diff --git a/README.md b/README.md
index ada3039897..b06839745f 100644
--- a/README.md
+++ b/README.md
@@ -611,12 +611,19 @@ per-turn user and account concurrency slots, which are released between turns.
 ```yaml
 gateway:
   openai_ws:
+    # Total time to receive and decompress the first client message.
+    client_first_message_timeout_seconds: 30
     # Close a client socket idle between completed turns; 0 disables this safeguard.
     ingress_inter_turn_idle_timeout_seconds: 300
     # Distributed API-key limit for live client ingress sessions; 0 disables it.
     max_ingress_connections_per_api_key: 64
 ```
 
+The first-message timeout is a total read deadline. Deployments that accept
+large contexts or image-heavy requests over slower links can raise it to
+120-300 seconds. It expires before HTTP bridge routing, so bridge mode does not
+override this limit.
+
 The connection cap is coordinated through Redis using a 60-second lease that
 is refreshed every 20 seconds. A process that cannot confirm a lease for a
 full lease lifetime closes its local WebSocket rather than continuing outside
diff --git a/backend/internal/config/config.go b/backend/internal/config/config.go
index 857171d0ae..40947ef952 100644
--- a/backend/internal/config/config.go
+++ b/backend/internal/config/config.go
@@ -924,6 +924,9 @@ func (c *UserMessageQueueConfig) GetEffectiveMode() string {
 	return ""
 }
 
+// DefaultOpenAIWSClientFirstMessageTimeoutSeconds preserves the legacy ingress deadline.
+const DefaultOpenAIWSClientFirstMessageTimeoutSeconds = 30
+
 // GatewayOpenAIWSConfig OpenAI Responses WebSocket 配置。
 // 注意：默认全局开启；如需回滚可使用 force_http 或关闭 enabled。
 type GatewayOpenAIWSConfig struct {
@@ -931,6 +934,9 @@ type GatewayOpenAIWSConfig struct {
 	ModeRouterV2Enabled bool `mapstructure:"mode_router_v2_enabled"`
 	// IngressModeDefault: ingress 默认模式（off/ctx_pool/passthrough/http_bridge）
 	IngressModeDefault string `mapstructure:"ingress_mode_default"`
+	// ClientFirstMessageTimeoutSeconds bounds the total time to read and decompress
+	// the first client response.create message after the WebSocket upgrade.
+	ClientFirstMessageTimeoutSeconds int `mapstructure:"client_first_message_timeout_seconds"`
 	// IngressInterTurnIdleTimeoutSeconds bounds the time a client may remain idle
 	// between completed ingress turns. Zero disables this protection.
 	IngressInterTurnIdleTimeoutSeconds int `mapstructure:"ingress_inter_turn_idle_timeout_seconds"`
@@ -1965,6 +1971,7 @@ func setDefaults() {
 	viper.SetDefault("gateway.openai_ws.enabled", true)
 	viper.SetDefault("gateway.openai_ws.mode_router_v2_enabled", false)
 	viper.SetDefault("gateway.openai_ws.ingress_mode_default", "ctx_pool")
+	viper.SetDefault("gateway.openai_ws.client_first_message_timeout_seconds", DefaultOpenAIWSClientFirstMessageTimeoutSeconds)
 	viper.SetDefault("gateway.openai_ws.ingress_inter_turn_idle_timeout_seconds", 300)
 	viper.SetDefault("gateway.openai_ws.max_ingress_connections_per_api_key", 64)
 	viper.SetDefault("gateway.openai_ws.oauth_enabled", true)
@@ -2755,6 +2762,9 @@ func (c *Config) Validate() error {
 	if c.Gateway.OpenAIWS.MaxConnsPerAccount <= 0 {
 		return fmt.Errorf("gateway.openai_ws.max_conns_per_account must be positive")
 	}
+	if c.Gateway.OpenAIWS.ClientFirstMessageTimeoutSeconds <= 0 {
+		return fmt.Errorf("gateway.openai_ws.client_first_message_timeout_seconds must be positive")
+	}
 	if c.Gateway.OpenAIWS.IngressInterTurnIdleTimeoutSeconds < 0 {
 		return fmt.Errorf("gateway.openai_ws.ingress_inter_turn_idle_timeout_seconds must be non-negative")
 	}
diff --git a/backend/internal/config/config_test.go b/backend/internal/config/config_test.go
index 2a0e3a2580..9a2d725eed 100644
--- a/backend/internal/config/config_test.go
+++ b/backend/internal/config/config_test.go
@@ -227,6 +227,13 @@ func TestLoadDefaultOpenAIWSConfig(t *testing.T) {
 	if cfg.Gateway.OpenAIWS.IngressModeDefault != "ctx_pool" {
 		t.Fatalf("Gateway.OpenAIWS.IngressModeDefault = %q, want %q", cfg.Gateway.OpenAIWS.IngressModeDefault, "ctx_pool")
 	}
+	if cfg.Gateway.OpenAIWS.ClientFirstMessageTimeoutSeconds != DefaultOpenAIWSClientFirstMessageTimeoutSeconds {
+		t.Fatalf(
+			"Gateway.OpenAIWS.ClientFirstMessageTimeoutSeconds = %d, want %d",
+			cfg.Gateway.OpenAIWS.ClientFirstMessageTimeoutSeconds,
+			DefaultOpenAIWSClientFirstMessageTimeoutSeconds,
+		)
+	}
 	if cfg.Gateway.OpenAIWS.IngressInterTurnIdleTimeoutSeconds != 300 {
 		t.Fatalf("Gateway.OpenAIWS.IngressInterTurnIdleTimeoutSeconds = %d, want 300", cfg.Gateway.OpenAIWS.IngressInterTurnIdleTimeoutSeconds)
 	}
@@ -235,6 +242,15 @@ func TestLoadDefaultOpenAIWSConfig(t *testing.T) {
 	}
 }
 
