diff --git a/appservice/consumers/roomserver.go b/appservice/consumers/roomserver.go
index a4bcfa7d9..d44f32b38 100644
--- a/appservice/consumers/roomserver.go
+++ b/appservice/consumers/roomserver.go
@@ -22,6 +22,7 @@ import (
 	"math"
 	"net/http"
 	"net/url"
+	"strconv"
 	"time"
 
 	"github.com/matrix-org/gomatrixserverlib"
@@ -151,10 +152,17 @@ func (s *OutputRoomEventConsumer) onMessage(
 		return true
 	}
 
+	txnID := ""
+	// Try to get the message metadata, if we're able to, use the timestamp as the txnID
+	metadata, err := msgs[0].Metadata()
+	if err == nil {
+		txnID = strconv.Itoa(int(metadata.Timestamp.UnixNano()))
+	}
+
 	// Send event to any relevant application services. If we hit
 	// an error here, return false, so that we negatively ack.
 	log.WithField("appservice", state.ID).Debugf("Appservice worker sending %d events(s) from roomserver", len(events))
-	return s.sendEvents(ctx, state, events) == nil
+	return s.sendEvents(ctx, state, events, txnID) == nil
 }
 
 // sendEvents passes events to the appservice by using the transactions
@@ -162,6 +170,7 @@ func (s *OutputRoomEventConsumer) onMessage(
 func (s *OutputRoomEventConsumer) sendEvents(
 	ctx context.Context, state *appserviceState,
 	events []*gomatrixserverlib.HeaderedEvent,
+	txnID string,
 ) error {
 	// Create the transaction body.
 	transaction, err := json.Marshal(
@@ -173,13 +182,14 @@ func (s *OutputRoomEventConsumer) sendEvents(
 		return err
 	}
 
-	// TODO: We should probably be more intelligent and pick something not
-	// in the control of the event. A NATS timestamp header or something maybe.
-	txnID := events[0].Event.OriginServerTS()
+	// If txnID is not defined, generate one from the events.
+	if txnID == "" {
+		txnID = fmt.Sprintf("%d_%d", events[0].Event.OriginServerTS(), len(transaction))
+	}
 
 	// Send the transaction to the appservice.
 	// https://matrix.org/docs/spec/application_service/r0.1.2#put-matrix-app-v1-transactions-txnid
-	address := fmt.Sprintf("%s/transactions/%d?access_token=%s", state.URL, txnID, url.QueryEscape(state.HSToken))
+	address := fmt.Sprintf("%s/transactions/%s?access_token=%s", state.URL, txnID, url.QueryEscape(state.HSToken))
 	req, err := http.NewRequestWithContext(ctx, "PUT", address, bytes.NewBuffer(transaction))
 	if err != nil {
 		return err
diff --git a/build/gobind-pinecone/monolith.go b/build/gobind-pinecone/monolith.go
index 91bbb6873..500403ae4 100644
--- a/build/gobind-pinecone/monolith.go
+++ b/build/gobind-pinecone/monolith.go
@@ -255,7 +255,7 @@ func (m *DendriteMonolith) Start() {
 	m.logger.SetOutput(BindLogger{})
 	logrus.SetOutput(BindLogger{})
 
-	m.PineconeRouter = pineconeRouter.NewRouter(logrus.WithField("pinecone", "router"), sk, false)
+	m.PineconeRouter = pineconeRouter.NewRouter(logrus.WithField("pinecone", "router"), sk)
 	m.PineconeQUIC = pineconeSessions.NewSessions(logrus.WithField("pinecone", "sessions"), m.PineconeRouter, []string{"matrix"})
 	m.PineconeMulticast = pineconeMulticast.NewMulticast(logrus.WithField("pinecone", "multicast"), m.PineconeRouter)
 	m.PineconeManager = pineconeConnections.NewConnectionManager(m.PineconeRouter, nil)
diff --git a/cmd/dendrite-demo-pinecone/main.go b/cmd/dendrite-demo-pinecone/main.go
index ff9cb5aa1..99e597e59 100644
--- a/cmd/dendrite-demo-pinecone/main.go
+++ b/cmd/dendrite-demo-pinecone/main.go
@@ -151,7 +151,7 @@ func main() {
 	base := base.NewBaseDendrite(cfg, "Monolith")
 	defer base.Close() // nolint: errcheck
 
