merge upstream main

2026-02-02 22:13:50 +08:00
parent 7ade9baa15
commit 0170d19fa7
319 changed files with 40485 additions and 8969 deletions
--- a/backend/internal/pkg/antigravity/oauth.go
+++ b/backend/internal/pkg/antigravity/oauth.go
@@ -33,7 +33,7 @@ const (
 		"https://www.googleapis.com/auth/experimentsandconfigs"

 	// User-Agent（与 Antigravity-Manager 保持一致）
-	UserAgent = "antigravity/1.11.9 windows/amd64"
+	UserAgent = "antigravity/1.15.8 windows/amd64"

 	// Session 过期时间
 	SessionTTL = 30 * time.Minute
--- a/backend/internal/pkg/antigravity/request_transformer.go
+++ b/backend/internal/pkg/antigravity/request_transformer.go
@@ -369,8 +369,10 @@ func buildParts(content json.RawMessage, toolIDToName map[string]string, allowDu
 				Text:    block.Thinking,
 				Thought: true,
 			}
-			// 保留原有 signature（Claude 模型需要有效的 signature）
-			if block.Signature != "" {
+			// signature 处理：
+			// - Claude 模型（allowDummyThought=false）：必须是上游返回的真实 signature（dummy 视为缺失）
+			// - Gemini 模型（allowDummyThought=true）：优先透传真实 signature，缺失时使用 dummy signature
+			if block.Signature != "" && (allowDummyThought || block.Signature != dummyThoughtSignature) {
 				part.ThoughtSignature = block.Signature
 			} else if !allowDummyThought {
 				// Claude 模型需要有效 signature；在缺失时降级为普通文本，并在上层禁用 thinking mode。
@@ -409,12 +411,12 @@ func buildParts(content json.RawMessage, toolIDToName map[string]string, allowDu
 				},
 			}
 			// tool_use 的 signature 处理：
-			// - Gemini 模型：使用 dummy signature（跳过 thought_signature 校验）
-			// - Claude 模型：透传上游返回的真实 signature（Vertex/Google 需要完整签名链路）
-			if allowDummyThought {
-				part.ThoughtSignature = dummyThoughtSignature
-			} else if block.Signature != "" && block.Signature != dummyThoughtSignature {
+			// - Claude 模型（allowDummyThought=false）：必须是上游返回的真实 signature（dummy 视为缺失）
+			// - Gemini 模型（allowDummyThought=true）：优先透传真实 signature，缺失时使用 dummy signature
+			if block.Signature != "" && (allowDummyThought || block.Signature != dummyThoughtSignature) {
 				part.ThoughtSignature = block.Signature
+			} else if allowDummyThought {
+				part.ThoughtSignature = dummyThoughtSignature
 			}
 			parts = append(parts, part)

--- a/backend/internal/pkg/antigravity/request_transformer_test.go
+++ b/backend/internal/pkg/antigravity/request_transformer_test.go
@@ -100,7 +100,7 @@ func TestBuildParts_ToolUseSignatureHandling(t *testing.T) {
 		{"type": "tool_use", "id": "t1", "name": "Bash", "input": {"command": "ls"}, "signature": "sig_tool_abc"}
 	]`

-	t.Run("Gemini uses dummy tool_use signature", func(t *testing.T) {
+	t.Run("Gemini preserves provided tool_use signature", func(t *testing.T) {
 		toolIDToName := make(map[string]string)
 		parts, _, err := buildParts(json.RawMessage(content), toolIDToName, true)
 		if err != nil {
@@ -109,6 +109,23 @@ func TestBuildParts_ToolUseSignatureHandling(t *testing.T) {
 		if len(parts) != 1 || parts[0].FunctionCall == nil {
 			t.Fatalf("expected 1 functionCall part, got %+v", parts)
 		}
+		if parts[0].ThoughtSignature != "sig_tool_abc" {
+			t.Fatalf("expected preserved tool signature %q, got %q", "sig_tool_abc", parts[0].ThoughtSignature)
+		}
+	})
+
+	t.Run("Gemini falls back to dummy tool_use signature when missing", func(t *testing.T) {
+		contentNoSig := `[
+			{"type": "tool_use", "id": "t1", "name": "Bash", "input": {"command": "ls"}}
+		]`
+		toolIDToName := make(map[string]string)
+		parts, _, err := buildParts(json.RawMessage(contentNoSig), toolIDToName, true)
+		if err != nil {
+			t.Fatalf("buildParts() error = %v", err)
+		}
+		if len(parts) != 1 || parts[0].FunctionCall == nil {
+			t.Fatalf("expected 1 functionCall part, got %+v", parts)
+		}
 		if parts[0].ThoughtSignature != dummyThoughtSignature {
 			t.Fatalf("expected dummy tool signature %q, got %q", dummyThoughtSignature, parts[0].ThoughtSignature)
 		}
--- a/backend/internal/pkg/antigravity/response_transformer.go
+++ b/backend/internal/pkg/antigravity/response_transformer.go
@@ -20,6 +20,15 @@ func TransformGeminiToClaude(geminiResp []byte, originalModel string) ([]byte, *
 		v1Resp.Response = directResp
 		v1Resp.ResponseID = directResp.ResponseID
 		v1Resp.ModelVersion = directResp.ModelVersion
+	} else if len(v1Resp.Response.Candidates) == 0 {
+		// 第一次解析成功但 candidates 为空，说明是直接的 GeminiResponse 格式
+		var directResp GeminiResponse
+		if err2 := json.Unmarshal(geminiResp, &directResp); err2 != nil {
+			return nil, nil, fmt.Errorf("parse gemini response as direct: %w", err2)
+		}
+		v1Resp.Response = directResp
+		v1Resp.ResponseID = directResp.ResponseID
+		v1Resp.ModelVersion = directResp.ModelVersion
 	}

 	// 使用处理器转换
@@ -174,16 +183,20 @@ func (p *NonStreamingProcessor) processPart(part *GeminiPart) {
 				p.trailingSignature = ""
 			}

-			p.textBuilder += part.Text
-
-			// 非空 text 带签名 - 立即刷新并输出空 thinking 块
+			// 非空 text 带签名 - 特殊处理：先输出 text，再输出空 thinking 块
 			if signature != "" {
-				p.flushText()
+				p.contentBlocks = append(p.contentBlocks, ClaudeContentItem{
+					Type: "text",
+					Text: part.Text,
+				})
 				p.contentBlocks = append(p.contentBlocks, ClaudeContentItem{
 					Type:      "thinking",
 					Thinking:  "",
 					Signature: signature,
 				})
+			} else {
+				// 普通 text (无签名) - 累积到 builder
+				p.textBuilder += part.Text
 			}
 		}
 	}
--- a/backend/internal/pkg/gemini/models.go
+++ b/backend/internal/pkg/gemini/models.go
@@ -16,14 +16,11 @@ type ModelsListResponse struct {
 func DefaultModels() []Model {
 	methods := []string{"generateContent", "streamGenerateContent"}
 	return []Model{
-		{Name: "models/gemini-3-pro-preview", SupportedGenerationMethods: methods},
-		{Name: "models/gemini-3-flash-preview", SupportedGenerationMethods: methods},
-		{Name: "models/gemini-2.5-pro", SupportedGenerationMethods: methods},
-		{Name: "models/gemini-2.5-flash", SupportedGenerationMethods: methods},
 		{Name: "models/gemini-2.0-flash", SupportedGenerationMethods: methods},
-		{Name: "models/gemini-1.5-pro", SupportedGenerationMethods: methods},
-		{Name: "models/gemini-1.5-flash", SupportedGenerationMethods: methods},
-		{Name: "models/gemini-1.5-flash-8b", SupportedGenerationMethods: methods},
+		{Name: "models/gemini-2.5-flash", SupportedGenerationMethods: methods},
+		{Name: "models/gemini-2.5-pro", SupportedGenerationMethods: methods},
+		{Name: "models/gemini-3-flash-preview", SupportedGenerationMethods: methods},
+		{Name: "models/gemini-3-pro-preview", SupportedGenerationMethods: methods},
 	}
 }

--- a/backend/internal/pkg/geminicli/models.go
+++ b/backend/internal/pkg/geminicli/models.go
@@ -12,10 +12,10 @@ type Model struct {
 // DefaultModels is the curated Gemini model list used by the admin UI "test account" flow.
 var DefaultModels = []Model{
 	{ID: "gemini-2.0-flash", Type: "model", DisplayName: "Gemini 2.0 Flash", CreatedAt: ""},
-	{ID: "gemini-2.5-pro", Type: "model", DisplayName: "Gemini 2.5 Pro", CreatedAt: ""},
 	{ID: "gemini-2.5-flash", Type: "model", DisplayName: "Gemini 2.5 Flash", CreatedAt: ""},
-	{ID: "gemini-3-pro-preview", Type: "model", DisplayName: "Gemini 3 Pro Preview", CreatedAt: ""},
+	{ID: "gemini-2.5-pro", Type: "model", DisplayName: "Gemini 2.5 Pro", CreatedAt: ""},
 	{ID: "gemini-3-flash-preview", Type: "model", DisplayName: "Gemini 3 Flash Preview", CreatedAt: ""},
+	{ID: "gemini-3-pro-preview", Type: "model", DisplayName: "Gemini 3 Pro Preview", CreatedAt: ""},
 }

 // DefaultTestModel is the default model to preselect in test flows.
--- a/backend/internal/pkg/oauth/oauth.go
+++ b/backend/internal/pkg/oauth/oauth.go
@@ -13,20 +13,26 @@ import (
 	"time"
 )

-// Claude OAuth Constants (from CRS project)
+// Claude OAuth Constants
 const (
 	// OAuth Client ID for Claude
 	ClientID = "9d1c250a-e61b-44d9-88ed-5944d1962f5e"