+func TestLoadOpenAIWSClientFirstMessageTimeoutFromEnv(t *testing.T) {
+	resetViperWithJWTSecret(t)
+	t.Setenv("GATEWAY_OPENAI_WS_CLIENT_FIRST_MESSAGE_TIMEOUT_SECONDS", "120")
+
+	cfg, err := Load()
+	require.NoError(t, err)
+	require.Equal(t, 120, cfg.Gateway.OpenAIWS.ClientFirstMessageTimeoutSeconds)
+}
+
 func TestLoadDefaultOpenAICompactModel(t *testing.T) {
 	resetViperWithJWTSecret(t)
 
@@ -1720,6 +1736,16 @@ func TestValidateConfig_OpenAIWSRules(t *testing.T) {
 			mutate:  func(c *Config) { c.Gateway.OpenAIWS.MaxConnsPerAccount = 0 },
 			wantErr: "gateway.openai_ws.max_conns_per_account",
 		},
+		{
+			name:    "client_first_message_timeout_seconds 必须为正数",
+			mutate:  func(c *Config) { c.Gateway.OpenAIWS.ClientFirstMessageTimeoutSeconds = 0 },
+			wantErr: "gateway.openai_ws.client_first_message_timeout_seconds",
+		},
+		{
+			name:    "client_first_message_timeout_seconds 不能为负数",
+			mutate:  func(c *Config) { c.Gateway.OpenAIWS.ClientFirstMessageTimeoutSeconds = -1 },
+			wantErr: "gateway.openai_ws.client_first_message_timeout_seconds",
+		},
 		{
 			name:    "ingress_inter_turn_idle_timeout_seconds 不能为负数",
 			mutate:  func(c *Config) { c.Gateway.OpenAIWS.IngressInterTurnIdleTimeoutSeconds = -1 },
diff --git a/backend/internal/handler/openai_gateway_compact_log_test.go b/backend/internal/handler/openai_gateway_compact_log_test.go
index e18509b4b3..16afd30c31 100644
--- a/backend/internal/handler/openai_gateway_compact_log_test.go
+++ b/backend/internal/handler/openai_gateway_compact_log_test.go
@@ -66,6 +66,20 @@ func (s *handlerInMemoryLogSink) ContainsFieldValue(field, substr string) bool {
 	return false
 }
 
