From a11b756e9c07cbedc761d93ef3286d275cfa53bf Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 5 Feb 2026 19:25:11 +0000
Subject: [PATCH 01/28] Initial plan


From 06fd58d8f8a3ad50cb28f038eeacf4d8a3579e96 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 5 Feb 2026 19:33:57 +0000
Subject: [PATCH 02/28] feat: set default User-Agent to Chrome with dynamic
 version based on date

Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>
---
 app/dns/nameserver_doh.go              |  2 ++
 app/observatory/burst/ping.go          |  3 +++
 common/protocol/http/headers.go        | 10 ++++++++++
 common/protocol/http/headers_test.go   | 13 +++++++++++++
 infra/conf/transport_authenticators.go |  8 +++-----
 proxy/http/server.go                   |  2 +-
 transport/internet/reality/reality.go  |  3 ++-
 transport/internet/tls/ech.go          |  2 ++
 8 files changed, 36 insertions(+), 7 deletions(-)

diff --git a/app/dns/nameserver_doh.go b/app/dns/nameserver_doh.go
index c0c1af265058..9d6f30f6e725 100644
--- a/app/dns/nameserver_doh.go
+++ b/app/dns/nameserver_doh.go
@@ -18,6 +18,7 @@ import (
 	"github.com/xtls/xray-core/common/net"
 	"github.com/xtls/xray-core/common/net/cnc"
 	"github.com/xtls/xray-core/common/protocol/dns"
+	http_proto "github.com/xtls/xray-core/common/protocol/http"
 	"github.com/xtls/xray-core/common/session"
 	"github.com/xtls/xray-core/common/utils"
 	dns_feature "github.com/xtls/xray-core/features/dns"
@@ -214,6 +215,7 @@ func (s *DoHNameServer) dohHTTPSContext(ctx context.Context, b []byte) ([]byte,
 
 	req.Header.Add("Accept", "application/dns-message")
 	req.Header.Add("Content-Type", "application/dns-message")
+	req.Header.Set("User-Agent", http_proto.ChromeUA())
 	req.Header.Set("X-Padding", utils.H2Base62Pad(crypto.RandBetween(100, 1000)))
 
 	hc := s.httpClient
diff --git a/app/observatory/burst/ping.go b/app/observatory/burst/ping.go
index fcb40f1a706a..ea880cdcd88a 100644
--- a/app/observatory/burst/ping.go
+++ b/app/observatory/burst/ping.go
@@ -6,6 +6,8 @@ import (
 	"net/http"
 	"time"
 
+	http_proto "github.com/xtls/xray-core/common/protocol/http"
+
 	"github.com/xtls/xray-core/common/net"
 	"github.com/xtls/xray-core/features/routing"
 	"github.com/xtls/xray-core/transport/internet/tagged"
@@ -61,6 +63,7 @@ func (s *pingClient) MeasureDelay(httpMethod string) (time.Duration, error) {
 	if err != nil {
 		return rttFailed, err
 	}
+	req.Header.Set("User-Agent", http_proto.ChromeUA())
 
 	start := time.Now()
 	resp, err := s.httpClient.Do(req)
diff --git a/common/protocol/http/headers.go b/common/protocol/http/headers.go
index db3aa6705eb2..502fbae7c961 100644
--- a/common/protocol/http/headers.go
+++ b/common/protocol/http/headers.go
@@ -4,10 +4,20 @@ import (
 	"net/http"
 	"strconv"
 	"strings"
+	"time"
 
 	"github.com/xtls/xray-core/common/net"
 )
 
+// ChromeUA generates a Chrome browser User-Agent string.
+// The version number changes monthly, starting from 143 in January 2026.
+func ChromeUA() string {
+	t := time.Now()
+	majorVersion := 143 + (t.Year()-2026)*12 + int(t.Month()) - 1
+	return "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/" +
+		strconv.Itoa(majorVersion) + ".0.0.0 Safari/537.36"
+}
+
 // ParseXForwardedFor parses X-Forwarded-For header in http headers, and return the IP list in it.
 func ParseXForwardedFor(header http.Header) []net.Address {
 	xff := header.Get("X-Forwarded-For")
diff --git a/common/protocol/http/headers_test.go b/common/protocol/http/headers_test.go
index 80e243aebc55..87870e4b931f 100644
--- a/common/protocol/http/headers_test.go
+++ b/common/protocol/http/headers_test.go
@@ -115,3 +115,16 @@ func TestParseHost(t *testing.T) {
 		}
 	}
 }
+
+func TestChromeUA(t *testing.T) {
+ua := ChromeUA()
+if !strings.Contains(ua, "Chrome/") {
+t.Error("ChromeUA should contain Chrome/ identifier")
+}
+if !strings.Contains(ua, "Mozilla/5.0") {
+t.Error("ChromeUA should contain Mozilla/5.0 prefix")
+}
+if !strings.HasSuffix(ua, "Safari/537.36") {
+t.Error("ChromeUA should end with Safari/537.36")
+}
+}
diff --git a/infra/conf/transport_authenticators.go b/infra/conf/transport_authenticators.go
index 2274c5addc01..9b896a9bf437 100644
--- a/infra/conf/transport_authenticators.go
+++ b/infra/conf/transport_authenticators.go
@@ -4,6 +4,7 @@ import (
 	"sort"
 
 	"github.com/xtls/xray-core/common/errors"
+	http_proto "github.com/xtls/xray-core/common/protocol/http"
 	"github.com/xtls/xray-core/transport/internet/headers/http"
 	"github.com/xtls/xray-core/transport/internet/headers/noop"
 	"google.golang.org/protobuf/proto"
@@ -40,11 +41,8 @@ func (v *AuthenticatorRequest) Build() (*http.RequestConfig, error) {
 				Value: []string{"www.baidu.com", "www.bing.com"},
 			},
 			{
-				Name: "User-Agent",
-				Value: []string{
-					"Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.143 Safari/537.36",
-					"Mozilla/5.0 (iPhone; CPU iPhone OS 10_0_2 like Mac OS X) AppleWebKit/601.1 (KHTML, like Gecko) CriOS/53.0.2785.109 Mobile/14A456 Safari/601.1.46",
-				},
+				Name:  "User-Agent",
+				Value: []string{http_proto.ChromeUA()},
 			},
 			{
 				Name:  "Accept-Encoding",
diff --git a/proxy/http/server.go b/proxy/http/server.go
index 90a07b38a585..a9751e060a05 100644
--- a/proxy/http/server.go
+++ b/proxy/http/server.go
@@ -229,7 +229,7 @@ func (s *Server) handlePlainHTTP(ctx context.Context, request *http.Request, wri
 
 	// Prevent UA from being set to golang's default ones
 	if request.Header.Get("User-Agent") == "" {
-		request.Header.Set("User-Agent", "")
+		request.Header.Set("User-Agent", http_proto.ChromeUA())
 	}
 
 	content := &session.Content{
diff --git a/transport/internet/reality/reality.go b/transport/internet/reality/reality.go
index 21b185ea1d15..09b4b60db9b2 100644
--- a/transport/internet/reality/reality.go
+++ b/transport/internet/reality/reality.go
@@ -27,6 +27,7 @@ import (
 	"github.com/xtls/xray-core/common/crypto"
 	"github.com/xtls/xray-core/common/errors"
 	"github.com/xtls/xray-core/common/net"
+	http_proto "github.com/xtls/xray-core/common/protocol/http"
 	"github.com/xtls/xray-core/core"
 	"github.com/xtls/xray-core/transport/internet/tls"
 	"golang.org/x/crypto/hkdf"
@@ -222,7 +223,7 @@ func UClient(c net.Conn, config *Config, ctx context.Context, dest net.Destinati
 				if req == nil {
 					return
 				}
-				req.Header.Set("User-Agent", fingerprint.Client) // TODO: User-Agent map
+				req.Header.Set("User-Agent", http_proto.ChromeUA())
 				if first && config.Show {
 					fmt.Printf("REALITY localAddr: %v\treq.UserAgent(): %v\n", localAddr, req.UserAgent())
 				}
diff --git a/transport/internet/tls/ech.go b/transport/internet/tls/ech.go
index 389d0699adfd..25c2295194a7 100644
--- a/transport/internet/tls/ech.go
+++ b/transport/internet/tls/ech.go
@@ -27,6 +27,7 @@ import (
 	"github.com/xtls/reality/hpke"
 	"github.com/xtls/xray-core/common/errors"
 	"github.com/xtls/xray-core/common/net"
+	http_proto "github.com/xtls/xray-core/common/protocol/http"
 	"github.com/xtls/xray-core/common/utils"
 	"github.com/xtls/xray-core/transport/internet"
 	"golang.org/x/crypto/cryptobyte"
@@ -257,6 +258,7 @@ func dnsQuery(server string, domain string, sockopt *internet.SocketConfig) ([]b
 		}
 		req.Header.Set("Accept", "application/dns-message")
 		req.Header.Set("Content-Type", "application/dns-message")
+		req.Header.Set("User-Agent", http_proto.ChromeUA())
 		req.Header.Set("X-Padding", utils.H2Base62Pad(crypto.RandBetween(100, 1000)))
 
 		resp, err := client.Do(req)

