Merge e8083ed0f7 into 12eabbd76d

eth/backend.go

@@ -456,8 +456,13 @@ func (s *Ethereum) Start() error {
 	// Start the networking layer
 	s.handler.Start(s.p2pServer.MaxPeers)
 
-	// Start the connection manager
+	// Start the transaction tracker; it emits per-block inclusion and
-	s.dropper.Start(s.p2pServer, func() bool { return !s.Synced() })
+	// finalization signals to peerStats, which the dropper queries for
+	// protection decisions.
+	s.handler.txTracker.Start(s.blockchain, s.handler.peerStats)
+
+	// Start the connection manager with inclusion-based peer protection.
+	s.dropper.Start(s.p2pServer, func() bool { return !s.Synced() }, s.handler.peerStats.GetAllPeerStats)
 
 	// start log indexer
 	s.filterMaps.Start()
@@ -581,6 +586,7 @@ func (s *Ethereum) Stop() error {
 	// Stop all the peer-related stuff first.
 	s.discmix.Close()
 	s.dropper.Stop()
+	s.handler.txTracker.Stop()
 	s.handler.Stop()
 
 	// Then stop everything else.

eth/dropper.go

@@ -17,6 +17,7 @@
 package eth
 
 import (
+	"cmp"
 	mrand "math/rand"
 	"slices"
 	"sync"
@@ -24,6 +25,7 @@ import (
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/mclock"
+	"github.com/ethereum/go-ethereum/eth/peerstats"
 	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/metrics"
 	"github.com/ethereum/go-ethereum/p2p"
@@ -40,6 +42,10 @@ const (
 	// dropping when no more peers can be added. Larger numbers result in more
 	// aggressive drop behavior.
 	peerDropThreshold = 0
+	// Fraction of inbound/dialed peers to protect based on inclusion stats.
+	// The top inclusionProtectionFrac of each category (by score) are
+	// shielded from random dropping. 0.1 = top 10%.
+	inclusionProtectionFrac = 0.1
 )
 
 var (
@@ -47,18 +53,77 @@ var (
 	droppedInbound = metrics.NewRegisteredMeter("eth/dropper/inbound", nil)
 	// droppedOutbound is the number of outbound peers dropped
 	droppedOutbound = metrics.NewRegisteredMeter("eth/dropper/outbound", nil)
+	// dropSkipped counts times a drop was attempted but no peer was dropped,
+	// for any reason (pool has headroom, all candidates trusted/static/young,
+	// or protected by inclusion stats).
+	dropSkipped = metrics.NewRegisteredMeter("eth/dropper/skipped", nil)
 )
 
-// dropper monitors the state of the peer pool and makes changes as follows:
+// Callback type to get per-peer inclusion statistics.
-//   - during sync the Downloader handles peer connections, so dropper is disabled
+type getPeerStatsFunc func() map[string]peerstats.PeerStats
-//   - if not syncing and the peer count is close to the limit, it drops peers
+
-//     randomly every peerDropInterval to make space for new peers
+// protectionCategory defines a peer scoring function and the fraction of peers
-//   - peers are dropped separately from the inboud pool and from the dialed pool
+// to protect per inbound/dialed category. Multiple categories are unioned.
+type protectionCategory struct {
+	name  string
+	score func(peerstats.PeerStats) float64
+	frac  float64 // fraction of max peers to protect (0.0–1.0)
+}
+
+// protectionCategories is the list of protection criteria. Each category
+// independently selects its top-N peers per pool; the union is protected.
+var protectionCategories = []protectionCategory{
+	{"recent-finalized", func(s peerstats.PeerStats) float64 { return s.RecentFinalized }, inclusionProtectionFrac},
+	{"recent-included", func(s peerstats.PeerStats) float64 { return s.RecentIncluded }, inclusionProtectionFrac},
+	{"request-latency", func(s peerstats.PeerStats) float64 {
+		// Low-latency peers should rank higher. Peers with too few samples
+		// score 0 so the existing `score <= 0` filter excludes them — this
+		// prevents a single lucky-fast reply from winning protection. Peers
+		// whose EMA reaches the timeout also score 0 by this path because
+		// the reciprocal of a very large duration is tiny but positive; the
+		// per-pool top-N will still push faster peers ahead of them.
+		if s.RequestSuccesses+s.RequestTimeouts < peerstats.MinLatencySamples {
+			return 0
+		}
+		// Freshness gate: a peer that earned a fast EMA but then went
+		// silent on announcements (no requests → no fresh samples) must
+		// not keep that score indefinitely. Ignore stale data.
+		if time.Since(s.LastLatencySample) > peerstats.MaxLatencyStaleness {
+			return 0
+		}
+		if s.RequestLatencyEMA <= 0 {
+			return 0
+		}
+		return 1.0 / float64(s.RequestLatencyEMA)
+	}, inclusionProtectionFrac},
+}
+
+// dropper monitors the state of the peer pool and introduces churn by
+// periodically disconnecting a random peer to make room for new connections.
+// The main goal is to allow new peers to join the network and to facilitate
+// continuous topology adaptation.
+//
+// Behavior:
+//   - During sync the Downloader handles peer connections, so dropper is disabled.
+//   - When not syncing and a peer category (inbound or dialed) is close to its
+//     limit, a random peer from that category is disconnected every 3–7 minutes.
+//   - Trusted and static peers are never dropped.
+//   - Recently connected peers are also protected from dropping to give them time
+//     to prove their value before being at risk of disconnection.
+//   - Some peers are protected from dropping based on their contribution
+//     to the tx pool. Each pool (inbound/dialed) independently selects its
+//     top fraction of peers by a per-peer EMA score — a slow EMA of
+//     finalized inclusions (~1-day half-life, rewards sustained long-term
+//     contribution) and a fast EMA of recent block inclusions (rewards
+//     current activity). The union of all protected sets is shielded from
+//     random dropping, and the drop target is chosen randomly from the
+//     remainder.
 type dropper struct {
 	maxDialPeers    int // maximum number of dialed peers
 	maxInboundPeers int // maximum number of inbound peers
 	peersFunc       getPeersFunc
 	syncingFunc     getSyncingFunc
+	peerStatsFunc   getPeerStatsFunc // optional: inclusion stats for protection
 
 	// peerDropTimer introduces churn if we are close to limit capacity.
 	// We handle Dialed and Inbound connections separately
@@ -88,10 +153,12 @@ func newDropper(maxDialPeers, maxInboundPeers int) *dropper {
 	return cm
 }
 
-// Start the dropper.
+// Start the dropper. peerStatsFunc is optional (nil disables inclusion
-func (cm *dropper) Start(srv *p2p.Server, syncingFunc getSyncingFunc) {
+// protection).
+func (cm *dropper) Start(srv *p2p.Server, syncingFunc getSyncingFunc, peerStatsFunc getPeerStatsFunc) {
 	cm.peersFunc = srv.Peers
 	cm.syncingFunc = syncingFunc
+	cm.peerStatsFunc = peerStatsFunc
 	cm.wg.Add(1)
 	go cm.loop()
 }
@@ -114,30 +181,101 @@ func (cm *dropper) dropRandomPeer() bool {
 	}
 	numDialed := len(peers) - numInbound
 
+	// Fast path: if neither pool is near capacity, every non-trusted/non-static
+	// peer is already do-not-drop by pool-threshold rules. No point computing
+	// inclusion protection.
+	if cm.maxDialPeers-numDialed > peerDropThreshold &&
+		cm.maxInboundPeers-numInbound > peerDropThreshold {
+		dropSkipped.Mark(1)
+		return false
+	}
+
+	// Compute the set of inclusion-protected peers before filtering.
+	protected := cm.protectedPeers(peers)
+
 	selectDoNotDrop := func(p *p2p.Peer) bool {
-		// Avoid dropping trusted and static peers, or recent peers.
-		// Only drop peers if their respective category (dialed/inbound)
-		// is close to limit capacity.
 		return p.Trusted() || p.StaticDialed() ||
 			p.Lifetime() < mclock.AbsTime(doNotDropBefore) ||
 			(p.DynDialed() && cm.maxDialPeers-numDialed > peerDropThreshold) ||
-			(p.Inbound() && cm.maxInboundPeers-numInbound > peerDropThreshold)
+			(p.Inbound() && cm.maxInboundPeers-numInbound > peerDropThreshold) ||
+			protected[p]
 	}
 
 	droppable := slices.DeleteFunc(peers, selectDoNotDrop)
-	if len(droppable) > 0 {
+	if len(droppable) == 0 {
-		p := droppable[mrand.Intn(len(droppable))]
+		dropSkipped.Mark(1)
-		log.Debug("Dropping random peer", "inbound", p.Inbound(),
+		return false
-			"id", p.ID(), "duration", common.PrettyDuration(p.Lifetime()), "peercountbefore", len(peers))
-		p.Disconnect(p2p.DiscUselessPeer)
-		if p.Inbound() {
-			droppedInbound.Mark(1)
-		} else {
-			droppedOutbound.Mark(1)
-		}
-		return true
 	}
-	return false
+	p := droppable[mrand.Intn(len(droppable))]
+	log.Debug("Dropping random peer", "inbound", p.Inbound(),
+		"id", p.ID(), "duration", common.PrettyDuration(p.Lifetime()), "peercountbefore", len(peers))
+	p.Disconnect(p2p.DiscUselessPeer)
+	if p.Inbound() {
+		droppedInbound.Mark(1)
+	} else {
+		droppedOutbound.Mark(1)
+	}
+	return true
+}
+
+// protectedPeers computes the set of peers that should not be dropped based
+// on inclusion stats. Each protection category independently selects its
+// top-N peers per inbound/dialed pool; the union is returned.
+func (cm *dropper) protectedPeers(peers []*p2p.Peer) map[*p2p.Peer]bool {
+	if cm.peerStatsFunc == nil {
+		return nil
+	}
+	stats := cm.peerStatsFunc()
+	if len(stats) == 0 {
+		return nil
+	}
+	// Split peers by direction.
+	var inbound, dialed []*p2p.Peer
+	for _, p := range peers {
+		if p.Inbound() {
+			inbound = append(inbound, p)
+		} else {
+			dialed = append(dialed, p)
+		}
+	}
+	result := protectedPeersByPool(inbound, dialed, stats)
+	if len(result) > 0 {
+		log.Debug("Protecting high-value peers from drop", "protected", len(result))
+	}
+	return result
+}
+
+// protectedPeersByPool selects the union of top-N peers per protection
+// category across the given already-split inbound and dialed pools.
+// Factored from protectedPeers so tests can exercise the per-pool
+// selection logic without needing to construct direction-flagged
+// *p2p.Peer instances (which require unexported p2p types).
+func protectedPeersByPool(inbound, dialed []*p2p.Peer, stats map[string]peerstats.PeerStats) map[*p2p.Peer]bool {
+	result := make(map[*p2p.Peer]bool)
+	// protectPool selects the top-frac peers from pool by score and adds them to result.
+	protectPool := func(pool []*p2p.Peer, score func(*p2p.Peer) float64, frac float64) {
+		n := int(float64(len(pool)) * frac)
+		if n == 0 {
+			return
+		}
+		sorted := slices.SortedFunc(slices.Values(pool), func(a, b *p2p.Peer) int {
+			return cmp.Compare(score(b), score(a)) // descending
+		})
+		top := slices.DeleteFunc(sorted[:min(n, len(sorted))], func(p *p2p.Peer) bool {
+			return score(p) <= 0
+		})
+		for _, p := range top {
+			result[p] = true
+		}
+	}
+	for _, cat := range protectionCategories {
+		score := func(p *p2p.Peer) float64 {
+			return cat.score(stats[p.ID().String()])
+		}
+		protectPool(inbound, score, cat.frac)
+		protectPool(dialed, score, cat.frac)
+	}
+	return result
 }
 