+func (s *handlerInMemoryLogSink) FieldValueForMessage(message, field string) (any, bool) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	for _, event := range s.events {
+		if event == nil || event.Message != message || event.Fields == nil {
+			continue
+		}
+		if value, ok := event.Fields[field]; ok {
+			return value, true
+		}
+	}
+	return nil, false
+}
+
 func captureHandlerStructuredLog(t *testing.T) (*handlerInMemoryLogSink, func()) {
 	t.Helper()
 	handlerStructuredLogCaptureMu.Lock()
diff --git a/backend/internal/handler/openai_gateway_handler.go b/backend/internal/handler/openai_gateway_handler.go
index cd18aa7a1b..83c4b4ac23 100644
--- a/backend/internal/handler/openai_gateway_handler.go
+++ b/backend/internal/handler/openai_gateway_handler.go
@@ -1403,7 +1403,8 @@ func (h *OpenAIGatewayHandler) ResponsesWebSocket(c *gin.Context) {
 		c.Request = c.Request.WithContext(ctx)
 	}
 
-	readCtx, cancel := context.WithTimeout(ctx, 30*time.Second)
+	firstMessageTimeout := service.ResolveOpenAIWSClientFirstMessageTimeout(h.cfg)
+	readCtx, cancel := context.WithTimeout(ctx, firstMessageTimeout)
 	msgType, firstMessage, err := wsConn.Read(readCtx)
 	cancel()
 	if err != nil {
@@ -1418,7 +1419,7 @@ func (h *OpenAIGatewayHandler) ResponsesWebSocket(c *gin.Context) {
 			zap.String("client_ip", clientIP),
 			zap.String("close_status", closeStatus),
 			zap.String("close_reason", closeReason),
-			zap.Duration("read_timeout", 30*time.Second),
+			zap.Duration("read_timeout", firstMessageTimeout),
 		)
 		closeOpenAIClientWS(wsConn, coderws.StatusPolicyViolation, "missing first response.create message")
 		return
diff --git a/backend/internal/handler/openai_gateway_handler_test.go b/backend/internal/handler/openai_gateway_handler_test.go
index 21f5b4686c..d855f364a7 100644
--- a/backend/internal/handler/openai_gateway_handler_test.go
+++ b/backend/internal/handler/openai_gateway_handler_test.go
@@ -833,6 +833,40 @@ func TestOpenAIResponsesWebSocket_IngressCapacityRejected(t *testing.T) {
 	require.Equal(t, coderws.StatusTryAgainLater, closeErr.Code)
 }
 
+func TestOpenAIResponsesWebSocket_FirstMessageTimeoutUsesConfig(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+	logSink, restore := captureHandlerStructuredLog(t)
+	defer restore()
+
+	h := newOpenAIHandlerForPreviousResponseIDValidation(t, nil)
+	h.cfg = &config.Config{}
+	h.cfg.Gateway.OpenAIWS.ClientFirstMessageTimeoutSeconds = 1
+	wsServer := newOpenAIWSHandlerTestServer(t, h, middleware.AuthSubject{UserID: 1, Concurrency: 1})
+	defer wsServer.Close()
+
+	dialCtx, cancelDial := context.WithTimeout(context.Background(), 3*time.Second)
+	clientConn, _, err := coderws.Dial(dialCtx, "ws"+strings.TrimPrefix(wsServer.URL, "http")+"/openai/v1/responses", nil)
+	cancelDial()
+	require.NoError(t, err)
+	defer func() { _ = clientConn.CloseNow() }()
+
+	started := time.Now()
+	readCtx, cancelRead := context.WithTimeout(context.Background(), 5*time.Second)
+	_, _, err = clientConn.Read(readCtx)
+	cancelRead()
+	elapsed := time.Since(started)
+
+	require.Error(t, err)
+	require.NotErrorIs(t, err, context.DeadlineExceeded)
+	require.GreaterOrEqual(t, elapsed, 500*time.Millisecond)
+	require.Less(t, elapsed, 4*time.Second)
+	require.Eventually(t, func() bool {
+		readTimeout, ok := logSink.FieldValueForMessage("openai.websocket_read_first_message_failed", "read_timeout")
+		return ok && readTimeout == time.Second &&
+			logSink.ContainsMessageAtLevel("openai.websocket_read_first_message_failed", "warn")
+	}, time.Second, 10*time.Millisecond)
+}
+
 func TestOpenAIResponsesWebSocket_IngressLeaseReleasedOnEarlyReturn(t *testing.T) {
 	gin.SetMode(gin.TestMode)
 	cache := &concurrencyCacheMock{
diff --git a/backend/internal/service/openai_ws_http_bridge.go b/backend/internal/service/openai_ws_http_bridge.go
index 77a5e59329..091b3592d1 100644
--- a/backend/internal/service/openai_ws_http_bridge.go
+++ b/backend/internal/service/openai_ws_http_bridge.go
@@ -22,6 +22,15 @@ const (
 	openAIWSHTTPBridgeErrorBodyLimitBytes         = 64 * 1024
 )
 