From b61d73738e28efcc07657e36aa55dad3f37df06b Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 5 Feb 2026 19:34:58 +0000
Subject: [PATCH 03/28] fix: add minimum version constraint for ChromeUA and
 improve test

Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>
---
 common/protocol/http/headers.go      |  4 ++++
 common/protocol/http/headers_test.go | 24 ++++++++++++++----------
 2 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/common/protocol/http/headers.go b/common/protocol/http/headers.go
index 502fbae7c961..02445de62702 100644
--- a/common/protocol/http/headers.go
+++ b/common/protocol/http/headers.go
@@ -14,6 +14,10 @@ import (
 func ChromeUA() string {
 	t := time.Now()
 	majorVersion := 143 + (t.Year()-2026)*12 + int(t.Month()) - 1
+	// Ensure minimum version of 143 for dates before January 2026
+	if majorVersion < 143 {
+		majorVersion = 143
+	}
 	return "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/" +
 		strconv.Itoa(majorVersion) + ".0.0.0 Safari/537.36"
 }
diff --git a/common/protocol/http/headers_test.go b/common/protocol/http/headers_test.go
index 87870e4b931f..0184a623feec 100644
--- a/common/protocol/http/headers_test.go
+++ b/common/protocol/http/headers_test.go
@@ -117,14 +117,18 @@ func TestParseHost(t *testing.T) {
 }
 
 func TestChromeUA(t *testing.T) {
-ua := ChromeUA()
-if !strings.Contains(ua, "Chrome/") {
-t.Error("ChromeUA should contain Chrome/ identifier")
-}
-if !strings.Contains(ua, "Mozilla/5.0") {
-t.Error("ChromeUA should contain Mozilla/5.0 prefix")
-}
-if !strings.HasSuffix(ua, "Safari/537.36") {
-t.Error("ChromeUA should end with Safari/537.36")
-}
+	ua := ChromeUA()
+	if !strings.Contains(ua, "Chrome/") {
+		t.Error("ChromeUA should contain Chrome/ identifier")
+	}
+	if !strings.Contains(ua, "Mozilla/5.0") {
+		t.Error("ChromeUA should contain Mozilla/5.0 prefix")
+	}
+	if !strings.HasSuffix(ua, "Safari/537.36") {
+		t.Error("ChromeUA should end with Safari/537.36")
+	}
+	// Verify version is at least the minimum (143)
+	if !strings.Contains(ua, "Chrome/1") {
+		t.Error("ChromeUA should have a Chrome version starting with 1")
+	}
 }

From a7c0037c2b94ac6cd8cfb9114cad29c2f0025d98 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 5 Feb 2026 20:01:42 +0000
Subject: [PATCH 04/28] refactor: move ChromeUA to utils as var, add UA to
 XHTTP/WS/HTTPUpgrade/gRPC, revert proxy/http

Co-authored-by: Fangliding <63339210+Fangliding@users.noreply.github.com>
---
 app/dns/nameserver_doh.go                |  3 +--
 app/observatory/burst/ping.go            |  4 ++--
 common/protocol/http/headers.go          | 14 --------------
 common/protocol/http/headers_test.go     | 17 -----------------
 common/utils/browser.go                  | 18 ++++++++++++++++++
 infra/conf/transport_authenticators.go   |  4 ++--
 proxy/http/server.go                     |  2 +-
 transport/internet/grpc/dial.go          |  9 +++++++--
 transport/internet/httpupgrade/dialer.go |  4 ++++
 transport/internet/reality/reality.go    |  4 ++--
 transport/internet/splithttp/config.go   |  6 +++++-
 transport/internet/tls/ech.go            |  3 +--
 transport/internet/websocket/config.go   |  6 +++++-
 13 files changed, 48 insertions(+), 46 deletions(-)
 create mode 100644 common/utils/browser.go

diff --git a/app/dns/nameserver_doh.go b/app/dns/nameserver_doh.go
index 9d6f30f6e725..2126bcd85457 100644
--- a/app/dns/nameserver_doh.go
+++ b/app/dns/nameserver_doh.go
@@ -18,7 +18,6 @@ import (
 	"github.com/xtls/xray-core/common/net"
 	"github.com/xtls/xray-core/common/net/cnc"
 	"github.com/xtls/xray-core/common/protocol/dns"
-	http_proto "github.com/xtls/xray-core/common/protocol/http"
 	"github.com/xtls/xray-core/common/session"
 	"github.com/xtls/xray-core/common/utils"
 	dns_feature "github.com/xtls/xray-core/features/dns"
@@ -215,7 +214,7 @@ func (s *DoHNameServer) dohHTTPSContext(ctx context.Context, b []byte) ([]byte,
 
 	req.Header.Add("Accept", "application/dns-message")
 	req.Header.Add("Content-Type", "application/dns-message")
-	req.Header.Set("User-Agent", http_proto.ChromeUA())
+	req.Header.Set("User-Agent", utils.ChromeUA)
 	req.Header.Set("X-Padding", utils.H2Base62Pad(crypto.RandBetween(100, 1000)))
 
 	hc := s.httpClient
diff --git a/app/observatory/burst/ping.go b/app/observatory/burst/ping.go
index ea880cdcd88a..f469643841bc 100644
--- a/app/observatory/burst/ping.go
+++ b/app/observatory/burst/ping.go
@@ -6,7 +6,7 @@ import (
 	"net/http"
 	"time"
 
-	http_proto "github.com/xtls/xray-core/common/protocol/http"
+	"github.com/xtls/xray-core/common/utils"
 
 	"github.com/xtls/xray-core/common/net"
 	"github.com/xtls/xray-core/features/routing"
@@ -63,7 +63,7 @@ func (s *pingClient) MeasureDelay(httpMethod string) (time.Duration, error) {
 	if err != nil {
 		return rttFailed, err
 	}
-	req.Header.Set("User-Agent", http_proto.ChromeUA())
+	req.Header.Set("User-Agent", utils.ChromeUA)
 
 	start := time.Now()
 	resp, err := s.httpClient.Do(req)
diff --git a/common/protocol/http/headers.go b/common/protocol/http/headers.go
index 02445de62702..db3aa6705eb2 100644
--- a/common/protocol/http/headers.go
+++ b/common/protocol/http/headers.go
@@ -4,24 +4,10 @@ import (
 	"net/http"
 	"strconv"
 	"strings"
-	"time"
 
 	"github.com/xtls/xray-core/common/net"
 )
 
-// ChromeUA generates a Chrome browser User-Agent string.
-// The version number changes monthly, starting from 143 in January 2026.
-func ChromeUA() string {
-	t := time.Now()
-	majorVersion := 143 + (t.Year()-2026)*12 + int(t.Month()) - 1
-	// Ensure minimum version of 143 for dates before January 2026
-	if majorVersion < 143 {
-		majorVersion = 143
-	}
-	return "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/" +
-		strconv.Itoa(majorVersion) + ".0.0.0 Safari/537.36"
-}
-
 // ParseXForwardedFor parses X-Forwarded-For header in http headers, and return the IP list in it.
 func ParseXForwardedFor(header http.Header) []net.Address {
 	xff := header.Get("X-Forwarded-For")
diff --git a/common/protocol/http/headers_test.go b/common/protocol/http/headers_test.go
index 0184a623feec..80e243aebc55 100644
--- a/common/protocol/http/headers_test.go
+++ b/common/protocol/http/headers_test.go
@@ -115,20 +115,3 @@ func TestParseHost(t *testing.T) {
 		}
 	}
 }
-
-func TestChromeUA(t *testing.T) {
-	ua := ChromeUA()
-	if !strings.Contains(ua, "Chrome/") {
-		t.Error("ChromeUA should contain Chrome/ identifier")
-	}
-	if !strings.Contains(ua, "Mozilla/5.0") {
-		t.Error("ChromeUA should contain Mozilla/5.0 prefix")
-	}
-	if !strings.HasSuffix(ua, "Safari/537.36") {
-		t.Error("ChromeUA should end with Safari/537.36")
-	}
-	// Verify version is at least the minimum (143)
-	if !strings.Contains(ua, "Chrome/1") {
-		t.Error("ChromeUA should have a Chrome version starting with 1")
-	}
-}
diff --git a/common/utils/browser.go b/common/utils/browser.go
new file mode 100644
index 000000000000..7f8c416592e4
--- /dev/null
+++ b/common/utils/browser.go
@@ -0,0 +1,18 @@
+package utils
+
+import (
+"strconv"
+"time"
+)
+
+func browserVersion() int {
+now := time.Now()
+ver := 143 + (now.Year()-2026)*12 + int(now.Month()) - 1
+if ver < 143 {
+ver = 143
+}
+return ver
+}
+
+// ChromeUA provides default browser User-Agent. Version 143 = Jan 2026, +1 per month.
+var ChromeUA = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/" + strconv.Itoa(browserVersion()) + ".0.0.0 Safari/537.36"
diff --git a/infra/conf/transport_authenticators.go b/infra/conf/transport_authenticators.go
index 9b896a9bf437..ea286f41d4a1 100644
--- a/infra/conf/transport_authenticators.go
+++ b/infra/conf/transport_authenticators.go
@@ -4,7 +4,7 @@ import (
 	"sort"
 