 // randomDuration generates a random duration between min and max.

eth/dropper_test.go

@@ -0,0 +1,378 @@
+// Copyright 2026 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package eth
+
+import (
+	"fmt"
+	"testing"
+	"time"
+
+	"github.com/ethereum/go-ethereum/eth/peerstats"
+	"github.com/ethereum/go-ethereum/p2p"
+	"github.com/ethereum/go-ethereum/p2p/enode"
+)
+
+func makePeers(n int) []*p2p.Peer {
+	peers := make([]*p2p.Peer, n)
+	for i := range peers {
+		id := enode.ID{byte(i)}
+		peers[i] = p2p.NewPeer(id, fmt.Sprintf("peer%d", i), nil)
+	}
+	return peers
+}
+
+func TestProtectedPeersNoStats(t *testing.T) {
+	cm := &dropper{maxDialPeers: 20, maxInboundPeers: 30}
+	cm.peerStatsFunc = func() map[string]peerstats.PeerStats { return nil }
+
+	peers := makePeers(10)
+	protected := cm.protectedPeers(peers)
+	if len(protected) != 0 {
+		t.Fatalf("expected no protected peers with nil stats, got %d", len(protected))
+	}
+}
+
+func TestProtectedPeersEmptyStats(t *testing.T) {
+	cm := &dropper{maxDialPeers: 20, maxInboundPeers: 30}
+	cm.peerStatsFunc = func() map[string]peerstats.PeerStats {
+		return map[string]peerstats.PeerStats{}
+	}
+
+	peers := makePeers(10)
+	protected := cm.protectedPeers(peers)
+	if len(protected) != 0 {
+		t.Fatalf("expected no protected peers with empty stats, got %d", len(protected))
+	}
+}
+
+func TestProtectedPeersTopPeer(t *testing.T) {
+	// 20 peers, 10% of 20 = 2 protected per category.
+	cm := &dropper{maxDialPeers: 20, maxInboundPeers: 30}
+
+	peers := makePeers(20)
+	stats := make(map[string]peerstats.PeerStats)
+	stats[peers[0].ID().String()] = peerstats.PeerStats{RecentFinalized: 100}
+	stats[peers[1].ID().String()] = peerstats.PeerStats{RecentIncluded: 5.0}
+
+	cm.peerStatsFunc = func() map[string]peerstats.PeerStats { return stats }
+
+	protected := cm.protectedPeers(peers)
+	if len(protected) != 2 {
+		t.Fatalf("expected 2 protected peers, got %d", len(protected))
+	}
+	if !protected[peers[0]] {
+		t.Fatal("peer 0 should be protected (top RecentFinalized)")
+	}
+	if !protected[peers[1]] {
+		t.Fatal("peer 1 should be protected (top RecentIncluded)")
+	}
+}
+
+func TestProtectedPeersZeroScore(t *testing.T) {
+	cm := &dropper{maxDialPeers: 20, maxInboundPeers: 30}
+
+	peers := makePeers(10)
+	stats := make(map[string]peerstats.PeerStats)
+	for _, p := range peers {
+		stats[p.ID().String()] = peerstats.PeerStats{}
+	}
+	cm.peerStatsFunc = func() map[string]peerstats.PeerStats { return stats }
+
+	protected := cm.protectedPeers(peers)
+	if len(protected) != 0 {
+		t.Fatalf("expected no protection with zero scores, got %d", len(protected))
+	}
+}
+
+func TestProtectedPeersOverlap(t *testing.T) {
+	// One peer is top in both categories — counted once.
+	cm := &dropper{maxDialPeers: 20, maxInboundPeers: 30}
+
+	peers := makePeers(20)
+	stats := make(map[string]peerstats.PeerStats)
+	stats[peers[0].ID().String()] = peerstats.PeerStats{RecentFinalized: 100, RecentIncluded: 5.0}
+
+	cm.peerStatsFunc = func() map[string]peerstats.PeerStats { return stats }
+
+	protected := cm.protectedPeers(peers)
+	if len(protected) != 1 {
+		t.Fatalf("expected 1 protected peer (overlap), got %d", len(protected))
+	}
+}
+
+func TestProtectedPeersNilFunc(t *testing.T) {
+	cm := &dropper{maxDialPeers: 20, maxInboundPeers: 30}
+	// peerStatsFunc is nil (default).
+
+	peers := makePeers(10)
+	protected := cm.protectedPeers(peers)
+	if protected != nil {
+		t.Fatalf("expected nil with nil stats func, got %v", protected)
+	}
+}
+
+// TestProtectedByPoolPerPoolTopN verifies that the top-N selection runs
+// independently in each of the inbound and dialed pools, not globally.
+// With 10 peers per pool and inclusionProtectionFrac=0.1, exactly 1 peer
+// is protected per pool per category — so 2 total (one per pool), both
+// for the RecentFinalized category since we don't set RecentIncluded.
+func TestProtectedByPoolPerPoolTopN(t *testing.T) {
+	inbound := makePeers(10)
+	dialed := makePeers(10)
+	// Distinguish dialed peer IDs from inbound so stats maps don't collide.
+	for i := range dialed {
+		id := enode.ID{byte(100 + i)}
+		dialed[i] = p2p.NewPeer(id, fmt.Sprintf("dialed%d", i), nil)
+	}
+	// Strictly increasing scores: highest wins in each pool.
+	stats := make(map[string]peerstats.PeerStats)
+	for i, p := range inbound {
+		stats[p.ID().String()] = peerstats.PeerStats{RecentFinalized: float64(1 + i)}
+	}
+	for i, p := range dialed {
+		stats[p.ID().String()] = peerstats.PeerStats{RecentFinalized: float64(1 + i)}
+	}
+
+	protected := protectedPeersByPool(inbound, dialed, stats)
+
+	// Expect top 1 of inbound (inbound[9]) and top 1 of dialed (dialed[9]).
+	if len(protected) != 2 {
+		t.Fatalf("expected 2 protected peers (1 per pool), got %d", len(protected))
+	}
+	if !protected[inbound[9]] {
+		t.Error("expected top inbound peer to be protected")
+	}
+	if !protected[dialed[9]] {
+		t.Error("expected top dialed peer to be protected")
+	}
+}
+
+// TestProtectedByPoolCrossCategoryOverlap verifies that the union across
+// protection categories is correctly deduplicated: a peer that wins in
+// multiple categories appears once, and category winners are all
+// protected. Uses a pool large enough that frac*len yields n=2 per
+// category, so cross-category overlap is observable.
+func TestProtectedByPoolCrossCategoryOverlap(t *testing.T) {
+	// 20 dialed peers so 0.1 * 20 = 2 protected per category.
+	dialed := makePeers(20)
+	// P0: high RecentFinalized only. P1: high RecentIncluded only. P2: high both.
+	// With n=2 per category:
+	//   RecentFinalized winners: P2 (tie-broken-ok), P0
+	//   RecentIncluded winners: P2, P1
+	// Union: {P0, P1, P2}.
+	stats := make(map[string]peerstats.PeerStats)
+	stats[dialed[0].ID().String()] = peerstats.PeerStats{RecentFinalized: 100, RecentIncluded: 0}
+	stats[dialed[1].ID().String()] = peerstats.PeerStats{RecentFinalized: 0, RecentIncluded: 5.0}
+	stats[dialed[2].ID().String()] = peerstats.PeerStats{RecentFinalized: 200, RecentIncluded: 10.0}
+
+	protected := protectedPeersByPool(nil, dialed, stats)
+
+	if len(protected) != 3 {
+		t.Fatalf("expected 3 protected peers (union of category winners), got %d", len(protected))
+	}
+	for _, idx := range []int{0, 1, 2} {
+		if !protected[dialed[idx]] {
+			t.Errorf("peer %d should be protected", idx)
+		}
+	}
+}
+
+// TestProtectedByPoolPerPoolIndependence locks in that selection runs
+// per-pool, not globally. Every inbound peer scores higher than every
+// dialed peer, so a global top-N would pick only inbound peers. Per-pool
+// top-N must still protect the top dialed peers.
+func TestProtectedByPoolPerPoolIndependence(t *testing.T) {
+	// 20 inbound, 20 dialed — frac=0.1 → 2 protected per pool per category.
+	// Global top-4 of RecentFinalized would be inbound[16..19] — zero dialed.
+	inbound := makePeers(20)
+	dialed := make([]*p2p.Peer, 20)
+	for i := range dialed {
+		id := enode.ID{byte(100 + i)}
+		dialed[i] = p2p.NewPeer(id, fmt.Sprintf("dialed%d", i), nil)
+	}
+	stats := make(map[string]peerstats.PeerStats)
+	// Every inbound peer outscores every dialed peer.
+	for i, p := range inbound {
+		stats[p.ID().String()] = peerstats.PeerStats{RecentFinalized: float64(1000 + i)}
+	}
+	for i, p := range dialed {
+		stats[p.ID().String()] = peerstats.PeerStats{RecentFinalized: float64(1 + i)}
+	}
+
+	protected := protectedPeersByPool(inbound, dialed, stats)
+
+	// Per-pool top-2 of RecentFinalized:
+	//   inbound: inbound[18], inbound[19]
+	//   dialed:  dialed[18], dialed[19]
+	// Global top-N would contain zero dialed peers, so asserting the top
+	// dialed peers are protected enforces per-pool independence.
+	if !protected[dialed[19]] {
+		t.Fatal("top dialed peer must be protected regardless of globally-higher inbound peers")
+	}
+	if !protected[dialed[18]] {
+		t.Fatal("second-top dialed peer must be protected regardless of globally-higher inbound peers")
+	}
+	if !protected[inbound[19]] || !protected[inbound[18]] {
+		t.Fatal("top inbound peers must also be protected")
+	}
+	if len(protected) != 4 {
+		t.Fatalf("expected 4 protected peers (top-2 of each pool), got %d", len(protected))
+	}
+}
+
+// TestProtectedByPoolRequestLatencyBasic verifies the latency protection
+// category: with no competing inclusion stats, the lowest-latency peers
+// (among those with enough samples) win top-N protection.
+func TestProtectedByPoolRequestLatencyBasic(t *testing.T) {
+	dialed := makePeers(20) // frac=0.1 → n=2 per category
+	stats := make(map[string]peerstats.PeerStats)
+	// Three peers have enough samples; the two fastest should win.
+	stats[dialed[0].ID().String()] = peerstats.PeerStats{
+		RequestLatencyEMA: 50 * time.Millisecond,
+		RequestSuccesses:  peerstats.MinLatencySamples,
+		LastLatencySample: time.Now(),
+	}
+	stats[dialed[1].ID().String()] = peerstats.PeerStats{
+		RequestLatencyEMA: 100 * time.Millisecond,
+		RequestSuccesses:  peerstats.MinLatencySamples,
+		LastLatencySample: time.Now(),
+	}
+	stats[dialed[2].ID().String()] = peerstats.PeerStats{
+		RequestLatencyEMA: 2 * time.Second,
+		RequestSuccesses:  peerstats.MinLatencySamples,
+		LastLatencySample: time.Now(),
+	}
+
+	protected := protectedPeersByPool(nil, dialed, stats)
+
+	if !protected[dialed[0]] {
+		t.Error("fastest peer should be protected")
+	}
+	if !protected[dialed[1]] {
+		t.Error("second-fastest peer should be protected")
+	}
+	if protected[dialed[2]] {
+		t.Error("slowest peer should not be in top-2")
+	}
+	if len(protected) != 2 {
+		t.Fatalf("expected top-2 latency protection, got %d", len(protected))
+	}
+}
+
+// TestProtectedByPoolRequestLatencyBootstrapGuard verifies that peers with
+// fewer than MinLatencySamples do not earn latency-based protection, even
+// if their few samples indicate very low latency.
+func TestProtectedByPoolRequestLatencyBootstrapGuard(t *testing.T) {
+	dialed := makePeers(20)
+	stats := make(map[string]peerstats.PeerStats)
+	// A lucky-fast peer with only 1 sample — must NOT be protected.
+	stats[dialed[0].ID().String()] = peerstats.PeerStats{
+		RequestLatencyEMA: 1 * time.Millisecond,
+		RequestSuccesses:  1,
+	}
+	// A warmed-up but slower peer — should be protected on latency.
+	stats[dialed[1].ID().String()] = peerstats.PeerStats{
+		RequestLatencyEMA: 500 * time.Millisecond,
+		RequestSuccesses:  peerstats.MinLatencySamples,
+		LastLatencySample: time.Now(),
+	}
+
+	protected := protectedPeersByPool(nil, dialed, stats)
+
+	if protected[dialed[0]] {
+		t.Error("under-sampled peer should not be protected (bootstrap guard)")
+	}
+	if !protected[dialed[1]] {
+		t.Error("warmed-up peer should be protected")
+	}
+}
+
+// TestProtectedByPoolRequestLatencyPerPool verifies that the latency
+// category selects top-N per pool independently, consistent with the
+// other categories. An inbound peer with lower latency does not prevent
+// a dialed peer from being protected as top of the dialed pool.
+func TestProtectedByPoolRequestLatencyPerPool(t *testing.T) {
+	inbound := makePeers(20)
+	dialed := make([]*p2p.Peer, 20)
+	for i := range dialed {
+		id := enode.ID{byte(100 + i)}
+		dialed[i] = p2p.NewPeer(id, fmt.Sprintf("dialed%d", i), nil)
+	}
+	stats := make(map[string]peerstats.PeerStats)
+	// All inbound peers are very fast (50ms).
+	for _, p := range inbound {
+		stats[p.ID().String()] = peerstats.PeerStats{
+			RequestLatencyEMA: 50 * time.Millisecond,
+			RequestSuccesses:  peerstats.MinLatencySamples,
+			LastLatencySample: time.Now(),
+		}
+	}
+	// Dialed peers are slower (1s) — globally they would all lose, but
+	// per-pool top-N should still protect two of them.
+	for _, p := range dialed {
+		stats[p.ID().String()] = peerstats.PeerStats{
+			RequestLatencyEMA: 1 * time.Second,
+			RequestSuccesses:  peerstats.MinLatencySamples,
+			LastLatencySample: time.Now(),
+		}
+	}
+
+	protected := protectedPeersByPool(inbound, dialed, stats)
+
+	// 2 from inbound + 2 from dialed = 4.
+	var dialedProtected int
+	for _, p := range dialed {
+		if protected[p] {
+			dialedProtected++
+		}
+	}
+	if dialedProtected != 2 {
+		t.Fatalf("expected 2 dialed peers protected by per-pool top-N, got %d", dialedProtected)
+	}
+}
+
+// TestProtectedByPoolRequestLatencyStale verifies that the freshness gate
+// excludes peers whose latency EMA is valid (meeting the sample count and
+// fast value) but whose last sample is older than MaxLatencyStaleness.
+// A peer cannot serve a burst of fast replies, go silent on announcements,
+// and keep latency-based protection indefinitely.
+func TestProtectedByPoolRequestLatencyStale(t *testing.T) {
+	dialed := makePeers(20)
+	stats := make(map[string]peerstats.PeerStats)
+	// Fresh, fast peer — should be protected.
+	stats[dialed[0].ID().String()] = peerstats.PeerStats{
+		RequestLatencyEMA: 50 * time.Millisecond,
+		RequestSuccesses:  peerstats.MinLatencySamples,
+		LastLatencySample: time.Now(),
+	}
+	// Stale, fast peer — was fast, but hasn't answered in too long.
+	// Same EMA and sample count as the fresh peer; only staleness differs.
+	stats[dialed[1].ID().String()] = peerstats.PeerStats{
+		RequestLatencyEMA: 50 * time.Millisecond,
+		RequestSuccesses:  peerstats.MinLatencySamples,
+		LastLatencySample: time.Now().Add(-2 * peerstats.MaxLatencyStaleness),
+	}
+
+	protected := protectedPeersByPool(nil, dialed, stats)
+
+	if !protected[dialed[0]] {
+		t.Error("fresh fast peer must be protected")
+	}
+	if protected[dialed[1]] {
+		t.Error("stale peer must NOT keep latency protection despite fast EMA")
+	}
+}

