diff --git a/examples/plugin/README.md b/examples/plugin/README.md
index e763a20ce..7dcb28ac0 100644
--- a/examples/plugin/README.md
+++ b/examples/plugin/README.md
@@ -12,6 +12,7 @@ This directory contains standard dynamic library plugin examples for the CLIProx
 - `protocol-format/`: minimal executor focused on input/output format declarations.
 - `request-translator/`: request translation capability only.
 - `request-normalizer/`: request normalization capability only.
+- `codex-service-tier/`: Go-only request normalizer that sets Codex `gpt-5.4` requests to the priority service tier when enabled.
 - `response-translator/`: response translation capability only.
 - `response-normalizer/`: response normalization capability only.
 - `thinking/`: thinking applier capability only.
@@ -20,7 +21,20 @@ This directory contains standard dynamic library plugin examples for the CLIProx
 - `management-api/`: Management API capability only.
 - `host-callback/`: minimal Management API route that demonstrates host callbacks.
 
-Each example directory contains `go/`, `c/`, and `rust/` subdirectories.
+Most standard capability examples contain `go/`, `c/`, and `rust/` subdirectories. Specialized examples may provide only the implementation language they need.
+
+## Codex Service Tier
+
+`codex-service-tier` declares the request normalization capability. When `fast` is `true`, it sets `service_tier` to `priority` for requests where `req.ToFormat` is `codex` and `req.Model` is `gpt-5.4`.
+
+```yaml
+plugins:
+  configs:
+    codex-service-tier:
+      enabled: true
+      priority: 1
+      fast: false
+```
 
 ## Build All Examples
 
diff --git a/examples/plugin/README_CN.md b/examples/plugin/README_CN.md
index fc8605590..9841b8bc2 100644
--- a/examples/plugin/README_CN.md
+++ b/examples/plugin/README_CN.md
@@ -12,6 +12,7 @@
 - `protocol-format/`：使用最小执行器重点演示输入和输出格式声明。
 - `request-translator/`：只演示请求转换能力。
 - `request-normalizer/`：只演示请求规整能力。
+- `codex-service-tier/`：仅 Go 实现的请求规整插件，启用后会将 Codex `gpt-5.4` 请求设置为 priority service tier。
 - `response-translator/`：只演示响应转换能力。
 - `response-normalizer/`：只演示响应规整能力。
 - `thinking/`：只演示 Thinking 处理能力。
@@ -20,7 +21,20 @@
 - `management-api/`：只演示 Management API 扩展能力。
 - `host-callback/`：使用最小 Management API 路由演示宿主回调。
 
-每个示例目录都包含 `go/`、`c/` 和 `rust/` 三个子目录。
+多数标准能力示例都包含 `go/`、`c/` 和 `rust/` 三个子目录。专用示例可能只提供所需的实现语言。
+
+## Codex Service Tier
+
+`codex-service-tier` 声明请求规整能力。当 `fast` 为 `true` 时，如果 `req.ToFormat` 为 `codex` 且 `req.Model` 为 `gpt-5.4`，它会将 `service_tier` 设置为 `priority`。
+
+```yaml
+plugins:
+  configs:
+    codex-service-tier:
+      enabled: true
+      priority: 1
+      fast: false
+```
 
