommunityDefiniti
  *  activities. Their `a` addresses are `kind:ownerPubkey:dTag`. */
 private val VENUE_KINDS = setOf(CommunityDefinitionEvent.KIND, LiveActivitiesEvent.KIND)
 
+/** The kinds a Concord plane wrap can be — the only ones worth asking `venueForPlaneAuthor` about. */
+private val STREAM_WRAP_KINDS = setOf(ConcordStreamEnvelope.KIND_WRAP, ConcordStreamEnvelope.KIND_WRAP_EPHEMERAL)
+
+/**
+ * Marmot (MLS) carries the group id in an `h` tag exactly like NIP-29 does, but an MLS group is not a
+ * room we can name: the id is an opaque MLS value with no metadata event and no channel object behind
+ * it. Reading it as a venue would put that id in front of the user as a room name — and, on a
+ * `POST_VENUE`, get-or-create a phantom public chat for it (the id is 64-hex). These keep their prior
+ * reading: no `p` tags, so they land on the unattributed safety net.
+ */
+private val MLS_GROUP_KINDS = setOf(GroupEvent.KIND, WelcomeEvent.KIND)
+
 /**
  * Infers *why* a relay wants NIP-42 auth from what Amethyst is currently doing with it — the
  * events pending delivery and the active subscription filters (both from the [INostrClient]).
@@ -48,10 +64,19 @@ private val VENUE_KINDS = setOf(CommunityDefinitionEvent.KIND, LiveActivitiesEve
  *
  * Sends (from the outbox) are read from the events themselves:
  *
+ * - a pending Concord plane wrap (recognized by [venueForPlaneAuthor], since the wrap is *signed* by
+ *   the plane's stream key) => [AuthPurposeKind.POST_VENUE] for that community;
+ * - a pending `h`-tagged event => [AuthPurposeKind.POST_VENUE] for that NIP-29 relay group (except
+ *   the [MLS_GROUP_KINDS], whose `h` names something unnameable);
  * - a pending gift wrap (kind 1059) => sending a DM to its `p` recipient ([AuthPurposeKind.SEND_DM]);
  * - a pending channel/community/live post => [AuthPurposeKind.POST_VENUE] for that venue;
  * - any other pending event with `p` tags => delivering it to those users' inboxes ([AuthPurposeKind.NOTIFY_INBOX]).
  *
+ * The two room rules come first because both would otherwise be read as something else entirely: a
+ * Concord wrap is kind 1059 `p`-tagged to a *throwaway* pubkey, so the gift-wrap rule would explain a
+ * community post as a DM to a stranger nobody can name, and a NIP-29 chat message mentioning someone
+ * would be explained as a notification rather than as a message into the group.
+ *
  * Reads prefer the purpose the subscription **declared**. Assemblers build every filter as an
  * [ExplainedFilter] carrying a [SubPurpose][com.vitorpamplona.amethyst.commons.relayClient.subscriptions.SubPurpose]
  * and the entity ids it serves, so we simply read it (see `toAuthPurposeKind`). That is the only way
@@ -66,9 +91,14 @@ private val VENUE_KINDS = setOf(CommunityDefinitionEvent.KIND, LiveActivitiesEve
  *   is prompted about instead of silently failing.
  */
 object RelayAuthPurposeDeriver {
+    /**
+     * @param venueForPlaneAuthor maps the pubkey that *signed* a pending event to the room it streams
+     *   for — today, a Concord plane address to its community id. Returns null for anything else.
+     */
     fun derive(
         pendingEvents: List<Event>,
         activeFilters: Map<String, List<Filter>>,
+        venueForPlaneAuthor: (HexKey) -> String? = { null },
     ): List<AuthPurpose> {
         val dmRecipients = mutableSetOf<HexKey>()
         val notifyRecipients = mutableSetOf<HexKey>()
@@ -78,7 +108,12 @@ object RelayAuthPurposeDeriver {
         pendingEvents.forEach { event ->
             val pubkeys = event.tags.mapNotNull(PTag::parseKey)
             val venues = event.tags.mapNotNull(ATag::parseAddress).filter { it.kind in VENUE_KINDS }
+            // Only a stream wrap can belong to a plane, so only a wrap pays for the lookup.
