diff --git a/go.mod b/go.mod
index bbf0ae4..2452abf 100644
--- a/go.mod
+++ b/go.mod
@@ -4,7 +4,7 @@ go 1.24.1
 
 require (
 	fiatjaf.com/lib v0.3.1
-	fiatjaf.com/nostr v0.0.0-20251104112613-38a6ca92b954
+	fiatjaf.com/nostr v0.0.0-20251112024900-1c43f0d66643
 	github.com/bep/debounce v1.2.1
 	github.com/btcsuite/btcd/btcec/v2 v2.3.6
 	github.com/chzyer/readline v0.0.0-20180603132655-2972be24d48e
diff --git a/go.sum b/go.sum
index 556b0db..0b64989 100644
--- a/go.sum
+++ b/go.sum
@@ -1,7 +1,7 @@
 fiatjaf.com/lib v0.3.1 h1:/oFQwNtFRfV+ukmOCxfBEAuayoLwXp4wu2/fz5iHpwA=
 fiatjaf.com/lib v0.3.1/go.mod h1:Ycqq3+mJ9jAWu7XjbQI1cVr+OFgnHn79dQR5oTII47g=
-fiatjaf.com/nostr v0.0.0-20251104112613-38a6ca92b954 h1:CMD8D3TgEjGhuIBNMnvZ0EXOW0JR9O3w8AI6Yuzt8Ec=
-fiatjaf.com/nostr v0.0.0-20251104112613-38a6ca92b954/go.mod h1:Nq86Jjsd0OmsOEImUg0iCcLuqM5B67Nj2eu/2dP74Ss=
+fiatjaf.com/nostr v0.0.0-20251112024900-1c43f0d66643 h1:GcoAN1FQV+rayCIklvj+mIB/ZR3Oni98C3bS/M+vzts=
+fiatjaf.com/nostr v0.0.0-20251112024900-1c43f0d66643/go.mod h1:Nq86Jjsd0OmsOEImUg0iCcLuqM5B67Nj2eu/2dP74Ss=
 github.com/FastFilter/xorfilter v0.2.1 h1:lbdeLG9BdpquK64ZsleBS8B4xO/QW1IM0gMzF7KaBKc=
 github.com/FastFilter/xorfilter v0.2.1/go.mod h1:aumvdkhscz6YBZF9ZA/6O4fIoNod4YR50kIVGGZ7l9I=
 github.com/ImVexed/fasturl v0.0.0-20230304231329-4e41488060f3 h1:ClzzXMDDuUbWfNNZqGeYq4PnYOlwlOVIvSyNaIy0ykg=
diff --git a/req.go b/req.go
index 2725054..7b28049 100644
--- a/req.go
+++ b/req.go
@@ -1,14 +1,19 @@
 package main
 
 import (
+	"bufio"
 	"context"
 	"fmt"
+	"math"
 	"os"
 	"slices"
 	"strings"
 	"sync"
 
 	"fiatjaf.com/nostr"
+	"fiatjaf.com/nostr/eventstore"
+	"fiatjaf.com/nostr/eventstore/slicestore"
+	"fiatjaf.com/nostr/eventstore/wrappers"
 	"fiatjaf.com/nostr/nip42"
 	"fiatjaf.com/nostr/nip77"
 	"github.com/fatih/color"
@@ -38,6 +43,11 @@ example:
 	DisableSliceFlagSeparator: true,
 	Flags: append(defaultKeyFlags,
 		append(reqFilterFlags,
+			&cli.StringFlag{
+				Name:      "only-missing",
+				Usage:     "use nip77 negentropy to only fetch events that aren't present in the given jsonl file",
+				TakesFile: true,
+			},
 			&cli.BoolFlag{
 				Name:  "ids-only",
 				Usage: "use nip77 to fetch just a list of ids",
@@ -53,7 +63,7 @@ example:
 				DefaultText: "false, will only use manually-specified relays",
 			},
 			&cli.UintFlag{
-				Name:    "outbox-relays-number",
+				Name:    "outbox-relays-per-pubkey",
 				Aliases: []string{"n"},
 				Usage:   "number of outbox relays to use for each pubkey",
 				Value:   3,
@@ -90,6 +100,13 @@ example:
 	),
 	ArgsUsage: "[relay...]",
 	Action: func(ctx context.Context, c *cli.Command) error {
+		negentropy := c.Bool("ids-only") || c.IsSet("only-missing")
+		if negentropy {
+			if c.Bool("paginate") || c.Bool("stream") || c.Bool("outbox") {
+				return fmt.Errorf("negentropy is incompatible with --stream, --outbox or --paginate")
+			}
+		}
+
 		if c.Bool("paginate") && c.Bool("stream") {
 			return fmt.Errorf("incompatible flags --paginate and --stream")
 		}
@@ -99,7 +116,7 @@ example:
 		}
 