+// ResolveOpenAIWSClientFirstMessageTimeout returns the effective client ingress deadline.
+func ResolveOpenAIWSClientFirstMessageTimeout(cfg *config.Config) time.Duration {
+	seconds := config.DefaultOpenAIWSClientFirstMessageTimeoutSeconds
+	if cfg != nil && cfg.Gateway.OpenAIWS.ClientFirstMessageTimeoutSeconds > 0 {
+		seconds = cfg.Gateway.OpenAIWS.ClientFirstMessageTimeoutSeconds
+	}
+	return time.Duration(seconds) * time.Second
+}
+
 func ResolveOpenAIWSClientReadLimitBytes(cfg *config.Config) int64 {
 	if cfg == nil || cfg.Gateway.OpenAIWS.ClientReadLimitBytes <= 0 {
 		return openAIWSClientReadLimitBytesDefault
diff --git a/backend/internal/service/openai_ws_http_bridge_test.go b/backend/internal/service/openai_ws_http_bridge_test.go
index b1bfb4d342..cbc11abcc2 100644
--- a/backend/internal/service/openai_ws_http_bridge_test.go
+++ b/backend/internal/service/openai_ws_http_bridge_test.go
@@ -19,6 +19,17 @@ import (
 	"github.com/tidwall/gjson"
 )
 
+func TestResolveOpenAIWSClientFirstMessageTimeout(t *testing.T) {
+	defaultTimeout := time.Duration(config.DefaultOpenAIWSClientFirstMessageTimeoutSeconds) * time.Second
+	require.Equal(t, defaultTimeout, ResolveOpenAIWSClientFirstMessageTimeout(nil))
+
+	cfg := &config.Config{}
+	require.Equal(t, defaultTimeout, ResolveOpenAIWSClientFirstMessageTimeout(cfg))
+
+	cfg.Gateway.OpenAIWS.ClientFirstMessageTimeoutSeconds = 120
+	require.Equal(t, 120*time.Second, ResolveOpenAIWSClientFirstMessageTimeout(cfg))
+}
+
 func TestPrepareOpenAIWSHTTPBridgeBodyStripsWSFields(t *testing.T) {
 	body, err := prepareOpenAIWSHTTPBridgeBody([]byte(`{"type":"response.create","generate":true,"model":"gpt-5","stream":false,"previous_response_id":"resp_prev","input":"hi"}`))
 	require.NoError(t, err)
diff --git a/deploy/config.example.yaml b/deploy/config.example.yaml
index fdeccc00c3..7b98993c53 100644
--- a/deploy/config.example.yaml
+++ b/deploy/config.example.yaml
@@ -266,6 +266,8 @@ gateway:
     # ingress 默认模式：off|ctx_pool|passthrough|http_bridge（仅 mode_router_v2_enabled=true 生效）
     # 兼容旧值：shared/dedicated 会按 ctx_pool 处理。
     ingress_mode_default: ctx_pool
+    # 完整读取并解压首条客户端消息的总超时（秒）；大请求或慢链路可调高到 120-300。
+    client_first_message_timeout_seconds: 30
     # Close a client WebSocket that stays idle between completed turns (seconds). Set 0 to disable.
     ingress_inter_turn_idle_timeout_seconds: 300
     # Limit live client WebSocket ingress sessions per API key across all instances. Set 0 to disable.