+            val planeVenue = if (event.kind in STREAM_WRAP_KINDS) venueForPlaneAuthor(event.pubKey) else null
+            val groupId = if (event.kind in MLS_GROUP_KINDS) null else event.tags.firstNotNullOfOrNull(GroupIdTag::parse)
             when {
+                planeVenue != null -> postVenues.add(planeVenue)
+                groupId != null -> postVenues.add(groupId)
                 event.kind == GiftWrapEvent.KIND -> dmRecipients.addAll(pubkeys)
                 event.kind == ChannelMessageEvent.KIND -> event.tags.channelRootId()?.let(postVenues::add)
                 venues.isNotEmpty() -> venues.forEach { postVenues.add(it.toValue()) }
diff --git a/amethyst/src/main/java/com/vitorpamplona/amethyst/service/relayClient/authCommand/model/RelayAuthVenues.kt b/amethyst/src/main/java/com/vitorpamplona/amethyst/service/relayClient/authCommand/model/RelayAuthVenues.kt
new file mode 100644
index 0000000000..f6605d7184
--- /dev/null
+++ b/amethyst/src/main/java/com/vitorpamplona/amethyst/service/relayClient/authCommand/model/RelayAuthVenues.kt
@@ -0,0 +1,81 @@
+/*
+ * 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.service.relayClient.authCommand.model
+
+import com.vitorpamplona.quartz.concord.cord02Community.ConcordCommunityListEntry
+import com.vitorpamplona.quartz.nip01Core.relay.normalizer.NormalizedRelayUrl
+import com.vitorpamplona.quartz.nip01Core.relay.normalizer.RelayUrlNormalizer
+import com.vitorpamplona.quartz.nip29RelayGroups.GroupId
+
+/**
+ * The rooms an account joined that the NIP-51 venue lists don't describe: NIP-29 relay groups (the
+ * kind-10009 list) and Concord communities (the kind-13302 list).
+ *
+ * Both are venues in the "…it's my relay, or a room I joined" sense, and both are invisible to every
+ * other signal in the auth path — a NIP-29 group's content is `#h`-scoped and never names the user,
+ * and a Concord plane is authored by and addressed to derived stream keys — so this is what feeds
+ * them to [RelayAuthPermissionLedger] and [RelayAuthFirstParty]. Pure, so the id/url matching is
+ * testable without an [com.vitorpamplona.amethyst.model.Account].
+ *
+ * Everything here is per account, deliberately: these lists come off *this* account's own list events,
+ * so one account's rooms can never grant another account's identity away. That rules out the
+ * process-wide joined sets (Buzz workspaces) — they carry no account, so folding them in here would
+ * auto-authenticate every logged-in account on a workspace only one of them joined.
+ */
+object RelayAuthVenues {
+    /**
+     * The relays these rooms live on. A NIP-29 group id is only meaningful together with its host, so
+     * the [GroupId] carries an already-normalized url; a Concord entry stores raw url strings written
+     * by whoever created the community, so those are normalized here — comparing them verbatim
+     * against a challenge's relay url is what makes a trailing slash or a `wss://` case difference
+     * quietly drop the whole community.
+     */
+    fun hostRelays(
+        joinedGroups: Set<GroupId>,
+        joinedCommunities: List<ConcordCommunityListEntry>,
+    ): Set<NormalizedRelayUrl> =
+        buildSet {
+            joinedGroups.mapTo(this) { it.relayUrl }
+            joinedCommunities.forEach { entry ->
+                entry.relays.forEach { url -> RelayUrlNormalizer.normalizeOrNull(url)?.let(::add) }
+            }
+        }
+
+    /**
+     * True when [venueId], as served by [relayUrl], names one of these rooms. These are the ids the
+     * subscription assemblers declare as their filters' entity ids, so this is what turns a
+     * `READ_VENUE`/`POST_VENUE` on a joined room into a trusted venue.
+     *
+     * A NIP-29 group id is matched **together with its host**: ids are scoped to their relay and are
+     * routinely generic (`_` is the spec's relay-wide group), so an id alone would let a group we
+     * merely browsed on some other relay pass for one we joined. A Concord community id is a 64-hex
+     * derived value that names exactly one community wherever it is served, so it matches on its own
+     * — and its relays are covered by [hostRelays] anyway.
