diff --git a/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/concord/cord05Invites/CommunityInvite.kt b/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/concord/cord05Invites/CommunityInvite.kt
new file mode 100644
index 0000000000..95d94ffc61
--- /dev/null
+++ b/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/concord/cord05Invites/CommunityInvite.kt
@@ -0,0 +1,69 @@
+/*
+ * 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.concord.cord05Invites
+
+import kotlinx.serialization.SerialName
+import kotlinx.serialization.Serializable
+
+/** An encrypted-media image reference (CORD-02): where the bytes are and how to decrypt them. */
+@Serializable
+class ImagePointer(
+    val url: String = "",
+    val key: String = "",
+    val nonce: String = "",
+    val hash: String = "",
+)
+
+/** A channel grant carried in an invite: its id, delivered [key], [epoch], and [name]. */
+@Serializable
+class InviteChannel(
+    val id: String,
+    val key: String,
+    val epoch: Long,
+    val name: String = "",
+)
+
+/**
+ * The contents of a Concord invite (CORD-05) — everything a joiner needs to
+ * become a member: the self-certifying [communityId] with its [owner]/[ownerSalt]
+ * proof, the access [communityRoot] at [rootEpoch], per-[channels] grants,
+ * bootstrap [relays], display [name]/[icon], optional [expiresAt] and creator
+ * attribution.
+ *
+ * Field names are pinned to the Concord v2 reference client (snake_case on the
+ * wire) so bundles interoperate. This object is JSON-serialized and encrypted —
+ * into a kind-33301 bundle (link invites) or a NIP-59 giftwrap (direct invites).
+ */
+@Serializable
+class CommunityInvite(
+    @SerialName("community_id") val communityId: String,
+    val owner: String,
+    @SerialName("owner_salt") val ownerSalt: String,
+    @SerialName("community_root") val communityRoot: String,
+    @SerialName("root_epoch") val rootEpoch: Long = 0,
+    val channels: List<InviteChannel> = emptyList(),
+    val relays: List<String> = emptyList(),
+    val name: String = "",
+    val icon: ImagePointer? = null,
+    @SerialName("expires_at") val expiresAt: Long? = null,
+    @SerialName("creator_npub") val creatorNpub: String? = null,
+    val label: String? = null,
+)
diff --git a/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/concord/cord05Invites/ConcordInviteBundle.kt b/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/concord/cord05Invites/ConcordInviteBundle.kt
new file mode 100644
index 0000000000..0d301703a4
--- /dev/null
+++ b/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/concord/cord05Invites/ConcordInviteBundle.kt
@@ -0,0 +1,122 @@
+/*
+ * 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.concord.cord05Invites
+
+import com.vitorpamplona.quartz.concord.cord04Roles.ConcordJson
+import com.vitorpamplona.quartz.concord.crypto.ConcordKeyDerivation
+import com.vitorpamplona.quartz.concord.events.ConcordKinds
+import com.vitorpamplona.quartz.nip01Core.core.Event
+import com.vitorpamplona.quartz.nip01Core.core.hexToByteArrayOrNull
+import com.vitorpamplona.quartz.nip01Core.core.toHexKey
+import com.vitorpamplona.quartz.nip01Core.crypto.KeyPair
+import com.vitorpamplona.quartz.nip01Core.signers.NostrSignerSync
+import com.vitorpamplona.quartz.nip44Encryption.Nip44
+import com.vitorpamplona.quartz.utils.RandomInstance
+
+/** A freshly minted public invite link: the shareable URL, the link keys, and the bundle to publish. */
+class MintedInviteLink(
+    val url: String,
+    val linkSignerPubKey: String,
+    val linkSignerPrivKey: ByteArray,
+    val token: ByteArray,
+    val bundleEvent: Event,
+)
+
+/**
+ * The public invite bundle (CORD-05): a kind-33301 addressable event whose
+ * content is the [CommunityInvite] NIP-44-encrypted under the bundle key derived
+ * from the link's 16-byte unlock token. The event is signed by a per-link
+ * `link_signer` keypair (so re-posting refreshes keys) and tagged
+ * `["d",""],["vsk","6"]`.
+ *
+ * A server that indexes the naddr never holds the token, so it can never open the
+ * bundle. Pinned to the Concord v2 reference client.
