diff --git a/client/client.go b/client/client.go
index 0066d6c6..f624aa6f 100644
--- a/client/client.go
+++ b/client/client.go
@@ -249,6 +249,9 @@ func (c *CSAPI) Unsafe_SendEventUnsyncedWithTxnID(t TestLike, roomID string, e b
 	if e.StateKey != nil {
 		paths = []string{"_matrix", "client", "v3", "rooms", roomID, "state", e.Type, *e.StateKey}
 	}
+	if e.Sender != "" {
+		t.Fatalf("Event.Sender must not be set, as this is set by the client in use (%s)", c.UserID)
+	}
 	res := c.MustDo(t, "PUT", paths, WithJSONBody(t, e.Content))
 	body := ParseJSON(t, res)
 	eventID := GetJSONFieldStr(t, body, "event_id")
diff --git a/internal/b/blueprints.go b/internal/b/blueprints.go
index 70976776..11aea5c2 100644
--- a/internal/b/blueprints.go
+++ b/internal/b/blueprints.go
@@ -97,24 +97,6 @@ type Event struct {
 	Sender   string
 	StateKey *string
 	Content  map[string]interface{}
-
-	/* The following fields are ignored in blueprints as clients are unable to set them.
-	 * They are used with federation.Server.
-	 */
-
-	Unsigned map[string]interface{}
-
-	// The events needed to authenticate this event.
-	// This can be either []EventReference for room v1/v2, or []string for room v3 onwards.
-	// If it is left at nil, MustCreateEvent will populate it automatically based on the room state.
-	AuthEvents interface{}
-
-	// The prev events of the event if we want to override or falsify them.
-	// If it is left at nil, MustCreateEvent will populate it automatically based on the forward extremities.
-	PrevEvents interface{}
-
-	// If this is a redaction, the event that it redacts
-	Redacts string
 }
 
 func MustValidate(bp Blueprint) Blueprint {
diff --git a/internal/federation/server.go b/internal/federation/server.go
index c82827a7..448db2c8 100644
--- a/internal/federation/server.go
+++ b/internal/federation/server.go
@@ -29,7 +29,6 @@ import (
 	"github.com/matrix-org/gomatrixserverlib"
 	"github.com/matrix-org/util"
 
-	"github.com/matrix-org/complement/internal/b"
 	"github.com/matrix-org/complement/internal/config"
 	"github.com/matrix-org/complement/internal/docker"
 )
@@ -162,7 +161,7 @@ func (s *Server) MakeAliasMapping(aliasLocalpart, roomID string) string {
 
 // MustMakeRoom will add a room to this server so it is accessible to other servers when prompted via federation.
 // The `events` will be added to this room. Returns the created room.
-func (s *Server) MustMakeRoom(t *testing.T, roomVer gomatrixserverlib.RoomVersion, events []b.Event) *ServerRoom {
+func (s *Server) MustMakeRoom(t *testing.T, roomVer gomatrixserverlib.RoomVersion, events []Event) *ServerRoom {
 	if !s.listening {
 		s.t.Fatalf("MustMakeRoom() called before Listen() - this is not supported because Listen() chooses a high-numbered port and thus changes the server name and thus changes the room ID. Ensure you Listen() first!")
 	}
@@ -291,7 +290,7 @@ func (s *Server) DoFederationRequest(
 
 // MustCreateEvent will create and sign a new latest event for the given room.
 // It does not insert this event into the room however. See ServerRoom.AddEvent for that.
-func (s *Server) MustCreateEvent(t *testing.T, room *ServerRoom, ev b.Event) gomatrixserverlib.PDU {
+func (s *Server) MustCreateEvent(t *testing.T, room *ServerRoom, ev Event) gomatrixserverlib.PDU {
 	t.Helper()
 	content, err := json.Marshal(ev.Content)
 	if err != nil {
@@ -451,7 +450,7 @@ func (s *Server) MustLeaveRoom(t *testing.T, deployment *docker.Deployment, remo
 		}
 	} else {
 		// make the leave event
-		leaveEvent = s.MustCreateEvent(t, room, b.Event{
+		leaveEvent = s.MustCreateEvent(t, room, Event{
 			Type:     "m.room.member",
 			StateKey: &userID,
 			Sender:   userID,
diff --git a/internal/federation/server_room.go b/internal/federation/server_room.go
index 82e1ef7f..a0b46c55 100644
--- a/internal/federation/server_room.go
+++ b/internal/federation/server_room.go
@@ -11,6 +11,24 @@ import (
 	"github.com/matrix-org/complement/internal/b"
 )
 