+     */
+    fun isJoinedRoom(
+        venueId: String,
+        relayUrl: NormalizedRelayUrl?,
+        joinedGroups: Set<GroupId>,
+        joinedCommunities: List<ConcordCommunityListEntry>,
+    ): Boolean =
+        (relayUrl != null && GroupId(venueId, relayUrl) in joinedGroups) ||
+            joinedCommunities.any { it.id == venueId }
+}
diff --git a/amethyst/src/test/java/com/vitorpamplona/amethyst/service/relayClient/authCommand/model/RelayAuthFirstPartyTest.kt b/amethyst/src/test/java/com/vitorpamplona/amethyst/service/relayClient/authCommand/model/RelayAuthFirstPartyTest.kt
index 0f248049ee..354750736b 100644
--- a/amethyst/src/test/java/com/vitorpamplona/amethyst/service/relayClient/authCommand/model/RelayAuthFirstPartyTest.kt
+++ b/amethyst/src/test/java/com/vitorpamplona/amethyst/service/relayClient/authCommand/model/RelayAuthFirstPartyTest.kt
@@ -88,4 +88,14 @@ class RelayAuthFirstPartyTest {
         val groupRelay = NormalizedRelayUrl("wss://chat.wisp.talk/")
         assertFalse(RelayAuthFirstParty.hasReason(me, groupRelay, emptyList(), emptySet(), emptySet()))
     }
+
+    @Test
+    fun aRelayHostingAJoinedConcordCommunityIsFirstParty() {
+        // Concord is the harder case of the same rule: a plane wrap this account publishes is signed
+        // by the plane's *stream key*, so even its own outbound traffic carries someone else's pubkey
+        // and the pendingEvents rule can never fire. The joined-communities list is the only signal.
+        val concordRelay = NormalizedRelayUrl("wss://relay.dreamith.to/")
+        val planeWrap = event(other)
+        assertTrue(RelayAuthFirstParty.hasReason(me, concordRelay, listOf(planeWrap), emptySet(), setOf(concordRelay)))
+    }
 }
diff --git a/amethyst/src/test/java/com/vitorpamplona/amethyst/service/relayClient/authCommand/model/RelayAuthPurposeDeriverTest.kt b/amethyst/src/test/java/com/vitorpamplona/amethyst/service/relayClient/authCommand/model/RelayAuthPurposeDeriverTest.kt
index 904a5dad57..aa5fab5c58 100644
--- a/amethyst/src/test/java/com/vitorpamplona/amethyst/service/relayClient/authCommand/model/RelayAuthPurposeDeriverTest.kt
+++ b/amethyst/src/test/java/com/vitorpamplona/amethyst/service/relayClient/authCommand/model/RelayAuthPurposeDeriverTest.kt
@@ -229,6 +229,114 @@ class RelayAuthPurposeDeriverTest {
         assertEquals(setOf(alice), purposes[0].counterparties)
     }
 
+    // ---- rooms whose traffic doesn't look like a room -----------------------------------------
+
+    @Test
+    fun postingIntoARelayGroupIsAVenuePostAndNotANotification() {
+        // A NIP-29 chat message is `#h`-scoped; the mention it carries would otherwise make this read
+        // as "delivering a notification to alice" instead of "posting into the group".
+        val groupId = "abcd1234"
+        val ev =
+            Event(
+                id = "00".repeat(32),
+                pubKey = "11".repeat(32),
+                createdAt = 1_700_000_000L,
+                kind = 9,
+                tags = arrayOf(arrayOf("h", groupId), arrayOf("p", alice)),
+                content = "hi",
+                sig = "22".repeat(64),
+            )
+
+        val purposes = RelayAuthPurposeDeriver.derive(listOf(ev), emptyMap())
+
+        assertEquals(listOf(AuthPurposeKind.POST_VENUE), purposes.map { it.kind })
+        assertEquals(setOf(groupId), purposes[0].venues)
+    }
+
+    @Test
+    fun aMarmotGroupMessageIsNotTreatedAsARoomWeCanName() {
+        // MLS carries its group id in an `h` tag exactly like NIP-29, but the id is an opaque MLS
+        // value with no metadata event behind it — and it is 64-hex, so a POST_VENUE on it would have
+        // the label get-or-create a phantom public chat. Stays on the unattributed safety net.