 	"github.com/xtls/xray-core/common/errors"
-	http_proto "github.com/xtls/xray-core/common/protocol/http"
+	"github.com/xtls/xray-core/common/utils"
 	"github.com/xtls/xray-core/transport/internet/headers/http"
 	"github.com/xtls/xray-core/transport/internet/headers/noop"
 	"google.golang.org/protobuf/proto"
@@ -42,7 +42,7 @@ func (v *AuthenticatorRequest) Build() (*http.RequestConfig, error) {
 			},
 			{
 				Name:  "User-Agent",
-				Value: []string{http_proto.ChromeUA()},
+				Value: []string{utils.ChromeUA},
 			},
 			{
 				Name:  "Accept-Encoding",
diff --git a/proxy/http/server.go b/proxy/http/server.go
index a9751e060a05..90a07b38a585 100644
--- a/proxy/http/server.go
+++ b/proxy/http/server.go
@@ -229,7 +229,7 @@ func (s *Server) handlePlainHTTP(ctx context.Context, request *http.Request, wri
 
 	// Prevent UA from being set to golang's default ones
 	if request.Header.Get("User-Agent") == "" {
-		request.Header.Set("User-Agent", http_proto.ChromeUA())
+		request.Header.Set("User-Agent", "")
 	}
 
 	content := &session.Content{
diff --git a/transport/internet/grpc/dial.go b/transport/internet/grpc/dial.go
index 454b32808852..bb426351bee0 100644
--- a/transport/internet/grpc/dial.go
+++ b/transport/internet/grpc/dial.go
@@ -6,6 +6,7 @@ import (
 	"time"
 
 	"github.com/xtls/xray-core/common"
+	"github.com/xtls/xray-core/common/utils"
 	c "github.com/xtls/xray-core/common/ctx"
 	"github.com/xtls/xray-core/common/errors"
 	"github.com/xtls/xray-core/common/net"
@@ -167,8 +168,12 @@ func getGrpcClient(ctx context.Context, dest net.Destination, streamSettings *in
 		dialOptions = append(dialOptions, grpc.WithInitialWindowSize(grpcSettings.InitialWindowsSize))
 	}
 
-	if grpcSettings.UserAgent != "" {
-		dialOptions = append(dialOptions, grpc.WithUserAgent(grpcSettings.UserAgent))
+	userAgent := grpcSettings.UserAgent
+	if userAgent == "" {
+		userAgent = utils.ChromeUA
+	}
+	if userAgent != "" {
+		dialOptions = append(dialOptions, grpc.WithUserAgent(userAgent))
 	}
 
 	var grpcDestHost string
diff --git a/transport/internet/httpupgrade/dialer.go b/transport/internet/httpupgrade/dialer.go
index c10bd97e5d3c..1a5c758d32a3 100644
--- a/transport/internet/httpupgrade/dialer.go
+++ b/transport/internet/httpupgrade/dialer.go
@@ -8,6 +8,7 @@ import (
 	"strings"
 
 	"github.com/xtls/xray-core/common"
+	"github.com/xtls/xray-core/common/utils"
 	"github.com/xtls/xray-core/common/errors"
 	"github.com/xtls/xray-core/common/net"
 	"github.com/xtls/xray-core/transport/internet"
@@ -86,6 +87,9 @@ func dialhttpUpgrade(ctx context.Context, dest net.Destination, streamSettings *
 	for key, value := range transportConfiguration.Header {
 		AddHeader(req.Header, key, value)
 	}
+if req.Header.Get("User-Agent") == "" {
+		req.Header.Set("User-Agent", utils.ChromeUA)
+	}
 	req.Header.Set("Connection", "Upgrade")
 	req.Header.Set("Upgrade", "websocket")
 
diff --git a/transport/internet/reality/reality.go b/transport/internet/reality/reality.go
index 09b4b60db9b2..1f6de2b5b17b 100644
--- a/transport/internet/reality/reality.go
+++ b/transport/internet/reality/reality.go
@@ -27,7 +27,7 @@ import (
 	"github.com/xtls/xray-core/common/crypto"
 	"github.com/xtls/xray-core/common/errors"
 	"github.com/xtls/xray-core/common/net"
-	http_proto "github.com/xtls/xray-core/common/protocol/http"
+	"github.com/xtls/xray-core/common/utils"
 	"github.com/xtls/xray-core/core"
 	"github.com/xtls/xray-core/transport/internet/tls"
 	"golang.org/x/crypto/hkdf"
@@ -223,7 +223,7 @@ func UClient(c net.Conn, config *Config, ctx context.Context, dest net.Destinati
 				if req == nil {
 					return
 				}
-				req.Header.Set("User-Agent", http_proto.ChromeUA())
+				req.Header.Set("User-Agent", utils.ChromeUA)
 				if first && config.Show {
 					fmt.Printf("REALITY localAddr: %v\treq.UserAgent(): %v\n", localAddr, req.UserAgent())
 				}
diff --git a/transport/internet/splithttp/config.go b/transport/internet/splithttp/config.go
index 9ecd5a436503..189e2efeb0fd 100644
--- a/transport/internet/splithttp/config.go
+++ b/transport/internet/splithttp/config.go
@@ -6,6 +6,7 @@ import (
 
 	"github.com/xtls/xray-core/common"
 	"github.com/xtls/xray-core/common/crypto"
+	"github.com/xtls/xray-core/common/utils"
 	"github.com/xtls/xray-core/transport/internet"
 )
 
@@ -44,9 +45,12 @@ func (c *Config) GetNormalizedQuery() string {
 
 func (c *Config) GetRequestHeader() http.Header {
 	header := http.Header{}
-	for k, v := range c.Headers {
+for k, v := range c.Headers {
 		header.Add(k, v)
 	}
+	if header.Get("User-Agent") == "" {
+		header.Set("User-Agent", utils.ChromeUA)
+	}
 	return header
 }
 
diff --git a/transport/internet/tls/ech.go b/transport/internet/tls/ech.go
index 25c2295194a7..6ba38aeadd0e 100644
--- a/transport/internet/tls/ech.go
+++ b/transport/internet/tls/ech.go
@@ -27,7 +27,6 @@ import (
 	"github.com/xtls/reality/hpke"
 	"github.com/xtls/xray-core/common/errors"
 	"github.com/xtls/xray-core/common/net"
-	http_proto "github.com/xtls/xray-core/common/protocol/http"
 	"github.com/xtls/xray-core/common/utils"
 	"github.com/xtls/xray-core/transport/internet"
 	"golang.org/x/crypto/cryptobyte"
@@ -258,7 +257,7 @@ func dnsQuery(server string, domain string, sockopt *internet.SocketConfig) ([]b
 		}
 		req.Header.Set("Accept", "application/dns-message")
 		req.Header.Set("Content-Type", "application/dns-message")
-		req.Header.Set("User-Agent", http_proto.ChromeUA())
+		req.Header.Set("User-Agent", utils.ChromeUA)
 		req.Header.Set("X-Padding", utils.H2Base62Pad(crypto.RandBetween(100, 1000)))
 
 		resp, err := client.Do(req)
diff --git a/transport/internet/websocket/config.go b/transport/internet/websocket/config.go
index 4f2c0a14dd58..f3d5f71bf67b 100644
--- a/transport/internet/websocket/config.go
+++ b/transport/internet/websocket/config.go
@@ -4,6 +4,7 @@ import (
 	"net/http"
 
 	"github.com/xtls/xray-core/common"
+	"github.com/xtls/xray-core/common/utils"
 	"github.com/xtls/xray-core/transport/internet"
 )
 
@@ -20,9 +21,12 @@ func (c *Config) GetNormalizedPath() string {
 
 func (c *Config) GetRequestHeader() http.Header {
 	header := http.Header{}
-	for k, v := range c.Header {
+for k, v := range c.Header {
 		header.Add(k, v)
 	}
+	if header.Get("User-Agent") == "" {
+		header.Set("User-Agent", utils.ChromeUA)
+	}
 	return header
 }
 

From f0021d65f644f43d4aa9de57d2da8b411cbb84fe Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 5 Feb 2026 20:04:07 +0000
Subject: [PATCH 05/28] fix: apply gofmt and remove redundant check in grpc
 dial