-	pRouter := pineconeRouter.NewRouter(logrus.WithField("pinecone", "router"), sk, false)
+	pRouter := pineconeRouter.NewRouter(logrus.WithField("pinecone", "router"), sk)
 	pQUIC := pineconeSessions.NewSessions(logrus.WithField("pinecone", "sessions"), pRouter, []string{"matrix"})
 	pMulticast := pineconeMulticast.NewMulticast(logrus.WithField("pinecone", "multicast"), pRouter)
 	pManager := pineconeConnections.NewConnectionManager(pRouter, nil)
diff --git a/cmd/dendrite-upgrade-tests/tests.go b/cmd/dendrite-upgrade-tests/tests.go
index ff1e09dda..5c9589df2 100644
--- a/cmd/dendrite-upgrade-tests/tests.go
+++ b/cmd/dendrite-upgrade-tests/tests.go
@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"log"
 	"strings"
+	"time"
 
 	"github.com/matrix-org/gomatrix"
 	"github.com/matrix-org/gomatrixserverlib"
@@ -81,11 +82,14 @@ func runTests(baseURL, branchName string) error {
 			client: users[1].client, text: "4: " + branchName,
 		},
 	}
+	wantEventIDs := make(map[string]struct{}, 8)
 	for _, msg := range msgs {
-		_, err = msg.client.SendText(dmRoomID, msg.text)
+		var resp *gomatrix.RespSendEvent
+		resp, err = msg.client.SendText(dmRoomID, msg.text)
 		if err != nil {
 			return fmt.Errorf("failed to send text in dm room: %s", err)
 		}
+		wantEventIDs[resp.EventID] = struct{}{}
 	}
 
 	// attempt to create/join the shared public room
@@ -113,11 +117,48 @@ func runTests(baseURL, branchName string) error {
 	}
 	// send messages
 	for _, msg := range msgs {
-		_, err = msg.client.SendText(publicRoomID, "public "+msg.text)
+		resp, err := msg.client.SendText(publicRoomID, "public "+msg.text)
 		if err != nil {
 			return fmt.Errorf("failed to send text in public room: %s", err)
 		}
+		wantEventIDs[resp.EventID] = struct{}{}
 	}
+
+	// Sync until we have all expected messages
+	doneCh := make(chan struct{})
+	go func() {
+		syncClient := users[0].client
+		since := ""
+		for len(wantEventIDs) > 0 {
+			select {
+			case <-doneCh:
+				return
+			default:
+			}
+			syncResp, err := syncClient.SyncRequest(1000, since, "1", false, "")
+			if err != nil {
+				continue
+			}
+			for _, room := range syncResp.Rooms.Join {
+				for _, ev := range room.Timeline.Events {
+					if ev.Type != "m.room.message" {
+						continue
+					}
+					delete(wantEventIDs, ev.ID)
+				}
+			}
+			since = syncResp.NextBatch
+		}
+		close(doneCh)
+	}()
+
+	select {
+	case <-time.After(time.Second * 10):
+		close(doneCh)
+		return fmt.Errorf("failed to receive all expected messages: %+v", wantEventIDs)
+	case <-doneCh:
+	}
+
 	log.Printf("OK! rooms(public=%s, dm=%s) users(%s, %s)\n", publicRoomID, dmRoomID, users[0].userID, users[1].userID)
 	return nil
 }
diff --git a/docs/CONTRIBUTING.md b/docs/CONTRIBUTING.md
index 771af9ecf..6ba05f46f 100644
--- a/docs/CONTRIBUTING.md
+++ b/docs/CONTRIBUTING.md
@@ -11,8 +11,8 @@ possible to get started.
 