+        val ev =
+            Event(
+                id = "00".repeat(32),
+                pubKey = "11".repeat(32),
+                createdAt = 1_700_000_000L,
+                kind = 445,
+                tags = arrayOf(arrayOf("h", "d".repeat(64))),
+                content = "",
+                sig = "22".repeat(64),
+            )
+
+        val purposes = RelayAuthPurposeDeriver.derive(listOf(ev), emptyMap())
+
+        assertEquals(listOf(AuthPurposeKind.OTHER), purposes.map { it.kind })
+    }
+
+    @Test
+    fun aPendingEventThatIsNotAWrapIsNeverAskedAboutPlanes() {
+        // The plane lookup walks every joined community on every pending event; only a stream wrap
+        // can belong to a plane, so only a wrap may pay for it.
+        var asked = 0
+        RelayAuthPurposeDeriver.derive(
+            pendingEvents = listOf(event(1, listOf(alice)), event(GiftWrapEvent.KIND, listOf(bob))),
+            activeFilters = emptyMap(),
+            venueForPlaneAuthor = {
+                asked++
+                null
+            },
+        )
+
+        assertEquals(1, asked)
+    }
+
+    @Test
+    fun postingIntoAConcordChannelIsAVenuePostAndNotADmToItsThrowawayPTag() {
+        // A Concord plane wrap is kind 1059 signed by the plane's stream key and `p`-tagged to a fresh
+        // random pubkey. On tag shape alone it is a gift wrap, so the prompt used to offer to "send a
+        // message" to a key that belongs to nobody and will never be seen again.
+        val planeAddress = "9".repeat(64)
+        val communityId = "c".repeat(64)
+        val throwaway = "e".repeat(64)
+        val wrap =
+            Event(
+                id = "00".repeat(32),
+                pubKey = planeAddress,
+                createdAt = 1_700_000_000L,
+                kind = GiftWrapEvent.KIND,
+                tags = arrayOf(arrayOf("p", throwaway)),
+                content = "",
+                sig = "22".repeat(64),
+            )
+
+        val purposes =
+            RelayAuthPurposeDeriver.derive(
+                pendingEvents = listOf(wrap),
+                activeFilters = emptyMap(),
+                venueForPlaneAuthor = { if (it == planeAddress) communityId else null },
+            )
+
+        assertEquals(listOf(AuthPurposeKind.POST_VENUE), purposes.map { it.kind })
+        assertEquals(setOf(communityId), purposes[0].venues)
+        assertEquals(emptySet<String>(), purposes[0].counterparties)
+    }
+
+    @Test
+    fun aGiftWrapFromAnUnknownAuthorIsStillADm() {
+        // The plane lookup must not swallow real NIP-17 traffic: an author we don't recognize as a
+        // plane keeps the gift-wrap reading.