eth/fetcher/tx_fetcher.go

@@ -180,10 +180,12 @@ type TxFetcher struct {
 	alternates map[common.Hash]map[string]struct{} // In-flight transaction alternate origins if retrieval fails
 
 	// Callbacks
-	validateMeta func(common.Hash, byte) error      // Validate a tx metadata based on the local txpool
+	validateMeta    func(common.Hash, byte) error                          // Validate a tx metadata based on the local txpool
-	addTxs       func([]*types.Transaction) []error // Insert a batch of transactions into local txpool
+	addTxs          func([]*types.Transaction) []error                     // Insert a batch of transactions into local txpool
-	fetchTxs     func(string, []common.Hash) error  // Retrieves a set of txs from a remote peer
+	fetchTxs        func(string, []common.Hash) error                      // Retrieves a set of txs from a remote peer
-	dropPeer     func(string)                       // Drops a peer in case of announcement violation
+	dropPeer        func(string)                                           // Drops a peer in case of announcement violation
+	onAccepted      func(peer string, hashes []common.Hash)                // Optional: notified with accepted tx hashes per peer
+	onRequestResult func(peer string, latency time.Duration, timeout bool) // Optional: notified once per completed/timed-out tx request
 
 	step     chan struct{}    // Notification channel when the fetcher loop iterates
 	clock    mclock.Clock     // Monotonic clock or simulated clock for tests
@@ -194,39 +196,41 @@ type TxFetcher struct {
 // NewTxFetcher creates a transaction fetcher to retrieve transaction
 // based on hash announcements.
 // Chain can be nil to disable on-chain checks.
-func NewTxFetcher(chain *core.BlockChain, validateMeta func(common.Hash, byte) error, addTxs func([]*types.Transaction) []error, fetchTxs func(string, []common.Hash) error, dropPeer func(string)) *TxFetcher {
+func NewTxFetcher(chain *core.BlockChain, validateMeta func(common.Hash, byte) error, addTxs func([]*types.Transaction) []error, fetchTxs func(string, []common.Hash) error, dropPeer func(string), onAccepted func(string, []common.Hash), onRequestResult func(string, time.Duration, bool)) *TxFetcher {
-	return NewTxFetcherForTests(chain, validateMeta, addTxs, fetchTxs, dropPeer, mclock.System{}, time.Now, nil)
+	return NewTxFetcherForTests(chain, validateMeta, addTxs, fetchTxs, dropPeer, onAccepted, onRequestResult, mclock.System{}, time.Now, nil)
 }
 