+type Event struct {
+	Type     string
+	Sender   string
+	StateKey *string
+	Content  map[string]interface{}
+
+	Unsigned map[string]interface{}
+	// The events needed to authenticate this event.
+	// This can be either []EventReference for room v1/v2, or []string for room v3 onwards.
+	// If it is left at nil, MustCreateEvent will populate it automatically based on the room state.
+	AuthEvents interface{}
+	// The prev events of the event if we want to override or falsify them.
+	// If it is left at nil, MustCreateEvent will populate it automatically based on the forward extremities.
+	PrevEvents interface{}
+	// If this is a redaction, the event that it redacts
+	Redacts string
+}
+
 // ServerRoom represents a room on this test federation server
 type ServerRoom struct {
 	Version            gomatrixserverlib.RoomVersion
@@ -212,13 +230,13 @@ func initialPowerLevelsContent(roomCreator string) (c gomatrixserverlib.PowerLev
 }
 
 // InitialRoomEvents returns the initial set of events that get created when making a room.
-func InitialRoomEvents(roomVer gomatrixserverlib.RoomVersion, creator string) []b.Event {
+func InitialRoomEvents(roomVer gomatrixserverlib.RoomVersion, creator string) []Event {
 	// need to serialise/deserialise to get map[string]interface{} annoyingly
 	plContent := initialPowerLevelsContent(creator)
 	plBytes, _ := json.Marshal(plContent)
 	var plContentMap map[string]interface{}
 	json.Unmarshal(plBytes, &plContentMap)
-	return []b.Event{
+	return []Event{
 		{
 			Type:     "m.room.create",
 			StateKey: b.Ptr(""),
diff --git a/tests/csapi/sync_test.go b/tests/csapi/sync_test.go
index 98ee05af..918e9637 100644
--- a/tests/csapi/sync_test.go
+++ b/tests/csapi/sync_test.go
@@ -291,17 +291,16 @@ func TestSync(t *testing.T) {
 			// a good event - in another room - to act as a sentinel. It's not
 			// guaranteed, but hopefully if the sentinel is received, so was the
 			// redaction.
-			redactionEvent := srv.MustCreateEvent(t, redactionRoom, b.Event{
+			redactionEvent := srv.MustCreateEvent(t, redactionRoom, federation.Event{
 				Type:    "m.room.redaction",
 				Sender:  charlie,
 				Content: map[string]interface{}{},
-				Redacts: "$12345",
-			})
+				Redacts: "$12345"})
 			redactionRoom.AddEvent(redactionEvent)
 			t.Logf("Created redaction event %s", redactionEvent.EventID())
 			srv.MustSendTransaction(t, deployment, "hs1", []json.RawMessage{redactionEvent.JSON()}, nil)
 
-			sentinelEvent := srv.MustCreateEvent(t, sentinelRoom, b.Event{
+			sentinelEvent := srv.MustCreateEvent(t, sentinelRoom, federation.Event{
 				Type:    "m.room.test",
 				Sender:  charlie,
 				Content: map[string]interface{}{"body": "1234"},
@@ -318,7 +317,7 @@ func TestSync(t *testing.T) {
 			pdus := make([]json.RawMessage, 11)
 			var lastSentEventId string
 			for i := range pdus {
-				ev := srv.MustCreateEvent(t, redactionRoom, b.Event{
+				ev := srv.MustCreateEvent(t, redactionRoom, federation.Event{
 					Type:    "m.room.message",
 					Sender:  charlie,
 					Content: map[string]interface{}{},
diff --git a/tests/direct_messaging_test.go b/tests/direct_messaging_test.go
index 7ed86598..93854111 100644
--- a/tests/direct_messaging_test.go
+++ b/tests/direct_messaging_test.go
@@ -126,7 +126,7 @@ func TestIsDirectFlagFederation(t *testing.T) {
 
 	bob := srv.UserID("bob")
 	room := srv.MustMakeRoom(t, roomVer, federation.InitialRoomEvents(roomVer, bob))
-	dmInviteEvent := srv.MustCreateEvent(t, room, b.Event{
+	dmInviteEvent := srv.MustCreateEvent(t, room, federation.Event{
 		Type:     "m.room.member",
 		StateKey: &alice.UserID,
 		Sender:   bob,
diff --git a/tests/federation_redaction_test.go b/tests/federation_redaction_test.go
index ef9a89a6..29c2c00b 100644
--- a/tests/federation_redaction_test.go
+++ b/tests/federation_redaction_test.go
@@ -1,12 +1,13 @@
 package tests
 
 import (
+	"testing"
+	"time"
+
 	"github.com/matrix-org/complement/internal/b"
 	"github.com/matrix-org/complement/internal/federation"
 	"github.com/matrix-org/complement/runtime"
 	"github.com/matrix-org/gomatrixserverlib"
-	"testing"
-	"time"
 )
 