+        val purposes =
+            RelayAuthPurposeDeriver.derive(
+                pendingEvents = listOf(event(GiftWrapEvent.KIND, listOf(alice))),
+                activeFilters = emptyMap(),
+                venueForPlaneAuthor = { null },
+            )
+
+        assertEquals(listOf(AuthPurposeKind.SEND_DM), purposes.map { it.kind })
+        assertEquals(setOf(alice), purposes[0].counterparties)
+    }
+
     @Test
     fun readingMyInboxAndSendingADmAreBothReported() {
         val purposes =
diff --git a/amethyst/src/test/java/com/vitorpamplona/amethyst/service/relayClient/authCommand/model/RelayAuthVenueCoverageTest.kt b/amethyst/src/test/java/com/vitorpamplona/amethyst/service/relayClient/authCommand/model/RelayAuthVenueCoverageTest.kt
new file mode 100644
index 0000000000..6b423aa049
--- /dev/null
+++ b/amethyst/src/test/java/com/vitorpamplona/amethyst/service/relayClient/authCommand/model/RelayAuthVenueCoverageTest.kt
@@ -0,0 +1,125 @@
+/*
+ * 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.service.relayClient.authCommand.model
+
+import com.vitorpamplona.amethyst.commons.relayauth.AuthPurpose
+import com.vitorpamplona.amethyst.commons.relayauth.AuthPurposeKind
+import com.vitorpamplona.amethyst.commons.relayauth.RelayAuthContext
+import com.vitorpamplona.amethyst.commons.relayauth.RelayAuthCustomToggles
+import com.vitorpamplona.amethyst.commons.relayauth.RelayAuthDecision
+import com.vitorpamplona.amethyst.commons.relayauth.RelayAuthPermissionStore
+import com.vitorpamplona.amethyst.commons.relayauth.RelayAuthPolicy
+import com.vitorpamplona.amethyst.commons.relayauth.RelayAuthVerdict
+import kotlinx.coroutines.test.runTest
+import org.junit.Assert.assertEquals
+import org.junit.Test
+
+/**
+ * "…it's my relay, or a room I joined" must actually cover every room the app lets you join. NIP-29
+ * relay groups and Concord communities were invisible to it: neither id is on the public-chat or
+ * NIP-72 community lists the venue check consulted, so a relay whose only job is hosting a group the
+ * user joined fell through to a prompt on every connection (or, with nothing attributable yet, to a
+ * silent denial that left the room empty).
+ */
+class RelayAuthVenueCoverageTest {
+    private val groupRelay = "wss://groups.example.com/"
+    private val concordRelay = "wss://relay.dreamith.to/"
+    private val joinedGroupId = "abcd1234"
+    private val joinedCommunityId = "c".repeat(64)
+
+    private class NoStore : RelayAuthPermissionStore {
+        override suspend fun loadDecision(relayUrl: String): RelayAuthDecision? = null
+
+        override suspend fun storeDecision(
+            relayUrl: String,
+            decision: RelayAuthDecision,
+        ) = Unit
+
+        override suspend fun clearDecision(relayUrl: String) = Unit
+
+        override suspend fun allDecisions(): Map<String, RelayAuthDecision> = emptyMap()
+    }
+
+    private fun ledger(toggles: RelayAuthCustomToggles = RelayAuthCustomToggles()) =
+        RelayAuthPermissionLedger(
+            store = NoStore(),
+            globalPolicy = { RelayAuthPolicy.CUSTOM },
+            customToggles = { toggles },
+            isTrustedVenue = { _, venueId -> venueId == joinedGroupId || venueId == joinedCommunityId },
+            isVenueHostRelay = { it == groupRelay || it == concordRelay },
+        )
+
+    private fun readVenue(
+        relayUrl: String,
+        venueId: String,
+    ) = RelayAuthContext(relayUrl, listOf(AuthPurpose(AuthPurposeKind.READ_VENUE, venues = setOf(venueId))))
+
+    @Test
+    fun readingAJoinedRelayGroupAutoAuthenticates() =
+        runTest {
+            // The group's chat is `#h`-scoped: the subscription declares RELAY_GROUPS, which carries
+            // the group id as its venue. That id is on the kind-10009 list, so the venue toggle covers
+            // it exactly like a public chat the user joined.
+            assertEquals(RelayAuthVerdict.ALLOW, ledger().decide(readVenue(groupRelay, joinedGroupId)))
+        }
+
+    @Test
+    fun readingAJoinedConcordCommunityAutoAuthenticates() =
+        runTest {
+            assertEquals(RelayAuthVerdict.ALLOW, ledger().decide(readVenue(concordRelay, joinedCommunityId)))
+        }
+
+    @Test
+    fun aJoinedRoomsHostAutoAuthenticatesBeforeAnyOfItsFiltersExist() =
+        runTest {
+            // The challenge that matters arrives on connect, before the room's subscription is
+            // assembled — so there is no venue in the context to match. The host relay itself is the
+            // signal: nothing else is on it.
+            assertEquals(RelayAuthVerdict.ALLOW, ledger().decide(RelayAuthContext(groupRelay)))
+        }
+
+    @Test
+    fun aJoinedRoomsHostStillAsksWhenTheVenueToggleIsOff() =
+        runTest {
+            // Turning the toggle off must mean "ask me", not "deny in silence": hosting a room the user
+            // joined is an explanation, so the challenge is attributable even with no purposes.
