fix(p2p): handle pre-release versions in bee260 backward compatibility check

pkg/p2p/libp2p/libp2p.go

@@ -655,11 +655,13 @@ func (s *Service) handleIncoming(stream network.Stream) {
 		return
 	}
 
+	bee260Compat := s.bee260BackwardCompatibility(peerID)
+
 	i, err := s.handshakeService.Handle(
 		s.ctx,
 		handshakeStream,
 		peerMultiaddrs,
-		handshake.WithBee260Compatibility(s.bee260BackwardCompatibility(peerID)),
+		handshake.WithBee260Compatibility(bee260Compat),
 	)
 	if err != nil {
 		s.logger.Debug("stream handler: handshake: handle failed", "peer_id", peerID, "error", err)
@@ -1070,11 +1072,13 @@ func (s *Service) Connect(ctx context.Context, addrs []ma.Multiaddr) (address *b
 		return nil, fmt.Errorf("build peer multiaddrs: %w", err)
 	}
 
+	bee260Compat := s.bee260BackwardCompatibility(peerID)
+
 	i, err := s.handshakeService.Handshake(
 		s.ctx,
 		handshakeStream,
 		peerMultiaddrs,
-		handshake.WithBee260Compatibility(s.bee260BackwardCompatibility(peerID)),
+		handshake.WithBee260Compatibility(bee260Compat),
 	)
 	if err != nil {
 		_ = handshakeStream.Reset()
@@ -1484,7 +1488,15 @@ func (s *Service) bee260BackwardCompatibility(peerID libp2ppeer.ID) bool {
 	if err != nil {
 		return false
 	}
-	return v.LessThan(version270)
+
+	// Compare major.minor.patch only (ignore pre-release)
+	// This way 2.7.0-rc12 is treated as >= 2.7.0
+	vCore, err := semver.NewVersion(fmt.Sprintf("%d.%d.%d", v.Major, v.Minor, v.Patch))
+	if err != nil {
+		return false
+	}
+	result := vCore.LessThan(version270)
+	return result
 }
 
 // appendSpace adds a leading space character if the string is not empty.

pkg/p2p/libp2p/version_test.go

@@ -0,0 +1,165 @@
+// Copyright 2026 The Swarm Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package libp2p
+
+import (
+	"context"
+	"testing"
+
+	"github.com/ethersphere/bee/v2/pkg/crypto"
+	"github.com/ethersphere/bee/v2/pkg/log"
+	"github.com/ethersphere/bee/v2/pkg/statestore/mock"
+	"github.com/ethersphere/bee/v2/pkg/swarm"
+	libp2ppeer "github.com/libp2p/go-libp2p/core/peer"
+)
+
+func TestBee260BackwardCompatibility(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name      string
+		userAgent string
+		want      bool
+	}{
+		// Versions < 2.7.0 should require backward compatibility
+		{
+			name:      "version 2.6.0",
+			userAgent: "bee/2.6.0 go1.22.0 linux/amd64",
+			want:      true,
+		},
+		{
+			name:      "version 2.6.5",
+			userAgent: "bee/2.6.5 go1.22.0 linux/amd64",
+			want:      true,
+		},
+		{
+			name:      "version 2.5.0",
+			userAgent: "bee/2.5.0 go1.21.0 linux/amd64",
+			want:      true,
+		},
+		{
+			name:      "version 2.6.0-beta1",
+			userAgent: "bee/2.6.0-beta1 go1.22.0 linux/amd64",
+			want:      true,
+		},
+		// Versions >= 2.7.0 should NOT require backward compatibility
+		{
+			name:      "version 2.7.0",
+			userAgent: "bee/2.7.0 go1.23.0 linux/amd64",
+			want:      false,
+		},
+		{
+			name:      "version 2.8.0",
+			userAgent: "bee/2.8.0 go1.23.0 linux/amd64",
+			want:      false,
+		},
+		{
+			name:      "version 3.0.0",
+			userAgent: "bee/3.0.0 go1.25.0 linux/amd64",
+			want:      false,
+		},
+		// Pre-release versions >= 2.7.0 should NOT require backward compatibility
+		// This is the critical fix: 2.7.0-rcX should be treated as >= 2.7.0
+		{
+			name:      "version 2.7.0-rc1",
+			userAgent: "bee/2.7.0-rc1 go1.23.0 linux/amd64",
+			want:      false,
+		},
+		{
+			name:      "version 2.7.0-rc12",
+			userAgent: "bee/2.7.0-rc12-b39629d5-dirty go1.25.6 linux/amd64",
+			want:      false,
+		},
+		{
+			name:      "version 2.7.0-beta1",
+			userAgent: "bee/2.7.0-beta1 go1.23.0 linux/amd64",
+			want:      false,
+		},
+		{
+			name:      "version 2.8.0-rc1",
+			userAgent: "bee/2.8.0-rc1 go1.24.0 linux/amd64",
+			want:      false,
+		},
+		{
+			name:      "version 2.9.0-beta1",
+			userAgent: "bee/2.9.0-beta1 go1.24.0 linux/amd64",
+			want:      false,
+		},
+		// Edge cases that should return false (not requiring backward compat)
+		{
+			name:      "empty user agent",
+			userAgent: "",
+			want:      false,
+		},
+		{
+			name:      "malformed user agent missing space",
+			userAgent: "bee/2.6.0",
+			want:      false,
+		},
+		{
+			name:      "non-bee user agent",
+			userAgent: "other/1.0.0 go1.22.0 linux/amd64",
+			want:      false,
+		},
+		{
+			name:      "invalid version format",
+			userAgent: "bee/invalid go1.22.0 linux/amd64",
+			want:      false,
+		},
+		{
+			name:      "default libp2p user agent",
+			userAgent: "github.com/libp2p/go-libp2p",
+			want:      false,
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			// Create a service with minimal configuration
+			ctx, cancel := context.WithCancel(context.Background())
+			defer cancel()
+
+			swarmKey, err := crypto.GenerateSecp256k1Key()
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			overlay := swarm.RandAddress(t)
+			addr := ":0"
+			networkID := uint64(1)
+
+			statestore := mock.NewStateStore()
+			defer statestore.Close()
+
+			s, err := New(ctx, crypto.NewDefaultSigner(swarmKey), networkID, overlay, addr, nil, statestore, nil, log.Noop, nil, Options{})
+			if err != nil {
+				t.Fatal(err)
+			}
+			defer s.Close()
+
+			// Create a random test peer ID - we only need any valid libp2p peer ID
+			// The peerstore lookup will be mocked by setting the AgentVersion directly
+			libp2pPeerID, err := libp2ppeer.Decode("16Uiu2HAm3g4hXfCWTDhPBq3KkqpV3wGkPVgMJY3Jt8gGTYWiTWNZ")
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			// Set the user agent in the peerstore if provided
+			if tc.userAgent != "" {
+				if err := s.host.Peerstore().Put(libp2pPeerID, "AgentVersion", tc.userAgent); err != nil {
+					t.Fatal(err)
+				}
+			}
+
+			// Test the backward compatibility check
+			got := s.bee260BackwardCompatibility(libp2pPeerID)
+			if got != tc.want {
+				t.Errorf("bee260BackwardCompatibility() = %v, want %v (userAgent: %q)", got, tc.want, tc.userAgent)
+			}
+		})
+	}
+}