 	// OAuth endpoints
 	AuthorizeURL = "https://claude.ai/oauth/authorize"
-	TokenURL     = "https://console.anthropic.com/v1/oauth/token"
-	RedirectURI  = "https://console.anthropic.com/oauth/code/callback"
+	TokenURL     = "https://platform.claude.com/v1/oauth/token"
+	RedirectURI  = "https://platform.claude.com/oauth/code/callback"

-	// Scopes
-	ScopeProfile   = "user:profile"
+	// Scopes - Browser URL (includes org:create_api_key for user authorization)
+	ScopeOAuth = "org:create_api_key user:profile user:inference user:sessions:claude_code user:mcp_servers"
+	// Scopes - Internal API call (org:create_api_key not supported in API)
+	ScopeAPI = "user:profile user:inference user:sessions:claude_code user:mcp_servers"
+	// Scopes - Setup token (inference only)
 	ScopeInference = "user:inference"

+	// Code Verifier character set (RFC 7636 compliant)
+	codeVerifierCharset = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-._~"
+
 	// Session TTL
 	SessionTTL = 30 * time.Minute
 )
@@ -53,7 +59,6 @@ func NewSessionStore() *SessionStore {
 		sessions: make(map[string]*OAuthSession),
 		stopCh:   make(chan struct{}),
 	}
-	// Start cleanup goroutine
 	go store.cleanup()
 	return store
 }
@@ -78,7 +83,6 @@ func (s *SessionStore) Get(sessionID string) (*OAuthSession, bool) {
 	if !ok {
 		return nil, false
 	}
-	// Check if expired
 	if time.Since(session.CreatedAt) > SessionTTL {
 		return nil, false
 	}
@@ -122,13 +126,13 @@ func GenerateRandomBytes(n int) ([]byte, error) {
 	return b, nil
 }

-// GenerateState generates a random state string for OAuth
+// GenerateState generates a random state string for OAuth (base64url encoded)
 func GenerateState() (string, error) {
 	bytes, err := GenerateRandomBytes(32)
 	if err != nil {
 		return "", err
 	}
-	return hex.EncodeToString(bytes), nil
+	return base64URLEncode(bytes), nil
 }

 // GenerateSessionID generates a unique session ID
@@ -140,13 +144,30 @@ func GenerateSessionID() (string, error) {
 	return hex.EncodeToString(bytes), nil
 }

-// GenerateCodeVerifier generates a PKCE code verifier (32 bytes -> base64url)
+// GenerateCodeVerifier generates a PKCE code verifier using character set method
 func GenerateCodeVerifier() (string, error) {
-	bytes, err := GenerateRandomBytes(32)
-	if err != nil {
-		return "", err
+	const targetLen = 32
+	charsetLen := len(codeVerifierCharset)
+	limit := 256 - (256 % charsetLen)
+
+	result := make([]byte, 0, targetLen)
+	randBuf := make([]byte, targetLen*2)
+
+	for len(result) < targetLen {
+		if _, err := rand.Read(randBuf); err != nil {
+			return "", err
+		}
+		for _, b := range randBuf {
+			if int(b) < limit {
+				result = append(result, codeVerifierCharset[int(b)%charsetLen])
+				if len(result) >= targetLen {
+					break
+				}
+			}
+		}
 	}
-	return base64URLEncode(bytes), nil
+
+	return base64URLEncode(result), nil
 }

 // GenerateCodeChallenge generates a PKCE code challenge using S256 method
@@ -158,42 +179,31 @@ func GenerateCodeChallenge(verifier string) string {
 // base64URLEncode encodes bytes to base64url without padding
 func base64URLEncode(data []byte) string {
 	encoded := base64.URLEncoding.EncodeToString(data)
-	// Remove padding
 	return strings.TrimRight(encoded, "=")
 }

-// BuildAuthorizationURL builds the OAuth authorization URL
+// BuildAuthorizationURL builds the OAuth authorization URL with correct parameter order
 func BuildAuthorizationURL(state, codeChallenge, scope string) string {
-	params := url.Values{}
-	params.Set("response_type", "code")
-	params.Set("client_id", ClientID)
-	params.Set("redirect_uri", RedirectURI)
-	params.Set("scope", scope)
-	params.Set("state", state)
-	params.Set("code_challenge", codeChallenge)
-	params.Set("code_challenge_method", "S256")
+	encodedRedirectURI := url.QueryEscape(RedirectURI)
+	encodedScope := strings.ReplaceAll(url.QueryEscape(scope), "%20", "+")

-	return fmt.Sprintf("%s?%s", AuthorizeURL, params.Encode())
-}
-
-// TokenRequest represents the token exchange request body
-type TokenRequest struct {
-	GrantType    string `json:"grant_type"`
-	ClientID     string `json:"client_id"`
-	Code         string `json:"code"`
-	RedirectURI  string `json:"redirect_uri"`
-	CodeVerifier string `json:"code_verifier"`
-	State        string `json:"state"`
+	return fmt.Sprintf("%s?code=true&client_id=%s&response_type=code&redirect_uri=%s&scope=%s&code_challenge=%s&code_challenge_method=S256&state=%s",
+		AuthorizeURL,
+		ClientID,
+		encodedRedirectURI,
+		encodedScope,
+		codeChallenge,
+		state,
+	)
 }

 // TokenResponse represents the token response from OAuth provider
 type TokenResponse struct {
-	AccessToken  string `json:"access_token"`
-	TokenType    string `json:"token_type"`
-	ExpiresIn    int64  `json:"expires_in"`
-	RefreshToken string `json:"refresh_token,omitempty"`
-	Scope        string `json:"scope,omitempty"`
-	// Organization and Account info from OAuth response
+	AccessToken  string       `json:"access_token"`
+	TokenType    string       `json:"token_type"`
+	ExpiresIn    int64        `json:"expires_in"`
+	RefreshToken string       `json:"refresh_token,omitempty"`
+	Scope        string       `json:"scope,omitempty"`
 	Organization *OrgInfo     `json:"organization,omitempty"`
 	Account      *AccountInfo `json:"account,omitempty"`
 }
@@ -205,33 +215,6 @@ type OrgInfo struct {

 // AccountInfo represents account info from OAuth response
 type AccountInfo struct {
-	UUID string `json:"uuid"`
-}
-
-// RefreshTokenRequest represents the refresh token request
-type RefreshTokenRequest struct {
-	GrantType    string `json:"grant_type"`
-	RefreshToken string `json:"refresh_token"`
-	ClientID     string `json:"client_id"`
-}
-
-// BuildTokenRequest creates a token exchange request
-func BuildTokenRequest(code, codeVerifier, state string) *TokenRequest {
-	return &TokenRequest{
-		GrantType:    "authorization_code",
-		ClientID:     ClientID,
-		Code:         code,
-		RedirectURI:  RedirectURI,
-		CodeVerifier: codeVerifier,
-		State:        state,
-	}
-}
-
-// BuildRefreshTokenRequest creates a refresh token request
-func BuildRefreshTokenRequest(refreshToken string) *RefreshTokenRequest {
-	return &RefreshTokenRequest{
-		GrantType:    "refresh_token",
-		RefreshToken: refreshToken,
-		ClientID:     ClientID,
-	}
+	UUID         string `json:"uuid"`
+	EmailAddress string `json:"email_address"`
 }
--- a/backend/internal/pkg/response/response.go
+++ b/backend/internal/pkg/response/response.go
@@ -2,6 +2,7 @@
 package response

 import (
+	"log"
 	"math"
 	"net/http"

@@ -74,6 +75,12 @@ func ErrorFrom(c *gin.Context, err error) bool {
 	}

 	statusCode, status := infraerrors.ToHTTP(err)
+
+	// Log internal errors with full details for debugging
+	if statusCode >= 500 && c.Request != nil {
+		log.Printf("[ERROR] %s %s\n  Error: %s", c.Request.Method, c.Request.URL.Path, err.Error())
+	}
+
 	ErrorWithDetails(c, statusCode, status.Message, status.Reason, status.Metadata)
 	return true
 }
@@ -162,11 +169,11 @@ func ParsePagination(c *gin.Context) (page, pageSize int) {