 ## Sign off
 
-We ask that everyone who contributes to the project signs off their contributions
-in accordance with the [DCO](https://github.com/matrix-org/matrix-spec/blob/main/CONTRIBUTING.rst#sign-off).
+We require that everyone who contributes to the project signs off their contributions
+in accordance with the [Developer Certificate of Origin](https://github.com/matrix-org/matrix-spec/blob/main/CONTRIBUTING.rst#sign-off).
 In effect, this means adding a statement to your pull requests or commit messages
 along the lines of:
 
@@ -20,7 +20,18 @@ along the lines of:
 Signed-off-by: Full Name <email address>
 ```
 
-Unfortunately we can't accept contributions without it.
+Unfortunately we can't accept contributions without a sign-off.
+
+Please note that we can only accept contributions under a legally identifiable name,
+such as your name as it appears on government-issued documentation or common-law names
+(claimed by legitimate usage or repute). We cannot accept sign-offs from a pseudonym or
+alias and cannot accept anonymous contributions.
+
+If you would prefer to sign off privately instead (so as to not reveal your full
+name on a public pull request), you can do so by emailing a sign-off declaration
+and a link to your pull request directly to the [Matrix.org Foundation](https://matrix.org/foundation/)
+at `dco@matrix.org`. Once a private sign-off has been made, you will not be required
+to do so for future contributions.
 
 ## Getting up and running
 
diff --git a/docs/installation/4_database.md b/docs/installation/4_database.md
index f6222a8d2..68f2d44d0 100644
--- a/docs/installation/4_database.md
+++ b/docs/installation/4_database.md
@@ -10,24 +10,6 @@ permalink: /installation/database
 Dendrite uses SQL databases to store data. Depending on the database engine being used, you
 may need to perform some manual steps outlined below.
 
-## SQLite
-
-SQLite deployments do not require manual database creation. Simply configure the database
-filenames in the Dendrite configuration file and start Dendrite. The databases will be created
-and populated automatically.
-
-Note that Dendrite **cannot share a single SQLite database across multiple components**. Each
-component must be configured with its own SQLite database filename. You will have to remove
-the `global.database` section from your Dendrite config and add it to each individual section
-instead in order to use SQLite.
-
-### Connection strings
-
-Connection strings for SQLite databases take the following forms:
-
-* Current working directory path: `file:dendrite_component.db`
-* Full specified path: `file:///path/to/dendrite_component.db`
-
 ## PostgreSQL
 
 Dendrite can automatically populate the database with the relevant tables and indexes, but
@@ -106,3 +88,25 @@ for i in appservice federationapi mediaapi mscs roomserver syncapi keyserver use
     sudo -u postgres createdb -O dendrite dendrite_$i
 done
 ```
+
+## SQLite
+
+**WARNING:** The Dendrite SQLite backend is slower, less reliable and not recommended for
+production usage. You should use PostgreSQL instead. We may not be able to provide support if
+you run into issues with your deployment while using the SQLite backend.
+
+SQLite deployments do not require manual database creation. Simply configure the database
+filenames in the Dendrite configuration file and start Dendrite. The databases will be created
+and populated automatically.
+
+Note that Dendrite **cannot share a single SQLite database across multiple components**. Each
+component must be configured with its own SQLite database filename. You will have to remove
+the `global.database` section from your Dendrite config and add it to each individual section
+instead in order to use SQLite.
+
+### Connection strings
+
+Connection strings for SQLite databases take the following forms:
+
+* Current working directory path: `file:dendrite_component.db`
+* Full specified path: `file:///path/to/dendrite_component.db`
diff --git a/federationapi/producers/syncapi.go b/federationapi/producers/syncapi.go
index 4abd3fbe5..659ff1bcf 100644
--- a/federationapi/producers/syncapi.go
+++ b/federationapi/producers/syncapi.go
@@ -163,10 +163,10 @@ func (p *SyncAPIProducer) SendPresence(
 }
 