 ## 构建全部示例
 
diff --git a/examples/plugin/codex-service-tier/README.md b/examples/plugin/codex-service-tier/README.md
new file mode 100644
index 000000000..3c1bcddfb
--- /dev/null
+++ b/examples/plugin/codex-service-tier/README.md
@@ -0,0 +1,25 @@
+# Codex Service Tier Plugin
+
+This plugin is a request normalizer for Codex outbound requests.
+
+When the plugin is enabled and `fast` is set to `true`, it sets the top-level `service_tier` field to `priority` for requests where:
+
+- `req.ToFormat` is `codex`
+- `req.Model` is `gpt-5.5`
+
+Requests that do not match these conditions are returned unchanged.
+
+## Configuration
+
+Add the plugin under `plugins.configs`:
+
+```yaml
+plugins:
+  configs:
+    codex-service-tier:
+      enabled: true
+      priority: 1
+      fast: false
+```
+
+`fast` is a boolean field. Set it to `true` to enable priority service tier shaping for matching Codex `gpt-5.5` requests.
diff --git a/examples/plugin/codex-service-tier/go/go.mod b/examples/plugin/codex-service-tier/go/go.mod
new file mode 100644
index 000000000..599588ee1
--- /dev/null
+++ b/examples/plugin/codex-service-tier/go/go.mod
@@ -0,0 +1,17 @@
+module github.com/router-for-me/CLIProxyAPI/v7/examples/plugin/codex-service-tier/go
+
+go 1.26.0
+
+require (
+	github.com/router-for-me/CLIProxyAPI/v7 v7.0.0
+	github.com/tidwall/sjson v1.2.5
+	gopkg.in/yaml.v3 v3.0.1
+)
+
+require (
+	github.com/tidwall/gjson v1.18.0 // indirect
+	github.com/tidwall/match v1.1.1 // indirect
+	github.com/tidwall/pretty v1.2.0 // indirect
+)
+
+replace github.com/router-for-me/CLIProxyAPI/v7 => ../../../..
diff --git a/examples/plugin/codex-service-tier/go/go.sum b/examples/plugin/codex-service-tier/go/go.sum
new file mode 100644
index 000000000..9186dfd80
--- /dev/null
+++ b/examples/plugin/codex-service-tier/go/go.sum
@@ -0,0 +1,13 @@
+github.com/tidwall/gjson v1.14.2/go.mod h1:/wbyibRr2FHMks5tjHJ5F8dMZh3AcwJEMf5vlfC0lxk=
+github.com/tidwall/gjson v1.18.0 h1:FIDeeyB800efLX89e5a8Y0BNH+LOngJyGrIWxG2FKQY=
+github.com/tidwall/gjson v1.18.0/go.mod h1:/wbyibRr2FHMks5tjHJ5F8dMZh3AcwJEMf5vlfC0lxk=
+github.com/tidwall/match v1.1.1 h1:+Ho715JplO36QYgwN9PGYNhgZvoUSc9X2c80KVTi+GA=
+github.com/tidwall/match v1.1.1/go.mod h1:eRSPERbgtNPcGhD8UCthc6PmLEQXEWd3PRB5JTxsfmM=
+github.com/tidwall/pretty v1.2.0 h1:RWIZEg2iJ8/g6fDDYzMpobmaoGh5OLl4AXtGUGPcqCs=
+github.com/tidwall/pretty v1.2.0/go.mod h1:ITEVvHYasfjBbM0u2Pg8T2nJnzm8xPwvNhhsoaGGjNU=
+github.com/tidwall/sjson v1.2.5 h1:kLy8mja+1c9jlljvWTlSazM7cKDRfJuR/bOJhcY5NcY=
+github.com/tidwall/sjson v1.2.5/go.mod h1:Fvgq9kS/6ociJEDnK0Fk1cpYF4FIW6ZF7LAe+6jwd28=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
diff --git a/examples/plugin/codex-service-tier/go/main.go b/examples/plugin/codex-service-tier/go/main.go
new file mode 100644
index 000000000..09726d165
--- /dev/null
+++ b/examples/plugin/codex-service-tier/go/main.go
@@ -0,0 +1,246 @@
+package main
+
+/*
+#include <stdint.h>
+#include <stdlib.h>
+
+typedef struct {
+	void* ptr;
+	size_t len;
+} cliproxy_buffer;
+
+typedef struct {
+	uint32_t abi_version;
+	void* host_ctx;
+	void* call;
+	void* free_buffer;
+} cliproxy_host_api;
+
+typedef int (*cliproxy_plugin_call_fn)(char*, uint8_t*, size_t, cliproxy_buffer*);
+typedef void (*cliproxy_plugin_free_fn)(void*, size_t);
+typedef void (*cliproxy_plugin_shutdown_fn)(void);
+
+typedef struct {
+	uint32_t abi_version;
+	cliproxy_plugin_call_fn call;
+	cliproxy_plugin_free_fn free_buffer;
+	cliproxy_plugin_shutdown_fn shutdown;
+} cliproxy_plugin_api;
+
+extern int cliproxyPluginCall(char*, uint8_t*, size_t, cliproxy_buffer*);
+extern void cliproxyPluginFree(void*, size_t);
+extern void cliproxyPluginShutdown(void);
+*/
+import "C"
+
+import (
+	"encoding/json"
+	"strings"
+	"sync/atomic"
+	"unsafe"
+
+	"github.com/router-for-me/CLIProxyAPI/v7/sdk/pluginabi"
+	"github.com/router-for-me/CLIProxyAPI/v7/sdk/pluginapi"
+	"github.com/tidwall/sjson"
+	"gopkg.in/yaml.v3"
+)
+
+var fastEnabled atomic.Bool
+
+type envelope struct {
+	OK     bool            `json:"ok"`