Co-authored-by: Fangliding <63339210+Fangliding@users.noreply.github.com>
---
 common/utils/browser.go                  | 16 ++++++++--------
 transport/internet/grpc/dial.go          |  6 ++----
 transport/internet/httpupgrade/dialer.go |  4 ++--
 transport/internet/splithttp/config.go   |  2 +-
 transport/internet/websocket/config.go   |  2 +-
 5 files changed, 14 insertions(+), 16 deletions(-)

diff --git a/common/utils/browser.go b/common/utils/browser.go
index 7f8c416592e4..80f68d5329d2 100644
--- a/common/utils/browser.go
+++ b/common/utils/browser.go
@@ -1,17 +1,17 @@
 package utils
 
 import (
-"strconv"
-"time"
+	"strconv"
+	"time"
 )
 
 func browserVersion() int {
-now := time.Now()
-ver := 143 + (now.Year()-2026)*12 + int(now.Month()) - 1
-if ver < 143 {
-ver = 143
-}
-return ver
+	now := time.Now()
+	ver := 143 + (now.Year()-2026)*12 + int(now.Month()) - 1
+	if ver < 143 {
+		ver = 143
+	}
+	return ver
 }
 
 // ChromeUA provides default browser User-Agent. Version 143 = Jan 2026, +1 per month.
diff --git a/transport/internet/grpc/dial.go b/transport/internet/grpc/dial.go
index bb426351bee0..e0b0aa03f8a7 100644
--- a/transport/internet/grpc/dial.go
+++ b/transport/internet/grpc/dial.go
@@ -6,11 +6,11 @@ import (
 	"time"
 
 	"github.com/xtls/xray-core/common"
-	"github.com/xtls/xray-core/common/utils"
 	c "github.com/xtls/xray-core/common/ctx"
 	"github.com/xtls/xray-core/common/errors"
 	"github.com/xtls/xray-core/common/net"
 	"github.com/xtls/xray-core/common/session"
+	"github.com/xtls/xray-core/common/utils"
 	"github.com/xtls/xray-core/transport/internet"
 	"github.com/xtls/xray-core/transport/internet/grpc/encoding"
 	"github.com/xtls/xray-core/transport/internet/reality"
@@ -172,9 +172,7 @@ func getGrpcClient(ctx context.Context, dest net.Destination, streamSettings *in
 	if userAgent == "" {
 		userAgent = utils.ChromeUA
 	}
-	if userAgent != "" {
-		dialOptions = append(dialOptions, grpc.WithUserAgent(userAgent))
-	}
+	dialOptions = append(dialOptions, grpc.WithUserAgent(userAgent))
 
 	var grpcDestHost string
 	if dest.Address.Family().IsDomain() {
diff --git a/transport/internet/httpupgrade/dialer.go b/transport/internet/httpupgrade/dialer.go
index 1a5c758d32a3..4d718eb8036e 100644
--- a/transport/internet/httpupgrade/dialer.go
+++ b/transport/internet/httpupgrade/dialer.go
@@ -8,9 +8,9 @@ import (
 	"strings"
 
 	"github.com/xtls/xray-core/common"
-	"github.com/xtls/xray-core/common/utils"
 	"github.com/xtls/xray-core/common/errors"
 	"github.com/xtls/xray-core/common/net"
+	"github.com/xtls/xray-core/common/utils"
 	"github.com/xtls/xray-core/transport/internet"
 	"github.com/xtls/xray-core/transport/internet/stat"
 	"github.com/xtls/xray-core/transport/internet/tls"
@@ -87,7 +87,7 @@ func dialhttpUpgrade(ctx context.Context, dest net.Destination, streamSettings *
 	for key, value := range transportConfiguration.Header {
 		AddHeader(req.Header, key, value)
 	}
-if req.Header.Get("User-Agent") == "" {
+	if req.Header.Get("User-Agent") == "" {
 		req.Header.Set("User-Agent", utils.ChromeUA)
 	}
 	req.Header.Set("Connection", "Upgrade")
diff --git a/transport/internet/splithttp/config.go b/transport/internet/splithttp/config.go
index 189e2efeb0fd..1819f0e9daef 100644
--- a/transport/internet/splithttp/config.go
+++ b/transport/internet/splithttp/config.go
@@ -45,7 +45,7 @@ func (c *Config) GetNormalizedQuery() string {
 
 func (c *Config) GetRequestHeader() http.Header {
 	header := http.Header{}
-for k, v := range c.Headers {
+	for k, v := range c.Headers {
 		header.Add(k, v)
 	}
 	if header.Get("User-Agent") == "" {
diff --git a/transport/internet/websocket/config.go b/transport/internet/websocket/config.go
index f3d5f71bf67b..bd38cd4fe837 100644
--- a/transport/internet/websocket/config.go
+++ b/transport/internet/websocket/config.go
@@ -21,7 +21,7 @@ func (c *Config) GetNormalizedPath() string {
 
 func (c *Config) GetRequestHeader() http.Header {
 	header := http.Header{}
-for k, v := range c.Header {
+	for k, v := range c.Header {
 		header.Add(k, v)
 	}
 	if header.Get("User-Agent") == "" {

From 0bb84811d4cefbb54eee527ba223444bcc4e5133 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 5 Feb 2026 20:10:00 +0000
Subject: [PATCH 06/28] feat: add User-Agent to HTTP proxy client and regular
 observatory

Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>
---
 app/observatory/observer.go | 5 ++++-
 proxy/http/client.go        | 5 +++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/app/observatory/observer.go b/app/observatory/observer.go
index a6fba3adb445..0ff9ba64e078 100644
--- a/app/observatory/observer.go
+++ b/app/observatory/observer.go
@@ -15,6 +15,7 @@ import (
 	"github.com/xtls/xray-core/common/session"
 	"github.com/xtls/xray-core/common/signal/done"
 	"github.com/xtls/xray-core/common/task"
+	"github.com/xtls/xray-core/common/utils"
 	"github.com/xtls/xray-core/core"
 	"github.com/xtls/xray-core/features/extension"
 	"github.com/xtls/xray-core/features/outbound"
@@ -162,7 +163,9 @@ func (o *Observer) probe(outbound string) ProbeResult {
 		if o.config.ProbeUrl != "" {
 			probeURL = o.config.ProbeUrl
 		}
-		response, err := httpClient.Get(probeURL)
+		req, _ := http.NewRequest(http.MethodGet, probeURL, nil)
+		req.Header.Set("User-Agent", utils.ChromeUA)
+		response, err := httpClient.Do(req)
 		if err != nil {
 			return errors.New("outbound failed to relay connection").Base(err)
 		}
diff --git a/proxy/http/client.go b/proxy/http/client.go
index 1f804d0bb7d8..365d13bfaaca 100644
--- a/proxy/http/client.go
+++ b/proxy/http/client.go
@@ -21,6 +21,7 @@ import (
 	"github.com/xtls/xray-core/common/session"
 	"github.com/xtls/xray-core/common/signal"
 	"github.com/xtls/xray-core/common/task"
+	"github.com/xtls/xray-core/common/utils"
 	"github.com/xtls/xray-core/core"
 	"github.com/xtls/xray-core/features/policy"
 	"github.com/xtls/xray-core/transport"
@@ -220,6 +221,10 @@ func setUpHTTPTunnel(ctx context.Context, dest net.Destination, target string, u
 		req.Header.Set(h.Key, h.Value)
 	}
 
+	if req.Header.Get("User-Agent") == "" {
+		req.Header.Set("User-Agent", utils.ChromeUA)
+	}
+
 	connectHTTP1 := func(rawConn net.Conn) (net.Conn, error) {
 		req.Header.Set("Proxy-Connection", "Keep-Alive")
 

From e3fb26773e4732665907fd5c6b4220ddfe8d1e01 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 5 Feb 2026 20:11:49 +0000
Subject: [PATCH 07/28] refactor: rename browserVersion() to ChromeVersion()

Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>
---
 common/utils/browser.go | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/common/utils/browser.go b/common/utils/browser.go
index 80f68d5329d2..9de6f64a749e 100644
--- a/common/utils/browser.go
+++ b/common/utils/browser.go
@@ -5,7 +5,7 @@ import (
 	"time"
 )
 
-func browserVersion() int {
+func ChromeVersion() int {
 	now := time.Now()
 	ver := 143 + (now.Year()-2026)*12 + int(now.Month()) - 1
 	if ver < 143 {
@@ -15,4 +15,4 @@ func browserVersion() int {
 }
 
 // ChromeUA provides default browser User-Agent. Version 143 = Jan 2026, +1 per month.
-var ChromeUA = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/" + strconv.Itoa(browserVersion()) + ".0.0.0 Safari/537.36"
+var ChromeUA = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/" + strconv.Itoa(ChromeVersion()) + ".0.0.0 Safari/537.36"

From c661bc1c2ae4b1f9694b52214339b6fb4e3c2a06 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 5 Feb 2026 20:56:11 +0000
Subject: [PATCH 08/28] fix: remove extra blank lines in burst/ping.go and
 http/client.go

Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>
---
 app/observatory/burst/ping.go | 3 +--
 proxy/http/client.go          | 1 -
 2 files changed, 1 insertion(+), 3 deletions(-)

diff --git a/app/observatory/burst/ping.go b/app/observatory/burst/ping.go
index f469643841bc..f08adb571e3d 100644
--- a/app/observatory/burst/ping.go
+++ b/app/observatory/burst/ping.go
@@ -6,9 +6,8 @@ import (
 	"net/http"
 	"time"
 