 func (p *SyncAPIProducer) SendDeviceListUpdate(
-	ctx context.Context, deviceListUpdate gomatrixserverlib.RawJSON, origin string,
+	ctx context.Context, deviceListUpdate gomatrixserverlib.RawJSON, origin gomatrixserverlib.ServerName,
 ) (err error) {
 	m := nats.NewMsg(p.TopicDeviceListUpdate)
-	m.Header.Set("origin", origin)
+	m.Header.Set("origin", string(origin))
 	m.Data = deviceListUpdate
 	log.Debugf("Sending device list update: %+v", m.Header)
 	_, err = p.JetStream.PublishMsg(m, nats.Context(ctx))
diff --git a/federationapi/routing/send.go b/federationapi/routing/send.go
index a9714c65a..060af676d 100644
--- a/federationapi/routing/send.go
+++ b/federationapi/routing/send.go
@@ -359,7 +359,7 @@ func (t *txnReq) processEDUs(ctx context.Context) {
 				}
 			}
 		case gomatrixserverlib.MDeviceListUpdate:
-			if err := t.producer.SendDeviceListUpdate(ctx, e.Content, e.Origin); err != nil {
+			if err := t.producer.SendDeviceListUpdate(ctx, e.Content, t.Origin); err != nil {
 				util.GetLogger(ctx).WithError(err).Error("failed to InputDeviceListUpdate")
 			}
 		case gomatrixserverlib.MReceipt:
diff --git a/go.mod b/go.mod
index d151b2995..263a0065d 100644
--- a/go.mod
+++ b/go.mod
@@ -23,7 +23,7 @@ require (
 	github.com/matrix-org/go-sqlite3-js v0.0.0-20220419092513-28aa791a1c91
 	github.com/matrix-org/gomatrix v0.0.0-20210324163249-be2af5ef2e16
 	github.com/matrix-org/gomatrixserverlib v0.0.0-20220912142654-7b96db48888a
-	github.com/matrix-org/pinecone v0.0.0-20220912093434-b215925d5534
+	github.com/matrix-org/pinecone v0.0.0-20220914131522-608215eb1b29
 	github.com/matrix-org/util v0.0.0-20200807132607-55161520e1d4
 	github.com/mattn/go-sqlite3 v1.14.13
 	github.com/nats-io/nats-server/v2 v2.9.0
diff --git a/go.sum b/go.sum
index 3cad3f530..abdc11665 100644
--- a/go.sum
+++ b/go.sum
@@ -390,8 +390,8 @@ github.com/matrix-org/gomatrix v0.0.0-20210324163249-be2af5ef2e16 h1:ZtO5uywdd5d
 github.com/matrix-org/gomatrix v0.0.0-20210324163249-be2af5ef2e16/go.mod h1:/gBX06Kw0exX1HrwmoBibFA98yBk/jxKpGVeyQbff+s=
 github.com/matrix-org/gomatrixserverlib v0.0.0-20220912142654-7b96db48888a h1:XeGBDZZsUe4kgj3myl0EiuDNVWxszJecMTrON3Wn9sI=
 github.com/matrix-org/gomatrixserverlib v0.0.0-20220912142654-7b96db48888a/go.mod h1:jX38yp3SSLJNftBg3PXU1ayd0PCLIiDHQ4xAc9DIixk=
-github.com/matrix-org/pinecone v0.0.0-20220912093434-b215925d5534 h1:XuJYAJNkdG3zj9cO0yQSvL+Sp2xogsTOuZRx7PwdtoA=
-github.com/matrix-org/pinecone v0.0.0-20220912093434-b215925d5534/go.mod h1:K0N1ixHQxXoCyqolDqVxPM3ArrDtcMs8yegOx2Lfv9k=
+github.com/matrix-org/pinecone v0.0.0-20220914131522-608215eb1b29 h1:/AIaqhK1BBi2sMEVQdgZRV8H8sNloAGCgztLZhsPqD0=
+github.com/matrix-org/pinecone v0.0.0-20220914131522-608215eb1b29/go.mod h1:K0N1ixHQxXoCyqolDqVxPM3ArrDtcMs8yegOx2Lfv9k=
 github.com/matrix-org/util v0.0.0-20190711121626-527ce5ddefc7/go.mod h1:vVQlW/emklohkZnOPwD3LrZUBqdfsbiyO3p1lNV8F6U=
 github.com/matrix-org/util v0.0.0-20200807132607-55161520e1d4 h1:eCEHXWDv9Rm335MSuB49mFUK44bwZPFSDde3ORE3syk=
 github.com/matrix-org/util v0.0.0-20200807132607-55161520e1d4/go.mod h1:vVQlW/emklohkZnOPwD3LrZUBqdfsbiyO3p1lNV8F6U=
diff --git a/roomserver/api/query.go b/roomserver/api/query.go
index 32d63bb51..aa7dc4735 100644
--- a/roomserver/api/query.go
+++ b/roomserver/api/query.go
@@ -439,6 +439,7 @@ type QueryMembershipAtEventRequest struct {
 