 	// 支持 page_size 和 limit 两种参数名
 	if ps := c.Query("page_size"); ps != "" {
-		if val, err := parseInt(ps); err == nil && val > 0 && val <= 100 {
+		if val, err := parseInt(ps); err == nil && val > 0 && val <= 1000 {
 			pageSize = val
 		}
 	} else if l := c.Query("limit"); l != "" {
-		if val, err := parseInt(l); err == nil && val > 0 && val <= 100 {
+		if val, err := parseInt(l); err == nil && val > 0 && val <= 1000 {
 			pageSize = val
 		}
 	}
--- a/backend/internal/pkg/tlsfingerprint/dialer.go
+++ b/backend/internal/pkg/tlsfingerprint/dialer.go
@@ -0,0 +1,568 @@
+// Package tlsfingerprint provides TLS fingerprint simulation for HTTP clients.
+// It uses the utls library to create TLS connections that mimic Node.js/Claude Code clients.
+package tlsfingerprint
+
+import (
+	"bufio"
+	"context"
+	"encoding/base64"
+	"fmt"
+	"log/slog"
+	"net"
+	"net/http"
+	"net/url"
+
+	utls "github.com/refraction-networking/utls"
+	"golang.org/x/net/proxy"
+)
+
+// Profile contains TLS fingerprint configuration.
+type Profile struct {
+	Name         string // Profile name for identification
+	CipherSuites []uint16
+	Curves       []uint16
+	PointFormats []uint8
+	EnableGREASE bool
+}
+
+// Dialer creates TLS connections with custom fingerprints.
+type Dialer struct {
+	profile    *Profile
+	baseDialer func(ctx context.Context, network, addr string) (net.Conn, error)
+}
+
+// HTTPProxyDialer creates TLS connections through HTTP/HTTPS proxies with custom fingerprints.
+// It handles the CONNECT tunnel establishment before performing TLS handshake.
+type HTTPProxyDialer struct {
+	profile  *Profile
+	proxyURL *url.URL
+}
+
+// SOCKS5ProxyDialer creates TLS connections through SOCKS5 proxies with custom fingerprints.
+// It uses golang.org/x/net/proxy to establish the SOCKS5 tunnel.
+type SOCKS5ProxyDialer struct {
+	profile  *Profile
+	proxyURL *url.URL
+}
+
+// Default TLS fingerprint values captured from Claude CLI 2.x (Node.js 20.x + OpenSSL 3.x)
+// Captured using: tshark -i lo -f "tcp port 8443" -Y "tls.handshake.type == 1" -V
+// JA3 Hash: 1a28e69016765d92e3b381168d68922c
+//
+// Note: JA3/JA4 may have slight variations due to:
+// - Session ticket presence/absence
+// - Extension negotiation state
+var (
+	// defaultCipherSuites contains all 59 cipher suites from Claude CLI
+	// Order is critical for JA3 fingerprint matching
+	defaultCipherSuites = []uint16{
+		// TLS 1.3 cipher suites (MUST be first)
+		0x1302, // TLS_AES_256_GCM_SHA384
+		0x1303, // TLS_CHACHA20_POLY1305_SHA256
+		0x1301, // TLS_AES_128_GCM_SHA256
+
+		// ECDHE + AES-GCM
+		0xc02f, // TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
+		0xc02b, // TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256
+		0xc030, // TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
+		0xc02c, // TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384
+
+		// DHE + AES-GCM
+		0x009e, // TLS_DHE_RSA_WITH_AES_128_GCM_SHA256
+
+		// ECDHE/DHE + AES-CBC-SHA256/384
+		0xc027, // TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256
+		0x0067, // TLS_DHE_RSA_WITH_AES_128_CBC_SHA256
+		0xc028, // TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384
+		0x006b, // TLS_DHE_RSA_WITH_AES_256_CBC_SHA256
+
+		// DHE-DSS/RSA + AES-GCM
+		0x00a3, // TLS_DHE_DSS_WITH_AES_256_GCM_SHA384
+		0x009f, // TLS_DHE_RSA_WITH_AES_256_GCM_SHA384
+
+		// ChaCha20-Poly1305
+		0xcca9, // TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256
+		0xcca8, // TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256
+		0xccaa, // TLS_DHE_RSA_WITH_CHACHA20_POLY1305_SHA256
+
+		// AES-CCM (256-bit)
+		0xc0af, // TLS_ECDHE_ECDSA_WITH_AES_256_CCM_8
+		0xc0ad, // TLS_ECDHE_ECDSA_WITH_AES_256_CCM
+		0xc0a3, // TLS_DHE_RSA_WITH_AES_256_CCM_8
+		0xc09f, // TLS_DHE_RSA_WITH_AES_256_CCM
+
+		// ARIA (256-bit)
+		0xc05d, // TLS_ECDHE_ECDSA_WITH_ARIA_256_GCM_SHA384
+		0xc061, // TLS_ECDHE_RSA_WITH_ARIA_256_GCM_SHA384
+		0xc057, // TLS_DHE_DSS_WITH_ARIA_256_GCM_SHA384
+		0xc053, // TLS_DHE_RSA_WITH_ARIA_256_GCM_SHA384
+
+		// DHE-DSS + AES-GCM (128-bit)
+		0x00a2, // TLS_DHE_DSS_WITH_AES_128_GCM_SHA256
+
+		// AES-CCM (128-bit)
+		0xc0ae, // TLS_ECDHE_ECDSA_WITH_AES_128_CCM_8
+		0xc0ac, // TLS_ECDHE_ECDSA_WITH_AES_128_CCM
+		0xc0a2, // TLS_DHE_RSA_WITH_AES_128_CCM_8
+		0xc09e, // TLS_DHE_RSA_WITH_AES_128_CCM
+
+		// ARIA (128-bit)
+		0xc05c, // TLS_ECDHE_ECDSA_WITH_ARIA_128_GCM_SHA256
+		0xc060, // TLS_ECDHE_RSA_WITH_ARIA_128_GCM_SHA256
+		0xc056, // TLS_DHE_DSS_WITH_ARIA_128_GCM_SHA256
+		0xc052, // TLS_DHE_RSA_WITH_ARIA_128_GCM_SHA256
+
+		// ECDHE/DHE + AES-CBC-SHA384/256 (more)
+		0xc024, // TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384
+		0x006a, // TLS_DHE_DSS_WITH_AES_256_CBC_SHA256
+		0xc023, // TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256
+		0x0040, // TLS_DHE_DSS_WITH_AES_128_CBC_SHA256
+
+		// ECDHE/DHE + AES-CBC-SHA (legacy)
+		0xc00a, // TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA
+		0xc014, // TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA
+		0x0039, // TLS_DHE_RSA_WITH_AES_256_CBC_SHA
+		0x0038, // TLS_DHE_DSS_WITH_AES_256_CBC_SHA
+		0xc009, // TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA
+		0xc013, // TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA
+		0x0033, // TLS_DHE_RSA_WITH_AES_128_CBC_SHA
+		0x0032, // TLS_DHE_DSS_WITH_AES_128_CBC_SHA
+
+		// RSA + AES-GCM/CCM/ARIA (non-PFS, 256-bit)
+		0x009d, // TLS_RSA_WITH_AES_256_GCM_SHA384
+		0xc0a1, // TLS_RSA_WITH_AES_256_CCM_8
+		0xc09d, // TLS_RSA_WITH_AES_256_CCM
+		0xc051, // TLS_RSA_WITH_ARIA_256_GCM_SHA384
+
+		// RSA + AES-GCM/CCM/ARIA (non-PFS, 128-bit)
+		0x009c, // TLS_RSA_WITH_AES_128_GCM_SHA256
+		0xc0a0, // TLS_RSA_WITH_AES_128_CCM_8
+		0xc09c, // TLS_RSA_WITH_AES_128_CCM
+		0xc050, // TLS_RSA_WITH_ARIA_128_GCM_SHA256
+
+		// RSA + AES-CBC (non-PFS, legacy)
+		0x003d, // TLS_RSA_WITH_AES_256_CBC_SHA256
+		0x003c, // TLS_RSA_WITH_AES_128_CBC_SHA256
+		0x0035, // TLS_RSA_WITH_AES_256_CBC_SHA
+		0x002f, // TLS_RSA_WITH_AES_128_CBC_SHA
+
+		// Renegotiation indication
+		0x00ff, // TLS_EMPTY_RENEGOTIATION_INFO_SCSV
+	}
+
+	// defaultCurves contains the 10 supported groups from Claude CLI (including FFDHE)
+	defaultCurves = []utls.CurveID{
+		utls.X25519,          // 0x001d
+		utls.CurveP256,       // 0x0017 (secp256r1)
+		utls.CurveID(0x001e), // x448
+		utls.CurveP521,       // 0x0019 (secp521r1)
+		utls.CurveP384,       // 0x0018 (secp384r1)
+		utls.CurveID(0x0100), // ffdhe2048
+		utls.CurveID(0x0101), // ffdhe3072
+		utls.CurveID(0x0102), // ffdhe4096
+		utls.CurveID(0x0103), // ffdhe6144
+		utls.CurveID(0x0104), // ffdhe8192
+	}
+
+	// defaultPointFormats contains all 3 point formats from Claude CLI
+	defaultPointFormats = []uint8{
+		0, // uncompressed
+		1, // ansiX962_compressed_prime
+		2, // ansiX962_compressed_char2
+	}
+
+	// defaultSignatureAlgorithms contains the 20 signature algorithms from Claude CLI
+	defaultSignatureAlgorithms = []utls.SignatureScheme{
+		0x0403, // ecdsa_secp256r1_sha256
+		0x0503, // ecdsa_secp384r1_sha384
+		0x0603, // ecdsa_secp521r1_sha512
+		0x0807, // ed25519
+		0x0808, // ed448
+		0x0809, // rsa_pss_pss_sha256
+		0x080a, // rsa_pss_pss_sha384
+		0x080b, // rsa_pss_pss_sha512
+		0x0804, // rsa_pss_rsae_sha256
+		0x0805, // rsa_pss_rsae_sha384
+		0x0806, // rsa_pss_rsae_sha512
+		0x0401, // rsa_pkcs1_sha256
+		0x0501, // rsa_pkcs1_sha384
+		0x0601, // rsa_pkcs1_sha512
+		0x0303, // ecdsa_sha224
+		0x0301, // rsa_pkcs1_sha224
+		0x0302, // dsa_sha224
+		0x0402, // dsa_sha256
+		0x0502, // dsa_sha384
+		0x0602, // dsa_sha512
+	}
+)
+
+// NewDialer creates a new TLS fingerprint dialer.
+// baseDialer is used for TCP connection establishment (supports proxy scenarios).
+// If baseDialer is nil, direct TCP dial is used.
+func NewDialer(profile *Profile, baseDialer func(ctx context.Context, network, addr string) (net.Conn, error)) *Dialer {
+	if baseDialer == nil {
+		baseDialer = (&net.Dialer{}).DialContext
+	}
+	return &Dialer{profile: profile, baseDialer: baseDialer}
+}
+
+// NewHTTPProxyDialer creates a new TLS fingerprint dialer that works through HTTP/HTTPS proxies.