 // NewTxFetcherForTests is a testing method to mock out the realtime clock with
 // a simulated version and the internal randomness with a deterministic one.
 // Chain can be nil to disable on-chain checks.
 func NewTxFetcherForTests(
-	chain *core.BlockChain, validateMeta func(common.Hash, byte) error, addTxs func([]*types.Transaction) []error, fetchTxs func(string, []common.Hash) error, dropPeer func(string),
+	chain *core.BlockChain, validateMeta func(common.Hash, byte) error, addTxs func([]*types.Transaction) []error, fetchTxs func(string, []common.Hash) error, dropPeer func(string), onAccepted func(string, []common.Hash), onRequestResult func(string, time.Duration, bool),
 	clock mclock.Clock, realTime func() time.Time, rand *mrand.Rand) *TxFetcher {
 	return &TxFetcher{
-		notify:         make(chan *txAnnounce),
+		notify:          make(chan *txAnnounce),
-		cleanup:        make(chan *txDelivery),
+		cleanup:         make(chan *txDelivery),
-		drop:           make(chan *txDrop),
+		drop:            make(chan *txDrop),
-		quit:           make(chan struct{}),
+		quit:            make(chan struct{}),
-		waitlist:       make(map[common.Hash]map[string]struct{}),
+		waitlist:        make(map[common.Hash]map[string]struct{}),
-		waittime:       make(map[common.Hash]mclock.AbsTime),
+		waittime:        make(map[common.Hash]mclock.AbsTime),
-		waitslots:      make(map[string]map[common.Hash]*txMetadataWithSeq),
+		waitslots:       make(map[string]map[common.Hash]*txMetadataWithSeq),
-		announces:      make(map[string]map[common.Hash]*txMetadataWithSeq),
+		announces:       make(map[string]map[common.Hash]*txMetadataWithSeq),
-		announced:      make(map[common.Hash]map[string]struct{}),
+		announced:       make(map[common.Hash]map[string]struct{}),
-		fetching:       make(map[common.Hash]string),
+		fetching:        make(map[common.Hash]string),
-		requests:       make(map[string]*txRequest),
+		requests:        make(map[string]*txRequest),
-		alternates:     make(map[common.Hash]map[string]struct{}),
+		alternates:      make(map[common.Hash]map[string]struct{}),
-		underpriced:    lru.NewCache[common.Hash, time.Time](maxTxUnderpricedSetSize),
+		underpriced:     lru.NewCache[common.Hash, time.Time](maxTxUnderpricedSetSize),
-		txOnChainCache: lru.NewCache[common.Hash, struct{}](txOnChainCacheLimit),
+		txOnChainCache:  lru.NewCache[common.Hash, struct{}](txOnChainCacheLimit),
-		chain:          chain,
+		chain:           chain,
-		validateMeta:   validateMeta,
+		validateMeta:    validateMeta,
-		addTxs:         addTxs,
+		addTxs:          addTxs,
-		fetchTxs:       fetchTxs,
+		fetchTxs:        fetchTxs,
-		dropPeer:       dropPeer,
+		dropPeer:        dropPeer,
-		clock:          clock,
+		onAccepted:      onAccepted,
-		realTime:       realTime,
+		onRequestResult: onRequestResult,
-		rand:           rand,
+		clock:           clock,
+		realTime:        realTime,
+		rand:            rand,
 	}
 }
 
@@ -344,6 +348,8 @@ func (f *TxFetcher) Enqueue(peer string, txs []*types.Transaction, direct bool)
 		)
 		batch := txs[i:end]
 
+		var accepted []common.Hash
+
 		for j, err := range f.addTxs(batch) {
 			// Track the transaction hash if the price is too low for us.
 			// Avoid re-request this transaction when we receive another
@@ -353,7 +359,8 @@ func (f *TxFetcher) Enqueue(peer string, txs []*types.Transaction, direct bool)
 			}
 			// Track a few interesting failure types
 			switch {
-			case err == nil: // Noop, but need to handle to not count these
+			case err == nil:
+				accepted = append(accepted, batch[j].Hash())
 
 			case errors.Is(err, txpool.ErrAlreadyKnown):
 				duplicate++
@@ -385,6 +392,10 @@ func (f *TxFetcher) Enqueue(peer string, txs []*types.Transaction, direct bool)
 		underpricedMeter.Mark(underpriced)
 		otherRejectMeter.Mark(otherreject)
 
+		// Notify the tracker which txs from this peer were accepted.
+		if f.onAccepted != nil && len(accepted) > 0 {
+			f.onAccepted(peer, accepted)
+		}
 		// If 'other reject' is >25% of the deliveries in any batch, sleep a bit.
 		if otherreject > int64((len(batch)+3)/4) {
 			log.Debug("Peer delivering stale or invalid transactions", "peer", peer, "rejected", otherreject)
@@ -664,6 +675,14 @@ func (f *TxFetcher) loop() {
 					// Keep track of the request as dangling, but never expire
 					f.requests[peer].hashes = nil
 					txFetcherSlowPeers.Inc(1)
+					// Record the request as a timeout-latency sample. The slow
+					// EMA in the consumer counts timeouts as the timeout value
+					// itself, so a peer that times out repeatedly drags its
+					// score down without us having to wait for an eventual
+					// (possibly never-arriving) reply.
+					if f.onRequestResult != nil {
+						f.onRequestResult(peer, txFetchTimeout, true)
+					}
 				}
 			}
 			// Schedule a new transaction retrieval
@@ -760,6 +779,11 @@ func (f *TxFetcher) loop() {
 				if req.hashes == nil {
 					txFetcherSlowPeers.Dec(1)
 					txFetcherSlowWait.Update(time.Duration(f.clock.Now() - req.time).Nanoseconds())
+					// Already counted as a timeout sample at the timeout site;
+					// don't double-record on eventual delivery.
+				} else if f.onRequestResult != nil {
+					// Normal in-time delivery. Record the actual round-trip.
+					f.onRequestResult(delivery.origin, time.Duration(f.clock.Now()-req.time), false)
 				}
 				delete(f.requests, delivery.origin)
 

eth/fetcher/tx_fetcher_test.go

@@ -22,6 +22,7 @@ import (
 	"math/big"
 	"math/rand"
 	"slices"
+	"sync"
 	"testing"
 	"time"
 
@@ -97,7 +98,7 @@ func newTestTxFetcher() *TxFetcher {
 			return make([]error, len(txs))
 		},
 		func(string, []common.Hash) error { return nil },
-		nil,
+		nil, nil, nil,
 	)
 }
 
@@ -2203,6 +2204,8 @@ func TestTransactionForgotten(t *testing.T) {
 		},
 		func(string, []common.Hash) error { return nil },
 		func(string) {},
+		nil,
+		nil,
 		mockClock,
 		mockTime,
 		rand.New(rand.NewSource(0)), // Use fixed seed for deterministic behavior
@@ -2283,3 +2286,103 @@ func TestTransactionForgotten(t *testing.T) {
 		t.Errorf("wrong final underpriced cache size: got %d, want 1", size)
 	}
 }
+
+// resultRecorder is a thread-safe recorder for onRequestResult callbacks.
+type resultRecorder struct {
+	mu      sync.Mutex
+	samples []resultSample
+}
+
+type resultSample struct {
+	peer    string
+	latency time.Duration
+	timeout bool
+}
+
+func (r *resultRecorder) record(peer string, latency time.Duration, timeout bool) {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	r.samples = append(r.samples, resultSample{peer, latency, timeout})
+}
+
+func (r *resultRecorder) snapshot() []resultSample {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	out := make([]resultSample, len(r.samples))
+	copy(out, r.samples)
+	return out
+}
+
+// TestTransactionFetcherRequestResultOnDelivery asserts that an in-time
+// direct delivery fires the onRequestResult callback with timeout=false.
+func TestTransactionFetcherRequestResultOnDelivery(t *testing.T) {
+	rec := &resultRecorder{}
+	testTransactionFetcherParallel(t, txFetcherTest{
+		init: func() *TxFetcher {
+			f := newTestTxFetcher()
+			f.onRequestResult = rec.record
+			return f
+		},
+		steps: []interface{}{
+			doTxNotify{peer: "A", hashes: []common.Hash{testTxsHashes[0]}, types: []byte{testTxs[0].Type()}, sizes: []uint32{uint32(testTxs[0].Size())}},
+			doWait{time: txArriveTimeout, step: true},
+			doWait{time: 200 * time.Millisecond, step: false},
+			doTxEnqueue{peer: "A", txs: []*types.Transaction{testTxs[0]}, direct: true},
+			doFunc(func() {
+				samples := rec.snapshot()
+				if len(samples) != 1 {
+					t.Fatalf("expected 1 sample, got %d (%v)", len(samples), samples)
+				}
+				if samples[0].peer != "A" {
+					t.Errorf("peer mismatch: got %q, want A", samples[0].peer)
+				}
+				if samples[0].latency != 200*time.Millisecond {
+					t.Errorf("latency mismatch: got %v, want 200ms", samples[0].latency)
+				}
+				if samples[0].timeout {
+					t.Error("expected timeout=false for delivery")
+				}
+			}),
+		},
+	})
+}
+
+// TestTransactionFetcherRequestResultOnTimeout asserts that a timed-out
+// request fires onRequestResult with timeout=true and the timeout value,
+// and a subsequent (late) delivery does not fire a duplicate sample.
+func TestTransactionFetcherRequestResultOnTimeout(t *testing.T) {
+	rec := &resultRecorder{}
+	testTransactionFetcherParallel(t, txFetcherTest{
+		init: func() *TxFetcher {
+			f := newTestTxFetcher()
+			f.onRequestResult = rec.record
+			return f
+		},
+		steps: []interface{}{
+			doTxNotify{peer: "A", hashes: []common.Hash{testTxsHashes[0]}, types: []byte{testTxs[0].Type()}, sizes: []uint32{uint32(testTxs[0].Size())}},
+			doWait{time: txArriveTimeout, step: true},
+			doWait{time: txFetchTimeout, step: true},
+			doFunc(func() {
+				samples := rec.snapshot()
+				if len(samples) != 1 {
+					t.Fatalf("expected 1 timeout sample, got %d (%v)", len(samples), samples)
+				}
+				if samples[0].peer != "A" {
+					t.Errorf("peer mismatch: got %q, want A", samples[0].peer)
+				}
+				if samples[0].latency != txFetchTimeout {
+					t.Errorf("latency mismatch: got %v, want %v", samples[0].latency, txFetchTimeout)
+				}
+				if !samples[0].timeout {
+					t.Error("expected timeout=true for timed-out request")
+				}
+			}),
+			doTxEnqueue{peer: "A", txs: []*types.Transaction{testTxs[0]}, direct: true},
+			doFunc(func() {
+				if len(rec.snapshot()) != 1 {
+					t.Fatalf("late delivery double-counted: got %d samples, want 1", len(rec.snapshot()))
+				}
+			}),
+		},
+	})
+}

eth/handler.go

@@ -36,8 +36,10 @@ import (
 	"github.com/ethereum/go-ethereum/eth/downloader"
 	"github.com/ethereum/go-ethereum/eth/ethconfig"
 	"github.com/ethereum/go-ethereum/eth/fetcher"
+	"github.com/ethereum/go-ethereum/eth/peerstats"
 	"github.com/ethereum/go-ethereum/eth/protocols/eth"
 	"github.com/ethereum/go-ethereum/eth/protocols/snap"
+	"github.com/ethereum/go-ethereum/eth/txtracker"
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/event"
 	"github.com/ethereum/go-ethereum/log"
@@ -122,6 +124,8 @@ type handler struct {
 
 	downloader     *downloader.Downloader
 	txFetcher      *fetcher.TxFetcher
+	txTracker      *txtracker.Tracker
+	peerStats      *peerstats.Stats
 	peers          *peerSet
 	txBroadcastKey [16]byte
 
