diff --git a/commons/src/commonTest/kotlin/com/vitorpamplona/amethyst/commons/model/concord/ConcordBannedTypingTest.kt b/commons/src/commonTest/kotlin/com/vitorpamplona/amethyst/commons/model/concord/ConcordBannedTypingTest.kt
new file mode 100644
index 0000000000..a89e26789e
--- /dev/null
+++ b/commons/src/commonTest/kotlin/com/vitorpamplona/amethyst/commons/model/concord/ConcordBannedTypingTest.kt
@@ -0,0 +1,113 @@
+/*
+ * 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.model.concord
+
+import com.vitorpamplona.amethyst.commons.actions.ConcordActions
+import com.vitorpamplona.amethyst.commons.actions.ConcordModeration
+import com.vitorpamplona.quartz.concord.cord02Community.ConcordCommunityFactory
+import com.vitorpamplona.quartz.concord.cord02Community.ConcordCommunityListEntry
+import com.vitorpamplona.quartz.concord.cord02Community.NewConcordCommunity
+import com.vitorpamplona.quartz.nip01Core.core.hexToByteArray
+import com.vitorpamplona.quartz.nip01Core.core.toHexKey
+import com.vitorpamplona.quartz.nip01Core.crypto.KeyPair
+import com.vitorpamplona.quartz.nip01Core.signers.NostrSignerInternal
+import com.vitorpamplona.quartz.utils.TimeUtils
+import kotlinx.coroutines.test.runTest
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertTrue
+
+/**
+ * The receive half of the soft-ban audit's A4: a banned member's typing heartbeat must not reach
+ * the "… is typing" row. The send half is a guard in the app's own action layer, which a malicious
+ * or modified client simply won't run — so this filter, on the receive side, is the only one that
+ * actually protects the room. It shipped without a test; this is it.
+ */
+class ConcordBannedTypingTest {
+    private val owner = NostrSignerInternal(KeyPair())
+    private val troll = NostrSignerInternal(KeyPair())
+    private val regular = NostrSignerInternal(KeyPair())
+
+    private fun entryFor(community: NewConcordCommunity) =
+        ConcordCommunityListEntry(
+            id = community.communityIdHex,
+            owner = community.ownerPubKey,
+            ownerSalt = community.ownerSalt.toHexKey(),
+            root = community.communityRoot.toHexKey(),
+            rootEpoch = community.rootEpoch,
+            controlPk = community.controlPkHex,
+            controlRoot = community.controlRoot.toHexKey(),
+            relays = listOf("wss://r.example"),
+            name = "Nostrichs",
+        )
+
+    @Test
+    fun dropsABannedMembersTypingHeartbeatAndKeepsEveryoneElses() =
+        runTest {
+            val community = ConcordCommunityFactory.create(owner, "Nostrichs", createdAt = 1L, relays = listOf("wss://r.example"))
+            val session = ConcordCommunitySession(entryFor(community), owner.pubKey)
+            community.genesisWraps.forEach { session.ingest(it) }
+
+            val channelId = community.generalChannelIdHex
+            val plane = ConcordActions.publicChannel(community.communityRoot, community.generalChannelId, community.rootEpoch)
+            val now = TimeUtils.now()
+
+            // Ban first, so what follows tests the filter rather than an entry seated before the ban.
+            // The banlist edition folds through the Control Plane exactly as it would on the wire.
+            session.ingest(
+                ConcordModeration.ban(
+                    actor = owner,
+                    controlPlane = session.controlPlaneKeys(),
+                    communityId = community.communityIdHex.hexToByteArray(),
+                    member = troll.pubKey,
+                    current = session.controlEditions(),
+                    createdAt = now,
+                    owner = community.ownerPubKey,
+                ),
+            )
+            assertTrue(
+                session.state.value
+                    ?.authority
+                    ?.isBanned(troll.pubKey) == true,
+                "the ban must have folded before the heartbeats are judged",
+            )
+
+            // The banned member keeps broadcasting — a modified client ignores the send-side guard.
+            session.ingest(ConcordActions.buildChannelTyping(troll, plane, channelId, community.rootEpoch, now))
+            assertEquals(
+                null,
+                session.typing.value[channelId]?.get(troll.pubKey.lowercase()),
+                "a banned member must never be seated in the typing row",
+            )
+
+            // The filter is targeted, not a blanket mute: an ordinary member still types normally.
+            session.ingest(ConcordActions.buildChannelTyping(regular, plane, channelId, community.rootEpoch, now))
+            assertTrue(
+                session.typing.value[channelId]?.containsKey(regular.pubKey.lowercase()) == true,
+                "an unbanned member's typing heartbeat must still show",
+            )
+            assertEquals(
+                null,
+                session.typing.value[channelId]?.get(troll.pubKey.lowercase()),
+                "seating one member must not drag the banned one in",
+            )
+        }
+}