+// It establishes a CONNECT tunnel before performing TLS handshake with custom fingerprint.
+func NewHTTPProxyDialer(profile *Profile, proxyURL *url.URL) *HTTPProxyDialer {
+	return &HTTPProxyDialer{profile: profile, proxyURL: proxyURL}
+}
+
+// NewSOCKS5ProxyDialer creates a new TLS fingerprint dialer that works through SOCKS5 proxies.
+// It establishes a SOCKS5 tunnel before performing TLS handshake with custom fingerprint.
+func NewSOCKS5ProxyDialer(profile *Profile, proxyURL *url.URL) *SOCKS5ProxyDialer {
+	return &SOCKS5ProxyDialer{profile: profile, proxyURL: proxyURL}
+}
+
+// DialTLSContext establishes a TLS connection through SOCKS5 proxy with the configured fingerprint.
+// Flow: SOCKS5 CONNECT to target -> TLS handshake with utls on the tunnel
+func (d *SOCKS5ProxyDialer) DialTLSContext(ctx context.Context, network, addr string) (net.Conn, error) {
+	slog.Debug("tls_fingerprint_socks5_connecting", "proxy", d.proxyURL.Host, "target", addr)
+
+	// Step 1: Create SOCKS5 dialer
+	var auth *proxy.Auth
+	if d.proxyURL.User != nil {
+		username := d.proxyURL.User.Username()
+		password, _ := d.proxyURL.User.Password()
+		auth = &proxy.Auth{
+			User:     username,
+			Password: password,
+		}
+	}
+
+	// Determine proxy address
+	proxyAddr := d.proxyURL.Host
+	if d.proxyURL.Port() == "" {
+		proxyAddr = net.JoinHostPort(d.proxyURL.Hostname(), "1080") // Default SOCKS5 port
+	}
+
+	socksDialer, err := proxy.SOCKS5("tcp", proxyAddr, auth, proxy.Direct)
+	if err != nil {
+		slog.Debug("tls_fingerprint_socks5_dialer_failed", "error", err)
+		return nil, fmt.Errorf("create SOCKS5 dialer: %w", err)
+	}
+
+	// Step 2: Establish SOCKS5 tunnel to target
+	slog.Debug("tls_fingerprint_socks5_establishing_tunnel", "target", addr)
+	conn, err := socksDialer.Dial("tcp", addr)
+	if err != nil {
+		slog.Debug("tls_fingerprint_socks5_connect_failed", "error", err)
+		return nil, fmt.Errorf("SOCKS5 connect: %w", err)
+	}
+	slog.Debug("tls_fingerprint_socks5_tunnel_established")
+
+	// Step 3: Perform TLS handshake on the tunnel with utls fingerprint
+	host, _, err := net.SplitHostPort(addr)
+	if err != nil {
+		host = addr
+	}
+	slog.Debug("tls_fingerprint_socks5_starting_handshake", "host", host)
+
+	// Build ClientHello specification from profile (Node.js/Claude CLI fingerprint)
+	spec := buildClientHelloSpecFromProfile(d.profile)
+	slog.Debug("tls_fingerprint_socks5_clienthello_spec",
+		"cipher_suites", len(spec.CipherSuites),
+		"extensions", len(spec.Extensions),
+		"compression_methods", spec.CompressionMethods,
+		"tls_vers_max", fmt.Sprintf("0x%04x", spec.TLSVersMax),
+		"tls_vers_min", fmt.Sprintf("0x%04x", spec.TLSVersMin))
+
+	if d.profile != nil {
+		slog.Debug("tls_fingerprint_socks5_using_profile", "name", d.profile.Name, "grease", d.profile.EnableGREASE)
+	}
+
+	// Create uTLS connection on the tunnel
+	tlsConn := utls.UClient(conn, &utls.Config{
+		ServerName: host,
+	}, utls.HelloCustom)
+
+	if err := tlsConn.ApplyPreset(spec); err != nil {
+		slog.Debug("tls_fingerprint_socks5_apply_preset_failed", "error", err)
+		_ = conn.Close()
+		return nil, fmt.Errorf("apply TLS preset: %w", err)
+	}
+
+	if err := tlsConn.Handshake(); err != nil {
+		slog.Debug("tls_fingerprint_socks5_handshake_failed", "error", err)
+		_ = conn.Close()
+		return nil, fmt.Errorf("TLS handshake failed: %w", err)
+	}
+
+	state := tlsConn.ConnectionState()
+	slog.Debug("tls_fingerprint_socks5_handshake_success",
+		"version", fmt.Sprintf("0x%04x", state.Version),
+		"cipher_suite", fmt.Sprintf("0x%04x", state.CipherSuite),
+		"alpn", state.NegotiatedProtocol)
+
+	return tlsConn, nil
+}
+
+// DialTLSContext establishes a TLS connection through HTTP proxy with the configured fingerprint.
+// Flow: TCP connect to proxy -> CONNECT tunnel -> TLS handshake with utls
+func (d *HTTPProxyDialer) DialTLSContext(ctx context.Context, network, addr string) (net.Conn, error) {
+	slog.Debug("tls_fingerprint_http_proxy_connecting", "proxy", d.proxyURL.Host, "target", addr)
+
+	// Step 1: TCP connect to proxy server
+	var proxyAddr string
+	if d.proxyURL.Port() != "" {
+		proxyAddr = d.proxyURL.Host
+	} else {
+		// Default ports
+		if d.proxyURL.Scheme == "https" {
+			proxyAddr = net.JoinHostPort(d.proxyURL.Hostname(), "443")
+		} else {
+			proxyAddr = net.JoinHostPort(d.proxyURL.Hostname(), "80")
+		}
+	}
+
+	dialer := &net.Dialer{}
+	conn, err := dialer.DialContext(ctx, "tcp", proxyAddr)
+	if err != nil {
+		slog.Debug("tls_fingerprint_http_proxy_connect_failed", "error", err)
+		return nil, fmt.Errorf("connect to proxy: %w", err)
+	}
+	slog.Debug("tls_fingerprint_http_proxy_connected", "proxy_addr", proxyAddr)
+
+	// Step 2: Send CONNECT request to establish tunnel
+	req := &http.Request{
+		Method: "CONNECT",
+		URL:    &url.URL{Opaque: addr},
+		Host:   addr,
+		Header: make(http.Header),
+	}
+
+	// Add proxy authentication if present
+	if d.proxyURL.User != nil {
+		username := d.proxyURL.User.Username()
+		password, _ := d.proxyURL.User.Password()
+		auth := base64.StdEncoding.EncodeToString([]byte(username + ":" + password))
+		req.Header.Set("Proxy-Authorization", "Basic "+auth)
+	}
+
+	slog.Debug("tls_fingerprint_http_proxy_sending_connect", "target", addr)
+	if err := req.Write(conn); err != nil {
+		_ = conn.Close()
+		slog.Debug("tls_fingerprint_http_proxy_write_failed", "error", err)
+		return nil, fmt.Errorf("write CONNECT request: %w", err)
+	}
+
+	// Step 3: Read CONNECT response
+	br := bufio.NewReader(conn)
+	resp, err := http.ReadResponse(br, req)
+	if err != nil {
+		_ = conn.Close()
+		slog.Debug("tls_fingerprint_http_proxy_read_response_failed", "error", err)
+		return nil, fmt.Errorf("read CONNECT response: %w", err)
+	}
+	defer func() { _ = resp.Body.Close() }()
+
+	if resp.StatusCode != http.StatusOK {
+		_ = conn.Close()
+		slog.Debug("tls_fingerprint_http_proxy_connect_failed_status", "status_code", resp.StatusCode, "status", resp.Status)
+		return nil, fmt.Errorf("proxy CONNECT failed: %s", resp.Status)
+	}
+	slog.Debug("tls_fingerprint_http_proxy_tunnel_established")
+
+	// Step 4: Perform TLS handshake on the tunnel with utls fingerprint
+	host, _, err := net.SplitHostPort(addr)
+	if err != nil {
+		host = addr
+	}
+	slog.Debug("tls_fingerprint_http_proxy_starting_handshake", "host", host)
+
+	// Build ClientHello specification (reuse the shared method)
+	spec := buildClientHelloSpecFromProfile(d.profile)
+	slog.Debug("tls_fingerprint_http_proxy_clienthello_spec",
+		"cipher_suites", len(spec.CipherSuites),
+		"extensions", len(spec.Extensions))
+
+	if d.profile != nil {
+		slog.Debug("tls_fingerprint_http_proxy_using_profile", "name", d.profile.Name, "grease", d.profile.EnableGREASE)
+	}
+
+	// Create uTLS connection on the tunnel
+	// Note: TLS 1.3 cipher suites are handled automatically by utls when TLS 1.3 is in SupportedVersions
+	tlsConn := utls.UClient(conn, &utls.Config{
+		ServerName: host,
+	}, utls.HelloCustom)
+
+	if err := tlsConn.ApplyPreset(spec); err != nil {
+		slog.Debug("tls_fingerprint_http_proxy_apply_preset_failed", "error", err)
+		_ = conn.Close()
+		return nil, fmt.Errorf("apply TLS preset: %w", err)
+	}
+
+	if err := tlsConn.HandshakeContext(ctx); err != nil {
+		slog.Debug("tls_fingerprint_http_proxy_handshake_failed", "error", err)
+		_ = conn.Close()
+		return nil, fmt.Errorf("TLS handshake failed: %w", err)
+	}
+
+	state := tlsConn.ConnectionState()
+	slog.Debug("tls_fingerprint_http_proxy_handshake_success",
+		"version", fmt.Sprintf("0x%04x", state.Version),
+		"cipher_suite", fmt.Sprintf("0x%04x", state.CipherSuite),
+		"alpn", state.NegotiatedProtocol)
+
+	return tlsConn, nil
+}
+
+// DialTLSContext establishes a TLS connection with the configured fingerprint.
+// This method is designed to be used as http.Transport.DialTLSContext.
+func (d *Dialer) DialTLSContext(ctx context.Context, network, addr string) (net.Conn, error) {
+	// Establish TCP connection using base dialer (supports proxy)
+	slog.Debug("tls_fingerprint_dialing_tcp", "addr", addr)
+	conn, err := d.baseDialer(ctx, network, addr)
+	if err != nil {
+		slog.Debug("tls_fingerprint_tcp_dial_failed", "error", err)
