diff --git a/backend/internal/config/config.go b/backend/internal/config/config.go
index f5853682ac..3fe4860443 100644
--- a/backend/internal/config/config.go
+++ b/backend/internal/config/config.go
@@ -2375,7 +2375,7 @@ func setDefaults() {
 	viper.SetDefault("gateway.disable_codex_originator_normalization", false)
 	viper.SetDefault("gateway.codex_image_generation_bridge_enabled", false)
 	viper.SetDefault("gateway.openai_passthrough_allow_timeout_headers", false)
-	viper.SetDefault("gateway.openai_compact_model", "gpt-5.4")
+	viper.SetDefault("gateway.openai_compact_model", "gpt-5.5")
 	viper.SetDefault("gateway.live.max_session_duration_seconds", 3600)
 	// OpenAI Responses WebSocket（默认开启；可通过 force_http 紧急回滚）
 	viper.SetDefault("gateway.openai_ws.enabled", true)
diff --git a/backend/internal/config/config_test.go b/backend/internal/config/config_test.go
index 717960a91a..8bf9704c63 100644
--- a/backend/internal/config/config_test.go
+++ b/backend/internal/config/config_test.go
@@ -574,7 +574,7 @@ func TestLoadDefaultOpenAICompactModel(t *testing.T) {
 
 	cfg, err := Load()
 	require.NoError(t, err)
-	require.Equal(t, "gpt-5.4", cfg.Gateway.OpenAICompactModel)
+	require.Equal(t, "gpt-5.5", cfg.Gateway.OpenAICompactModel)
 }
 
 func TestLoadOpenAICompactModelFromEnv(t *testing.T) {
diff --git a/deploy/.env.example b/deploy/.env.example
index 3c0c1a009c..47f249b6aa 100644
--- a/deploy/.env.example
+++ b/deploy/.env.example
@@ -285,9 +285,9 @@ RATE_LIMIT_OVERLOAD_COOLDOWN_MINUTES=10
 #
 # 默认：false
 GATEWAY_FORCE_CODEX_CLI=false
-# OpenAI /responses/compact 上游模型（默认 gpt-5.4）。
+# OpenAI /responses/compact 上游模型（默认 gpt-5.5）。
 # 当 compact 端点暂未支持更新模型时，可通过这里降级规避失败。
-GATEWAY_OPENAI_COMPACT_MODEL=gpt-5.4
+GATEWAY_OPENAI_COMPACT_MODEL=gpt-5.5
 