 // QueryMembershipAtEventResponse is the response to QueryMembershipAtEventRequest.
 type QueryMembershipAtEventResponse struct {
-	// Memberships is a map from eventID to a list of events (if any).
+	// Memberships is a map from eventID to a list of events (if any). Events that
+	// do not have known state will return an empty array here.
 	Memberships map[string][]*gomatrixserverlib.HeaderedEvent `json:"memberships"`
 }
diff --git a/roomserver/internal/input/input.go b/roomserver/internal/input/input.go
index a8a3e0248..c47793f0a 100644
--- a/roomserver/internal/input/input.go
+++ b/roomserver/internal/input/input.go
@@ -176,7 +176,8 @@ func (r *Inputer) Start() error {
 		},
 		nats.HeadersOnly(),
 		nats.DeliverAll(),
-		nats.AckAll(),
+		nats.AckExplicit(),
+		nats.ReplayInstant(),
 		nats.BindStream(r.InputRoomEventTopic),
 	)
 	return err
diff --git a/roomserver/internal/input/input_latest_events.go b/roomserver/internal/input/input_latest_events.go
index 205a33e83..a223820ef 100644
--- a/roomserver/internal/input/input_latest_events.go
+++ b/roomserver/internal/input/input_latest_events.go
@@ -264,16 +264,27 @@ func (u *latestEventsUpdater) latestState() error {
 		return fmt.Errorf("roomState.CalculateAndStoreStateAfterEvents: %w", err)
 	}
 
-	// Now that we have a new state snapshot based on the latest events,
-	// we can compare that new snapshot to the previous one and see what
-	// has changed. This gives us one list of removed state events and
-	// another list of added ones. Replacing a value for a state-key tuple
-	// will result one removed (the old event) and one added (the new event).
-	u.removed, u.added, err = roomState.DifferenceBetweeenStateSnapshots(
-		ctx, u.oldStateNID, u.newStateNID,
-	)
-	if err != nil {
-		return fmt.Errorf("roomState.DifferenceBetweenStateSnapshots: %w", err)
+	// Include information about what changed in the state transition. If the
+	// event rewrites the state (i.e. is a federated join) then we will simply
+	// include the entire state snapshot as added events, as the "RewritesState"
+	// flag in the output event signals downstream components to purge their
+	// room state first. If it doesn't rewrite the state then we will work out
+	// what the difference is between the state snapshots and send that. In all
+	// cases where a state event is being replaced, the old state event will
+	// appear in "removed" and the replacement will appear in "added".
+	if u.rewritesState {
+		u.removed = []types.StateEntry{}
+		u.added, err = roomState.LoadStateAtSnapshot(ctx, u.newStateNID)
+		if err != nil {
+			return fmt.Errorf("roomState.LoadStateAtSnapshot: %w", err)
+		}
+	} else {
+		u.removed, u.added, err = roomState.DifferenceBetweeenStateSnapshots(
+			ctx, u.oldStateNID, u.newStateNID,
+		)
+		if err != nil {
+			return fmt.Errorf("roomState.DifferenceBetweenStateSnapshots: %w", err)
+		}
 	}
 
 	if removed := len(u.removed) - len(u.added); !u.rewritesState && removed > 0 {
diff --git a/roomserver/internal/query/query.go b/roomserver/internal/query/query.go
index d08c5c491..b41a92e94 100644
--- a/roomserver/internal/query/query.go
+++ b/roomserver/internal/query/query.go
@@ -208,6 +208,9 @@ func (r *Queryer) QueryMembershipForUser(
 	return err
 }
 