 // test that a redaction is sent out over federation even if we don't have the original event
@@ -56,13 +57,12 @@ func TestFederationRedactSendsWithoutEvent(t *testing.T) {
 	alice.JoinRoom(t, roomAlias, []string{srv.ServerName()})
 
 	// inject event to redact in the room
-	badEvent := srv.MustCreateEvent(t, serverRoom, b.Event{
+	badEvent := srv.MustCreateEvent(t, serverRoom, federation.Event{
 		Type:   "m.room.message",
 		Sender: charlie,
 		Content: map[string]interface{}{
 			"body": "666",
-		},
-	})
+		}})
 	serverRoom.AddEvent(badEvent)
 
 	eventID := badEvent.EventID()
@@ -70,9 +70,12 @@ func TestFederationRedactSendsWithoutEvent(t *testing.T) {
 	eventToRedact := eventID + ":" + fullServerName
 
 	// the client sends a request to the local homeserver to send the redaction
-	res := alice.SendRedaction(t, serverRoom.RoomID, b.Event{Type: wantEventType, Content: map[string]interface{}{
-		"msgtype": "m.room.redaction"},
-		Redacts: eventToRedact}, eventToRedact)
+	res := alice.SendRedaction(t, serverRoom.RoomID, b.Event{
+		Type: wantEventType,
+		Content: map[string]interface{}{
+			"reason": "reasons...",
+		},
+	}, eventToRedact)
 
 	// wait for redaction to arrive at remote homeserver
 	waiter.Wait(t, 1*time.Second)
diff --git a/tests/federation_room_event_auth_test.go b/tests/federation_room_event_auth_test.go
index 58d3f08e..3a317ba4 100644
--- a/tests/federation_room_event_auth_test.go
+++ b/tests/federation_room_event_auth_test.go
@@ -118,7 +118,7 @@ func TestInboundFederationRejectsEventsWithRejectedAuthEvents(t *testing.T) {
 	charlieMembershipEvent := room.CurrentState("m.room.member", charlie)
 
 	// have Charlie send a PL event which will be rejected
-	rejectedEvent := srv.MustCreateEvent(t, room, b.Event{
+	rejectedEvent := srv.MustCreateEvent(t, room, federation.Event{
 		Type:     "m.room.power_levels",
 		StateKey: b.Ptr(""),
 		Sender:   charlie,
@@ -140,7 +140,7 @@ func TestInboundFederationRejectsEventsWithRejectedAuthEvents(t *testing.T) {
 
 	// create an event to be pulled in as an outlier, which is valid according to its prev events,
 	// but uses the rejected event among its auth events.
-	outlierEvent := srv.MustCreateEvent(t, room, b.Event{
+	outlierEvent := srv.MustCreateEvent(t, room, federation.Event{
 		Type:     "m.room.member",
 		StateKey: &charlie,
 		Sender:   charlie,
@@ -166,7 +166,7 @@ func TestInboundFederationRejectsEventsWithRejectedAuthEvents(t *testing.T) {
 		charlieMembershipEvent,
 		outlierEvent,
 	}
-	sentEvent1 := srv.MustCreateEvent(t, room, b.Event{
+	sentEvent1 := srv.MustCreateEvent(t, room, federation.Event{
 		Type:       "m.room.message",
 		Sender:     charlie,
 		Content:    map[string]interface{}{"body": "sentEvent1"},
@@ -178,7 +178,7 @@ func TestInboundFederationRejectsEventsWithRejectedAuthEvents(t *testing.T) {
 
 	// another a regular event which refers to the outlier event, but
 	// this time we will give a different answer to /event_auth
-	sentEvent2 := srv.MustCreateEvent(t, room, b.Event{
+	sentEvent2 := srv.MustCreateEvent(t, room, federation.Event{
 		Type:       "m.room.message",
 		Sender:     charlie,
 		Content:    map[string]interface{}{"body": "sentEvent1"},
@@ -190,7 +190,7 @@ func TestInboundFederationRejectsEventsWithRejectedAuthEvents(t *testing.T) {
 	t.Logf("Created sent event 2 %s", sentEvent2.EventID())
 