 # OAuth Images /responses 主控模型，与 image_generation.model 独立。
 # 上游下线主控模型时可修改此项并重建/重启容器，无需重新编译。
diff --git a/deploy/config.example.yaml b/deploy/config.example.yaml
index 0ff4c9086e..0245408fde 100644
--- a/deploy/config.example.yaml
+++ b/deploy/config.example.yaml
@@ -305,11 +305,11 @@ gateway:
   # OpenAI 透传模式是否放行客户端超时头（如 x-stainless-timeout）
   # 默认 false：过滤超时头，降低上游提前断流风险。
   openai_passthrough_allow_timeout_headers: false
-  # Model used for OpenAI /responses/compact upstream requests (default: gpt-5.4).
-  # OpenAI /responses/compact 上游模型（默认 gpt-5.4）。
+  # Model used for OpenAI /responses/compact upstream requests (default: gpt-5.5).
+  # OpenAI /responses/compact 上游模型（默认 gpt-5.5）。
   # Use this to avoid compact failures when newer models are not yet supported by the compact endpoint.
   # 当 compact 端点暂未支持更新模型时，可通过这里降级规避失败。
-  openai_compact_model: "gpt-5.4"
+  openai_compact_model: "gpt-5.5"
   # ChatGPT Frameless Live 单会话硬上限（秒）。
   live:
     max_session_duration_seconds: 3600
diff --git a/deploy/docker-compose.dev.yml b/deploy/docker-compose.dev.yml
index a42a2c9c7b..c2a2ac9246 100644
--- a/deploy/docker-compose.dev.yml
+++ b/deploy/docker-compose.dev.yml
@@ -56,7 +56,7 @@ services:
       # Gateway values come from Compose .env or the shell.
       # Fallbacks mirror Sub2API backend defaults so omitted values preserve behavior.
       - GATEWAY_FORCE_CODEX_CLI=${GATEWAY_FORCE_CODEX_CLI:-false}
-      - GATEWAY_OPENAI_COMPACT_MODEL=${GATEWAY_OPENAI_COMPACT_MODEL:-gpt-5.4}
+      - GATEWAY_OPENAI_COMPACT_MODEL=${GATEWAY_OPENAI_COMPACT_MODEL:-gpt-5.5}
       - SUB2API_IMAGES_MAIN_MODEL=${SUB2API_IMAGES_MAIN_MODEL:-gpt-5.6-luna}
       - GATEWAY_OPENAI_RESPONSE_HEADER_TIMEOUT=${GATEWAY_OPENAI_RESPONSE_HEADER_TIMEOUT:-0}
       - GATEWAY_OPENAI_WS_FORCE_HTTP=${GATEWAY_OPENAI_WS_FORCE_HTTP:-false}
diff --git a/deploy/docker-compose.local.yml b/deploy/docker-compose.local.yml
index 4edc40c7f0..8a14f4d7aa 100644
--- a/deploy/docker-compose.local.yml
+++ b/deploy/docker-compose.local.yml
@@ -164,7 +164,7 @@ services:
       # Gateway values come from Compose .env or the shell.
       # Fallbacks mirror Sub2API backend defaults so omitted values preserve behavior.
       - GATEWAY_FORCE_CODEX_CLI=${GATEWAY_FORCE_CODEX_CLI:-false}
-      - GATEWAY_OPENAI_COMPACT_MODEL=${GATEWAY_OPENAI_COMPACT_MODEL:-gpt-5.4}
+      - GATEWAY_OPENAI_COMPACT_MODEL=${GATEWAY_OPENAI_COMPACT_MODEL:-gpt-5.5}
       - SUB2API_IMAGES_MAIN_MODEL=${SUB2API_IMAGES_MAIN_MODEL:-gpt-5.6-luna}
       - GATEWAY_OPENAI_RESPONSE_HEADER_TIMEOUT=${GATEWAY_OPENAI_RESPONSE_HEADER_TIMEOUT:-0}
       - GATEWAY_OPENAI_WS_FORCE_HTTP=${GATEWAY_OPENAI_WS_FORCE_HTTP:-false}
diff --git a/deploy/docker-compose.standalone.yml b/deploy/docker-compose.standalone.yml
index babed5b984..7273dd0fed 100644
--- a/deploy/docker-compose.standalone.yml
+++ b/deploy/docker-compose.standalone.yml
@@ -111,7 +111,7 @@ services:
       # Gateway values come from Compose .env or the shell.
       # Fallbacks mirror Sub2API backend defaults so omitted values preserve behavior.
       - GATEWAY_FORCE_CODEX_CLI=${GATEWAY_FORCE_CODEX_CLI:-false}
-      - GATEWAY_OPENAI_COMPACT_MODEL=${GATEWAY_OPENAI_COMPACT_MODEL:-gpt-5.4}
+      - GATEWAY_OPENAI_COMPACT_MODEL=${GATEWAY_OPENAI_COMPACT_MODEL:-gpt-5.5}
       - SUB2API_IMAGES_MAIN_MODEL=${SUB2API_IMAGES_MAIN_MODEL:-gpt-5.6-luna}
       - GATEWAY_OPENAI_RESPONSE_HEADER_TIMEOUT=${GATEWAY_OPENAI_RESPONSE_HEADER_TIMEOUT:-0}
       - GATEWAY_OPENAI_WS_FORCE_HTTP=${GATEWAY_OPENAI_WS_FORCE_HTTP:-false}
diff --git a/deploy/docker-compose.yml b/deploy/docker-compose.yml
index abb420f4c9..e6b84a54d3 100644
--- a/deploy/docker-compose.yml
+++ b/deploy/docker-compose.yml
@@ -161,7 +161,7 @@ services:
       # Gateway values come from Compose .env or the shell.
       # Fallbacks mirror Sub2API backend defaults so omitted values preserve behavior.
       - GATEWAY_FORCE_CODEX_CLI=${GATEWAY_FORCE_CODEX_CLI:-false}
-      - GATEWAY_OPENAI_COMPACT_MODEL=${GATEWAY_OPENAI_COMPACT_MODEL:-gpt-5.4}
+      - GATEWAY_OPENAI_COMPACT_MODEL=${GATEWAY_OPENAI_COMPACT_MODEL:-gpt-5.5}
       - SUB2API_IMAGES_MAIN_MODEL=${SUB2API_IMAGES_MAIN_MODEL:-gpt-5.6-luna}
       - GATEWAY_OPENAI_RESPONSE_HEADER_TIMEOUT=${GATEWAY_OPENAI_RESPONSE_HEADER_TIMEOUT:-0}
       - GATEWAY_OPENAI_WS_FORCE_HTTP=${GATEWAY_OPENAI_WS_FORCE_HTTP:-false}