@@ -181,7 +185,9 @@ func newHandler(config *handlerConfig) (*handler, error) {
 		}
 		return nil
 	}
-	h.txFetcher = fetcher.NewTxFetcher(h.chain, validateMeta, addTxs, fetchTx, h.removePeer)
+	h.txTracker = txtracker.New()
+	h.peerStats = peerstats.New()
+	h.txFetcher = fetcher.NewTxFetcher(h.chain, validateMeta, addTxs, fetchTx, h.removePeer, h.txTracker.NotifyAccepted, h.peerStats.NotifyRequestResult)
 	return h, nil
 }
 
@@ -396,6 +402,7 @@ func (h *handler) unregisterPeer(id string) {
 	}
 	h.downloader.UnregisterPeer(id)
 	h.txFetcher.Drop(id)
+	h.peerStats.NotifyPeerDrop(id)
 
 	if err := h.peers.unregisterPeer(id); err != nil {
 		logger.Error("Ethereum peer removal failed", "err", err)

eth/peerstats/peerstats.go

@@ -0,0 +1,193 @@
+// Copyright 2026 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+// Package peerstats maintains per-peer quality metrics used by the peer
+// dropper to protect high-value peers from random disconnection.
+//
+// The package is a passive accumulator: it exposes entry points for its
+// signal producers (txtracker for inclusion/finalization, the tx fetcher
+// for latency, the handler for peer-drop cleanup) and a read-only
+// snapshot for its consumer (the dropper). It has no goroutine of its
+// own — all mutation is serialized by a single mutex.
+//
+// Signal sources:
+//   - NotifyBlock(inclusions, finalized) — per-block deltas from txtracker
+//     (computed under txtracker's own lock, then passed in after release)
+//   - NotifyRequestResult(peer, latency, timeout) — per-request outcomes
+//     from the fetcher; timeouts are reported with the timeout value so
+//     slow peers contribute to the EMA, and the timeout flag increments
+//     the per-peer timeout counter
+//   - NotifyPeerDrop(peer) — called from the handler on disconnect
+package peerstats
+
+import (
+	"sync"
+	"time"
+)
+
+const (
+	// EMA smoothing factor for per-block inclusion rate.
+	emaAlpha = 0.05
+	// EMA smoothing factor for per-block finalization rate. Very slow on
+	// purpose: finalization is permanent, and the score should reflect
+	// sustained contribution over long windows, not recent bursts.
+	// Half-life ≈ 6930 chain heads (~23 hours on 12s blocks).
+	finalizedEMAAlpha = 0.0001
+	// EMA smoothing factor for per-request latency average. Slow on purpose:
+	// short bursts shouldn't shift the score, sustained behavior should.
+	// Half-life ≈ ln(0.5)/ln(0.99) ≈ 69 samples.
+	latencyEMAAlpha = 0.01
+	// MinLatencySamples is the number of latency samples a peer must accumulate
+	// before its RequestLatencyEMA is considered meaningful for protection.
+	// Prevents a single lucky-fast reply from displacing established peers.
+	MinLatencySamples = 100
+	// MaxLatencyStaleness is the oldest allowed age of a peer's last
+	// latency sample before their RequestLatencyEMA is disregarded for
+	// protection. Prevents a peer from earning a fast score during a
+	// burst of activity and then holding protection indefinitely by
+	// going silent on tx announcements (no further requests → no fresh
+	// samples → EMA frozen at its last value).
+	MaxLatencyStaleness = 10 * time.Minute
+)
+
+// PeerStats is the exported per-peer snapshot returned by GetAllPeerStats.
+type PeerStats struct {
+	RecentFinalized   float64       // EMA of per-block finalization credits (slow)
+	RecentIncluded    float64       // EMA of per-block inclusions (fast)
+	RequestLatencyEMA time.Duration // Slow EMA of tx-request response latency (timeouts count as the timeout value)
+	RequestSuccesses  int64         // Requests answered before timeout
+	RequestTimeouts   int64         // Requests that timed out
+	LastLatencySample time.Time     // Wall-clock time of the most recent request result (for staleness gate)
+}
+
+// peerStats is the internal mutable state per peer.
+type peerStats struct {
+	recentFinalized   float64
+	recentIncluded    float64
+	requestLatencyEMA time.Duration
+	requestSuccesses  int64
+	requestTimeouts   int64
+	lastLatencySample time.Time
+}
+
+// Stats is the per-peer quality aggregator.
+type Stats struct {
+	mu    sync.Mutex
+	peers map[string]*peerStats
+}
+
+// New creates an empty Stats.
+func New() *Stats {
+	return &Stats{peers: make(map[string]*peerStats)}
+}
+
+// NotifyBlock ingests a per-block update. `inclusions` is the count of the head
+// block's transactions attributed to each peer; peers with a positive
+// count get a stats entry created if one doesn't exist (this is how
+// peerstats learns about newly-active peers). Peers not in the map but
+// already tracked have their EMA decay with a zero sample.
+//
+// `finalized` is per-peer credits accumulated since the last NotifyBlock;
+// credits are only applied to peers already tracked — we don't resurrect
+// dropped peers from historical finalization data.
+//
+// NotifyBlock must NOT be called while the caller holds any other lock that
+// could be acquired by peerstats callers in reverse order. Current callers
+// (txtracker.handleChainHead) release their lock before invoking NotifyBlock.
+func (s *Stats) NotifyBlock(inclusions, finalized map[string]int) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	// Ensure a stats entry exists for any peer that just had an inclusion.
+	// This is the primary path by which peerstats learns about a peer's
+	// inclusion activity.
+	for peer, count := range inclusions {
+		if count > 0 && s.peers[peer] == nil {
+			s.peers[peer] = &peerStats{}
+		}
+	}
+	// Update inclusion and finalization EMAs for every tracked peer. A
+	// peer not present in the respective delta map gets a 0 contribution
+	// — pure decay. Finalization credits for peers no longer tracked are
+	// ignored (don't resurrect dropped peers from historical data).
+	for peer, ps := range s.peers {
+		ps.recentIncluded = (1-emaAlpha)*ps.recentIncluded + emaAlpha*float64(inclusions[peer])
+		ps.recentFinalized = (1-finalizedEMAAlpha)*ps.recentFinalized + finalizedEMAAlpha*float64(finalized[peer])
+	}
+}
+
+// NotifyRequestResult records a tx-request outcome for the given peer.
+// latency is the round-trip time (for timeouts, pass the timeout value).
+// timeout indicates whether the request timed out rather than receiving a
+// normal delivery. Both cases update the latency EMA; the timeout flag
+// additionally increments the per-peer timeout counter.
+// Creates a peer entry if one doesn't exist.
+func (s *Stats) NotifyRequestResult(peer string, latency time.Duration, timeout bool) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	ps := s.peers[peer]
+	if ps == nil {
+		ps = &peerStats{}
+		s.peers[peer] = ps
+	}
+	if ps.requestSuccesses+ps.requestTimeouts == 0 {
+		// Bootstrap the EMA with the first sample so it doesn't drift up
+		// from zero over many samples before reaching realistic values.
+		ps.requestLatencyEMA = latency
+	} else {
+		ps.requestLatencyEMA = time.Duration(
+			float64(ps.requestLatencyEMA)*(1-latencyEMAAlpha) +
+				float64(latency)*latencyEMAAlpha,
+		)
+	}
+	if timeout {
+		ps.requestTimeouts++
+	} else {
+		ps.requestSuccesses++
+	}
+	ps.lastLatencySample = time.Now()
+}
+
+// NotifyPeerDrop removes a peer's stats on disconnect. A rare stale
+// latency sample racing with the drop may recreate the peer entry with
+// one sample; that entry can never earn protection (MinLatencySamples
+// guard) and is harmless.
+func (s *Stats) NotifyPeerDrop(peer string) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	delete(s.peers, peer)
+}
+
+// GetAllPeerStats returns a snapshot of per-peer stats. Called by the
+// dropper every few minutes; allocation cost is negligible at that rate.
+func (s *Stats) GetAllPeerStats() map[string]PeerStats {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	result := make(map[string]PeerStats, len(s.peers))
+	for id, ps := range s.peers {
+		result[id] = PeerStats{
+			RecentFinalized:   ps.recentFinalized,
+			RecentIncluded:    ps.recentIncluded,
+			RequestLatencyEMA: ps.requestLatencyEMA,
+			RequestSuccesses:  ps.requestSuccesses,
+			RequestTimeouts:   ps.requestTimeouts,
+			LastLatencySample: ps.lastLatencySample,
+		}
+	}
+	return result
+}