 	// finally, a genuine regular event.
-	sentinelEvent := srv.MustCreateEvent(t, room, b.Event{
+	sentinelEvent := srv.MustCreateEvent(t, room, federation.Event{
 		Type:    "m.room.message",
 		Sender:  charlie,
 		Content: map[string]interface{}{"body": "sentinelEvent"},
diff --git a/tests/federation_room_get_missing_events_test.go b/tests/federation_room_get_missing_events_test.go
index 48c84e01..a568af79 100644
--- a/tests/federation_room_get_missing_events_test.go
+++ b/tests/federation_room_get_missing_events_test.go
@@ -73,7 +73,7 @@ func TestGetMissingEventsGapFilling(t *testing.T) {
 	var missingEventIDs []string
 	numMissingEvents := 5
 	for i := 0; i < numMissingEvents; i++ {
-		missingEvent := srv.MustCreateEvent(t, srvRoom, b.Event{
+		missingEvent := srv.MustCreateEvent(t, srvRoom, federation.Event{
 			Sender: bob,
 			Type:   "m.room.message",
 			Content: map[string]interface{}{
@@ -86,7 +86,7 @@ func TestGetMissingEventsGapFilling(t *testing.T) {
 	}
 
 	// 3) Inject a final event into Complement
-	mostRecentEvent := srv.MustCreateEvent(t, srvRoom, b.Event{
+	mostRecentEvent := srv.MustCreateEvent(t, srvRoom, federation.Event{
 		Sender: bob,
 		Type:   "m.room.message",
 		Content: map[string]interface{}{
@@ -237,7 +237,7 @@ func TestOutboundFederationIgnoresMissingEventWithBadJSONForRoomVersion6(t *test
 	room.AddEvent(signedBadEvent)
 
 	// send the first "good" event, referencing the broken event as a prev_event
-	sentEvent := srv.MustCreateEvent(t, room, b.Event{
+	sentEvent := srv.MustCreateEvent(t, room, federation.Event{
 		Type:   "m.room.message",
 		Sender: charlie,
 		Content: map[string]interface{}{
@@ -291,7 +291,7 @@ func TestOutboundFederationIgnoresMissingEventWithBadJSONForRoomVersion6(t *test
 	// it just ignores it, so we need to send another event referring to the
 	// first one and check that we get a /get_missing_events request.
 
-	message3 := srv.MustCreateEvent(t, room, b.Event{
+	message3 := srv.MustCreateEvent(t, room, federation.Event{
 		Type:   "m.room.message",
 		Sender: charlie,
 		Content: map[string]interface{}{
diff --git a/tests/federation_room_join_test.go b/tests/federation_room_join_test.go
index 0d51963f..7ee127f9 100644
--- a/tests/federation_room_join_test.go
+++ b/tests/federation_room_join_test.go
@@ -158,7 +158,7 @@ func TestJoinFederatedRoomWithUnverifiableEvents(t *testing.T) {
 		room := srv.MustMakeRoom(t, ver, federation.InitialRoomEvents(ver, charlie))
 		roomAlias := srv.MakeAliasMapping("MissingSignatures", room.RoomID)
 		// create a normal event then remove the signatures key
-		signedEvent := srv.MustCreateEvent(t, room, b.Event{
+		signedEvent := srv.MustCreateEvent(t, room, federation.Event{
 			Sender:   charlie,
 			StateKey: b.Ptr(""),
 			Type:     "m.room.name",
@@ -181,7 +181,7 @@ func TestJoinFederatedRoomWithUnverifiableEvents(t *testing.T) {
 		room := srv.MustMakeRoom(t, ver, federation.InitialRoomEvents(ver, charlie))
 		roomAlias := srv.MakeAliasMapping("BadSignatures", room.RoomID)
 		// create a normal event then modify the signatures
-		signedEvent := srv.MustCreateEvent(t, room, b.Event{
+		signedEvent := srv.MustCreateEvent(t, room, federation.Event{
 			Sender:   charlie,
 			StateKey: b.Ptr(""),
 			Type:     "m.room.name",
@@ -212,7 +212,7 @@ func TestJoinFederatedRoomWithUnverifiableEvents(t *testing.T) {
 		roomAlias := srv.MakeAliasMapping("UnobtainableKeys", room.RoomID)
 		// create a normal event then modify the signatures to have a bogus key ID which Complement does
 		// not have the keys for
-		signedEvent := srv.MustCreateEvent(t, room, b.Event{
+		signedEvent := srv.MustCreateEvent(t, room, federation.Event{
 			Sender:   charlie,
 			StateKey: b.Ptr(""),
 			Type:     "m.room.name",
@@ -246,7 +246,7 @@ func TestJoinFederatedRoomWithUnverifiableEvents(t *testing.T) {
 		roomAlias := srv.MakeAliasMapping("UnverifiableAuthEvents", room.RoomID)
 