-	"github.com/xtls/xray-core/common/utils"
-
 	"github.com/xtls/xray-core/common/net"
+	"github.com/xtls/xray-core/common/utils"
 	"github.com/xtls/xray-core/features/routing"
 	"github.com/xtls/xray-core/transport/internet/tagged"
 )
diff --git a/proxy/http/client.go b/proxy/http/client.go
index 365d13bfaaca..f79ce5473740 100644
--- a/proxy/http/client.go
+++ b/proxy/http/client.go
@@ -220,7 +220,6 @@ func setUpHTTPTunnel(ctx context.Context, dest net.Destination, target string, u
 	for _, h := range header {
 		req.Header.Set(h.Key, h.Value)
 	}
-
 	if req.Header.Get("User-Agent") == "" {
 		req.Header.Set("User-Agent", utils.ChromeUA)
 	}

From 79d0d3f184f40de0d4ae5018517e0c00cf94ad5a Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 5 Feb 2026 21:15:14 +0000
Subject: [PATCH 09/28] feat: add version variation to reduce statistical
 fingerprinting

Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>
---
 common/utils/browser.go | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/common/utils/browser.go b/common/utils/browser.go
index 9de6f64a749e..aa54e1daa447 100644
--- a/common/utils/browser.go
+++ b/common/utils/browser.go
@@ -3,6 +3,8 @@ package utils
 import (
 	"strconv"
 	"time"
+
+	"github.com/xtls/xray-core/core"
 )
 
 func ChromeVersion() int {
@@ -11,6 +13,14 @@ func ChromeVersion() int {
 	if ver < 143 {
 		ver = 143
 	}
+	// Add variation based on core version to reduce statistical fingerprinting
+	if (core.Version_x+core.Version_y+core.Version_z)%2 == 1 {
+		if now.Day() < 15 {
+			ver--
+		} else {
+			ver++
+		}
+	}
 	return ver
 }
 

From c3796720b6485c16f310b36af54ed8005b6a5975 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 5 Feb 2026 21:27:15 +0000
Subject: [PATCH 10/28] feat: distribute version transition uniformly across
 days 15-30

Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>
---
 common/utils/browser.go | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/common/utils/browser.go b/common/utils/browser.go
index aa54e1daa447..0fca0a495c6f 100644
--- a/common/utils/browser.go
+++ b/common/utils/browser.go
@@ -13,13 +13,10 @@ func ChromeVersion() int {
 	if ver < 143 {
 		ver = 143
 	}
-	// Add variation based on core version to reduce statistical fingerprinting
-	if (core.Version_x+core.Version_y+core.Version_z)%2 == 1 {
-		if now.Day() < 15 {
-			ver--
-		} else {
-			ver++
-		}
+	// Distribute version transition across days 15-30 based on core version
+	transitionDay := 15 + int(core.Version_x+core.Version_y+core.Version_z)%16
+	if now.Day() >= transitionDay {
+		ver++
 	}
 	return ver
 }

From 87df4c9ae9ad36283920c3ad7e4426a252df7b10 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 5 Feb 2026 21:30:06 +0000
Subject: [PATCH 11/28] fix: use actual last day of month for version
 transition distribution

Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>
---
 common/utils/browser.go | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/common/utils/browser.go b/common/utils/browser.go
index 0fca0a495c6f..e50b8ffb2f6e 100644
--- a/common/utils/browser.go
+++ b/common/utils/browser.go
@@ -13,8 +13,10 @@ func ChromeVersion() int {
 	if ver < 143 {
 		ver = 143
 	}
-	// Distribute version transition across days 15-30 based on core version
-	transitionDay := 15 + int(core.Version_x+core.Version_y+core.Version_z)%16
+	// Distribute version transition across days 15 to end of month based on core version
+	lastDay := time.Date(now.Year(), now.Month()+1, 0, 0, 0, 0, 0, time.Local).Day()
+	daysRange := lastDay - 14 // days from 15 to lastDay
+	transitionDay := 15 + int(core.Version_x+core.Version_y+core.Version_z)%daysRange
 	if now.Day() >= transitionDay {
 		ver++
 	}

From 7270e09f47e42711b2c780494949bad727b952d3 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 5 Feb 2026 21:35:01 +0000
Subject: [PATCH 12/28] feat: distribute version -1 uniformly before day 15 as
 well

Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>
---
 common/utils/browser.go | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/common/utils/browser.go b/common/utils/browser.go
index e50b8ffb2f6e..bf719340951e 100644
--- a/common/utils/browser.go
+++ b/common/utils/browser.go
@@ -13,12 +13,22 @@ func ChromeVersion() int {
 	if ver < 143 {
 		ver = 143
 	}
-	// Distribute version transition across days 15 to end of month based on core version
-	lastDay := time.Date(now.Year(), now.Month()+1, 0, 0, 0, 0, 0, time.Local).Day()
-	daysRange := lastDay - 14 // days from 15 to lastDay
-	transitionDay := 15 + int(core.Version_x+core.Version_y+core.Version_z)%daysRange
-	if now.Day() >= transitionDay {
-		ver++
+	versionSum := int(core.Version_x + core.Version_y + core.Version_z)
+	day := now.Day()
+	if day < 15 {
+		// Days 1-14: distribute -1 transition uniformly
+		transitionDay := 1 + versionSum%14
+		if day >= transitionDay {
+			ver--
+		}
+	} else {
+		// Days 15 to end of month: distribute +1 transition uniformly
+		lastDay := time.Date(now.Year(), now.Month()+1, 0, 0, 0, 0, 0, time.Local).Day()
+		daysRange := lastDay - 14
+		transitionDay := 15 + versionSum%daysRange
+		if day >= transitionDay {
+			ver++
+		}
 	}
 	return ver
 }

From 91e1c4f41c25572dad74915ca008f81d3786410d Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 5 Feb 2026 21:37:45 +0000
Subject: [PATCH 13/28] feat: distribute boundary between -1/+1 zones across
 days 15-20

Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>
---
 common/utils/browser.go | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/common/utils/browser.go b/common/utils/browser.go
index bf719340951e..7a4ed948d9bc 100644
--- a/common/utils/browser.go
+++ b/common/utils/browser.go
@@ -15,17 +15,19 @@ func ChromeVersion() int {
 	}
 	versionSum := int(core.Version_x + core.Version_y + core.Version_z)
 	day := now.Day()
-	if day < 15 {
-		// Days 1-14: distribute -1 transition uniformly
-		transitionDay := 1 + versionSum%14
+	// Boundary between -1 and +1 zones is distributed between days 15-20
+	boundary := 15 + versionSum%6
+	if day < boundary {
+		// Before boundary: distribute -1 transition uniformly from day 1 to boundary-1
+		transitionDay := 1 + versionSum%(boundary-1)
 		if day >= transitionDay {
 			ver--
 		}
 	} else {
-		// Days 15 to end of month: distribute +1 transition uniformly
+		// From boundary to end of month: distribute +1 transition uniformly
 		lastDay := time.Date(now.Year(), now.Month()+1, 0, 0, 0, 0, 0, time.Local).Day()
-		daysRange := lastDay - 14
-		transitionDay := 15 + versionSum%daysRange
+		daysRange := lastDay - boundary + 1
+		transitionDay := boundary + versionSum%daysRange
 		if day >= transitionDay {
 			ver++
 		}

From d247358b34e75e6971decf743c21217a5298a9f6 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 5 Feb 2026 21:43:19 +0000
Subject: [PATCH 14/28] feat: add CPU ID to seed for machine-specific
 distribution

Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>
---
 common/utils/browser.go | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/common/utils/browser.go b/common/utils/browser.go
index 7a4ed948d9bc..14437e0a4a26 100644
--- a/common/utils/browser.go
+++ b/common/utils/browser.go
@@ -4,6 +4,7 @@ import (
 	"strconv"
 	"time"
 
+	"github.com/klauspost/cpuid/v2"
 	"github.com/xtls/xray-core/core"
 )
 
@@ -13,13 +14,14 @@ func ChromeVersion() int {
 	if ver < 143 {
 		ver = 143
 	}
-	versionSum := int(core.Version_x + core.Version_y + core.Version_z)
+	// Combine core version with CPU ID for machine-specific distribution
+	seed := int(core.Version_x+core.Version_y+core.Version_z) + cpuid.CPU.Family + cpuid.CPU.Model
 	day := now.Day()
 	// Boundary between -1 and +1 zones is distributed between days 15-20
-	boundary := 15 + versionSum%6
+	boundary := 15 + seed%6
 	if day < boundary {
 		// Before boundary: distribute -1 transition uniformly from day 1 to boundary-1
-		transitionDay := 1 + versionSum%(boundary-1)
+		transitionDay := 1 + seed%(boundary-1)
 		if day >= transitionDay {
 			ver--
 		}
@@ -27,7 +29,7 @@ func ChromeVersion() int {
 		// From boundary to end of month: distribute +1 transition uniformly
 		lastDay := time.Date(now.Year(), now.Month()+1, 0, 0, 0, 0, 0, time.Local).Day()
 		daysRange := lastDay - boundary + 1
-		transitionDay := boundary + versionSum%daysRange
+		transitionDay := boundary + seed%daysRange
 		if day >= transitionDay {
 			ver++
 		}

