cleaner invitation step messages

client/helpers/bgPollHelper.go

@@ -133,14 +133,20 @@ func ConsumeInboxFile(messageFilename string) ([]string, []string, string, error
 	}
 	// check if invitation answer (step-2 answer waiting for the initiator)
 	if fromServerMessage.Invitation != nil {
-		peer, _, invErr := invmsgs.Step3InitiatorFinalizesInviteeAndCreatesContactCard(fromServerMessage.Invitation)
+		invBytes, marshalErr := proto.Marshal(fromServerMessage.Invitation)
-		if invErr == nil && peer != nil {
+		if marshalErr == nil {
-			// Auto-send step-3 CC to invitee's servers.
+			step3Bytes, invErr := invmsgs.Step3InitiatorFinalizesInviteeAndCreatesContactCard(invBytes)
-			msgs, sendErr := invsrv.Step3PostCard(peer.InvitationId)
+			if invErr == nil && step3Bytes != nil {
-			if sendErr == nil {
+				peer := client.GetConfig().GetIdentity().Peers.GetFromInvitationId(fromServerMessage.Invitation.Uuid)
-				for i, bytemsg := range msgs {
+				if peer != nil {
-					if i < len(peer.ContactPullServers) {
+					// Auto-send step-3 CC to invitee's servers.
-						meowlib.HttpPostMessage(peer.ContactPullServers[i], bytemsg, client.GetConfig().HttpTimeOut)
+					msgs, sendErr := invsrv.Step3PostCard(peer.InvitationId)
+					if sendErr == nil {
+						for i, bytemsg := range msgs {
+							if i < len(peer.ContactPullServers) {
+								meowlib.HttpPostMessage(peer.ContactPullServers[i], bytemsg, client.GetConfig().HttpTimeOut)
+							}
+						}
 					}
 				}
 			}
@@ -169,14 +175,17 @@ func ConsumeInboxFile(messageFilename string) ([]string, []string, string, error
 
 			// Handle invitation step 3: initiator's full ContactCard arriving at the invitee.
 			if usermsg.Invitation != nil && usermsg.Invitation.Step == 3 {
-				finalizedPeer, finalErr := invmsgs.Step4InviteeFinalizesInitiator(usermsg)
+				invBytes, marshalErr := proto.Marshal(usermsg.Invitation)
-				if finalErr == nil && finalizedPeer != nil {
+				if marshalErr == nil {
-					// Auto-send step-4 confirmation to initiator's servers.
+					finalizedPeer, finalErr := invmsgs.Step4InviteeFinalizesInitiator(invBytes)
-					step4msgs, sendErr := invsrv.Step4PostConfirmation(finalizedPeer.InvitationId)
+					if finalErr == nil && finalizedPeer != nil {
-					if sendErr == nil {
+						// Auto-send step-4 confirmation to initiator's servers.
-						for i, bytemsg := range step4msgs {
+						step4msgs, sendErr := invsrv.Step4PostConfirmation(finalizedPeer.InvitationId)
-							if i < len(finalizedPeer.ContactPullServers) {
+						if sendErr == nil {
-								meowlib.HttpPostMessage(finalizedPeer.ContactPullServers[i], bytemsg, client.GetConfig().HttpTimeOut)
+							for i, bytemsg := range step4msgs {
+								if i < len(finalizedPeer.ContactPullServers) {
+									meowlib.HttpPostMessage(finalizedPeer.ContactPullServers[i], bytemsg, client.GetConfig().HttpTimeOut)
+								}
 							}
 						}
 					}

client/invitation/files/step1.go

@@ -3,28 +3,32 @@ package files
 import (
 	"os"
 
+	"forge.redroom.link/yves/meowlib"
 	"forge.redroom.link/yves/meowlib/client"
 	"forge.redroom.link/yves/meowlib/client/invitation/messages"
+	"google.golang.org/protobuf/proto"
 )
 