eth/peerstats/peerstats_test.go

@@ -0,0 +1,293 @@
+// Copyright 2026 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package peerstats
+
+import (
+	"testing"
+	"time"
+)
+
+// TestNotifyBlockBootstrapsFromInclusions verifies that a peer with a positive
+// inclusion count in the first NotifyBlock gets a stats entry created.
+func TestNotifyBlockBootstrapsFromInclusions(t *testing.T) {
+	s := New()
+	s.NotifyBlock(map[string]int{"peerA": 3}, nil)
+
+	stats := s.GetAllPeerStats()
+	if len(stats) != 1 {
+		t.Fatalf("expected 1 peer entry, got %d", len(stats))
+	}
+	ps, ok := stats["peerA"]
+	if !ok {
+		t.Fatal("expected peerA entry")
+	}
+	// EMA after first block: (1-0.05)*0 + 0.05*3 = 0.15
+	if ps.RecentIncluded <= 0 {
+		t.Fatalf("expected RecentIncluded > 0 after inclusion, got %f", ps.RecentIncluded)
+	}
+}
+
+// TestNotifyBlockDecaysKnownPeers verifies that peers already tracked get their
+// RecentIncluded EMA decayed when they have no inclusions in a block.
+func TestNotifyBlockDecaysKnownPeers(t *testing.T) {
+	s := New()
+	// Seed peerA with an inclusion.
+	s.NotifyBlock(map[string]int{"peerA": 3}, nil)
+	initial := s.GetAllPeerStats()["peerA"].RecentIncluded
+
+	// Empty block — peerA should decay.
+	s.NotifyBlock(nil, nil)
+	after := s.GetAllPeerStats()["peerA"].RecentIncluded
+
+	if after >= initial {
+		t.Fatalf("expected decay, got %f >= %f", after, initial)
+	}
+}
+
+// TestNotifyBlockDoesNotResurrectDroppedPeers verifies that finalization
+// credits to a peer with no entry don't create one.
+func TestNotifyBlockDoesNotResurrectFromFinalization(t *testing.T) {
+	s := New()
+	s.NotifyBlock(nil, map[string]int{"peerA": 5})
+
+	if stats := s.GetAllPeerStats(); len(stats) != 0 {
+		t.Fatalf("finalization credits must not create entries, got %d peers", len(stats))
+	}
+}
+
+// TestNotifyBlockDropThenFinalizeNoResurrect verifies the full drop→finalize
+// sequence: a dropped peer doesn't come back via finalization credits.
+func TestNotifyBlockDropThenFinalizeNoResurrect(t *testing.T) {
+	s := New()
+	s.NotifyBlock(map[string]int{"peerA": 1}, nil)
+	s.NotifyPeerDrop("peerA")
+	s.NotifyBlock(nil, map[string]int{"peerA": 10})
+
+	if stats := s.GetAllPeerStats(); len(stats) != 0 {
+		t.Fatalf("dropped peer must not be resurrected, got %d peers", len(stats))
+	}
+}
+
+// TestNotifyBlockFinalizationCredits an existing peer.
+func TestNotifyBlockFinalizationCredits(t *testing.T) {
+	s := New()
+	s.NotifyBlock(map[string]int{"peerA": 1}, nil)
+	s.NotifyBlock(nil, map[string]int{"peerA": 3})
+
+	// RecentFinalized is a slow EMA, not a cumulative count: assert it
+	// moved in the positive direction, not the exact value.
+	if got := s.GetAllPeerStats()["peerA"].RecentFinalized; got <= 0 {
+		t.Fatalf("expected RecentFinalized>0 after credits, got %f", got)
+	}
+}
+
+// TestNotifyBlockInclusionEMAUpdate verifies the EMA formula (1-α)·old + α·count.
+func TestNotifyBlockInclusionEMAUpdate(t *testing.T) {
+	s := New()
+	// Three inclusions: EMA = 0.05 * 3 = 0.15
+	s.NotifyBlock(map[string]int{"peerA": 3}, nil)
+	got := s.GetAllPeerStats()["peerA"].RecentIncluded
+	want := 0.15
+	if diff := got - want; diff < -1e-9 || diff > 1e-9 {
+		t.Fatalf("EMA after one sample: got %f, want %f", got, want)
+	}
+	// Next block with 10 inclusions: EMA = 0.95*0.15 + 0.05*10 = 0.6425
+	s.NotifyBlock(map[string]int{"peerA": 10}, nil)
+	got = s.GetAllPeerStats()["peerA"].RecentIncluded
+	want = 0.6425
+	if diff := got - want; diff < -1e-9 || diff > 1e-9 {
+		t.Fatalf("EMA after two samples: got %f, want %f", got, want)
+	}
+}
+
+// TestNotifyRequestResultFirstSampleBootstrap asserts that the first
+// latency sample seeds the EMA directly.
+func TestNotifyRequestResultFirstSampleBootstrap(t *testing.T) {
+	s := New()
+	s.NotifyRequestResult("peerA", 200*time.Millisecond, false)
+
+	ps := s.GetAllPeerStats()["peerA"]
+	if ps.RequestLatencyEMA != 200*time.Millisecond {
+		t.Fatalf("expected first sample to seed EMA at 200ms, got %v", ps.RequestLatencyEMA)
+	}
+	if ps.RequestSuccesses != 1 {
+		t.Fatalf("expected RequestSuccesses=1, got %d", ps.RequestSuccesses)
+	}
+	if ps.RequestTimeouts != 0 {
+		t.Fatalf("expected RequestTimeouts=0, got %d", ps.RequestTimeouts)
+	}
+}
+
+// TestNotifyRequestResultEMAUpdate verifies the EMA formula for latency.
+func TestNotifyRequestResultEMAUpdate(t *testing.T) {
+	s := New()
+	s.NotifyRequestResult("peerA", 100*time.Millisecond, false)
+	s.NotifyRequestResult("peerA", 1000*time.Millisecond, false)
+
+	// Expected: 0.99*100ms + 0.01*1000ms = 109ms
+	got := s.GetAllPeerStats()["peerA"].RequestLatencyEMA
+	want := 109 * time.Millisecond
+	delta := got - want
+	if delta < 0 {
+		delta = -delta
+	}
+	if delta > 1*time.Microsecond {
+		t.Fatalf("EMA mismatch: got %v, want %v", got, want)
+	}
+	ps := s.GetAllPeerStats()["peerA"]
+	if ps.RequestSuccesses != 2 {
+		t.Fatalf("expected RequestSuccesses=2, got %d", ps.RequestSuccesses)
+	}
+}
+
+// TestNotifyRequestResultSlowConvergence verifies the slow alpha
+// damps convergence under sustained timeouts.
+func TestNotifyRequestResultSlowConvergence(t *testing.T) {
+	s := New()
+	s.NotifyRequestResult("peerA", 100*time.Millisecond, false)
+	for i := 0; i < 50; i++ {
+		s.NotifyRequestResult("peerA", 5*time.Second, false)
+	}
+	got := s.GetAllPeerStats()["peerA"].RequestLatencyEMA
+	if got < 1*time.Second {
+		t.Fatalf("EMA did not move enough under sustained timeouts, got %v", got)
+	}
+	if got > 3*time.Second {
+		t.Fatalf("EMA converged too fast for slow alpha=0.01, got %v", got)
+	}
+}
+
+// TestNotifyPeerDropClearsStats verifies that a dropped peer disappears
+// from GetAllPeerStats.
+func TestNotifyPeerDropClearsStats(t *testing.T) {
+	s := New()
+	s.NotifyRequestResult("peerA", 200*time.Millisecond, false)
+	s.NotifyPeerDrop("peerA")
+
+	if _, ok := s.GetAllPeerStats()["peerA"]; ok {
+		t.Fatal("peerA stats should be removed after NotifyPeerDrop")
+	}
+}
+
+// TestStaleRequestLatencyAfterDrop documents the accepted behavior: a
+// late sample after NotifyPeerDrop recreates a 1-sample entry. The
+// dropper's MinLatencySamples=100 guard ensures this is harmless.
+func TestStaleRequestLatencyAfterDrop(t *testing.T) {
+	s := New()
+	s.NotifyRequestResult("peerA", 200*time.Millisecond, false)
+	s.NotifyPeerDrop("peerA")
+	// Late sample racing with the drop.
+	s.NotifyRequestResult("peerA", 50*time.Millisecond, false)
+
+	ps := s.GetAllPeerStats()["peerA"]
+	if ps.RequestSuccesses != 1 {
+		t.Fatalf("expected fresh RequestSuccesses=1, got %d", ps.RequestSuccesses)
+	}
+	if ps.RequestLatencyEMA != 50*time.Millisecond {
+		t.Fatalf("expected fresh bootstrap at 50ms, got %v", ps.RequestLatencyEMA)
+	}
+	// The dropper's MinLatencySamples guard (in eth/dropper.go) prevents
+	// this 1-sample entry from earning latency-based protection.
+}
+
+// TestMultiplePeersIsolated verifies per-peer isolation across signal types.
+func TestMultiplePeersIsolated(t *testing.T) {
+	s := New()
+	s.NotifyBlock(map[string]int{"peerA": 5, "peerB": 0}, nil)
+	s.NotifyRequestResult("peerA", 100*time.Millisecond, false)
+	s.NotifyRequestResult("peerB", 5*time.Second, false)
+	s.NotifyBlock(nil, map[string]int{"peerA": 2})
+
+	stats := s.GetAllPeerStats()
+	// Only peerA receives finalization credits; peerB's EMA stays at zero
+	// (no credits, pure decay from zero).
+	if stats["peerA"].RecentFinalized <= 0 || stats["peerB"].RecentFinalized != 0 {
+		t.Errorf("finalization leaked: A=%f B=%f", stats["peerA"].RecentFinalized, stats["peerB"].RecentFinalized)
+	}
+	if stats["peerA"].RequestLatencyEMA != 100*time.Millisecond {
+		t.Errorf("peerA latency: got %v, want 100ms", stats["peerA"].RequestLatencyEMA)
+	}
+	if stats["peerB"].RequestLatencyEMA != 5*time.Second {
+		t.Errorf("peerB latency: got %v, want 5s", stats["peerB"].RequestLatencyEMA)
+	}
+}
+
+// TestLatencyTimestampSet verifies that NotifyRequestResult stamps the
+// peer's LastLatencySample with approximately time.Now().
+func TestLatencyTimestampSet(t *testing.T) {
+	s := New()
+	before := time.Now()
+	s.NotifyRequestResult("peerA", 100*time.Millisecond, false)
+	after := time.Now()
+
+	got := s.GetAllPeerStats()["peerA"].LastLatencySample
+	if got.Before(before) || got.After(after) {
+		t.Fatalf("LastLatencySample = %v not in [%v, %v]", got, before, after)
+	}
+}
+
+// TestLatencyTimestampUpdatesOnEachSample verifies that a later
+// NotifyRequestResult call advances LastLatencySample.
+func TestLatencyTimestampUpdatesOnEachSample(t *testing.T) {
+	s := New()
+	s.NotifyRequestResult("peerA", 100*time.Millisecond, false)
+	first := s.GetAllPeerStats()["peerA"].LastLatencySample
+
+	// Small sleep so the second timestamp is detectably later.
+	time.Sleep(2 * time.Millisecond)
+	s.NotifyRequestResult("peerA", 200*time.Millisecond, false)
+	second := s.GetAllPeerStats()["peerA"].LastLatencySample
+
+	if !second.After(first) {
+		t.Fatalf("expected second sample timestamp > first, got first=%v second=%v", first, second)
+	}
+}
+
+// TestRequestResultTimeoutCounting verifies that timeout=true increments
+// RequestTimeouts (not RequestSuccesses) and still updates the EMA.
+func TestRequestResultTimeoutCounting(t *testing.T) {
+	s := New()
+	s.NotifyRequestResult("peerA", 5*time.Second, true)
+
+	ps := s.GetAllPeerStats()["peerA"]
+	if ps.RequestTimeouts != 1 {
+		t.Fatalf("expected RequestTimeouts=1, got %d", ps.RequestTimeouts)
+	}
+	if ps.RequestSuccesses != 0 {
+		t.Fatalf("expected RequestSuccesses=0, got %d", ps.RequestSuccesses)
+	}
+	if ps.RequestLatencyEMA != 5*time.Second {
+		t.Fatalf("EMA should bootstrap to timeout value, got %v", ps.RequestLatencyEMA)
+	}
+}
+
+// TestRequestResultMixedCounting verifies that a mix of successes and
+// timeouts increments the correct counters independently.
+func TestRequestResultMixedCounting(t *testing.T) {
+	s := New()
+	s.NotifyRequestResult("peerA", 100*time.Millisecond, false)
+	s.NotifyRequestResult("peerA", 100*time.Millisecond, false)
+	s.NotifyRequestResult("peerA", 5*time.Second, true)
+
+	ps := s.GetAllPeerStats()["peerA"]
+	if ps.RequestSuccesses != 2 {
+		t.Fatalf("expected RequestSuccesses=2, got %d", ps.RequestSuccesses)
+	}
+	if ps.RequestTimeouts != 1 {
+		t.Fatalf("expected RequestTimeouts=1, got %d", ps.RequestTimeouts)
+	}
+}