+ */
+object ConcordInviteBundle {
+    const val KIND = ConcordKinds.INVITE_BUNDLE
+    const val TAG_D = "d"
+    const val TAG_VSK = "vsk"
+    const val VSK_LIVE = "6"
+
+    private fun json(invite: CommunityInvite) = ConcordJson.instance.encodeToString(CommunityInvite.serializer(), invite)
+
+    /** Builds a kind-33301 bundle event carrying [invite], encrypted under [token] and signed by [linkSignerPrivKey]. */
+    fun build(
+        linkSignerPrivKey: ByteArray,
+        token: ByteArray,
+        invite: CommunityInvite,
+        createdAt: Long,
+    ): Event {
+        val bundleKey = ConcordKeyDerivation.inviteBundleKey(token)
+        val content = Nip44.v2.encrypt(json(invite), bundleKey).encodePayload()
+        val signer = NostrSignerSync(KeyPair(privKey = linkSignerPrivKey))
+        return signer.signNormal(createdAt, KIND, arrayOf(arrayOf(TAG_D, ""), arrayOf(TAG_VSK, VSK_LIVE)), content)
+    }
+
+    /** Decrypts a kind-33301 bundle [event] with the link [token], or null if it isn't a valid bundle. */
+    fun parse(
+        event: Event,
+        token: ByteArray,
+    ): CommunityInvite? {
+        if (event.kind != KIND) return null
+        return try {
+            val bundleKey = ConcordKeyDerivation.inviteBundleKey(token)
+            ConcordJson.decodeOrNull<CommunityInvite>(Nip44.v2.decrypt(event.content, bundleKey))
+        } catch (_: Exception) {
+            null
+        }
+    }
+
+    /**
+     * Validates that an [invite]'s owner + salt actually reproduce its
+     * community_id (CORD-02 self-certification), so a bundle can't smuggle a false
+     * owner or a fake key for a real community.
+     */
+    fun validate(invite: CommunityInvite): Boolean {
+        val owner = invite.owner.hexToByteArrayOrNull() ?: return false
+        val salt = invite.ownerSalt.hexToByteArrayOrNull() ?: return false
+        return ConcordKeyDerivation.communityId(owner, salt).toHexKey() == invite.communityId
+    }
+
+    /** True if the invite has an expiry in the past (blocks joining; preview still renders). Time in unix ms. */
+    fun isExpired(
+        invite: CommunityInvite,
+        nowMs: Long,
+    ): Boolean = invite.expiresAt?.let { it < nowMs } ?: false
+
+    /**
+     * Mints a complete public invite link for [invite]: generates a fresh 16-byte
+     * token and a per-link signer, builds the bundle event and the shareable
+     * `{base}/invite/{naddr}#{fragment}` URL (with optional bootstrap [relays]).
+     */
+    fun mintLink(
+        base: String,
+        invite: CommunityInvite,
+        createdAt: Long,
+        relays: List<String>? = null,
+    ): MintedInviteLink {
+        val token = RandomInstance.bytes(16)
+        val linkSigner = KeyPair()
+        val bundleEvent = build(linkSigner.privKey!!, token, invite, createdAt)
+        val url = ConcordInviteLink.buildUrl(base, linkSigner.pubKey.toHexKey(), token, relays)
+        return MintedInviteLink(url, linkSigner.pubKey.toHexKey(), linkSigner.privKey, token, bundleEvent)
+    }
+}
diff --git a/quartz/src/commonTest/kotlin/com/vitorpamplona/quartz/concord/cord05Invites/ConcordInviteJoinFlowTest.kt b/quartz/src/commonTest/kotlin/com/vitorpamplona/quartz/concord/cord05Invites/ConcordInviteJoinFlowTest.kt
new file mode 100644
index 0000000000..3d365679c8
--- /dev/null
+++ b/quartz/src/commonTest/kotlin/com/vitorpamplona/quartz/concord/cord05Invites/ConcordInviteJoinFlowTest.kt
@@ -0,0 +1,116 @@
+/*
+ * 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.concord.cord05Invites
+
+import com.vitorpamplona.quartz.concord.cord02Community.ConcordCommunityFactory
+import com.vitorpamplona.quartz.concord.cord02Community.ConcordCommunityState
+import com.vitorpamplona.quartz.concord.cord04Roles.ControlEdition
+import com.vitorpamplona.quartz.concord.crypto.ConcordKeyDerivation
+import com.vitorpamplona.quartz.concord.envelope.ConcordStreamEnvelope
+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 kotlinx.coroutines.test.runTest
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertFalse
+import kotlin.test.assertNotNull
+import kotlin.test.assertNull
+import kotlin.test.assertTrue
+
+/**
+ * The full public-invite path: create a community → mint an invite link → a
+ * stranger redeems the link, reconstructs the root, and reads the community's
+ * genesis Control Plane. This is the create-and-invite flow the app drives.