+		return nil, err
+	}
+	slog.Debug("tls_fingerprint_tcp_connected", "addr", addr)
+
+	// Extract hostname for SNI
+	host, _, err := net.SplitHostPort(addr)
+	if err != nil {
+		host = addr
+	}
+	slog.Debug("tls_fingerprint_sni_hostname", "host", host)
+
+	// Build ClientHello specification
+	spec := d.buildClientHelloSpec()
+	slog.Debug("tls_fingerprint_clienthello_spec",
+		"cipher_suites", len(spec.CipherSuites),
+		"extensions", len(spec.Extensions))
+
+	// Log profile info
+	if d.profile != nil {
+		slog.Debug("tls_fingerprint_using_profile", "name", d.profile.Name, "grease", d.profile.EnableGREASE)
+	} else {
+		slog.Debug("tls_fingerprint_using_default_profile")
+	}
+
+	// Create uTLS connection
+	// Note: TLS 1.3 cipher suites are handled automatically by utls when TLS 1.3 is in SupportedVersions
+	tlsConn := utls.UClient(conn, &utls.Config{
+		ServerName: host,
+	}, utls.HelloCustom)
+
+	// Apply fingerprint
+	if err := tlsConn.ApplyPreset(spec); err != nil {
+		slog.Debug("tls_fingerprint_apply_preset_failed", "error", err)
+		_ = conn.Close()
+		return nil, err
+	}
+	slog.Debug("tls_fingerprint_preset_applied")
+
+	// Perform TLS handshake
+	if err := tlsConn.HandshakeContext(ctx); err != nil {
+		slog.Debug("tls_fingerprint_handshake_failed",
+			"error", err,
+			"local_addr", conn.LocalAddr(),
+			"remote_addr", conn.RemoteAddr())
+		_ = conn.Close()
+		return nil, fmt.Errorf("TLS handshake failed: %w", err)
+	}
+
+	// Log successful handshake details
+	state := tlsConn.ConnectionState()
+	slog.Debug("tls_fingerprint_handshake_success",
+		"version", fmt.Sprintf("0x%04x", state.Version),
+		"cipher_suite", fmt.Sprintf("0x%04x", state.CipherSuite),
+		"alpn", state.NegotiatedProtocol)
+
+	return tlsConn, nil
+}
+
+// buildClientHelloSpec constructs the ClientHello specification based on the profile.
+func (d *Dialer) buildClientHelloSpec() *utls.ClientHelloSpec {
+	return buildClientHelloSpecFromProfile(d.profile)
+}
+
+// toUTLSCurves converts uint16 slice to utls.CurveID slice.
+func toUTLSCurves(curves []uint16) []utls.CurveID {
+	result := make([]utls.CurveID, len(curves))
+	for i, c := range curves {
+		result[i] = utls.CurveID(c)
+	}
+	return result
+}
+
+// buildClientHelloSpecFromProfile constructs ClientHelloSpec from a Profile.
+// This is a standalone function that can be used by both Dialer and HTTPProxyDialer.
+func buildClientHelloSpecFromProfile(profile *Profile) *utls.ClientHelloSpec {
+	// Get cipher suites
+	var cipherSuites []uint16
+	if profile != nil && len(profile.CipherSuites) > 0 {
+		cipherSuites = profile.CipherSuites
+	} else {
+		cipherSuites = defaultCipherSuites
+	}
+
+	// Get curves
+	var curves []utls.CurveID
+	if profile != nil && len(profile.Curves) > 0 {
+		curves = toUTLSCurves(profile.Curves)
+	} else {
+		curves = defaultCurves
+	}
+
+	// Get point formats
+	var pointFormats []uint8
+	if profile != nil && len(profile.PointFormats) > 0 {
+		pointFormats = profile.PointFormats
+	} else {
+		pointFormats = defaultPointFormats
+	}
+
+	// Check if GREASE is enabled
+	enableGREASE := profile != nil && profile.EnableGREASE
+
+	extensions := make([]utls.TLSExtension, 0, 16)
+
+	if enableGREASE {
+		extensions = append(extensions, &utls.UtlsGREASEExtension{})
+	}
+
+	// SNI extension - MUST be explicitly added for HelloCustom mode
+	// utls will populate the server name from Config.ServerName
+	extensions = append(extensions, &utls.SNIExtension{})
+
+	// Claude CLI extension order (captured from tshark):
+	// server_name(0), ec_point_formats(11), supported_groups(10), session_ticket(35),
+	// alpn(16), encrypt_then_mac(22), extended_master_secret(23),
+	// signature_algorithms(13), supported_versions(43),
+	// psk_key_exchange_modes(45), key_share(51)
+	extensions = append(extensions,
+		&utls.SupportedPointsExtension{SupportedPoints: pointFormats},
+		&utls.SupportedCurvesExtension{Curves: curves},
+		&utls.SessionTicketExtension{},
+		&utls.ALPNExtension{AlpnProtocols: []string{"http/1.1"}},
+		&utls.GenericExtension{Id: 22},
+		&utls.ExtendedMasterSecretExtension{},
+		&utls.SignatureAlgorithmsExtension{SupportedSignatureAlgorithms: defaultSignatureAlgorithms},
+		&utls.SupportedVersionsExtension{Versions: []uint16{
+			utls.VersionTLS13,
+			utls.VersionTLS12,
+		}},
+		&utls.PSKKeyExchangeModesExtension{Modes: []uint8{utls.PskModeDHE}},
+		&utls.KeyShareExtension{KeyShares: []utls.KeyShare{
+			{Group: utls.X25519},
+		}},
+	)
+
+	if enableGREASE {
+		extensions = append(extensions, &utls.UtlsGREASEExtension{})
+	}
+
+	return &utls.ClientHelloSpec{
+		CipherSuites:       cipherSuites,
+		CompressionMethods: []uint8{0}, // null compression only (standard)
+		Extensions:         extensions,
+		TLSVersMax:         utls.VersionTLS13,
+		TLSVersMin:         utls.VersionTLS10,
+	}
+}
--- a/backend/internal/pkg/tlsfingerprint/dialer_integration_test.go
+++ b/backend/internal/pkg/tlsfingerprint/dialer_integration_test.go
@@ -0,0 +1,278 @@
+//go:build integration
+
+// Package tlsfingerprint provides TLS fingerprint simulation for HTTP clients.
+//
+// Integration tests for verifying TLS fingerprint correctness.
+// These tests make actual network requests to external services and should be run manually.
+//
+// Run with: go test -v -tags=integration ./internal/pkg/tlsfingerprint/...
+package tlsfingerprint
+
+import (
+	"context"
+	"encoding/json"
+	"io"
+	"net/http"
+	"strings"
+	"testing"
+	"time"
+)
+
+// skipIfExternalServiceUnavailable checks if the external service is available.
+// If not, it skips the test instead of failing.
+func skipIfExternalServiceUnavailable(t *testing.T, err error) {
+	t.Helper()
+	if err != nil {
+		// Check for common network/TLS errors that indicate external service issues
+		errStr := err.Error()
+		if strings.Contains(errStr, "certificate has expired") ||
+			strings.Contains(errStr, "certificate is not yet valid") ||
+			strings.Contains(errStr, "connection refused") ||
+			strings.Contains(errStr, "no such host") ||
+			strings.Contains(errStr, "network is unreachable") ||
+			strings.Contains(errStr, "timeout") {
+			t.Skipf("skipping test: external service unavailable: %v", err)
+		}
+		t.Fatalf("failed to get fingerprint: %v", err)
+	}
+}
+
+// TestJA3Fingerprint verifies the JA3/JA4 fingerprint matches expected value.
+// This test uses tls.peet.ws to verify the fingerprint.
+// Expected JA3 hash: 1a28e69016765d92e3b381168d68922c (Claude CLI / Node.js 20.x)
+// Expected JA4: t13d5911h1_a33745022dd6_1f22a2ca17c4 (d=domain) or t13i5911h1_... (i=IP)
+func TestJA3Fingerprint(t *testing.T) {
+	// Skip if network is unavailable or if running in short mode
+	if testing.Short() {
+		t.Skip("skipping integration test in short mode")
+	}
+
+	profile := &Profile{
+		Name:         "Claude CLI Test",
+		EnableGREASE: false,
+	}
+	dialer := NewDialer(profile, nil)
+
+	client := &http.Client{
+		Transport: &http.Transport{
+			DialTLSContext: dialer.DialTLSContext,
+		},
+		Timeout: 30 * time.Second,
+	}
+
+	// Use tls.peet.ws fingerprint detection API
+	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
+	defer cancel()
+
+	req, err := http.NewRequestWithContext(ctx, "GET", "https://tls.peet.ws/api/all", nil)
+	if err != nil {
+		t.Fatalf("failed to create request: %v", err)
+	}
+	req.Header.Set("User-Agent", "Claude Code/2.0.0 Node.js/20.0.0")
+
+	resp, err := client.Do(req)
+	skipIfExternalServiceUnavailable(t, err)
+	defer func() { _ = resp.Body.Close() }()
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		t.Fatalf("failed to read response: %v", err)
+	}
+
+	var fpResp FingerprintResponse
+	if err := json.Unmarshal(body, &fpResp); err != nil {
+		t.Logf("Response body: %s", string(body))
+		t.Fatalf("failed to parse fingerprint response: %v", err)
+	}
+
+	// Log all fingerprint information
+	t.Logf("JA3: %s", fpResp.TLS.JA3)
+	t.Logf("JA3 Hash: %s", fpResp.TLS.JA3Hash)
+	t.Logf("JA4: %s", fpResp.TLS.JA4)
+	t.Logf("PeetPrint: %s", fpResp.TLS.PeetPrint)
+	t.Logf("PeetPrint Hash: %s", fpResp.TLS.PeetPrintHash)
+
+	// Verify JA3 hash matches expected value