+// QueryMembershipAtEvent returns the known memberships at a given event.
+// If the state before an event is not known, an empty list will be returned
+// for that event instead.
 func (r *Queryer) QueryMembershipAtEvent(
 	ctx context.Context,
 	request *api.QueryMembershipAtEventRequest,
@@ -237,7 +240,11 @@ func (r *Queryer) QueryMembershipAtEvent(
 	}
 
 	for _, eventID := range request.EventIDs {
-		stateEntry := stateEntries[eventID]
+		stateEntry, ok := stateEntries[eventID]
+		if !ok {
+			response.Memberships[eventID] = []*gomatrixserverlib.HeaderedEvent{}
+			continue
+		}
 		memberships, err := helpers.GetMembershipsAtState(ctx, r.DB, stateEntry, false)
 		if err != nil {
 			return fmt.Errorf("unable to get memberships at state: %w", err)
diff --git a/roomserver/state/state.go b/roomserver/state/state.go
index a40a2e9ba..cb96d83ec 100644
--- a/roomserver/state/state.go
+++ b/roomserver/state/state.go
@@ -18,6 +18,7 @@ package state
 
 import (
 	"context"
+	"database/sql"
 	"fmt"
 	"sort"
 	"sync"
@@ -134,11 +135,14 @@ func (v *StateResolution) LoadMembershipAtEvent(
 	for i := range eventIDs {
 		eventID := eventIDs[i]
 		snapshotNID, err := v.db.SnapshotNIDFromEventID(ctx, eventID)
-		if err != nil {
+		if err != nil && err != sql.ErrNoRows {
 			return nil, fmt.Errorf("LoadStateAtEvent.SnapshotNIDFromEventID failed for event %s : %w", eventID, err)
 		}
 		if snapshotNID == 0 {
-			return nil, fmt.Errorf("LoadStateAtEvent.SnapshotNIDFromEventID(%s) returned 0 NID, was this event stored?", eventID)
+			// If we don't know a state snapshot for this event then we can't calculate
+			// memberships at the time of the event, so skip over it. This means that
+			// it isn't guaranteed that the response map will contain every single event.
+			continue
 		}
 		snapshotNIDMap[snapshotNID] = append(snapshotNIDMap[snapshotNID], eventID)
 	}
diff --git a/syncapi/streams/stream_pdu.go b/syncapi/streams/stream_pdu.go
index ffcf64df6..0ab6de886 100644
--- a/syncapi/streams/stream_pdu.go
+++ b/syncapi/streams/stream_pdu.go
@@ -388,7 +388,7 @@ func applyHistoryVisibilityFilter(
 	if err != nil {
 		// Not a fatal error, we can continue without the stateEvents,
 		// they are only needed if there are state events in the timeline.
-		logrus.WithError(err).Warnf("failed to get current room state")
+		logrus.WithError(err).Warnf("Failed to get current room state for history visibility")
 	}
 	alwaysIncludeIDs := make(map[string]struct{}, len(stateEvents))
 	for _, ev := range stateEvents {
@@ -397,7 +397,6 @@ func applyHistoryVisibilityFilter(
 	startTime := time.Now()
 	events, err := internal.ApplyHistoryVisibilityFilter(ctx, db, rsAPI, recentEvents, alwaysIncludeIDs, userID, "sync")
 	if err != nil {
-
 		return nil, err
 	}
 	logrus.WithFields(logrus.Fields{
@@ -405,7 +404,7 @@ func applyHistoryVisibilityFilter(
 		"room_id":  roomID,
 		"before":   len(recentEvents),
 		"after":    len(events),
-	}).Debug("applied history visibility (sync)")
+	}).Trace("Applied history visibility (sync)")
 	return events, nil
 }