+ */
+class ConcordInviteJoinFlowTest {
+    private val owner = NostrSignerInternal(KeyPair())
+
+    private suspend fun inviteFor(community: com.vitorpamplona.quartz.concord.cord02Community.NewConcordCommunity) =
+        CommunityInvite(
+            communityId = community.communityIdHex,
+            owner = community.ownerPubKey,
+            ownerSalt = community.ownerSalt.toHexKey(),
+            communityRoot = community.communityRoot.toHexKey(),
+            rootEpoch = community.rootEpoch,
+            relays = listOf("wss://relay.example"),
+            name = "Nostrichs",
+        )
+
+    @Test
+    fun createMintRedeemAndRead() =
+        runTest {
+            val community = ConcordCommunityFactory.create(owner, "Nostrichs", createdAt = 1L, relays = listOf("wss://relay.example"))
+            val minted = ConcordInviteBundle.mintLink("https://vector.chat", inviteFor(community), createdAt = 1L, relays = listOf("wss://relay.example"))
+
+            // The joiner only has the URL. Extract the token from the private fragment.
+            val parsedUrl = ConcordInviteLink.parseUrl(minted.url)
+            assertNotNull(parsedUrl)
+            assertEquals(minted.linkSignerPubKey, parsedUrl.linkSignerPubKey)
+
+            // Decrypt the fetched bundle with that token and verify self-certification.
+            val invite = ConcordInviteBundle.parse(minted.bundleEvent, parsedUrl.fragment.token)
+            assertNotNull(invite)
+            assertTrue(ConcordInviteBundle.validate(invite))
+            assertEquals(community.communityIdHex, invite.communityId)
+
+            // Reconstruct the root, derive the Control Plane, and read the genesis.
+            val controlPlane =
+                ConcordKeyDerivation.controlPlaneKey(
+                    invite.communityRoot.hexToByteArray(),
+                    invite.communityId.hexToByteArray(),
+                    invite.rootEpoch,
+                )
+            val editions = community.genesisWraps.mapNotNull { ControlEdition.fromRumor(ConcordStreamEnvelope.open(it, controlPlane).rumor) }
+            val state = ConcordCommunityState.fold(editions, invite.owner)
+            assertEquals("Nostrichs", state.metadata?.name)
+            assertTrue(state.channels.isNotEmpty()) // #general is visible to the new member
+        }
+
+    @Test
+    fun wrongTokenCannotOpenTheBundle() =
+        runTest {
+            val community = ConcordCommunityFactory.create(owner, "Secret", createdAt = 1L)
+            val minted = ConcordInviteBundle.mintLink("https://vector.chat", inviteFor(community), createdAt = 1L)
+            assertNull(ConcordInviteBundle.parse(minted.bundleEvent, ByteArray(16) { 0x01 })) // random token fails
+        }
+
+    @Test
+    fun validateRejectsForgedOwner() {
+        // owner + salt that do not reproduce the claimed community_id
+        val forged =
+            CommunityInvite(
+                communityId = "00".repeat(32),
+                owner = KeyPair().pubKey.toHexKey(),
+                ownerSalt = "aa".repeat(32),
+                communityRoot = "bb".repeat(32),
+            )
+        assertFalse(ConcordInviteBundle.validate(forged))
+    }
+
+    @Test
+    fun expiryBlocksJoiningButNotPreview() {
+        val invite = CommunityInvite("id", "o", "s", "r", expiresAt = 1_000L)
+        assertTrue(ConcordInviteBundle.isExpired(invite, nowMs = 2_000L))
+        assertFalse(ConcordInviteBundle.isExpired(invite, nowMs = 500L))
+    }
+}