feat(quartz): AdminCommandEvent for audio-room kick (kind 4312)

Adds the ephemeral host-issued admin command event nostrnests uses
for kick (and future moderation actions like mute/ban):

  AdminCommandEvent — kind 4312. Carries one Action (currently just
  KICK) in `content`, an `a`-tag pointing at the room (kind-30312
  address), and a `p`-tag for the target. The verb-in-content shape
  lets us extend with new actions without a wire schema bump.

  AdminCommandEvent.kick(roomATag, target) — builder.

  AdminCommandEvent.action() / .targetPubkey() / .room() — accessors
  for the recipient side. Unknown actions return null (forward-compat
  with verbs not yet in the enum).

  EventFactory — registered so LocalCache + Filter.match can decode
  incoming events properly.

Authority enforcement is the CLIENT'S job — the relay just stores
and forwards. Recipients filter on `kinds=[4312], #a=[room],
#p=[me]` and only honour commands whose signer is a participant
marked HOST or MODERATOR on the active kind-30312. The next commit
wires that gating + the disconnect side effect into AudioRoomViewModel.

Tests:
  * Build a kick template and verify the action/address/target tags
  * Round-trip parse exposes room, target pubkey and action
  * Unknown verb in `content` returns null from action()
  * Missing tags return null from accessors (no throw)

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/experimental/audiorooms/admin/AdminCommandEvent.kt

@@ -0,0 +1,99 @@
+/*
+ * 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.quartz.experimental.audiorooms.admin
+
+import androidx.compose.runtime.Immutable
+import com.vitorpamplona.quartz.nip01Core.core.Event
+import com.vitorpamplona.quartz.nip01Core.core.HexKey
+import com.vitorpamplona.quartz.nip01Core.signers.eventTemplate
+import com.vitorpamplona.quartz.nip01Core.tags.aTag.ATag
+import com.vitorpamplona.quartz.nip01Core.tags.aTag.aTag
+import com.vitorpamplona.quartz.nip01Core.tags.people.PTag
+import com.vitorpamplona.quartz.utils.TimeUtils
+
+/**
+ * Ephemeral host-issued admin command for nostrnests audio rooms
+ * (kind 4312). Carries one of [Action] targeting a single
+ * [PTag] within the room identified by [ATag].
+ *
+ * Recipients filter on `kinds=[4312], #a=[room], #p=[me]` and only
+ * honour commands whose signer is a participant marked HOST or
+ * MODERATOR on the active kind-30312 — relays don't enforce this,
+ * the client must.
+ *
+ * The tag layout matches the action / role-mutation events
+ * nostrnests emits today; the action keyword goes in `content`
+ * rather than as a separate tag so we can extend it with new
+ * verbs without re-versioning the spec.
+ */
+@Immutable
+class AdminCommandEvent(
+    id: HexKey,
+    pubKey: HexKey,
+    createdAt: Long,
+    tags: Array<Array<String>>,
+    content: String,
+    sig: HexKey,
+) : Event(id, pubKey, createdAt, KIND, tags, content, sig) {
+    /** The room this command applies to, if a single `a`-tag is present. */
+    fun room(): String? = tags.firstOrNull { it.firstOrNull() == "a" }?.getOrNull(1)
+
+    /** The pubkey the host is acting on. */
+    fun targetPubkey(): HexKey? = tags.firstOrNull { it.firstOrNull() == "p" }?.getOrNull(1)
+
+    /**
+     * The verb (e.g. "kick"). Returned uppercase so callers can
+     * `when (event.action()) { Action.KICK -> ... }` cleanly; the
+     * raw content is preserved on the event so a future verb can
+     * be inspected as a string.
+     */
+    fun action(): Action? = Action.fromCode(content)
+
+    enum class Action(
+        val code: String,
+    ) {
+        KICK("kick"),
+        ;
+
+        companion object {
+            fun fromCode(code: String): Action? = entries.firstOrNull { it.code.equals(code, ignoreCase = true) }
+        }
+    }
+
+    companion object {
+        const val KIND = 4312
+        const val ALT = "Audio room admin command"
+
+        /**
+         * Build a kick command tagged for [room] and [target]. The
+         * content carries the verb so the same kind can grow new
+         * actions (mute, ban, …) without a wire schema bump.
+         */
+        fun kick(
+            room: ATag,
+            target: HexKey,
+            createdAt: Long = TimeUtils.now(),
+        ) = eventTemplate<AdminCommandEvent>(KIND, Action.KICK.code, createdAt) {
+            aTag(room)
+            add(PTag(target).toTagArray())
+        }
+    }
+}