+            val verdict = ledger(RelayAuthCustomToggles(myRelaysAndVenues = false)).decide(RelayAuthContext(groupRelay))
+            assertEquals(RelayAuthVerdict.ASK, verdict)
+        }
+
+    @Test
+    fun aGroupOnARelayIHaveNotJoinedIsNotAutoAuthenticated() =
+        runTest {
+            // Browsing a group directory names a venue we never joined on a relay that hosts nothing of
+            // ours — explainable, so it asks, but it is never silently granted.
+            val verdict = ledger().decide(readVenue("wss://stranger.example.com/", "somebodyElsesGroup"))
+            assertEquals(RelayAuthVerdict.ASK, verdict)
+        }
+
+    @Test
+    fun aJoinedRoomsHostIsNotAutoAuthenticatedForABystanderAccount() =
+        runTest {
+            // The room belongs to another logged-in account; this one has no first-party reason to be
+            // on the relay, so it asks instead of revealing its npub on its own.
+            val verdict = ledger().decide(readVenue(groupRelay, joinedGroupId), isFirstParty = false)
+            assertEquals(RelayAuthVerdict.ASK, verdict)
+        }
+}
diff --git a/amethyst/src/test/java/com/vitorpamplona/amethyst/service/relayClient/authCommand/model/RelayAuthVenuesTest.kt b/amethyst/src/test/java/com/vitorpamplona/amethyst/service/relayClient/authCommand/model/RelayAuthVenuesTest.kt
new file mode 100644
index 0000000000..a20a331b94
--- /dev/null
+++ b/amethyst/src/test/java/com/vitorpamplona/amethyst/service/relayClient/authCommand/model/RelayAuthVenuesTest.kt
@@ -0,0 +1,111 @@
+/*
+ * 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.service.relayClient.authCommand.model
+
+import com.vitorpamplona.quartz.concord.cord02Community.ConcordCommunityListEntry
+import com.vitorpamplona.quartz.nip01Core.relay.normalizer.RelayUrlNormalizer
+import com.vitorpamplona.quartz.nip29RelayGroups.GroupId
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertTrue
+import org.junit.Test
+
+/** The joined-room sources behind the "…it's my relay, or a room I joined" auto-login toggle. */
+class RelayAuthVenuesTest {
+    private val groupHost = RelayUrlNormalizer.normalize("wss://groups.example.com")
+    private val communityId = "c".repeat(64)
+
+    private val joinedGroups = setOf(GroupId("abcd1234", groupHost))
+
+    private fun community(relays: List<String>) =
+        ConcordCommunityListEntry(
+            id = communityId,
+            owner = "1".repeat(64),
+            ownerSalt = "2".repeat(64),
+            root = "3".repeat(64),
+            relays = relays,
+            name = "Dreamith",
+        )
+
+    @Test
+    fun bothJoinedRoomKindsContributeTheirHostRelays() {
+        val relays = RelayAuthVenues.hostRelays(joinedGroups, listOf(community(listOf("wss://relay.dreamith.to"))))
+
+        assertEquals(
+            setOf(groupHost, RelayUrlNormalizer.normalize("wss://relay.dreamith.to")),
+            relays,
+        )
+    }
+
+    @Test
+    fun aConcordEntrysRawRelayStringIsNormalizedBeforeItIsCompared() {
+        // The community list stores whatever url the community's creator wrote. Comparing that
+        // verbatim against a normalized challenge url is how a whole community silently stops
+        // matching over a trailing slash or an upper-case host.