From 83fcb8b3f3ad71e01b97017fe55aa171109893a5 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 5 Feb 2026 22:00:17 +0000
Subject: [PATCH 15/28] chore: go mod tidy - cpuid is now a direct dependency

Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>
---
 go.mod | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/go.mod b/go.mod
index 77d8780c3560..4a97fead906a 100644
--- a/go.mod
+++ b/go.mod
@@ -9,6 +9,7 @@ require (
 	github.com/golang/mock v1.7.0-rc.1
 	github.com/google/go-cmp v0.7.0
 	github.com/gorilla/websocket v1.5.3
+	github.com/klauspost/cpuid/v2 v2.0.12
 	github.com/miekg/dns v1.1.72
 	github.com/pelletier/go-toml v1.9.5
 	github.com/pires/go-proxyproto v0.9.2
@@ -39,7 +40,6 @@ require (
 	github.com/google/btree v1.1.2 // indirect
 	github.com/juju/ratelimit v1.0.2 // indirect
 	github.com/klauspost/compress v1.17.4 // indirect
-	github.com/klauspost/cpuid/v2 v2.0.12 // indirect
 	github.com/kr/text v0.2.0 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/quic-go/qpack v0.6.0 // indirect

From 4c77ae8c214951e4ae8f5e882d7c40921a87adfb Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 5 Feb 2026 22:10:37 +0000
Subject: [PATCH 16/28] feat: simplify to 1/3 probability each for -1/0/+1
 version adjustment

Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>
---
 common/utils/browser.go | 25 +++++++------------------
 1 file changed, 7 insertions(+), 18 deletions(-)

diff --git a/common/utils/browser.go b/common/utils/browser.go
index 14437e0a4a26..edc01fdeba26 100644
--- a/common/utils/browser.go
+++ b/common/utils/browser.go
@@ -14,25 +14,14 @@ func ChromeVersion() int {
 	if ver < 143 {
 		ver = 143
 	}
-	// Combine core version with CPU ID for machine-specific distribution
+	// Combine core version with CPU ID for machine-specific seed
 	seed := int(core.Version_x+core.Version_y+core.Version_z) + cpuid.CPU.Family + cpuid.CPU.Model
-	day := now.Day()
-	// Boundary between -1 and +1 zones is distributed between days 15-20
-	boundary := 15 + seed%6
-	if day < boundary {
-		// Before boundary: distribute -1 transition uniformly from day 1 to boundary-1
-		transitionDay := 1 + seed%(boundary-1)
-		if day >= transitionDay {
-			ver--
-		}
-	} else {
-		// From boundary to end of month: distribute +1 transition uniformly
-		lastDay := time.Date(now.Year(), now.Month()+1, 0, 0, 0, 0, 0, time.Local).Day()
-		daysRange := lastDay - boundary + 1
-		transitionDay := boundary + seed%daysRange
-		if day >= transitionDay {
-			ver++
-		}
+	// 1/3 probability each for -1, 0, +1 based on seed % 3
+	switch seed % 3 {
+	case 0:
+		ver--
+	case 2:
+		ver++
 	}
 	return ver
 }

From 5d873b54320ca7df97a699a4096987335216a414 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 5 Feb 2026 22:15:58 +0000
Subject: [PATCH 17/28] fix: restore boundary logic, only apply 1/3 probability
 after boundary

Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>
---
 common/utils/browser.go | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/common/utils/browser.go b/common/utils/browser.go
index edc01fdeba26..71fde62896de 100644
--- a/common/utils/browser.go
+++ b/common/utils/browser.go
@@ -16,12 +16,22 @@ func ChromeVersion() int {
 	}
 	// Combine core version with CPU ID for machine-specific seed
 	seed := int(core.Version_x+core.Version_y+core.Version_z) + cpuid.CPU.Family + cpuid.CPU.Model
-	// 1/3 probability each for -1, 0, +1 based on seed % 3
-	switch seed % 3 {
-	case 0:
-		ver--
-	case 2:
-		ver++
+	// Boundary day uniformly distributed between 15-20 based on seed
+	boundary := 15 + seed%6
+	day := now.Day()
+	if day < boundary {
+		// Before boundary: uniformly distributed -1 within days 1 to boundary-1
+		if seed%(boundary-1) < day {
+			ver--
+		}
+	} else {
+		// After boundary: 1/3 probability each for -1, 0, +1
+		switch seed % 3 {
+		case 0:
+			ver--
+		case 2:
+			ver++
+		}
 	}
 	return ver
 }

From 82b67999426e490cacbc2b50f5dbf3191bd0727b Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 5 Feb 2026 22:24:28 +0000
Subject: [PATCH 18/28] feat: use CPU features as seed, avoid downgrade after
 boundary

Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>
---
 common/utils/browser.go | 27 ++++++++++++++++++---------
 1 file changed, 18 insertions(+), 9 deletions(-)

diff --git a/common/utils/browser.go b/common/utils/browser.go
index 71fde62896de..70919e4170ab 100644
--- a/common/utils/browser.go
+++ b/common/utils/browser.go
@@ -5,7 +5,6 @@ import (
 	"time"
 
 	"github.com/klauspost/cpuid/v2"
-	"github.com/xtls/xray-core/core"
 )
 
 func ChromeVersion() int {
@@ -14,8 +13,8 @@ func ChromeVersion() int {
 	if ver < 143 {
 		ver = 143
 	}
-	// Combine core version with CPU ID for machine-specific seed
-	seed := int(core.Version_x+core.Version_y+core.Version_z) + cpuid.CPU.Family + cpuid.CPU.Model
+	// Use CPU features as machine-specific seed
+	seed := cpuid.CPU.Family + cpuid.CPU.Model + cpuid.CPU.PhysicalCores + cpuid.CPU.LogicalCores + cpuid.CPU.CacheLine
 	// Boundary day uniformly distributed between 15-20 based on seed
 	boundary := 15 + seed%6
 	day := now.Day()
@@ -25,12 +24,22 @@ func ChromeVersion() int {
 			ver--
 		}
 	} else {
-		// After boundary: 1/3 probability each for -1, 0, +1
-		switch seed % 3 {
-		case 0:
-			ver--
-		case 2:
-			ver++
+		// After boundary: avoid downgrade
+		// If seed % 3 == 0, it would have gotten -1 before boundary, so allow -1/0/+1
+		// Otherwise, it didn't get -1 before, so only allow 0/+1
+		if seed%3 == 0 {
+			// Was -1 before boundary, can be -1/0/+1 after
+			switch seed % 3 {
+			case 0:
+				ver--
+			case 2:
+				ver++
+			}
+		} else {
+			// Was not -1 before boundary, can only be 0/+1 after
+			if seed%2 == 1 {
+				ver++
+			}
 		}
 	}
 	return ver

From 9f92e5b21cbbe763e3031d680179a09011511243 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 5 Feb 2026 22:48:50 +0000
Subject: [PATCH 19/28] feat: re-add x+y+z to seed, restore original 1/3
 strategy after boundary

Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>
---
 common/utils/browser.go | 27 +++++++++------------------
 1 file changed, 9 insertions(+), 18 deletions(-)

diff --git a/common/utils/browser.go b/common/utils/browser.go
index 70919e4170ab..ce59604aba71 100644
--- a/common/utils/browser.go
+++ b/common/utils/browser.go
@@ -5,6 +5,7 @@ import (
 	"time"
 
 	"github.com/klauspost/cpuid/v2"
+	"github.com/xtls/xray-core/core"
 )
 
 func ChromeVersion() int {
@@ -13,8 +14,8 @@ func ChromeVersion() int {
 	if ver < 143 {
 		ver = 143
 	}
-	// Use CPU features as machine-specific seed
-	seed := cpuid.CPU.Family + cpuid.CPU.Model + cpuid.CPU.PhysicalCores + cpuid.CPU.LogicalCores + cpuid.CPU.CacheLine
+	// Use CPU features + Xray version as seed (version changes ensure occasional different "upgrade strategies")
+	seed := cpuid.CPU.Family + cpuid.CPU.Model + cpuid.CPU.PhysicalCores + cpuid.CPU.LogicalCores + cpuid.CPU.CacheLine + int(core.Version_x) + int(core.Version_y) + int(core.Version_z)
 	// Boundary day uniformly distributed between 15-20 based on seed
 	boundary := 15 + seed%6
 	day := now.Day()
@@ -24,22 +25,12 @@ func ChromeVersion() int {
 			ver--
 		}
 	} else {
-		// After boundary: avoid downgrade
-		// If seed % 3 == 0, it would have gotten -1 before boundary, so allow -1/0/+1
-		// Otherwise, it didn't get -1 before, so only allow 0/+1
-		if seed%3 == 0 {
-			// Was -1 before boundary, can be -1/0/+1 after
-			switch seed % 3 {
-			case 0:
-				ver--
-			case 2:
-				ver++
-			}
-		} else {
-			// Was not -1 before boundary, can only be 0/+1 after
-			if seed%2 == 1 {
-				ver++
-			}
+		// After boundary: 1/3 probability each for -1/0/+1
+		switch seed % 3 {
+		case 0:
+			ver--
+		case 2:
+			ver++
 		}
 	}
 	return ver