eth/txtracker/tracker.go

@@ -0,0 +1,228 @@
+// Copyright 2026 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+// Package txtracker maps accepted transactions to their delivering peer
+// and observes chain-head and finalization events to emit per-block
+// per-peer signals to a StatsConsumer (typically eth/peerstats).
+//
+// The tracker owns the tx-hash → deliverer-peer map with FIFO eviction,
+// a chain-head subscription goroutine, and the computation of per-block
+// inclusion counts and finalization credits. It does NOT maintain
+// per-peer aggregates — that is peerstats' job.
+package txtracker
+
+import (
+	"sync"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/event"
+	"github.com/ethereum/go-ethereum/log"
+)
+
+const (
+	// Maximum number of tx→deliverer mappings to retain.
+	maxTracked = 262144
+)
+
+// Chain is the blockchain interface needed by the tracker.
+type Chain interface {
+	SubscribeChainHeadEvent(ch chan<- core.ChainHeadEvent) event.Subscription
+	GetBlockByNumber(number uint64) *types.Block
+	GetBlock(hash common.Hash, number uint64) *types.Block
+	CurrentFinalBlock() *types.Header
+}
+
+// StatsConsumer receives per-block signals about peer inclusion and
+// finalization. The tracker invokes NotifyBlock exactly once per handled chain
+// head, AFTER releasing its own lock, with:
+//
+//   - inclusions: per-peer count of transactions in the head block
+//   - finalized:  per-peer count of transactions in blocks that became
+//     finalized since the previous call (possibly zero-range)
+//
+// Either map may be empty but the slice/map itself is never nil when
+// called. NotifyBlock must not call back into the tracker.
+type StatsConsumer interface {
+	NotifyBlock(inclusions, finalized map[string]int)
+}
+
+// Tracker records which peer delivered each transaction and emits
+// per-block inclusion and finalization signals to a StatsConsumer.
+type Tracker struct {
+	mu    sync.Mutex
+	txs   map[common.Hash]string // hash → deliverer peer ID
+	order []common.Hash          // insertion order for FIFO eviction
+
+	chain        Chain
+	consumer     StatsConsumer
+	lastFinalNum uint64 // last finalized block number processed
+	headCh       chan core.ChainHeadEvent
+	sub          event.Subscription
+
+	quit chan struct{}
+	step chan struct{} // test sync: sent after each event is processed
+	wg   sync.WaitGroup
+}
+
+// New creates a new tracker.
+func New() *Tracker {
+	return &Tracker{
+		txs:  make(map[common.Hash]string),
+		quit: make(chan struct{}),
+		step: make(chan struct{}, 1),
+	}
+}
+
+// Start begins listening for chain head events. `consumer` receives
+// per-block signals; if nil, signals are computed but discarded
+// (useful in tests that exercise only the tx-lifecycle surface).
+func (t *Tracker) Start(chain Chain, consumer StatsConsumer) {
+	t.chain = chain
+	t.consumer = consumer
+	// Seed lastFinalNum so checkFinalization doesn't backfill from genesis.
+	if fh := chain.CurrentFinalBlock(); fh != nil {
+		t.lastFinalNum = fh.Number.Uint64()
+	}
+	t.headCh = make(chan core.ChainHeadEvent, 128)
+	t.sub = chain.SubscribeChainHeadEvent(t.headCh)
+	t.wg.Add(1)
+	go t.loop()
+}
+
+// Stop shuts down the tracker.
+func (t *Tracker) Stop() {
+	t.sub.Unsubscribe()
+	close(t.quit)
+	t.wg.Wait()
+}
+
+// NotifyAccepted records that a peer delivered transactions that were accepted
+// by the pool. Only accepted (not rejected/duplicate) txs should be recorded
+// to prevent attribution poisoning from replayed or invalid txs.
+// Safe to call from any goroutine.
+func (t *Tracker) NotifyAccepted(peer string, hashes []common.Hash) {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+
+	for _, hash := range hashes {
+		if _, ok := t.txs[hash]; ok {
+			continue // already tracked, keep first deliverer
+		}
+		t.txs[hash] = peer
+		t.order = append(t.order, hash)
+	}
+	// Evict oldest entries if over capacity.
+	for len(t.txs) > maxTracked {
+		oldest := t.order[0]
+		t.order = t.order[1:]
+		delete(t.txs, oldest)
+	}
+	// Compact the backing array when it grows too large. Reslicing
+	// with order[1:] doesn't free earlier slots in the array.
+	if cap(t.order) > 2*maxTracked {
+		t.order = append([]common.Hash(nil), t.order...)
+	}
+}
+
+func (t *Tracker) loop() {
+	defer t.wg.Done()
+
+	for {
+		select {
+		case ev := <-t.headCh:
+			t.handleChainHead(ev)
+			select {
+			case t.step <- struct{}{}:
+			default:
+			}
+		case <-t.sub.Err():
+			return
+		case <-t.quit:
+			return
+		}
+	}
+}
+
+// handleChainHead computes per-peer deltas for the new head block and any
+// newly-finalized blocks, then hands them to the StatsConsumer AFTER
+// releasing t.mu. The lock-release-before-consumer pattern avoids any
+// cross-package lock ordering.
+func (t *Tracker) handleChainHead(ev core.ChainHeadEvent) {
+	// Fetch the head block by hash (not just number) to avoid using a
+	// reorged block if the tracker goroutine lags behind the chain.
+	block := t.chain.GetBlock(ev.Header.Hash(), ev.Header.Number.Uint64())
+	if block == nil {
+		return
+	}
+
+	t.mu.Lock()
+	// Count per-peer inclusions in the head block.
+	inclusions := make(map[string]int)
+	for _, tx := range block.Transactions() {
+		if peer := t.txs[tx.Hash()]; peer != "" {
+			inclusions[peer]++
+		}
+	}
+	// Compute per-peer finalization credits since the last call.
+	finalized := t.collectFinalization()
+	t.mu.Unlock()
+
+	if t.consumer != nil {
+		t.consumer.NotifyBlock(inclusions, finalized)
+	}
+}
+
+// collectFinalization accumulates per-peer finalization credits for
+// blocks newly finalized since lastFinalNum. Returns a (possibly empty)
+// map; advances lastFinalNum. Must be called with t.mu held.
+func (t *Tracker) collectFinalization() map[string]int {
+	credits := make(map[string]int)
+	finalHeader := t.chain.CurrentFinalBlock()
+	if finalHeader == nil {
+		return credits
+	}
+	finalNum := finalHeader.Number.Uint64()
+	if finalNum <= t.lastFinalNum {
+		return credits
+	}
+	for num := t.lastFinalNum + 1; num <= finalNum; num++ {
+		block := t.chain.GetBlockByNumber(num)
+		if block == nil {
+			continue
+		}
+		for _, tx := range block.Transactions() {
+			if peer := t.txs[tx.Hash()]; peer != "" {
+				credits[peer]++
+			}
+		}
+	}
+	if total := sumCounts(credits); total > 0 {
+		log.Trace("Accumulated finalization credits",
+			"from", t.lastFinalNum+1, "to", finalNum, "txs", total)
+	}
+	t.lastFinalNum = finalNum
+	return credits
+}
+
+func sumCounts(m map[string]int) int {
+	var sum int
+	for _, v := range m {
+		sum += v
+	}
+	return sum
+}