 		relayUrls := c.Args().Slice()
-		if len(relayUrls) > 0 {
+		if len(relayUrls) > 0 && !negentropy {
 			// this is used both for the normal AUTH (after "auth-required:" is received) or forced pre-auth
 			// connect to all relays we expect to use in this call in parallel
 			forcePreAuthSigner := authSigner
@@ -152,20 +169,60 @@ example:
 			}
 
 			if len(relayUrls) > 0 || c.Bool("outbox") {
-				if c.Bool("ids-only") {
-					seen := make(map[nostr.ID]struct{}, max(500, filter.Limit))
-					for _, url := range relayUrls {
-						ch, err := nip77.FetchIDsOnly(ctx, url, filter)
+				if negentropy {
+					store := &slicestore.SliceStore{}
+					store.Init()
+
+					if syncFile := c.String("only-missing"); syncFile != "" {
+						file, err := os.Open(syncFile)
 						if err != nil {
-							log("negentropy call to %s failed: %s", url, err)
-							continue
+							return fmt.Errorf("failed to open sync file: %w", err)
 						}
-						for id := range ch {
-							if _, ok := seen[id]; ok {
+						defer file.Close()
+						scanner := bufio.NewScanner(file)
+						scanner.Buffer(make([]byte, 16*1024*1024), 256*1024*1024)
+						for scanner.Scan() {
+							var evt nostr.Event
+							if err := easyjson.Unmarshal([]byte(scanner.Text()), &evt); err != nil {
 								continue
 							}
-							seen[id] = struct{}{}
-							stdout(id)
+							if err := store.SaveEvent(evt); err != nil || err == eventstore.ErrDupEvent {
+								continue
+							}
+						}
+						if err := scanner.Err(); err != nil {
+							return fmt.Errorf("failed to read sync file: %w", err)
+						}
+					}
+
+					target := PrintingQuerierPublisher{
+						QuerierPublisher: wrappers.StorePublisher{Store: store, MaxLimit: math.MaxInt},
+					}
+
+					var source nostr.Querier = nil
+					if c.IsSet("only-missing") {
+						source = target
+					}
+
+					handle := nip77.SyncEventsFromIDs
+
+					if c.Bool("ids-only") {
+						seen := make(map[nostr.ID]struct{}, max(500, filter.Limit))
+						handle = func(ctx context.Context, dir nip77.Direction) {
+							for id := range dir.Items {
+								if _, ok := seen[id]; ok {
+									continue
+								}
+								seen[id] = struct{}{}
+								stdout(id.Hex())
+							}
+						}
+					}
+
+					for _, url := range relayUrls {
+						err := nip77.NegentropySync(ctx, url, filter, source, target, handle)
+						if err != nil {
+							log("negentropy sync from %s failed: %s", url, err)
 						}
 					}
 				} else {
@@ -194,7 +251,7 @@ example:
 						mu := sync.Mutex{}
 						for _, pubkey := range filter.Authors {
 							errg.Go(func() error {
-								n := int(c.Uint("outbox-relays-number"))
+								n := int(c.Uint("outbox-relays-per-pubkey"))
 								for _, url := range sys.FetchOutboxRelays(ctx, pubkey, n) {
 									if slices.Contains(relayUrls, url) {
 										// already hardcoded, ignore
@@ -395,3 +452,18 @@ func applyFlagsToFilter(c *cli.Command, filter *nostr.Filter) error {
 
 	return nil
 }
+
+type PrintingQuerierPublisher struct {
+	nostr.QuerierPublisher
+}
+
+func (p PrintingQuerierPublisher) Publish(ctx context.Context, evt nostr.Event) error {
+	if err := p.QuerierPublisher.Publish(ctx, evt); err == nil {
+		stdout(evt)
+		return nil
+	} else if err == eventstore.ErrDupEvent {
+		return nil
+	} else {
+		return err
+	}
+}