 // Step1Write creates a pending peer and writes the InvitationInitPayload to a file.
 // format: "qr" writes a QR-code PNG; anything else writes a compressed binary .mwiv file.
-func Step1Write(contactName string, myNickname string, invitationMessage string, serverUids []string, format string) (*client.Peer, error) {
+func Step1Write(contactName string, myNickname string, invitationMessage string, serverUids []string, format string) error {
-	payload, peer, err := messages.Step1InitiatorCreatesInviteeAndTempKey(contactName, myNickname, invitationMessage, serverUids)
+	payloadBytes, err := messages.Step1InitiatorCreatesInviteeAndTempKey(contactName, myNickname, invitationMessage, serverUids)
 	if err != nil {
-		return nil, err
+		return err
+	}
+	var payload meowlib.InvitationInitPayload
+	if err := proto.Unmarshal(payloadBytes, &payload); err != nil {
+		return err
+	}
+	mynick := myNickname
+	if mynick == "" {
+		mynick = client.GetConfig().GetIdentity().Nickname
 	}
 	c := client.GetConfig()
 	if format == "qr" {
-		filename := c.StoragePath + string(os.PathSeparator) + peer.MyName + "-" + peer.Name + ".png"
+		filename := c.StoragePath + string(os.PathSeparator) + mynick + "-" + contactName + ".png"
-		if err := payload.WriteQr(filename); err != nil {
+		return payload.WriteQr(filename)
-			return nil, err
-		}
-	} else {
-		filename := c.StoragePath + string(os.PathSeparator) + peer.MyName + "-" + peer.Name + ".mwiv"
-		if err := payload.WriteCompressed(filename); err != nil {
-			return nil, err
-		}
 	}
-	return peer, nil
+	filename := c.StoragePath + string(os.PathSeparator) + mynick + "-" + contactName + ".mwiv"
+	return payload.WriteCompressed(filename)
 }

client/invitation/files/step2.go

@@ -12,8 +12,8 @@ import (
 )
 
 // Step2ReadAndAnswer reads an InvitationInitPayload from a .mwiv file, creates the
-// invitee's peer entry, and writes the encrypted ContactCard (PackedUserMessage) to a
+// invitee's peer entry, and writes the serialized Invitation (step=2) to a .mwiv file
-// .mwiv file for the initiator to pick up and process in step 3.
+// for the initiator to pick up and process in step 3.
 func Step2ReadAndAnswer(invitationFile string, nickname string, myNickname string, serverUids []string) error {
 	if _, err := os.Stat(invitationFile); os.IsNotExist(err) {
 		return err
@@ -29,35 +29,23 @@ func Step2ReadAndAnswer(invitationFile string, nickname string, myNickname strin
 	if err != nil {
 		return err
 	}
+	payloadBytes, err := proto.Marshal(payload)
+	if err != nil {
+		return err
+	}
 
 	mynick := myNickname
 	if mynick == "" {
 		mynick = client.GetConfig().GetIdentity().Nickname
 	}
 
-	packed, peer, err := messages.Step2InviteeCreatesInitiatorAndEncryptedContactCard(payload, nickname, mynick, serverUids)
+	// messages.Step2 returns a serialized Invitation ready to write directly to file.
-	if err != nil {
+	invBytes, err := messages.Step2InviteeCreatesInitiatorAndEncryptedContactCard(payloadBytes, nickname, mynick, serverUids)
-		return err
-	}
-
-	// Wrap the PackedUserMessage in an Invitation so the initiator (step3) has the
-	// invitee's public key available for signature verification without an extra file.
-	packedBytes, err := proto.Marshal(packed)
-	if err != nil {
-		return err
-	}
-	invitation := &meowlib.Invitation{
-		Uuid:    peer.InvitationId,
-		Step:    2,
-		From:    peer.MyIdentity.Public,
-		Payload: packedBytes,
-	}
-	out, err := proto.Marshal(invitation)
 	if err != nil {
 		return err
 	}
 
 	c := client.GetConfig()
 	filename := c.StoragePath + string(os.PathSeparator) + mynick + "-" + nickname + ".mwiv"
-	return os.WriteFile(filename, out, 0600)
+	return os.WriteFile(filename, invBytes, 0600)
 }

client/invitation/messages/flow_test.go

@@ -29,114 +29,108 @@ func setupIdentity(t *testing.T, nickname string) (*client.Identity, func()) {
 	return id, cleanup
 }
 