From 169618a13c829d6d9542fd476774cc7a31629f9a Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 5 Feb 2026 22:51:34 +0000
Subject: [PATCH 20/28] feat: change post-boundary to uniformly distributed +1
 instead of 1/3

Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>
---
 common/utils/browser.go | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/common/utils/browser.go b/common/utils/browser.go
index ce59604aba71..a540e28fde11 100644
--- a/common/utils/browser.go
+++ b/common/utils/browser.go
@@ -25,11 +25,10 @@ func ChromeVersion() int {
 			ver--
 		}
 	} else {
-		// After boundary: 1/3 probability each for -1/0/+1
-		switch seed % 3 {
-		case 0:
-			ver--
-		case 2:
+		// After boundary: uniformly distributed whether +1
+		lastDay := time.Date(now.Year(), now.Month()+1, 0, 0, 0, 0, 0, now.Location()).Day()
+		daysAfter := lastDay - boundary + 1
+		if seed%daysAfter < day-boundary+1 {
 			ver++
 		}
 	}

From cb325e51eacde26618c52e91ba33d3af764f02ed Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 5 Feb 2026 22:59:54 +0000
Subject: [PATCH 21/28] refactor: simplify post-boundary +1 to intuitive 50%
 chance based on seed

Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>
---
 common/utils/browser.go | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/common/utils/browser.go b/common/utils/browser.go
index a540e28fde11..29fc005f32f8 100644
--- a/common/utils/browser.go
+++ b/common/utils/browser.go
@@ -25,10 +25,8 @@ func ChromeVersion() int {
 			ver--
 		}
 	} else {
-		// After boundary: uniformly distributed whether +1
-		lastDay := time.Date(now.Year(), now.Month()+1, 0, 0, 0, 0, 0, now.Location()).Day()
-		daysAfter := lastDay - boundary + 1
-		if seed%daysAfter < day-boundary+1 {
+		// After boundary: 50% chance to +1 based on seed
+		if seed%2 == 1 {
 			ver++
 		}
 	}

From 791b96b54a5ef5fa67c47c4240d38f097f334dd7 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 5 Feb 2026 23:03:30 +0000
Subject: [PATCH 22/28] feat: true uniform distribution for post-boundary +1
 based on days in range

Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>
---
 common/utils/browser.go | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/common/utils/browser.go b/common/utils/browser.go
index 29fc005f32f8..d9589d59c1fc 100644
--- a/common/utils/browser.go
+++ b/common/utils/browser.go
@@ -25,8 +25,10 @@ func ChromeVersion() int {
 			ver--
 		}
 	} else {
-		// After boundary: 50% chance to +1 based on seed
-		if seed%2 == 1 {
+		// After boundary: uniformly distributed +1 within days boundary to lastDay
+		lastDay := time.Date(now.Year(), now.Month()+1, 0, 0, 0, 0, 0, time.UTC).Day()
+		daysInRange := lastDay - boundary + 1
+		if seed%daysInRange < day-boundary+1 {
 			ver++
 		}
 	}

From 2259d53aeb25d0b4c3277fc83043082669d94dbf Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 5 Feb 2026 23:21:05 +0000
Subject: [PATCH 23/28] feat: subtract baseVersion mod 2 to avoid
 month-end/start version flipping

Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>
---
 common/utils/browser.go | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/common/utils/browser.go b/common/utils/browser.go
index d9589d59c1fc..2e9d7b672886 100644
--- a/common/utils/browser.go
+++ b/common/utils/browser.go
@@ -10,10 +10,11 @@ import (
 
 func ChromeVersion() int {
 	now := time.Now()
-	ver := 143 + (now.Year()-2026)*12 + int(now.Month()) - 1
-	if ver < 143 {
-		ver = 143
+	baseVer := 143 + (now.Year()-2026)*12 + int(now.Month()) - 1
+	if baseVer < 143 {
+		baseVer = 143
 	}
+	ver := baseVer
 	// Use CPU features + Xray version as seed (version changes ensure occasional different "upgrade strategies")
 	seed := cpuid.CPU.Family + cpuid.CPU.Model + cpuid.CPU.PhysicalCores + cpuid.CPU.LogicalCores + cpuid.CPU.CacheLine + int(core.Version_x) + int(core.Version_y) + int(core.Version_z)
 	// Boundary day uniformly distributed between 15-20 based on seed
@@ -32,7 +33,8 @@ func ChromeVersion() int {
 			ver++
 		}
 	}
-	return ver
+	// Subtract base version mod 2 to avoid month-end upgrade followed by month-start downgrade
+	return ver - baseVer%2
 }
 
 // ChromeUA provides default browser User-Agent. Version 143 = Jan 2026, +1 per month.

From 429fac8092945ca70690ac50a5dff9fc42adc2de Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 5 Feb 2026 23:41:06 +0000
Subject: [PATCH 24/28] feat: rewrite ChromeVersion with new strategy - release
 on 15th, 1-30 day upgrade delay

Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>
---
 common/utils/browser.go | 43 +++++++++++++++++++----------------------
 1 file changed, 20 insertions(+), 23 deletions(-)

diff --git a/common/utils/browser.go b/common/utils/browser.go
index 2e9d7b672886..be2858d0c992 100644
--- a/common/utils/browser.go
+++ b/common/utils/browser.go
@@ -10,32 +10,29 @@ import (
 
 func ChromeVersion() int {
 	now := time.Now()
-	baseVer := 143 + (now.Year()-2026)*12 + int(now.Month()) - 1
-	if baseVer < 143 {
-		baseVer = 143
+	// Assume Chrome releases on 15th each month, with Jan 2026 being version 144
+	// Calculate the latest Chrome version based on current date
+	latestVer := 144 + (now.Year()-2026)*12 + int(now.Month()) - 1
+	daysSinceRelease := now.Day() - 15
+	if daysSinceRelease < 0 {
+		latestVer-- // Before 15th, the new version hasn't released yet
+		// Days since previous month's release (15th)
+		lastDay := time.Date(now.Year(), now.Month(), 0, 0, 0, 0, 0, time.UTC).Day()
+		daysSinceRelease = now.Day() + (lastDay - 15)
 	}
-	ver := baseVer
-	// Use CPU features + Xray version as seed (version changes ensure occasional different "upgrade strategies")
+	if latestVer < 144 {
+		latestVer = 144
+	}
+	// Use CPU features + Xray version as seed
 	seed := cpuid.CPU.Family + cpuid.CPU.Model + cpuid.CPU.PhysicalCores + cpuid.CPU.LogicalCores + cpuid.CPU.CacheLine + int(core.Version_x) + int(core.Version_y) + int(core.Version_z)
-	// Boundary day uniformly distributed between 15-20 based on seed
-	boundary := 15 + seed%6
-	day := now.Day()
-	if day < boundary {
-		// Before boundary: uniformly distributed -1 within days 1 to boundary-1
-		if seed%(boundary-1) < day {
-			ver--
-		}
-	} else {
-		// After boundary: uniformly distributed +1 within days boundary to lastDay
-		lastDay := time.Date(now.Year(), now.Month()+1, 0, 0, 0, 0, 0, time.UTC).Day()
-		daysInRange := lastDay - boundary + 1
-		if seed%daysInRange < day-boundary+1 {
-			ver++
-		}
+	// User upgrade delay: 1-30 days uniformly distributed based on seed
+	upgradeDelay := seed%30 + 1
+	// If user's delay > days since release, they haven't upgraded yet
+	if upgradeDelay > daysSinceRelease {
+		return latestVer - 1
 	}
-	// Subtract base version mod 2 to avoid month-end upgrade followed by month-start downgrade
-	return ver - baseVer%2
+	return latestVer
 }
 
-// ChromeUA provides default browser User-Agent. Version 143 = Jan 2026, +1 per month.
+// ChromeUA provides default browser User-Agent. Chrome 144 = Jan 15, 2026, +1 per month.
 var ChromeUA = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/" + strconv.Itoa(ChromeVersion()) + ".0.0.0 Safari/537.36"

From 0d0e65df6b1eda97809962bf029790f3d9aa48a5 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 5 Feb 2026 23:48:21 +0000
Subject: [PATCH 25/28] refactor: simplify ChromeVersion logic - subtract
 upgrade delay from current date

Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>
---
 common/utils/browser.go | 33 +++++++++++++++------------------
 1 file changed, 15 insertions(+), 18 deletions(-)

diff --git a/common/utils/browser.go b/common/utils/browser.go
index be2858d0c992..736bb3e47739 100644
--- a/common/utils/browser.go
+++ b/common/utils/browser.go
@@ -10,28 +10,25 @@ import (
 
 func ChromeVersion() int {
 	now := time.Now()
-	// Assume Chrome releases on 15th each month, with Jan 2026 being version 144
-	// Calculate the latest Chrome version based on current date
+	// Chrome releases on 15th each month: 2026.1.15 = 144
+	// Calculate the latest Chrome version at the 15th of current month
 	latestVer := 144 + (now.Year()-2026)*12 + int(now.Month()) - 1
-	daysSinceRelease := now.Day() - 15
-	if daysSinceRelease < 0 {
-		latestVer-- // Before 15th, the new version hasn't released yet
-		// Days since previous month's release (15th)
-		lastDay := time.Date(now.Year(), now.Month(), 0, 0, 0, 0, 0, time.UTC).Day()
-		daysSinceRelease = now.Day() + (lastDay - 15)
-	}
-	if latestVer < 144 {
-		latestVer = 144
-	}
-	// Use CPU features + Xray version as seed
+	// Use CPU features + Xray version as seed for upgrade delay (1-30 days)
 	seed := cpuid.CPU.Family + cpuid.CPU.Model + cpuid.CPU.PhysicalCores + cpuid.CPU.LogicalCores + cpuid.CPU.CacheLine + int(core.Version_x) + int(core.Version_y) + int(core.Version_z)
-	// User upgrade delay: 1-30 days uniformly distributed based on seed
 	upgradeDelay := seed%30 + 1
-	// If user's delay > days since release, they haven't upgraded yet
-	if upgradeDelay > daysSinceRelease {
-		return latestVer - 1
+	// Subtract upgrade delay from current date to get user's Chrome version date
+	userDate := now.AddDate(0, 0, -upgradeDelay)
+	userVer := 144 + (userDate.Year()-2026)*12 + int(userDate.Month()) - 1
+	if userDate.Day() < 15 {
+		userVer--
+	}
+	if userVer < 144 {
+		userVer = 144
+	}
+	if userVer > latestVer {
+		userVer = latestVer
 	}
-	return latestVer
+	return userVer
 }
 
 // ChromeUA provides default browser User-Agent. Chrome 144 = Jan 15, 2026, +1 per month.

From 596c3e463d45d2c486d45cb2274d6bfc584ef2c5 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Fri, 6 Feb 2026 00:00:01 +0000
Subject: [PATCH 26/28] refactor: simplify ChromeVersion - subtract delay
 first, then calculate version

Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>
---
 common/utils/browser.go | 21 ++++++---------------
 1 file changed, 6 insertions(+), 15 deletions(-)

diff --git a/common/utils/browser.go b/common/utils/browser.go
index 736bb3e47739..9e511f1d098d 100644
--- a/common/utils/browser.go
+++ b/common/utils/browser.go
@@ -9,26 +9,17 @@ import (
 )
 
 func ChromeVersion() int {
-	now := time.Now()
-	// Chrome releases on 15th each month: 2026.1.15 = 144
-	// Calculate the latest Chrome version at the 15th of current month
-	latestVer := 144 + (now.Year()-2026)*12 + int(now.Month()) - 1
 	// Use CPU features + Xray version as seed for upgrade delay (1-30 days)
 	seed := cpuid.CPU.Family + cpuid.CPU.Model + cpuid.CPU.PhysicalCores + cpuid.CPU.LogicalCores + cpuid.CPU.CacheLine + int(core.Version_x) + int(core.Version_y) + int(core.Version_z)
 	upgradeDelay := seed%30 + 1
-	// Subtract upgrade delay from current date to get user's Chrome version date
-	userDate := now.AddDate(0, 0, -upgradeDelay)
-	userVer := 144 + (userDate.Year()-2026)*12 + int(userDate.Month()) - 1
+	// First subtract upgrade delay from current date
+	userDate := time.Now().AddDate(0, 0, -upgradeDelay)
+	// Then calculate Chrome version for that date (releases on 15th each month, 2026.1.15 = 144)
+	version := 144 + (userDate.Year()-2026)*12 + int(userDate.Month()) - 1
 	if userDate.Day() < 15 {
-		userVer--
+		version--
 	}
-	if userVer < 144 {
-		userVer = 144
-	}
-	if userVer > latestVer {
-		userVer = latestVer
-	}
-	return userVer
+	return version
 }
 
 // ChromeUA provides default browser User-Agent. Chrome 144 = Jan 15, 2026, +1 per month.

From be9e60ab0c46c22e43d9a189f39640ea2919e39f Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Fri, 6 Feb 2026 00:13:55 +0000
Subject: [PATCH 27/28] feat: change to 45-day release cycle based on Chrome
 144 release date (2026.1.13)

Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>
---
 common/utils/browser.go | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/common/utils/browser.go b/common/utils/browser.go
index 9e511f1d098d..eaa964521e36 100644
--- a/common/utils/browser.go
+++ b/common/utils/browser.go
@@ -9,18 +9,17 @@ import (
 )
 
 func ChromeVersion() int {
-	// Use CPU features + Xray version as seed for upgrade delay (1-30 days)
+	// Chrome 144 released on 2026.1.13, new version every 45 days
+	chrome144Release := time.Date(2026, 1, 13, 0, 0, 0, 0, time.UTC)
+	// Use CPU features + Xray version as seed for upgrade delay (1-45 days)
 	seed := cpuid.CPU.Family + cpuid.CPU.Model + cpuid.CPU.PhysicalCores + cpuid.CPU.LogicalCores + cpuid.CPU.CacheLine + int(core.Version_x) + int(core.Version_y) + int(core.Version_z)
-	upgradeDelay := seed%30 + 1
+	upgradeDelay := seed%45 + 1
 	// First subtract upgrade delay from current date
 	userDate := time.Now().AddDate(0, 0, -upgradeDelay)
-	// Then calculate Chrome version for that date (releases on 15th each month, 2026.1.15 = 144)
-	version := 144 + (userDate.Year()-2026)*12 + int(userDate.Month()) - 1
-	if userDate.Day() < 15 {
-		version--
-	}
-	return version
+	// Then calculate Chrome version for that date
+	daysSinceRelease := int(userDate.Sub(chrome144Release).Hours() / 24)
+	return 144 + daysSinceRelease/45
 }
 
-// ChromeUA provides default browser User-Agent. Chrome 144 = Jan 15, 2026, +1 per month.
+// ChromeUA provides default browser User-Agent. Chrome 144 = Jan 13, 2026, +1 per 45 days.
 var ChromeUA = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/" + strconv.Itoa(ChromeVersion()) + ".0.0.0 Safari/537.36"

From 1427b2098f42215f2d3fc614630e98dd3553fb32 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Fri, 6 Feb 2026 00:45:42 +0000
Subject: [PATCH 28/28] feat: new strategy with PRNG seeded by CPU, random
 25-45 day intervals from 2026.1.13

Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>
---
 common/utils/browser.go | 27 +++++++++++++++------------
 1 file changed, 15 insertions(+), 12 deletions(-)

diff --git a/common/utils/browser.go b/common/utils/browser.go
index eaa964521e36..91209f4bda50 100644
--- a/common/utils/browser.go
+++ b/common/utils/browser.go
@@ -1,25 +1,28 @@
 package utils
 
 import (
+	"math/rand"
 	"strconv"
 	"time"
 
 	"github.com/klauspost/cpuid/v2"
-	"github.com/xtls/xray-core/core"
 )
 
 func ChromeVersion() int {
-	// Chrome 144 released on 2026.1.13, new version every 45 days
-	chrome144Release := time.Date(2026, 1, 13, 0, 0, 0, 0, time.UTC)
-	// Use CPU features + Xray version as seed for upgrade delay (1-45 days)
-	seed := cpuid.CPU.Family + cpuid.CPU.Model + cpuid.CPU.PhysicalCores + cpuid.CPU.LogicalCores + cpuid.CPU.CacheLine + int(core.Version_x) + int(core.Version_y) + int(core.Version_z)
-	upgradeDelay := seed%45 + 1
-	// First subtract upgrade delay from current date
-	userDate := time.Now().AddDate(0, 0, -upgradeDelay)
-	// Then calculate Chrome version for that date
-	daysSinceRelease := int(userDate.Sub(chrome144Release).Hours() / 24)
-	return 144 + daysSinceRelease/45
+	// Use only CPU info as seed for PRNG
+	seed := int64(cpuid.CPU.Family + cpuid.CPU.Model + cpuid.CPU.PhysicalCores + cpuid.CPU.LogicalCores + cpuid.CPU.CacheLine)
+	rng := rand.New(rand.NewSource(seed))
+	// Start from Chrome 144 released on 2026.1.13
+	releaseDate := time.Date(2026, 1, 13, 0, 0, 0, 0, time.UTC)
+	version := 144
+	now := time.Now()
+	// Each version has random 25-45 day interval
+	for releaseDate.Before(now) {
+		releaseDate = releaseDate.AddDate(0, 0, rng.Intn(21)+25)
+		version++
+	}
+	return version - 1
 }
 
-// ChromeUA provides default browser User-Agent. Chrome 144 = Jan 13, 2026, +1 per 45 days.
+// ChromeUA provides default browser User-Agent based on CPU-seeded PRNG.
 var ChromeUA = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/" + strconv.Itoa(ChromeVersion()) + ".0.0.0 Safari/537.36"