eth/txtracker/tracker_test.go

@@ -0,0 +1,362 @@
+// Copyright 2026 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package txtracker
+
+import (
+	"math/big"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/event"
+	"github.com/ethereum/go-ethereum/trie"
+)
+
+// mockChain implements the Chain interface for testing.
+//
+// Blocks are stored by hash to exercise the reorg-safe lookup path in
+// tracker.handleChainHead (which calls GetBlock(hash, number)). A separate
+// canonicalByNum index maps each height to its canonical block hash, used
+// by GetBlockByNumber (the finalization path).
+type mockChain struct {
+	mu             sync.Mutex
+	headFeed       event.Feed
+	blocksByHash   map[common.Hash]*types.Block
+	canonicalByNum map[uint64]common.Hash
+	finalNum       uint64
+}
+
+func newMockChain() *mockChain {
+	return &mockChain{
+		blocksByHash:   make(map[common.Hash]*types.Block),
+		canonicalByNum: make(map[uint64]common.Hash),
+	}
+}
+
+func (c *mockChain) SubscribeChainHeadEvent(ch chan<- core.ChainHeadEvent) event.Subscription {
+	return c.headFeed.Subscribe(ch)
+}
+
+func (c *mockChain) GetBlockByNumber(number uint64) *types.Block {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	hash, ok := c.canonicalByNum[number]
+	if !ok {
+		return nil
+	}
+	return c.blocksByHash[hash]
+}
+
+func (c *mockChain) GetBlock(hash common.Hash, number uint64) *types.Block {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	return c.blocksByHash[hash]
+}
+
+func (c *mockChain) CurrentFinalBlock() *types.Header {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	if c.finalNum == 0 {
+		return nil
+	}
+	return &types.Header{Number: new(big.Int).SetUint64(c.finalNum)}
+}
+
+// addBlock adds a canonical block at the given height.
+func (c *mockChain) addBlock(num uint64, txs []*types.Transaction) *types.Block {
+	return c.addBlockAtHeight(num, num, txs, true)
+}
+
+// addBlockAtHeight adds a block at the given height. The salt parameter
+// ensures distinct block hashes for two blocks at the same height. If
+// canonical is true, the block becomes the canonical block for that height.
+func (c *mockChain) addBlockAtHeight(num, salt uint64, txs []*types.Transaction, canonical bool) *types.Block {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	header := &types.Header{
+		Number: new(big.Int).SetUint64(num),
+		Extra:  big.NewInt(int64(salt)).Bytes(),
+	}
+	block := types.NewBlock(header, &types.Body{Transactions: txs}, nil, trie.NewListHasher())
+	c.blocksByHash[block.Hash()] = block
+	if canonical {
+		c.canonicalByNum[num] = block.Hash()
+	}
+	return block
+}
+
+func (c *mockChain) setFinalBlock(num uint64) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	c.finalNum = num
+}
+
+// sendHead emits a chain head event for the canonical block at the given height.
+func (c *mockChain) sendHead(num uint64) {
+	c.mu.Lock()
+	hash := c.canonicalByNum[num]
+	block := c.blocksByHash[hash]
+	c.mu.Unlock()
+	if block == nil {
+		panic("sendHead: no canonical block at height")
+	}
+	c.headFeed.Send(core.ChainHeadEvent{Header: block.Header()})
+}
+
+// sendHeadBlock emits a chain head event for the given block (may be
+// non-canonical). Used for reorg tests.
+func (c *mockChain) sendHeadBlock(block *types.Block) {
+	c.headFeed.Send(core.ChainHeadEvent{Header: block.Header()})
+}
+
+func hashTxs(txs []*types.Transaction) []common.Hash {
+	hashes := make([]common.Hash, len(txs))
+	for i, tx := range txs {
+		hashes[i] = tx.Hash()
+	}
+	return hashes
+}
+
+func makeTx(nonce uint64) *types.Transaction {
+	return types.NewTx(&types.LegacyTx{Nonce: nonce, GasPrice: big.NewInt(1), Gas: 21000})
+}
+
+// mockConsumer captures NotifyBlock invocations so tests can assert on the
+// signals the tracker emits.
+type mockConsumer struct {
+	mu      sync.Mutex
+	signals []signal
+}
+
+type signal struct {
+	inclusions, finalized map[string]int
+}
+
+func (c *mockConsumer) NotifyBlock(inclusions, finalized map[string]int) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	// Deep-copy so tests inspecting older signals aren't tripped up by
+	// later iterations mutating the same map (they don't today, but
+	// this keeps the assertion model simple).
+	in := make(map[string]int, len(inclusions))
+	for k, v := range inclusions {
+		in[k] = v
+	}
+	fn := make(map[string]int, len(finalized))
+	for k, v := range finalized {
+		fn[k] = v
+	}
+	c.signals = append(c.signals, signal{in, fn})
+}
+
+func (c *mockConsumer) last() signal {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	if len(c.signals) == 0 {
+		return signal{}
+	}
+	return c.signals[len(c.signals)-1]
+}
+
+// waitStep blocks until the tracker has processed one event.
+func waitStep(t *testing.T, tr *Tracker) {
+	t.Helper()
+	select {
+	case <-tr.step:
+	case <-time.After(time.Second):
+		t.Fatal("timeout waiting for tracker step")
+	}
+}
+
+// TestNotifyAcceptedRecordsMapping verifies the tx-lifecycle surface:
+// NotifyAccepted records tx→peer mappings in insertion order, with
+// first-deliverer-wins semantics on duplicates.
+func TestNotifyAcceptedRecordsMapping(t *testing.T) {
+	tr := New()
+
+	txs := []*types.Transaction{makeTx(1), makeTx(2), makeTx(3)}
+	hashes := hashTxs(txs)
+	tr.NotifyAccepted("peerA", hashes)
+
+	tr.mu.Lock()
+	defer tr.mu.Unlock()
+	if len(tr.txs) != 3 {
+		t.Fatalf("expected 3 tracked txs, got %d", len(tr.txs))
+	}
+	if len(tr.order) != 3 {
+		t.Fatalf("expected order length 3, got %d", len(tr.order))
+	}
+	for i, h := range hashes {
+		if got := tr.txs[h]; got != "peerA" {
+			t.Fatalf("tx %d: expected deliverer=peerA, got %q", i, got)
+		}
+		if tr.order[i] != h {
+			t.Fatalf("order[%d] mismatch", i)
+		}
+	}
+}
+
+// TestNotifyAcceptedFirstDelivererWins verifies duplicate accepts
+// preserve the original deliverer.
+func TestNotifyAcceptedFirstDelivererWins(t *testing.T) {
+	tr := New()
+	tx := makeTx(1)
+	tr.NotifyAccepted("peerA", []common.Hash{tx.Hash()})
+	tr.NotifyAccepted("peerB", []common.Hash{tx.Hash()})
+
+	tr.mu.Lock()
+	defer tr.mu.Unlock()
+	if got := tr.txs[tx.Hash()]; got != "peerA" {
+		t.Fatalf("expected first deliverer peerA to win, got %q", got)
+	}
+	if len(tr.order) != 1 {
+		t.Fatalf("expected single order entry, got %d", len(tr.order))
+	}
+}
+
+// TestHandleChainHeadEmitsInclusions verifies the tracker emits a
+// correct per-peer inclusion map to its consumer when a head block
+// contains tracked transactions.
+func TestHandleChainHeadEmitsInclusions(t *testing.T) {
+	tr := New()
+	chain := newMockChain()
+	consumer := &mockConsumer{}
+	tr.Start(chain, consumer)
+	defer tr.Stop()
+
+	tx1, tx2 := makeTx(1), makeTx(2)
+	tr.NotifyAccepted("peerA", []common.Hash{tx1.Hash()})
+	tr.NotifyAccepted("peerB", []common.Hash{tx2.Hash()})
+
+	chain.addBlock(1, []*types.Transaction{tx1, tx2})
+	chain.sendHead(1)
+	waitStep(t, tr)
+
+	sig := consumer.last()
+	if sig.inclusions["peerA"] != 1 {
+		t.Errorf("peerA inclusions: got %d, want 1", sig.inclusions["peerA"])
+	}
+	if sig.inclusions["peerB"] != 1 {
+		t.Errorf("peerB inclusions: got %d, want 1", sig.inclusions["peerB"])
+	}
+	if len(sig.finalized) != 0 {
+		t.Errorf("expected empty finalized map, got %v", sig.finalized)
+	}
+}
+
+// TestHandleChainHeadEmptyBlock verifies an empty head block emits an
+// empty inclusion map (so peerstats can decay all known peers).
+func TestHandleChainHeadEmptyBlock(t *testing.T) {
+	tr := New()
+	chain := newMockChain()
+	consumer := &mockConsumer{}
+	tr.Start(chain, consumer)
+	defer tr.Stop()
+
+	chain.addBlock(1, nil)
+	chain.sendHead(1)
+	waitStep(t, tr)
+
+	sig := consumer.last()
+	if len(sig.inclusions) != 0 {
+		t.Errorf("expected empty inclusions, got %v", sig.inclusions)
+	}
+}
+
+// TestHandleChainHeadEmitsFinalization verifies that when finalization
+// advances, the consumer receives per-peer finalization credits
+// accumulated over the newly-finalized range.
+func TestHandleChainHeadEmitsFinalization(t *testing.T) {
+	tr := New()
+	chain := newMockChain()
+	consumer := &mockConsumer{}
+	tr.Start(chain, consumer)
+	defer tr.Stop()
+
+	tx := makeTx(1)
+	tr.NotifyAccepted("peerA", []common.Hash{tx.Hash()})
+
+	// Include in block 1, not yet finalized.
+	chain.addBlock(1, []*types.Transaction{tx})
+	chain.sendHead(1)
+	waitStep(t, tr)
+
+	if credits := consumer.last().finalized["peerA"]; credits != 0 {
+		t.Fatalf("expected no finalization credits before finalization, got %d", credits)
+	}
+
+	// Finalize block 1; next head triggers the finalization scan.
+	chain.setFinalBlock(1)
+	chain.addBlock(2, nil)
+	chain.sendHead(2)
+	waitStep(t, tr)
+
+	if credits := consumer.last().finalized["peerA"]; credits != 1 {
+		t.Fatalf("expected 1 finalization credit, got %d", credits)
+	}
+}
+
+// TestReorgSafety verifies the tracker resolves the head block by HASH
+// so a head event pointing at a sibling block does not emit inclusions
+// from the canonical block at the same height.
+func TestReorgSafety(t *testing.T) {
+	tr := New()
+	chain := newMockChain()
+	consumer := &mockConsumer{}
+	tr.Start(chain, consumer)
+	defer tr.Stop()
+
+	tx := makeTx(1)
+	tr.NotifyAccepted("peerA", []common.Hash{tx.Hash()})
+
+	// Two blocks at height 1: canonical A contains tx; sibling B does not.
+	blockA := chain.addBlockAtHeight(1, 1, []*types.Transaction{tx}, true)
+	blockB := chain.addBlockAtHeight(1, 2, nil, false)
+	if blockA.Hash() == blockB.Hash() {
+		t.Fatal("sibling blocks ended up with the same hash")
+	}
+
+	// Head announces sibling B — emit must contain no peerA inclusions.
+	chain.sendHeadBlock(blockB)
+	waitStep(t, tr)
+	if incl := consumer.last().inclusions["peerA"]; incl != 0 {
+		t.Fatalf("sibling-B head should emit 0 peerA inclusions, got %d", incl)
+	}
+
+	// Head announces canonical A — emit must contain 1 peerA inclusion.
+	chain.sendHeadBlock(blockA)
+	waitStep(t, tr)
+	if incl := consumer.last().inclusions["peerA"]; incl != 1 {
+		t.Fatalf("canonical-A head should emit 1 peerA inclusion, got %d", incl)
+	}
+}
+
+// TestHandleChainHeadNilConsumer verifies the tracker tolerates a nil
+// consumer (useful for tests that only exercise tx-lifecycle behavior).
+func TestHandleChainHeadNilConsumer(t *testing.T) {
+	tr := New()
+	chain := newMockChain()
+	tr.Start(chain, nil)
+	defer tr.Stop()
+
+	chain.addBlock(1, nil)
+	chain.sendHead(1)
+	waitStep(t, tr) // should not panic
+}

tests/fuzzers/txfetcher/txfetcher_fuzzer.go

@@ -84,7 +84,7 @@ func fuzz(input []byte) int {
 			return make([]error, len(txs))
 		},
 		func(string, []common.Hash) error { return nil },
-		nil,
+		nil, nil, nil,
 		clock,
 		func() time.Time {
 			nanoTime := int64(clock.Now())