+        val relays = RelayAuthVenues.hostRelays(emptySet(), listOf(community(listOf("wss://Relay.Dreamith.to/"))))
+
+        assertEquals(setOf(RelayUrlNormalizer.normalize("wss://relay.dreamith.to")), relays)
+    }
+
+    @Test
+    fun anUnparseableRelayIsDroppedRatherThanFailingTheWholeList() {
+        val relays = RelayAuthVenues.hostRelays(joinedGroups, listOf(community(listOf("not a url at all"))))
+
+        assertEquals(setOf(groupHost), relays)
+    }
+
+    @Test
+    fun aJoinedGroupIdAndCommunityIdAreBothJoinedRooms() {
+        val communities = listOf(community(listOf("wss://relay.dreamith.to")))
+
+        assertTrue(RelayAuthVenues.isJoinedRoom("abcd1234", groupHost, joinedGroups, communities))
+        assertTrue(RelayAuthVenues.isJoinedRoom(communityId, groupHost, joinedGroups, communities))
+    }
+
+    @Test
+    fun aRoomIHaveNotJoinedIsNotAJoinedRoom() {
+        val communities = listOf(community(listOf("wss://relay.dreamith.to")))
+
+        assertFalse(RelayAuthVenues.isJoinedRoom("someoneElsesGroup", groupHost, joinedGroups, communities))
+        assertFalse(RelayAuthVenues.isJoinedRoom("d".repeat(64), groupHost, joinedGroups, communities))
+    }
+
+    @Test
+    fun aGroupIdOnlyCountsOnTheRelayIJoinedItOn() {
+        // NIP-29 ids are relay-scoped and often generic — `_` is the spec's relay-wide group — so an
+        // id-only match would let a group merely browsed on some other relay pass for one I joined,
+        // and hand that relay an automatic login.
+        val elsewhere = RelayUrlNormalizer.normalize("wss://other.example.com")
+
+        assertFalse(RelayAuthVenues.isJoinedRoom("abcd1234", elsewhere, joinedGroups, emptyList()))
+        assertFalse(RelayAuthVenues.isJoinedRoom("abcd1234", null, joinedGroups, emptyList()))
+    }
+
+    @Test
+    fun aCommunityIdCountsWhereverItIsServed() {
+        // Unlike a group id, a Concord community id is a 64-hex derived value that names exactly one
+        // community anywhere — and a community's own relays are covered by hostRelays regardless.
+        val elsewhere = RelayUrlNormalizer.normalize("wss://other.example.com")
+        val communities = listOf(community(listOf("wss://relay.dreamith.to")))
+
+        assertTrue(RelayAuthVenues.isJoinedRoom(communityId, elsewhere, emptySet(), communities))
+    }
+}
diff --git a/commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/model/concord/ConcordCommunitySession.kt b/commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/model/concord/ConcordCommunitySession.kt
index 58f6156b89..ba91cfb8e4 100644
--- a/commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/model/concord/ConcordCommunitySession.kt
+++ b/commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/model/concord/ConcordCommunitySession.kt
@@ -277,6 +277,22 @@ class ConcordCommunitySession(
      */
     fun channelAddresses(): Set<HexKey> = lock.withLock { channelKeysByAddress.keys + historicalChannelKeysByAddress.keys }
 
+    /**
+     * True when [address] is one of this community's plane addresses — Control (current or a prior
+     * epoch we still hold), Guestbook, next-epoch rekey, or any folded Chat Plane.
+     *
+     * A membership test rather than a set to iterate, because the caller is the NIP-42 auth path
+     * asking "whose room is this wrap for?" on every challenge: answering that from
+     * [channelAddresses] + [historicalControlPlaneAddresses] allocates a fresh union per community
+     * per question, where four map lookups do.
+     */
+    fun ownsPlane(address: HexKey): Boolean =
+        address == controlPlaneAddress ||
+            address == guestbookAddress ||
+            address == nextBaseRekeyAddress ||
+            address in historicalControlKeys ||
+            lock.withLock { address in channelKeysByAddress || address in historicalChannelKeysByAddress }
+
     /** The Chat Plane stream address for [channelIdHex], once this community has folded that channel (else null). */
     fun channelPlaneAddress(channelIdHex: HexKey): HexKey? = lock.withLock { channelKeysByAddress.entries.firstOrNull { it.value.first == channelIdHex }?.key }
 
diff --git a/commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/model/concord/ConcordSessionManager.kt b/commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/model/concord/ConcordSessionManager.kt
index 0bb8faba0f..44da2aa96a 100644
--- a/commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/model/concord/ConcordSessionManager.kt
+++ b/commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/model/concord/ConcordSessionManager.kt
@@ -157,6 +157,13 @@ class ConcordSessionManager(
         return outcome.claimed
     }
 
+    /**
+     * The joined community [planeAddress] streams for, or null when it isn't one of ours. Lets the
+     * NIP-42 auth path name a pending plane wrap as a post into that community instead of reading its
+     * throwaway `p` tag as a DM recipient (see [ConcordSessionRegistry.communityIdForPlane]).