-// TestStep2ProducesPackedUserMessage verifies that Step2 returns a PackedUserMessage
+// TestStep1ReturnsBinaryPayload verifies that Step1 returns non-empty bytes that
-// (not just a peer) and that the message is encrypted with the initiator's temp key
+// deserialise to a valid InvitationInitPayload, and that the pending peer is stored
-// so Step3 can decrypt it.
+// with only a temp keypair (no real identity keys yet).
-func TestStep2ProducesPackedUserMessage(t *testing.T) {
+func TestStep1ReturnsBinaryPayload(t *testing.T) {
 	cfg := client.GetConfig()
 	cfg.SetMemPass("testpass") //nolint:errcheck
 
-	// --- STEP 1: initiator creates temp keypair and payload ---
 	initiator, cleanInit := setupIdentity(t, "alice")
 	defer cleanInit()
 
-	payload, initPeer, err := messages.Step1InitiatorCreatesInviteeAndTempKey("Bob", "Alice", "Hello!", nil)
+	step1Bytes, err := messages.Step1InitiatorCreatesInviteeAndTempKey("Bob", "Alice", "Hello!", nil)
 	require.NoError(t, err)
-	require.NotNil(t, payload)
+	require.NotEmpty(t, step1Bytes)
+
+	var payload meowlib.InvitationInitPayload
+	require.NoError(t, proto.Unmarshal(step1Bytes, &payload))
+	assert.NotEmpty(t, payload.Uuid)
+	assert.NotEmpty(t, payload.PublicKey)
+	assert.Equal(t, "Alice", payload.Name)
+	assert.Equal(t, "Hello!", payload.InvitationMessage)
+
+	// Peer is saved with temp keypair only — no real identity keys yet.
+	initPeer := initiator.Peers.GetFromName("Bob")
 	require.NotNil(t, initPeer)
-	// Initiator has only the temp keypair at this stage.
 	assert.Nil(t, initPeer.MyIdentity)
 	assert.NotNil(t, initPeer.InvitationKp)
+}
 
-	// --- STEP 2: invitee receives payload, creates peer, returns packed message ---
+// TestFullInvitationFlow runs all four steps end-to-end, passing the binary output of
-	_, cleanInvitee := setupIdentity(t, "bob")
+// each step directly to the next, and verifies that both peers end up with each other's
+// real keys after the exchange completes.
+func TestFullInvitationFlow(t *testing.T) {
+	cfg := client.GetConfig()
+	cfg.SetMemPass("testpass") //nolint:errcheck
+
+	// --- STEP 1: initiator creates temp keypair, gets binary payload ---
+	initiator, cleanInit := setupIdentity(t, "alice2")
+	defer cleanInit()
+
+	step1Bytes, err := messages.Step1InitiatorCreatesInviteeAndTempKey("Bob", "Alice", "", nil)
+	require.NoError(t, err)
+	require.NotEmpty(t, step1Bytes)
+
+	// --- STEP 2: invitee creates peer, returns serialized Invitation (step=2) ---
+	invitee, cleanInvitee := setupIdentity(t, "bob2")
 	defer cleanInvitee()
 
-	packed, inviteePeer, err := messages.Step2InviteeCreatesInitiatorAndEncryptedContactCard(
+	step2Bytes, err := messages.Step2InviteeCreatesInitiatorAndEncryptedContactCard(step1Bytes, "Alice", "Bob", nil)
-		payload, "Alice", "Bob", nil,
-	)
 	require.NoError(t, err)
-	require.NotNil(t, packed, "step2 must return a PackedUserMessage, not just a peer")
+	require.NotEmpty(t, step2Bytes, "step2 must return non-empty invitation bytes")
+
+	// Invitee now has a peer with full keypairs.
+	inviteePeer := invitee.Peers.GetFromName("Alice")
 	require.NotNil(t, inviteePeer)
-
-	// The packed message destination is the initiator's temp key (used as lookup key).
-	assert.Equal(t, payload.PublicKey, packed.Destination)
-
-	// The invitee peer has full keypairs now.
 	assert.NotNil(t, inviteePeer.MyIdentity)
 	assert.NotNil(t, inviteePeer.MyEncryptionKp)
 	assert.NotNil(t, inviteePeer.MyLookupKp)
 
-	// --- STEP 3: initiator decrypts invitee's packed message and finalises ---
+	// The step-2 wire format is a serialized Invitation.
+	var inv2 meowlib.Invitation
+	require.NoError(t, proto.Unmarshal(step2Bytes, &inv2))
+	assert.EqualValues(t, 2, inv2.Step)
+	assert.NotEmpty(t, inv2.Uuid)
+	assert.Equal(t, inviteePeer.MyIdentity.Public, inv2.From)
+	assert.NotEmpty(t, inv2.Payload)
+
+	// --- STEP 3: initiator decrypts invitee's card, returns serialized Invitation (step=3) ---
 	cfg.SetIdentity(initiator)
 