+	expectedJA3Hash := "1a28e69016765d92e3b381168d68922c"
+	if fpResp.TLS.JA3Hash == expectedJA3Hash {
+		t.Logf("✓ JA3 hash matches expected value: %s", expectedJA3Hash)
+	} else {
+		t.Errorf("✗ JA3 hash mismatch: got %s, expected %s", fpResp.TLS.JA3Hash, expectedJA3Hash)
+	}
+
+	// Verify JA4 fingerprint
+	// JA4 format: t[version][sni][cipher_count][ext_count][alpn]_[cipher_hash]_[ext_hash]
+	// Expected: t13d5910h1 (d=domain) or t13i5910h1 (i=IP)
+	// The suffix _a33745022dd6_1f22a2ca17c4 should match
+	expectedJA4Suffix := "_a33745022dd6_1f22a2ca17c4"
+	if strings.HasSuffix(fpResp.TLS.JA4, expectedJA4Suffix) {
+		t.Logf("✓ JA4 suffix matches expected value: %s", expectedJA4Suffix)
+	} else {
+		t.Errorf("✗ JA4 suffix mismatch: got %s, expected suffix %s", fpResp.TLS.JA4, expectedJA4Suffix)
+	}
+
+	// Verify JA4 prefix (t13d5911h1 or t13i5911h1)
+	// d = domain (SNI present), i = IP (no SNI)
+	// Since we connect to tls.peet.ws (domain), we expect 'd'
+	expectedJA4Prefix := "t13d5911h1"
+	if strings.HasPrefix(fpResp.TLS.JA4, expectedJA4Prefix) {
+		t.Logf("✓ JA4 prefix matches: %s (t13=TLS1.3, d=domain, 59=ciphers, 11=extensions, h1=HTTP/1.1)", expectedJA4Prefix)
+	} else {
+		// Also accept 'i' variant for IP connections
+		altPrefix := "t13i5911h1"
+		if strings.HasPrefix(fpResp.TLS.JA4, altPrefix) {
+			t.Logf("✓ JA4 prefix matches (IP variant): %s", altPrefix)
+		} else {
+			t.Errorf("✗ JA4 prefix mismatch: got %s, expected %s or %s", fpResp.TLS.JA4, expectedJA4Prefix, altPrefix)
+		}
+	}
+
+	// Verify JA3 contains expected cipher suites (TLS 1.3 ciphers at the beginning)
+	if strings.Contains(fpResp.TLS.JA3, "4866-4867-4865") {
+		t.Logf("✓ JA3 contains expected TLS 1.3 cipher suites")
+	} else {
+		t.Logf("Warning: JA3 does not contain expected TLS 1.3 cipher suites")
+	}
+
+	// Verify extension list (should be 11 extensions including SNI)
+	// Expected: 0-11-10-35-16-22-23-13-43-45-51
+	expectedExtensions := "0-11-10-35-16-22-23-13-43-45-51"
+	if strings.Contains(fpResp.TLS.JA3, expectedExtensions) {
+		t.Logf("✓ JA3 contains expected extension list: %s", expectedExtensions)
+	} else {
+		t.Logf("Warning: JA3 extension list may differ")
+	}
+}
+
+// TestProfileExpectation defines expected fingerprint values for a profile.
+type TestProfileExpectation struct {
+	Profile       *Profile
+	ExpectedJA3   string // Expected JA3 hash (empty = don't check)
+	ExpectedJA4   string // Expected full JA4 (empty = don't check)
+	JA4CipherHash string // Expected JA4 cipher hash - the stable middle part (empty = don't check)
+}
+
+// TestAllProfiles tests multiple TLS fingerprint profiles against tls.peet.ws.
+// Run with: go test -v -tags=integration -run TestAllProfiles ./internal/pkg/tlsfingerprint/...
+func TestAllProfiles(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping integration test in short mode")
+	}
+
+	// Define all profiles to test with their expected fingerprints
+	// These profiles are from config.yaml gateway.tls_fingerprint.profiles
+	profiles := []TestProfileExpectation{
+		{
+			// Linux x64 Node.js v22.17.1
+			// Expected JA3 Hash: 1a28e69016765d92e3b381168d68922c
+			// Expected JA4: t13d5911h1_a33745022dd6_1f22a2ca17c4
+			Profile: &Profile{
+				Name:         "linux_x64_node_v22171",
+				EnableGREASE: false,
+				CipherSuites: []uint16{4866, 4867, 4865, 49199, 49195, 49200, 49196, 158, 49191, 103, 49192, 107, 163, 159, 52393, 52392, 52394, 49327, 49325, 49315, 49311, 49245, 49249, 49239, 49235, 162, 49326, 49324, 49314, 49310, 49244, 49248, 49238, 49234, 49188, 106, 49187, 64, 49162, 49172, 57, 56, 49161, 49171, 51, 50, 157, 49313, 49309, 49233, 156, 49312, 49308, 49232, 61, 60, 53, 47, 255},
+				Curves:       []uint16{29, 23, 30, 25, 24, 256, 257, 258, 259, 260},
+				PointFormats: []uint8{0, 1, 2},
+			},
+			JA4CipherHash: "a33745022dd6", // stable part
+		},
+		{
+			// MacOS arm64 Node.js v22.18.0
+			// Expected JA3 Hash: 70cb5ca646080902703ffda87036a5ea
+			// Expected JA4: t13d5912h1_a33745022dd6_dbd39dd1d406
+			Profile: &Profile{
+				Name:         "macos_arm64_node_v22180",
+				EnableGREASE: false,
+				CipherSuites: []uint16{4866, 4867, 4865, 49199, 49195, 49200, 49196, 158, 49191, 103, 49192, 107, 163, 159, 52393, 52392, 52394, 49327, 49325, 49315, 49311, 49245, 49249, 49239, 49235, 162, 49326, 49324, 49314, 49310, 49244, 49248, 49238, 49234, 49188, 106, 49187, 64, 49162, 49172, 57, 56, 49161, 49171, 51, 50, 157, 49313, 49309, 49233, 156, 49312, 49308, 49232, 61, 60, 53, 47, 255},
+				Curves:       []uint16{29, 23, 30, 25, 24, 256, 257, 258, 259, 260},
+				PointFormats: []uint8{0, 1, 2},
+			},
+			JA4CipherHash: "a33745022dd6", // stable part (same cipher suites)
+		},
+	}
+
+	for _, tc := range profiles {
+		tc := tc // capture range variable
+		t.Run(tc.Profile.Name, func(t *testing.T) {
+			fp := fetchFingerprint(t, tc.Profile)
+			if fp == nil {
+				return // fetchFingerprint already called t.Fatal
+			}
+
+			t.Logf("Profile: %s", tc.Profile.Name)
+			t.Logf("  JA3:           %s", fp.JA3)
+			t.Logf("  JA3 Hash:      %s", fp.JA3Hash)
+			t.Logf("  JA4:           %s", fp.JA4)
+			t.Logf("  PeetPrint:     %s", fp.PeetPrint)
+			t.Logf("  PeetPrintHash: %s", fp.PeetPrintHash)
+
+			// Verify expectations
+			if tc.ExpectedJA3 != "" {
+				if fp.JA3Hash == tc.ExpectedJA3 {
+					t.Logf("  ✓ JA3 hash matches: %s", tc.ExpectedJA3)
+				} else {
+					t.Errorf("  ✗ JA3 hash mismatch: got %s, expected %s", fp.JA3Hash, tc.ExpectedJA3)
+				}
+			}
+
+			if tc.ExpectedJA4 != "" {
+				if fp.JA4 == tc.ExpectedJA4 {
+					t.Logf("  ✓ JA4 matches: %s", tc.ExpectedJA4)
+				} else {
+					t.Errorf("  ✗ JA4 mismatch: got %s, expected %s", fp.JA4, tc.ExpectedJA4)
+				}
+			}
+
+			// Check JA4 cipher hash (stable middle part)
+			// JA4 format: prefix_cipherHash_extHash
+			if tc.JA4CipherHash != "" {
+				if strings.Contains(fp.JA4, "_"+tc.JA4CipherHash+"_") {
+					t.Logf("  ✓ JA4 cipher hash matches: %s", tc.JA4CipherHash)
+				} else {
+					t.Errorf("  ✗ JA4 cipher hash mismatch: got %s, expected cipher hash %s", fp.JA4, tc.JA4CipherHash)
+				}
+			}
+		})
+	}
+}
+
+// fetchFingerprint makes a request to tls.peet.ws and returns the TLS fingerprint info.
+func fetchFingerprint(t *testing.T, profile *Profile) *TLSInfo {
+	t.Helper()
+
+	dialer := NewDialer(profile, nil)
+	client := &http.Client{
+		Transport: &http.Transport{
+			DialTLSContext: dialer.DialTLSContext,
+		},
+		Timeout: 30 * time.Second,
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
+	defer cancel()
+
+	req, err := http.NewRequestWithContext(ctx, "GET", "https://tls.peet.ws/api/all", nil)
+	if err != nil {
+		t.Fatalf("failed to create request: %v", err)
+		return nil
+	}
+	req.Header.Set("User-Agent", "Claude Code/2.0.0 Node.js/20.0.0")
+
+	resp, err := client.Do(req)
+	skipIfExternalServiceUnavailable(t, err)
+	defer func() { _ = resp.Body.Close() }()
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		t.Fatalf("failed to read response: %v", err)
+		return nil
+	}
+
+	var fpResp FingerprintResponse
+	if err := json.Unmarshal(body, &fpResp); err != nil {
+		t.Logf("Response body: %s", string(body))
+		t.Fatalf("failed to parse fingerprint response: %v", err)
+		return nil
+	}
+
+	return &fpResp.TLS
+}
--- a/backend/internal/pkg/tlsfingerprint/dialer_test.go
+++ b/backend/internal/pkg/tlsfingerprint/dialer_test.go
@@ -0,0 +1,160 @@
+// Package tlsfingerprint provides TLS fingerprint simulation for HTTP clients.
+//
+// Unit tests for TLS fingerprint dialer.
+// Integration tests that require external network are in dialer_integration_test.go
+// and require the 'integration' build tag.
+//
+// Run unit tests: go test -v ./internal/pkg/tlsfingerprint/...
+// Run integration tests: go test -v -tags=integration ./internal/pkg/tlsfingerprint/...
+package tlsfingerprint
+
+import (
+	"net/url"
+	"testing"
+)
+
+// FingerprintResponse represents the response from tls.peet.ws/api/all.
+type FingerprintResponse struct {
+	IP    string  `json:"ip"`
+	TLS   TLSInfo `json:"tls"`
+	HTTP2 any     `json:"http2"`
+}
+
+// TLSInfo contains TLS fingerprint details.
+type TLSInfo struct {