+     */
+    fun communityIdForPlane(planeAddress: HexKey): HexKey? = registry.communityIdForPlane(planeAddress)
+
     fun sessions() = registry.sessions()
 
     fun sessionFor(communityId: HexKey) = registry.sessionFor(communityId)
diff --git a/commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/model/concord/ConcordSessionRegistry.kt b/commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/model/concord/ConcordSessionRegistry.kt
index 09be414805..22c7dd47de 100644
--- a/commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/model/concord/ConcordSessionRegistry.kt
+++ b/commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/model/concord/ConcordSessionRegistry.kt
@@ -108,6 +108,19 @@ class ConcordSessionRegistry(
             out
         }
 
+    /**
+     * The joined community whose planes [planeAddress] belongs to, or null when no session claims it.
+     *
+     * The NIP-42 auth path reads this to recognize an outbound plane wrap for what it is. A wrap is
+     * signed by the plane's stream key and `p`-tagged to a throwaway pubkey, so on tag shape alone it
+     * is indistinguishable from a NIP-17 gift wrap — a post into a community would otherwise be
+     * explained to the user as a direct message to a stranger nobody can name.
+     */
+    fun communityIdForPlane(planeAddress: HexKey): HexKey? =
+        lock.withLock {
+            sessions.entries.firstOrNull { (_, session) -> session.ownsPlane(planeAddress) }?.key
+        }
+
     /**
      * Routes an inbound stream [wrap] to whichever session recognizes it, returning that session's
      * [ConcordIngestOutcome] (or [ConcordIngestOutcome.NOT_MINE] if none claim it). A wrap belongs to
diff --git a/commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/relayauth/RelayAuthResolver.kt b/commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/relayauth/RelayAuthResolver.kt
index 4445f01f4f..d9030c0889 100644
--- a/commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/relayauth/RelayAuthResolver.kt
+++ b/commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/relayauth/RelayAuthResolver.kt
@@ -24,8 +24,8 @@ package com.vitorpamplona.amethyst.commons.relayauth
  * The per-situation switches applied under [RelayAuthPolicy.CUSTOM]. Each independently authorizes
  * one category of relay; a situation with no matching toggle falls through to a prompt.
  *
- * @param myRelaysAndVenues your own relays, plus venues (public chats, communities, live streams)
- *   you've joined, subscribed to, or favorited.
+ * @param myRelaysAndVenues your own relays, plus venues (public chats, NIP-72 communities, live
+ *   streams, NIP-29 relay groups, Concord communities) you've joined, subscribed to, or favorited.
  * @param readFollows a relay serving the outbox of someone you follow (to download their posts).
  * @param messageFollows a relay serving the inbox of someone you follow (to send DMs, replies,
  *   notifications).
@@ -49,8 +49,10 @@ data class RelayAuthCustomToggles(
  * @param policy the top-level [RelayAuthPolicy].
  * @param toggles the [RelayAuthCustomToggles] applied when [policy] is [RelayAuthPolicy.CUSTOM].
  * @param isInMyRelayList the relay is in the user's own relay list.
- * @param servesTrustedVenue this relay hosts a venue (public chat, community, or live stream) the
- *   user has joined, subscribed to, or favorited.
+ * @param servesTrustedVenue this relay hosts a venue the user has joined, subscribed to, or
+ *   favorited — a public chat, a NIP-72 community, a live stream, a NIP-29 relay group, or a Concord
+ *   community. True either because a purpose names one of those venues or because the relay itself is
+ *   a joined room's host (a group/community relay serves nothing else).
  * @param servesFollowedReadCounterparty a followed user's outbox is served here (reading them).
  * @param servesFollowedWriteCounterparty a followed user's inbox is served here (messaging them).
  * @param servesStrangerWriteCounterparty a non-followed user's inbox is served here (messaging them).