-	// Simulate how the server delivers the step-2 answer: marshal the PackedUserMessage
+	step3Bytes, err := messages.Step3InitiatorFinalizesInviteeAndCreatesContactCard(step2Bytes)
-	// into an Invitation.Payload.
-	packedBytes, err := proto.Marshal(packed)
 	require.NoError(t, err)
+	require.NotEmpty(t, step3Bytes)
 
-	invitation := &meowlib.Invitation{
+	// Initiator's peer must now hold invitee's real keys; temp keypair must be gone.
-		Uuid:    payload.Uuid,
+	initPeer := initiator.Peers.GetFromName("Bob")
-		Step:    2,
+	require.NotNil(t, initPeer)
-		From:    inviteePeer.MyIdentity.Public,
+	assert.Equal(t, inviteePeer.MyIdentity.Public, initPeer.ContactPublicKey)
-		Payload: packedBytes,
+	assert.Equal(t, inviteePeer.MyEncryptionKp.Public, initPeer.ContactEncryption)
-	}
+	assert.Equal(t, inviteePeer.MyLookupKp.Public, initPeer.ContactLookupKey)
+	assert.Nil(t, initPeer.InvitationKp, "temp keypair must be cleared after step3")
+	assert.NotEmpty(t, initPeer.DrKpPublic)
+	assert.NotEmpty(t, initPeer.DrRootKey)
 
-	peer, myCC, err := messages.Step3InitiatorFinalizesInviteeAndCreatesContactCard(invitation)
+	// The step-3 wire format is a serialized Invitation.
+	var inv3 meowlib.Invitation
+	require.NoError(t, proto.Unmarshal(step3Bytes, &inv3))
+	assert.EqualValues(t, 3, inv3.Step)
+	assert.NotEmpty(t, inv3.Uuid)
+	assert.NotEmpty(t, inv3.Payload)
+
+	// --- STEP 4: invitee finalises initiator ---
+	cfg.SetIdentity(invitee)
+
+	finalPeer, err := messages.Step4InviteeFinalizesInitiator(step3Bytes)
 	require.NoError(t, err)
-	require.NotNil(t, peer)
+	require.NotNil(t, finalPeer)
-	require.NotNil(t, myCC, "step3 must produce the initiator's ContactCard to send to invitee")
 
-	// Initiator's peer must now hold invitee's real keys.
+	// Invitee's peer must now hold initiator's real keys and the invitation must be complete.
-	assert.Equal(t, inviteePeer.MyIdentity.Public, peer.ContactPublicKey)
+	assert.Equal(t, initPeer.MyIdentity.Public, finalPeer.ContactPublicKey)
-	assert.Equal(t, inviteePeer.MyEncryptionKp.Public, peer.ContactEncryption)
+	assert.Equal(t, initPeer.MyEncryptionKp.Public, finalPeer.ContactEncryption)
-	assert.Equal(t, inviteePeer.MyLookupKp.Public, peer.ContactLookupKey)
+	assert.Equal(t, initPeer.MyLookupKp.Public, finalPeer.ContactLookupKey)
-	assert.Nil(t, peer.InvitationKp, "temp keypair must be cleared after step3")
+	assert.False(t, finalPeer.InvitationPending(), "invitation must be fully finalized")
-	assert.NotEmpty(t, myCC.DrRootKey)
+	assert.NotEmpty(t, finalPeer.DrRootKey)
-	assert.NotEmpty(t, myCC.DrPublicKey)
+	assert.NotEmpty(t, finalPeer.ContactDrPublicKey)
-}
-
-// TestStep2Step3RoundTripPayload verifies that the PackedUserMessage produced by step2
-// actually carries the invitee's ContactCard when decrypted by the initiator.
-func TestStep2Step3RoundTripPayload(t *testing.T) {
-	cfg := client.GetConfig()
-	cfg.SetMemPass("testpass") //nolint:errcheck
-
-	initiator, cleanInit := setupIdentity(t, "alice2")
-	defer cleanInit()
-
-	payload, _, err := messages.Step1InitiatorCreatesInviteeAndTempKey("Bob", "Alice", "", nil)
-	require.NoError(t, err)
-
-	_, cleanInvitee := setupIdentity(t, "bob2")
-	defer cleanInvitee()
-
-	packed, inviteePeer, err := messages.Step2InviteeCreatesInitiatorAndEncryptedContactCard(payload, "Alice", "Bob", nil)
-	require.NoError(t, err)
-
-	// Confirm the message serialises cleanly (transport simulation).
-	packedBytes, err := proto.Marshal(packed)
-	require.NoError(t, err)
-	assert.NotEmpty(t, packedBytes)
-
-	// Switch back to initiator and run step3.
-	cfg.SetIdentity(initiator)
-
-	var roundTripped meowlib.PackedUserMessage
-	require.NoError(t, proto.Unmarshal(packedBytes, &roundTripped))
-
-	invitation := &meowlib.Invitation{
-		Uuid:    payload.Uuid,
-		Step:    2,
-		From:    inviteePeer.MyIdentity.Public,
-		Payload: packedBytes,
-	}
-
-	_, myCC, err := messages.Step3InitiatorFinalizesInviteeAndCreatesContactCard(invitation)
-	require.NoError(t, err)
-	require.NotNil(t, myCC)
-
-	// The initiator's CC must reference the invitee's invitation ID so the invitee
-	// can match it when step4 arrives.
-	assert.Equal(t, payload.Uuid, myCC.InvitationId)
 }