+	JA3           string `json:"ja3"`
+	JA3Hash       string `json:"ja3_hash"`
+	JA4           string `json:"ja4"`
+	PeetPrint     string `json:"peetprint"`
+	PeetPrintHash string `json:"peetprint_hash"`
+	ClientRandom  string `json:"client_random"`
+	SessionID     string `json:"session_id"`
+}
+
+// TestDialerWithProfile tests that different profiles produce different fingerprints.
+func TestDialerWithProfile(t *testing.T) {
+	// Create two dialers with different profiles
+	profile1 := &Profile{
+		Name:         "Profile 1 - No GREASE",
+		EnableGREASE: false,
+	}
+	profile2 := &Profile{
+		Name:         "Profile 2 - With GREASE",
+		EnableGREASE: true,
+	}
+
+	dialer1 := NewDialer(profile1, nil)
+	dialer2 := NewDialer(profile2, nil)
+
+	// Build specs and compare
+	// Note: We can't directly compare JA3 without making network requests
+	// but we can verify the specs are different
+	spec1 := dialer1.buildClientHelloSpec()
+	spec2 := dialer2.buildClientHelloSpec()
+
+	// Profile with GREASE should have more extensions
+	if len(spec2.Extensions) <= len(spec1.Extensions) {
+		t.Error("expected GREASE profile to have more extensions")
+	}
+}
+
+// TestHTTPProxyDialerBasic tests HTTP proxy dialer creation.
+// Note: This is a unit test - actual proxy testing requires a proxy server.
+func TestHTTPProxyDialerBasic(t *testing.T) {
+	profile := &Profile{
+		Name:         "Test Profile",
+		EnableGREASE: false,
+	}
+
+	// Test that dialer is created without panic
+	proxyURL := mustParseURL("http://proxy.example.com:8080")
+	dialer := NewHTTPProxyDialer(profile, proxyURL)
+
+	if dialer == nil {
+		t.Fatal("expected dialer to be created")
+	}
+	if dialer.profile != profile {
+		t.Error("expected profile to be set")
+	}
+	if dialer.proxyURL != proxyURL {
+		t.Error("expected proxyURL to be set")
+	}
+}
+
+// TestSOCKS5ProxyDialerBasic tests SOCKS5 proxy dialer creation.
+// Note: This is a unit test - actual proxy testing requires a proxy server.
+func TestSOCKS5ProxyDialerBasic(t *testing.T) {
+	profile := &Profile{
+		Name:         "Test Profile",
+		EnableGREASE: false,
+	}
+
+	// Test that dialer is created without panic
+	proxyURL := mustParseURL("socks5://proxy.example.com:1080")
+	dialer := NewSOCKS5ProxyDialer(profile, proxyURL)
+
+	if dialer == nil {
+		t.Fatal("expected dialer to be created")
+	}
+	if dialer.profile != profile {
+		t.Error("expected profile to be set")
+	}
+	if dialer.proxyURL != proxyURL {
+		t.Error("expected proxyURL to be set")
+	}
+}
+
+// TestBuildClientHelloSpec tests ClientHello spec construction.
+func TestBuildClientHelloSpec(t *testing.T) {
+	// Test with nil profile (should use defaults)
+	spec := buildClientHelloSpecFromProfile(nil)
+
+	if len(spec.CipherSuites) == 0 {
+		t.Error("expected cipher suites to be set")
+	}
+	if len(spec.Extensions) == 0 {
+		t.Error("expected extensions to be set")
+	}
+
+	// Verify default cipher suites are used
+	if len(spec.CipherSuites) != len(defaultCipherSuites) {
+		t.Errorf("expected %d cipher suites, got %d", len(defaultCipherSuites), len(spec.CipherSuites))
+	}
+
+	// Test with custom profile
+	customProfile := &Profile{
+		Name:         "Custom",
+		EnableGREASE: false,
+		CipherSuites: []uint16{0x1301, 0x1302},
+	}
+	spec = buildClientHelloSpecFromProfile(customProfile)
+
+	if len(spec.CipherSuites) != 2 {
+		t.Errorf("expected 2 cipher suites, got %d", len(spec.CipherSuites))
+	}
+}
+
+// TestToUTLSCurves tests curve ID conversion.
+func TestToUTLSCurves(t *testing.T) {
+	input := []uint16{0x001d, 0x0017, 0x0018}
+	result := toUTLSCurves(input)
+
+	if len(result) != len(input) {
+		t.Errorf("expected %d curves, got %d", len(input), len(result))
+	}
+
+	for i, curve := range result {
+		if uint16(curve) != input[i] {
+			t.Errorf("curve %d: expected 0x%04x, got 0x%04x", i, input[i], uint16(curve))
+		}
+	}
+}
+
+// Helper function to parse URL without error handling.
+func mustParseURL(rawURL string) *url.URL {
+	u, err := url.Parse(rawURL)
+	if err != nil {
+		panic(err)
+	}
+	return u
+}
--- a/backend/internal/pkg/tlsfingerprint/registry.go
+++ b/backend/internal/pkg/tlsfingerprint/registry.go
@@ -0,0 +1,171 @@
+// Package tlsfingerprint provides TLS fingerprint simulation for HTTP clients.
+package tlsfingerprint
+
+import (
+	"log/slog"
+	"sort"
+	"sync"
+
+	"github.com/Wei-Shaw/sub2api/internal/config"
+)
+
+// DefaultProfileName is the name of the built-in Claude CLI profile.
+const DefaultProfileName = "claude_cli_v2"
+
+// Registry manages TLS fingerprint profiles.
+// It holds a collection of profiles that can be used for TLS fingerprint simulation.
+// Profiles are selected based on account ID using modulo operation.
+type Registry struct {
+	mu           sync.RWMutex
+	profiles     map[string]*Profile
+	profileNames []string // Sorted list of profile names for deterministic selection
+}
+
+// NewRegistry creates a new TLS fingerprint profile registry.
+// It initializes with the built-in default profile.
+func NewRegistry() *Registry {
+	r := &Registry{
+		profiles:     make(map[string]*Profile),
+		profileNames: make([]string, 0),
+	}
+
+	// Register the built-in default profile
+	r.registerBuiltinProfile()
+
+	return r
+}
+
+// NewRegistryFromConfig creates a new registry and loads profiles from config.
+// If the config has custom profiles defined, they will be merged with the built-in default.
+func NewRegistryFromConfig(cfg *config.TLSFingerprintConfig) *Registry {
+	r := NewRegistry()
+
+	if cfg == nil || !cfg.Enabled {
+		slog.Debug("tls_registry_disabled", "reason", "disabled or no config")
+		return r
+	}
+
+	// Load custom profiles from config
+	for name, profileCfg := range cfg.Profiles {
+		profile := &Profile{
+			Name:         profileCfg.Name,
+			EnableGREASE: profileCfg.EnableGREASE,
+			CipherSuites: profileCfg.CipherSuites,
+			Curves:       profileCfg.Curves,
+			PointFormats: profileCfg.PointFormats,
+		}
+
+		// If the profile has empty values, they will use defaults in dialer
+		r.RegisterProfile(name, profile)
+		slog.Debug("tls_registry_loaded_profile", "key", name, "name", profileCfg.Name)
+	}
+
+	slog.Debug("tls_registry_initialized", "profile_count", len(r.profileNames), "profiles", r.profileNames)
+	return r
+}
+
+// registerBuiltinProfile adds the default Claude CLI profile to the registry.
+func (r *Registry) registerBuiltinProfile() {
+	defaultProfile := &Profile{
+		Name:         "Claude CLI 2.x (Node.js 20.x + OpenSSL 3.x)",
+		EnableGREASE: false, // Node.js does not use GREASE
+		// Empty slices will cause dialer to use built-in defaults
+		CipherSuites: nil,
+		Curves:       nil,
+		PointFormats: nil,
+	}
+	r.RegisterProfile(DefaultProfileName, defaultProfile)
+}
+
+// RegisterProfile adds or updates a profile in the registry.
+func (r *Registry) RegisterProfile(name string, profile *Profile) {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+
+	// Check if this is a new profile
+	_, exists := r.profiles[name]
+	r.profiles[name] = profile
+
+	if !exists {
+		r.profileNames = append(r.profileNames, name)
+		// Keep names sorted for deterministic selection
+		sort.Strings(r.profileNames)
+	}
+}
+
+// GetProfile returns a profile by name.
+// Returns nil if the profile does not exist.
+func (r *Registry) GetProfile(name string) *Profile {
+	r.mu.RLock()
+	defer r.mu.RUnlock()
+	return r.profiles[name]
+}
+
+// GetDefaultProfile returns the built-in default profile.
+func (r *Registry) GetDefaultProfile() *Profile {
+	return r.GetProfile(DefaultProfileName)
+}
+
+// GetProfileByAccountID returns a profile for the given account ID.
+// The profile is selected using: profileNames[accountID % len(profiles)]
+// This ensures deterministic profile assignment for each account.
+func (r *Registry) GetProfileByAccountID(accountID int64) *Profile {
+	r.mu.RLock()
+	defer r.mu.RUnlock()
+
+	if len(r.profileNames) == 0 {
+		return nil
+	}
+
+	// Use modulo to select profile index
+	// Use absolute value to handle negative IDs (though unlikely)
+	idx := accountID
+	if idx < 0 {
+		idx = -idx
+	}
+	selectedIndex := int(idx % int64(len(r.profileNames)))