 		// create a normal event then modify the signatures
-		rawEvent := srv.MustCreateEvent(t, room, b.Event{
+		rawEvent := srv.MustCreateEvent(t, room, federation.Event{
 			Sender:   charlie,
 			StateKey: &charlie,
 			Type:     "m.room.member",
@@ -271,7 +271,7 @@ func TestJoinFederatedRoomWithUnverifiableEvents(t *testing.T) {
 		t.Logf("Created badly signed auth event %s", badlySignedEvent.EventID())
 
 		// and now add another event which will use it as an auth event.
-		goodEvent := srv.MustCreateEvent(t, room, b.Event{
+		goodEvent := srv.MustCreateEvent(t, room, federation.Event{
 			Sender:   charlie,
 			StateKey: &charlie,
 			Type:     "m.room.member",
@@ -453,7 +453,7 @@ func testValidationForSendMembershipEndpoint(t *testing.T, baseApiPath, expected
 	}
 
 	t.Run("regular event", func(t *testing.T) {
-		event := srv.MustCreateEvent(t, room, b.Event{
+		event := srv.MustCreateEvent(t, room, federation.Event{
 			Type:    "m.room.message",
 			Sender:  charlie,
 			Content: map[string]interface{}{"body": "bzz"},
@@ -461,7 +461,7 @@ func testValidationForSendMembershipEndpoint(t *testing.T, baseApiPath, expected
 		assertRequestFails(t, event)
 	})
 	t.Run("non-state membership event", func(t *testing.T) {
-		event := srv.MustCreateEvent(t, room, b.Event{
+		event := srv.MustCreateEvent(t, room, federation.Event{
 			Type:    "m.room.member",
 			Sender:  charlie,
 			Content: map[string]interface{}{"body": "bzz"},
@@ -475,7 +475,7 @@ func testValidationForSendMembershipEndpoint(t *testing.T, baseApiPath, expected
 		if membershipType == expectedMembership {
 			continue
 		}
-		event := srv.MustCreateEvent(t, room, b.Event{
+		event := srv.MustCreateEvent(t, room, federation.Event{
 			Type:     "m.room.member",
 			Sender:   charlie,
 			StateKey: &charlie,
@@ -488,7 +488,7 @@ func testValidationForSendMembershipEndpoint(t *testing.T, baseApiPath, expected
 
 	// right sort of membership, but mismatched state_key
 	t.Run("event with mismatched state key", func(t *testing.T) {
-		event := srv.MustCreateEvent(t, room, b.Event{
+		event := srv.MustCreateEvent(t, room, federation.Event{
 			Type:     "m.room.member",
 			Sender:   charlie,
 			StateKey: b.Ptr(srv.UserID("doris")),
diff --git a/tests/federation_unreject_rejected_test.go b/tests/federation_unreject_rejected_test.go
index f7f38079..e255dfa9 100644
--- a/tests/federation_unreject_rejected_test.go
+++ b/tests/federation_unreject_rejected_test.go
@@ -44,20 +44,20 @@ func TestUnrejectRejectedEvents(t *testing.T) {
 	// Create the events. Event A will have whatever the current forward
 	// extremities are as prev events. Event B will refer to event A only
 	// to guarantee the test will work.
-	eventA := srv.MustCreateEvent(t, serverRoom, b.Event{
+	eventA := srv.MustCreateEvent(t, serverRoom, federation.Event{
 		Type:   "m.event.a",
 		Sender: bob,
 		Content: map[string]interface{}{
 			"event": "A",
 		},
 	})
-	eventB := srv.MustCreateEvent(t, serverRoom, b.Event{
-		Type:       "m.event.b",
-		Sender:     bob,
-		PrevEvents: []string{eventA.EventID()},
+	eventB := srv.MustCreateEvent(t, serverRoom, federation.Event{
+		Type:   "m.event.b",
+		Sender: bob,
 		Content: map[string]interface{}{
 			"event": "B",
 		},
+		PrevEvents: []string{eventA.EventID()},
 	})
 
 	// Send event B into the room. Event A at this point is unknown