client/invitation/messages/step1.go

@@ -1,22 +1,23 @@
 package messages
 
 import (
-	"forge.redroom.link/yves/meowlib"
 	"forge.redroom.link/yves/meowlib/client"
+	"google.golang.org/protobuf/proto"
 )
 
 // Step1InitiatorCreatesInviteeAndTempKey creates a minimal pending peer and a temporary
-// keypair, and returns the InvitationInitPayload to be transmitted to the invitee
+// keypair, and returns the serialized InvitationInitPayload bytes to be transmitted to
-// via any transport (file, QR, server…).
+// the invitee via any transport (file, QR, server…). The peer is already persisted by
-func Step1InitiatorCreatesInviteeAndTempKey(contactName string, myNickname string, invitationMessage string, serverUids []string) (*meowlib.InvitationInitPayload, *client.Peer, error) {
+// InvitationStep1 so no peer reference is returned.
+func Step1InitiatorCreatesInviteeAndTempKey(contactName string, myNickname string, invitationMessage string, serverUids []string) ([]byte, error) {
 	mynick := myNickname
 	if mynick == "" {
 		mynick = client.GetConfig().GetIdentity().Nickname
 	}
-	payload, peer, err := client.GetConfig().GetIdentity().InvitationStep1(mynick, contactName, serverUids, invitationMessage)
+	payload, _, err := client.GetConfig().GetIdentity().InvitationStep1(mynick, contactName, serverUids, invitationMessage)
 	if err != nil {
-		return nil, nil, err
+		return nil, err
 	}
 	client.GetConfig().GetIdentity().Save()
-	return payload, peer, nil
+	return proto.Marshal(payload)
 }

client/invitation/messages/step2.go

@@ -3,31 +3,45 @@ package messages
 import (
 	"forge.redroom.link/yves/meowlib"
 	"forge.redroom.link/yves/meowlib/client"
+	"google.golang.org/protobuf/proto"
 )
 