+	selectedName := r.profileNames[selectedIndex]
+
+	return r.profiles[selectedName]
+}
+
+// ProfileCount returns the number of registered profiles.
+func (r *Registry) ProfileCount() int {
+	r.mu.RLock()
+	defer r.mu.RUnlock()
+	return len(r.profiles)
+}
+
+// ProfileNames returns a sorted list of all registered profile names.
+func (r *Registry) ProfileNames() []string {
+	r.mu.RLock()
+	defer r.mu.RUnlock()
+
+	// Return a copy to prevent modification
+	names := make([]string, len(r.profileNames))
+	copy(names, r.profileNames)
+	return names
+}
+
+// Global registry instance for convenience
+var globalRegistry *Registry
+var globalRegistryOnce sync.Once
+
+// GlobalRegistry returns the global TLS fingerprint registry.
+// The registry is lazily initialized with the default profile.
+func GlobalRegistry() *Registry {
+	globalRegistryOnce.Do(func() {
+		globalRegistry = NewRegistry()
+	})
+	return globalRegistry
+}
+
+// InitGlobalRegistry initializes the global registry with configuration.
+// This should be called during application startup.
+// It is safe to call multiple times; subsequent calls will update the registry.
+func InitGlobalRegistry(cfg *config.TLSFingerprintConfig) *Registry {
+	globalRegistryOnce.Do(func() {
+		globalRegistry = NewRegistryFromConfig(cfg)
+	})
+	return globalRegistry
+}
--- a/backend/internal/pkg/tlsfingerprint/registry_test.go
+++ b/backend/internal/pkg/tlsfingerprint/registry_test.go
@@ -0,0 +1,243 @@
+package tlsfingerprint
+
+import (
+	"testing"
+
+	"github.com/Wei-Shaw/sub2api/internal/config"
+)
+
+func TestNewRegistry(t *testing.T) {
+	r := NewRegistry()
+
+	// Should have exactly one profile (the default)
+	if r.ProfileCount() != 1 {
+		t.Errorf("expected 1 profile, got %d", r.ProfileCount())
+	}
+
+	// Should have the default profile
+	profile := r.GetDefaultProfile()
+	if profile == nil {
+		t.Error("expected default profile to exist")
+	}
+
+	// Default profile name should be in the list
+	names := r.ProfileNames()
+	if len(names) != 1 || names[0] != DefaultProfileName {
+		t.Errorf("expected profile names to be [%s], got %v", DefaultProfileName, names)
+	}
+}
+
+func TestRegisterProfile(t *testing.T) {
+	r := NewRegistry()
+
+	// Register a new profile
+	customProfile := &Profile{
+		Name:         "Custom Profile",
+		EnableGREASE: true,
+	}
+	r.RegisterProfile("custom", customProfile)
+
+	// Should now have 2 profiles
+	if r.ProfileCount() != 2 {
+		t.Errorf("expected 2 profiles, got %d", r.ProfileCount())
+	}
+
+	// Should be able to retrieve the custom profile
+	retrieved := r.GetProfile("custom")
+	if retrieved == nil {
+		t.Fatal("expected custom profile to exist")
+	}
+	if retrieved.Name != "Custom Profile" {
+		t.Errorf("expected profile name 'Custom Profile', got '%s'", retrieved.Name)
+	}
+	if !retrieved.EnableGREASE {
+		t.Error("expected EnableGREASE to be true")
+	}
+}
+
+func TestGetProfile(t *testing.T) {
+	r := NewRegistry()
+
+	// Get existing profile
+	profile := r.GetProfile(DefaultProfileName)
+	if profile == nil {
+		t.Error("expected default profile to exist")
+	}
+
+	// Get non-existing profile
+	nonExistent := r.GetProfile("nonexistent")
+	if nonExistent != nil {
+		t.Error("expected nil for non-existent profile")
+	}
+}
+
+func TestGetProfileByAccountID(t *testing.T) {
+	r := NewRegistry()
+
+	// With only default profile, all account IDs should return the same profile
+	for i := int64(0); i < 10; i++ {
+		profile := r.GetProfileByAccountID(i)
+		if profile == nil {
+			t.Errorf("expected profile for account %d, got nil", i)
+		}
+	}
+
+	// Add more profiles
+	r.RegisterProfile("profile_a", &Profile{Name: "Profile A"})
+	r.RegisterProfile("profile_b", &Profile{Name: "Profile B"})
+
+	// Now we have 3 profiles: claude_cli_v2, profile_a, profile_b
+	// Names are sorted, so order is: claude_cli_v2, profile_a, profile_b
+	expectedOrder := []string{DefaultProfileName, "profile_a", "profile_b"}
+	names := r.ProfileNames()
+	for i, name := range expectedOrder {
+		if names[i] != name {
+			t.Errorf("expected name at index %d to be %s, got %s", i, name, names[i])
+		}
+	}
+
+	// Test modulo selection
+	// Account ID 0 % 3 = 0 -> claude_cli_v2
+	// Account ID 1 % 3 = 1 -> profile_a
+	// Account ID 2 % 3 = 2 -> profile_b
+	// Account ID 3 % 3 = 0 -> claude_cli_v2
+	testCases := []struct {
+		accountID    int64
+		expectedName string
+	}{
+		{0, "Claude CLI 2.x (Node.js 20.x + OpenSSL 3.x)"},
+		{1, "Profile A"},
+		{2, "Profile B"},
+		{3, "Claude CLI 2.x (Node.js 20.x + OpenSSL 3.x)"},
+		{4, "Profile A"},
+		{5, "Profile B"},
+		{100, "Profile A"}, // 100 % 3 = 1
+		{-1, "Profile A"},  // |-1| % 3 = 1
+		{-3, "Claude CLI 2.x (Node.js 20.x + OpenSSL 3.x)"}, // |-3| % 3 = 0
+	}
+
+	for _, tc := range testCases {
+		profile := r.GetProfileByAccountID(tc.accountID)
+		if profile == nil {
+			t.Errorf("expected profile for account %d, got nil", tc.accountID)
+			continue
+		}
+		if profile.Name != tc.expectedName {
+			t.Errorf("account %d: expected profile name '%s', got '%s'", tc.accountID, tc.expectedName, profile.Name)
+		}
+	}
+}
+
+func TestNewRegistryFromConfig(t *testing.T) {
+	// Test with nil config
+	r := NewRegistryFromConfig(nil)
+	if r.ProfileCount() != 1 {
+		t.Errorf("expected 1 profile with nil config, got %d", r.ProfileCount())
+	}
+
+	// Test with disabled config
+	disabledCfg := &config.TLSFingerprintConfig{
+		Enabled: false,
+	}
+	r = NewRegistryFromConfig(disabledCfg)
+	if r.ProfileCount() != 1 {
+		t.Errorf("expected 1 profile with disabled config, got %d", r.ProfileCount())
+	}
+
+	// Test with enabled config and custom profiles
+	enabledCfg := &config.TLSFingerprintConfig{
+		Enabled: true,
+		Profiles: map[string]config.TLSProfileConfig{
+			"custom1": {
+				Name:         "Custom Profile 1",
+				EnableGREASE: true,
+			},
+			"custom2": {
+				Name:         "Custom Profile 2",
+				EnableGREASE: false,
+			},
+		},
+	}
+	r = NewRegistryFromConfig(enabledCfg)
+
+	// Should have 3 profiles: default + 2 custom
+	if r.ProfileCount() != 3 {
+		t.Errorf("expected 3 profiles, got %d", r.ProfileCount())
+	}
+
+	// Check custom profiles exist
+	custom1 := r.GetProfile("custom1")
+	if custom1 == nil || custom1.Name != "Custom Profile 1" {
+		t.Error("expected custom1 profile to exist with correct name")
+	}
+	custom2 := r.GetProfile("custom2")
+	if custom2 == nil || custom2.Name != "Custom Profile 2" {
+		t.Error("expected custom2 profile to exist with correct name")
+	}
+}
+
+func TestProfileNames(t *testing.T) {
+	r := NewRegistry()
+
+	// Add profiles in non-alphabetical order
+	r.RegisterProfile("zebra", &Profile{Name: "Zebra"})
+	r.RegisterProfile("alpha", &Profile{Name: "Alpha"})
+	r.RegisterProfile("beta", &Profile{Name: "Beta"})
+
+	names := r.ProfileNames()
+
+	// Should be sorted alphabetically
+	expected := []string{"alpha", "beta", DefaultProfileName, "zebra"}
+	if len(names) != len(expected) {
+		t.Errorf("expected %d names, got %d", len(expected), len(names))
+	}
+	for i, name := range expected {
+		if names[i] != name {
+			t.Errorf("expected name at index %d to be %s, got %s", i, name, names[i])
+		}
+	}
+
+	// Test that returned slice is a copy (modifying it shouldn't affect registry)
+	names[0] = "modified"
+	originalNames := r.ProfileNames()
+	if originalNames[0] == "modified" {
+		t.Error("modifying returned slice should not affect registry")
+	}
+}
+
+func TestConcurrentAccess(t *testing.T) {
+	r := NewRegistry()
+
+	// Run concurrent reads and writes
+	done := make(chan bool)
+
+	// Writers
+	for i := 0; i < 10; i++ {
+		go func(id int) {
+			for j := 0; j < 100; j++ {
+				r.RegisterProfile("concurrent"+string(rune('0'+id)), &Profile{Name: "Concurrent"})
+			}
+			done <- true
+		}(i)
+	}
+
+	// Readers
+	for i := 0; i < 10; i++ {
+		go func(id int) {
+			for j := 0; j < 100; j++ {
+				_ = r.ProfileCount()
+				_ = r.ProfileNames()
+				_ = r.GetProfileByAccountID(int64(id * j))
+				_ = r.GetProfile(DefaultProfileName)
+			}
+			done <- true
+		}(i)
+	}
+
+	// Wait for all goroutines
+	for i := 0; i < 20; i++ {
+		<-done
+	}
+
+	// Test should pass without data races (run with -race flag)
+}