diff --git a/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/concord/cord03Channels/ConcordChannelKeyring.kt b/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/concord/cord03Channels/ConcordChannelKeyring.kt
index bdedd2b988..5a50702174 100644
--- a/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/concord/cord03Channels/ConcordChannelKeyring.kt
+++ b/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/concord/cord03Channels/ConcordChannelKeyring.kt
@@ -28,6 +28,7 @@ import com.vitorpamplona.quartz.nip01Core.core.HexKey
 import com.vitorpamplona.quartz.nip01Core.core.toHexKey
 import com.vitorpamplona.quartz.utils.TimeUtils
 import kotlinx.serialization.json.JsonArray
+import kotlinx.serialization.json.JsonElement
 import kotlinx.serialization.json.JsonObject
 import kotlinx.serialization.json.JsonPrimitive
 import kotlinx.serialization.json.contentOrNull
@@ -61,6 +62,9 @@ object ConcordChannelKeyring {
     const val CHANNEL_CUTS = "channel_cuts"
     const val PRIORS = "priors"
 
+    /** How many retired keys a channel keeps in `priors`, newest epochs first. */
+    const val MAX_PRIORS = 32
+
     private val HEX64 = Regex("^[0-9a-fA-F]{64}$")
 
     /** The current key held for [channelIdHex], or null (a keyless listing is not a key). */
@@ -185,9 +189,15 @@ object ConcordChannelKeyring {
                 JsonObject(mapOf("key" to JsonPrimitive(k), "epoch" to JsonPrimitive(epoch), "retired_at" to JsonPrimitive(at)))
             }
         if (added.isEmpty()) return extras
-        return JsonObject(extras + (PRIORS to JsonArray(existing + added)))
+        // Bounded: every rotation adds one, and a List entry that outgrows its fragment fails every
+        // List write (joins and leaves included), which is worse than losing the oldest era's history.
+        val all = existing + added
+        val kept = if (all.size <= MAX_PRIORS) all else all.sortedByDescending { priorEpoch(it) }.take(MAX_PRIORS)
+        return JsonObject(extras + (PRIORS to JsonArray(kept)))
     }
 
+    private fun priorEpoch(prior: JsonElement): Long = ((prior as? JsonObject)?.get("epoch") as? JsonPrimitive)?.longOrNull ?: Long.MIN_VALUE
+
     /**
      * [entry] after a rotation to [cutEpoch] cut this member from [channelIdHex] (CORD-06 §2): the
      * key leaves `channels` and the cut is recorded, so no older key can come back.
diff --git a/quartz/src/commonTest/kotlin/com/vitorpamplona/quartz/concord/cord03Channels/ConcordChannelKeyringTest.kt b/quartz/src/commonTest/kotlin/com/vitorpamplona/quartz/concord/cord03Channels/ConcordChannelKeyringTest.kt
index 82c2dd4087..d3081dd53c 100644
--- a/quartz/src/commonTest/kotlin/com/vitorpamplona/quartz/concord/cord03Channels/ConcordChannelKeyringTest.kt
+++ b/quartz/src/commonTest/kotlin/com/vitorpamplona/quartz/concord/cord03Channels/ConcordChannelKeyringTest.kt
@@ -145,6 +145,17 @@ class ConcordChannelKeyringTest {
         assertFalse(ConcordChannelKeyring.historicalKeys(rotated, chan).any { it.key == "13".repeat(32) })
     }
 
+    @Test
+    fun priorsKeepOnlyTheNewestEpochs() {
+        var e = entry(listOf(PrivateChannelKey(chan, 1.toString(16).padStart(64, '0'), 1, "mods")))
+        for (epoch in 2L..(ConcordChannelKeyring.MAX_PRIORS + 10)) {
+            e = assertNotNull(ConcordChannelKeyring.withRotatedKey(e, chan, epoch.toString(16).padStart(64, '0'), epoch, retiredAt = epoch))
+        }
+        val epochs = ConcordChannelKeyring.historicalKeys(e, chan).map { it.epoch }
+        assertEquals(ConcordChannelKeyring.MAX_PRIORS, epochs.size)
+        assertEquals(ConcordChannelKeyring.MAX_PRIORS + 9L, epochs.first())
+    }
+
     @Test
     fun aRotationKeepsEveryEarlierKeyReadableAfterARoundTrip() {
         // A channel created after the join has no `seed` anchor: the List is the only place its