-// Step2InviteeCreatesInitiatorAndEncryptedContactCard creates the invitee's peer entry
+// Step2InviteeCreatesInitiatorAndEncryptedContactCard deserialises the step-1 payload bytes,
-// from an InvitationInitPayload, then builds the invitee's ContactCard and returns it
+// creates the invitee's peer entry, builds and encrypts the invitee's ContactCard, and returns
-// as a PackedUserMessage asymmetrically encrypted with the initiator's temporary public
+// a serialized Invitation (step=2) whose Payload is the PackedUserMessage encrypted with the
-// key. The packed message is ready to be transmitted to the initiator via any transport
+// initiator's temporary public key. The bytes are transport-ready and consumed directly by
-// (file, QR, server…); Step3InitiatorFinalizesInviteeAndCreatesContactCard on the
+// Step3InitiatorFinalizesInviteeAndCreatesContactCard.
-// initiator side will decrypt and process it.
+func Step2InviteeCreatesInitiatorAndEncryptedContactCard(payloadBytes []byte, nickname string, myNickname string, serverUids []string) ([]byte, error) {
-func Step2InviteeCreatesInitiatorAndEncryptedContactCard(payload *meowlib.InvitationInitPayload, nickname string, myNickname string, serverUids []string) (*meowlib.PackedUserMessage, *client.Peer, error) {
 	mynick := myNickname
 	if mynick == "" {
 		mynick = client.GetConfig().GetIdentity().Nickname
 	}
-	peer, err := client.GetConfig().GetIdentity().InvitationStep2(mynick, nickname, serverUids, payload)
+	var payload meowlib.InvitationInitPayload
+	if err := proto.Unmarshal(payloadBytes, &payload); err != nil {
+		return nil, err
+	}
+	peer, err := client.GetConfig().GetIdentity().InvitationStep2(mynick, nickname, serverUids, &payload)
 	if err != nil {
-		return nil, nil, err
+		return nil, err
 	}
 	usermsg, err := peer.BuildInvitationStep2Message(peer.GetMyContact())
 	if err != nil {
-		return nil, nil, err
+		return nil, err
 	}
 	packed, err := peer.ProcessOutboundUserMessage(usermsg)
 	if err != nil {
-		return nil, nil, err
+		return nil, err
+	}
+	packedBytes, err := proto.Marshal(packed)
+	if err != nil {
+		return nil, err
+	}
+	inv := &meowlib.Invitation{
+		Uuid:    payload.Uuid,
+		Step:    2,
+		From:    peer.MyIdentity.Public,
+		Payload: packedBytes,
 	}
 	client.GetConfig().GetIdentity().Save()
-	return packed, peer, nil
+	return proto.Marshal(inv)
 }

client/invitation/messages/step3.go

@@ -8,39 +8,55 @@ import (
 	"google.golang.org/protobuf/proto"
 )
 
-// Step3InitiatorFinalizesInviteeAndCreatesContactCard is called by the initiator when a
+// Step3InitiatorFinalizesInviteeAndCreatesContactCard is called by the initiator when the
-// step-2 answer (invitee's encrypted ContactCard) arrives. It decrypts the card, upgrades
+// step-2 answer (serialized Invitation bytes) arrives. It decrypts the invitee's ContactCard,
-// the invitee's peer entry with the real keys, and returns the initiator's own ContactCard
+// upgrades the pending peer with the invitee's real keys, and returns a serialized Invitation
-// ready to be sent to the invitee via any transport.
+// (step=3) whose Payload is the initiator's ContactCard, ready to be consumed directly by
-func Step3InitiatorFinalizesInviteeAndCreatesContactCard(invitation *meowlib.Invitation) (*client.Peer, *meowlib.ContactCard, error) {
+// Step4InviteeFinalizesInitiator on the invitee side.
+func Step3InitiatorFinalizesInviteeAndCreatesContactCard(invitationBytes []byte) ([]byte, error) {
+	var invitation meowlib.Invitation
+	if err := proto.Unmarshal(invitationBytes, &invitation); err != nil {
+		return nil, err
+	}
+
 	var invitationAnswer meowlib.PackedUserMessage
 	if err := proto.Unmarshal(invitation.Payload, &invitationAnswer); err != nil {
-		return nil, nil, err
+		return nil, err
 	}
 
 	peer := client.GetConfig().GetIdentity().Peers.GetFromInvitationId(invitation.Uuid)
 	if peer == nil {
-		return nil, nil, errors.New("no peer for invitation uuid " + invitation.Uuid)
+		return nil, errors.New("no peer for invitation uuid " + invitation.Uuid)
 	}
 	// Guard against duplicate delivery (e.g., same answer from multiple servers).
 	if peer.InvitationKp == nil {
-		return nil, nil, nil
+		return nil, nil
 	}
 
 	usermsg, err := peer.ProcessInboundStep2UserMessage(&invitationAnswer, invitation.From)
 	if err != nil {
-		return nil, nil, err
+		return nil, err
 	}
 
 	var inviteeCC meowlib.ContactCard
 	if err := proto.Unmarshal(usermsg.Invitation.Payload, &inviteeCC); err != nil {
-		return nil, nil, err
+		return nil, err
 	}
 