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/utils/EventFactory.kt

@@ -28,6 +28,7 @@ import com.vitorpamplona.quartz.experimental.attestations.recommendation.Attesto
 import com.vitorpamplona.quartz.experimental.attestations.request.AttestationRequestEvent
 import com.vitorpamplona.quartz.experimental.audio.header.AudioHeaderEvent
 import com.vitorpamplona.quartz.experimental.audio.track.AudioTrackEvent
+import com.vitorpamplona.quartz.experimental.audiorooms.admin.AdminCommandEvent
 import com.vitorpamplona.quartz.experimental.edits.TextNoteModificationEvent
 import com.vitorpamplona.quartz.experimental.ephemChat.chat.EphemeralChatEvent
 import com.vitorpamplona.quartz.experimental.ephemChat.list.EphemeralChatListEvent
@@ -456,6 +457,7 @@ class EventFactory {
                 MeetingRoomEvent.KIND -> MeetingRoomEvent(id, pubKey, createdAt, tags, content, sig)
                 MeetingRoomPresenceEvent.KIND -> MeetingRoomPresenceEvent(id, pubKey, createdAt, tags, content, sig)
                 MeetingSpaceEvent.KIND -> MeetingSpaceEvent(id, pubKey, createdAt, tags, content, sig)
+                AdminCommandEvent.KIND -> AdminCommandEvent(id, pubKey, createdAt, tags, content, sig)
                 MintRecommendationEvent.KIND -> MintRecommendationEvent(id, pubKey, createdAt, tags, content, sig)
                 MediaFollowListEvent.KIND -> MediaFollowListEvent(id, pubKey, createdAt, tags, content, sig)
                 MediaStarterPackEvent.KIND -> MediaStarterPackEvent(id, pubKey, createdAt, tags, content, sig)

quartz/src/commonTest/kotlin/com/vitorpamplona/quartz/experimental/audiorooms/admin/AdminCommandEventTest.kt

@@ -0,0 +1,92 @@
+/*
+ * 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.quartz.experimental.audiorooms.admin
+
+import com.vitorpamplona.quartz.nip01Core.tags.aTag.ATag
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertNull
+import kotlin.test.assertTrue
+
+class AdminCommandEventTest {
+    private val host = "a".repeat(64)
+    private val target = "b".repeat(64)
+    private val roomATag = ATag(kind = 30312, pubKeyHex = host, dTag = "rt-1", relay = null)
+
+    @Test
+    fun kickTemplateCarriesActionContentAddressAndTarget() {
+        val template = AdminCommandEvent.kick(roomATag, target, createdAt = 100L)
+        assertEquals(AdminCommandEvent.KIND, template.kind)
+        assertEquals(AdminCommandEvent.Action.KICK.code, template.content)
+        // Single `a` tag pointing at the room.
+        val aTag = template.tags.firstOrNull { it.firstOrNull() == "a" }
+        assertEquals(roomATag.toTag(), aTag?.getOrNull(1))
+        // Single `p` tag pointing at the kicked user.
+        val pTag = template.tags.firstOrNull { it.firstOrNull() == "p" }
+        assertEquals(target, pTag?.getOrNull(1))
+    }
+
+    @Test
+    fun parseRoundTripExposesRoomTargetAction() {
+        val template = AdminCommandEvent.kick(roomATag, target, createdAt = 100L)
+        val event =
+            AdminCommandEvent(
+                id = "0".repeat(64),
+                pubKey = host,
+                createdAt = template.createdAt,
+                tags = template.tags,
+                content = template.content,
+                sig = "0".repeat(128),
+            )
+        assertEquals(AdminCommandEvent.Action.KICK, event.action())
+        assertEquals(target, event.targetPubkey())
+        assertTrue(event.room()!!.startsWith("30312:"))
+    }
+
+    @Test
+    fun unknownActionReturnsNull() {
+        val event =
+            AdminCommandEvent(
+                id = "0".repeat(64),
+                pubKey = host,
+                createdAt = 100L,
+                tags = arrayOf(arrayOf("a", "30312:host:rt"), arrayOf("p", target)),
+                content = "haunt",
+                sig = "0".repeat(128),
+            )
+        assertNull(event.action())
+    }
+
+    @Test
+    fun missingTagsReturnNullAccessors() {
+        val event =
+            AdminCommandEvent(
+                id = "0".repeat(64),
+                pubKey = host,
+                createdAt = 100L,
+                tags = arrayOf(),
+                content = "kick",
+                sig = "0".repeat(128),
+            )
+        assertNull(event.targetPubkey())
+        assertNull(event.room())
+    }
+}