-	myCC, peer, err := client.GetConfig().GetIdentity().InvitationStep3(&inviteeCC)
+	myCC, _, err := client.GetConfig().GetIdentity().InvitationStep3(&inviteeCC)
 	if err != nil {
-		return nil, nil, err
+		return nil, err
 	}
 	client.GetConfig().GetIdentity().Save()
-	return peer, myCC, nil
+
+	ccBytes, err := proto.Marshal(myCC)
+	if err != nil {
+		return nil, err
+	}
+	inv := &meowlib.Invitation{
+		Uuid:    myCC.InvitationId,
+		Step:    3,
+		Payload: ccBytes,
+	}
+	return proto.Marshal(inv)
 }

client/invitation/messages/step4.go

@@ -1,27 +1,25 @@
 package messages
 
 import (
-	"errors"
-
 	"forge.redroom.link/yves/meowlib"
 	"forge.redroom.link/yves/meowlib/client"
 	"google.golang.org/protobuf/proto"
 )
 
-// Step4InviteeFinalizesInitiator is called by the invitee's message processor when a
+// Step4InviteeFinalizesInitiator is called by the invitee when the step-3 answer
-// UserMessage with invitation.step == 3 arrives. It unmarshals the initiator's ContactCard
+// (serialized Invitation bytes) arrives. It unmarshals the initiator's ContactCard and
-// and completes the invitee's peer entry with the initiator's real keys.
+// completes the invitee's peer entry with the initiator's real keys.
-func Step4InviteeFinalizesInitiator(usermsg *meowlib.UserMessage) (*client.Peer, error) {
+func Step4InviteeFinalizesInitiator(invitationBytes []byte) (*client.Peer, error) {
-	if usermsg.Invitation == nil || usermsg.Invitation.Step != 3 {
+	var inv meowlib.Invitation
-		return nil, errors.New("expected invitation step 3")
+	if err := proto.Unmarshal(invitationBytes, &inv); err != nil {
-	}
+		return nil, err
-	var initiatorCC meowlib.ContactCard
+	}
-	if err := proto.Unmarshal(usermsg.Invitation.Payload, &initiatorCC); err != nil {
+	var initiatorCC meowlib.ContactCard
+	if err := proto.Unmarshal(inv.Payload, &initiatorCC); err != nil {
 		return nil, err
 	}
-	// Patch the invitation ID from the outer message in case it was not set in the CC.
 	if initiatorCC.InvitationId == "" {
-		initiatorCC.InvitationId = usermsg.Invitation.Uuid
+		initiatorCC.InvitationId = inv.Uuid
 	}
 	if err := client.GetConfig().GetIdentity().InvitationStep4(&initiatorCC); err != nil {
 		return nil, err

doc/invitation/sq_invitation.puml

@@ -1,13 +1,18 @@
 @startuml General Invitation Steps
 InitiatingUser -> InitiatingUser : STEP_1 = Create InivitedUser_Id generate a public key, invitation uid & message for InvitedUser optionnally password protected
+note right of InitiatingUser #Yellow: Invitee created, only temp key
 InitiatingUser -> InvitedUser: STEP_1_SEND= transmit step 1 data (QR Code, Bluetooth, messaging, mail, ...) optional password being tranmitted through another channel
 
 InvitedUser -> InvitedUser :Create InitatingUser_Id & InvitedUser ContactCard
+note right of InvitedUser #Yellow: Initiator created, empty
 InvitedUser -> InitiatingUser: STEP_2_SEND=transmit InvitedUser ContactCard (QR Codes, Bluetooth, messaging, mail, ...) encrypted with initiating user pub key
 
 InitiatingUser -> InitiatingUser : STEP_3=InitiatingUser_Id Accept Invitation and create answer (Generate InitiatingUser ContactCard and create finalized InvitedUser contact)
+note right of InitiatingUser #Lime: Invitee complete
 InitiatingUser -> InvitedUser: STEP_3_SEND=Send answer through invited user's message servers from contact card
 
 InvitedUser -> InvitedUser : Finalize InitiatingUser from its ContactCard
+note right of InvitedUser #Lime: Initiator complete
+
 InvitedUser -> InitiatingUser: STEP_4= Send confirmation to InitiatingUser that communication is possible  through initiating user's message servers from contact card
 @enduml