+	Result json.RawMessage `json:"result,omitempty"`
+	Error  *envelopeError  `json:"error,omitempty"`
+}
+
+type envelopeError struct {
+	Code    string `json:"code"`
+	Message string `json:"message"`
+}
+
+type lifecycleRequest struct {
+	ConfigYAML []byte `json:"config_yaml"`
+}
+
+type pluginConfig struct {
+	Fast bool `yaml:"fast"`
+}
+
+type registration struct {
+	SchemaVersion uint32                 `json:"schema_version"`
+	Metadata      pluginapi.Metadata     `json:"metadata"`
+	Capabilities  registrationCapability `json:"capabilities"`
+}
+
+type registrationCapability struct {
+	RequestNormalizer bool `json:"request_normalizer"`
+}
+
+func main() {}
+
+//export cliproxy_plugin_init
+func cliproxy_plugin_init(_ *C.cliproxy_host_api, plugin *C.cliproxy_plugin_api) C.int {
+	if plugin == nil {
+		return 1
+	}
+	plugin.abi_version = C.uint32_t(pluginabi.ABIVersion)
+	plugin.call = C.cliproxy_plugin_call_fn(C.cliproxyPluginCall)
+	plugin.free_buffer = C.cliproxy_plugin_free_fn(C.cliproxyPluginFree)
+	plugin.shutdown = C.cliproxy_plugin_shutdown_fn(C.cliproxyPluginShutdown)
+	return 0
+}
+
+//export cliproxyPluginCall
+func cliproxyPluginCall(method *C.char, request *C.uint8_t, requestLen C.size_t, response *C.cliproxy_buffer) C.int {
+	if response != nil {
+		response.ptr = nil
+		response.len = 0
+	}
+	if method == nil {
+		writeResponse(response, errorEnvelope("invalid_method", "method is required"))
+		return 1
+	}
+	var requestBytes []byte
+	if request != nil && requestLen > 0 {
+		requestBytes = C.GoBytes(unsafe.Pointer(request), C.int(requestLen))
+	}
+	raw, errHandle := handleMethod(C.GoString(method), requestBytes)
+	if errHandle != nil {
+		writeResponse(response, errorEnvelope("plugin_error", errHandle.Error()))
+		return 1
+	}
+	writeResponse(response, raw)
+	return 0
+}
+
+//export cliproxyPluginFree
+func cliproxyPluginFree(ptr unsafe.Pointer, len C.size_t) {
+	if ptr != nil {
+		C.free(ptr)
+	}
+}
+
+//export cliproxyPluginShutdown
+func cliproxyPluginShutdown() {}
+
+func handleMethod(method string, request []byte) ([]byte, error) {
+	switch method {
+	case pluginabi.MethodPluginRegister, pluginabi.MethodPluginReconfigure:
+		if errConfigure := configure(request); errConfigure != nil {
+			return nil, errConfigure
+		}
+		return okEnvelope(pluginRegistration())
+	case pluginabi.MethodRequestNormalize:
+		return normalizeRequest(request)
+	default:
+		return errorEnvelope("unknown_method", "unknown method: "+method), nil
+	}
+}
+
+func configure(raw []byte) error {
+	var req lifecycleRequest
+	if len(raw) > 0 {
+		if errUnmarshal := json.Unmarshal(raw, &req); errUnmarshal != nil {
+			return errUnmarshal
+		}
+	}
+
+	cfg := pluginConfig{}
+	if len(req.ConfigYAML) > 0 {
+		fast, errDecodeFast := decodeFastConfig(req.ConfigYAML)
+		if errDecodeFast != nil {
+			return errDecodeFast
+		}
+		cfg.Fast = fast
+	}
+	fastEnabled.Store(cfg.Fast)
+	return nil
+}
+
+func pluginRegistration() registration {
+	return registration{
+		SchemaVersion: pluginabi.SchemaVersion,
+		Metadata: pluginapi.Metadata{
+			Name:             "codex-service-tier",
+			Version:          "0.1.0",
+			Author:           "router-for-me",
+			GitHubRepository: "https://github.com/router-for-me/CLIProxyAPI",
+			Logo:             "https://raw.githubusercontent.com/router-for-me/CLIProxyAPI/main/docs/logo.png",
+			ConfigFields: []pluginapi.ConfigField{{
+				Name:        "fast",
+				Type:        pluginapi.ConfigFieldTypeBoolean,
+				Description: "Sets Codex gpt-5.5 Responses requests to the priority service tier.",
+			}},
+		},
+		Capabilities: registrationCapability{
+			RequestNormalizer: true,
+		},
+	}
+}
+
+func normalizeRequest(raw []byte) ([]byte, error) {
+	var req pluginapi.RequestTransformRequest
+	if errUnmarshal := json.Unmarshal(raw, &req); errUnmarshal != nil {
+		return nil, errUnmarshal
+	}
+	body := req.Body
+	if !shouldSetPriorityServiceTier(req) {
+		return okEnvelope(pluginapi.PayloadResponse{Body: body})
+	}
+	updated, okSet := setPriorityServiceTier(body)
+	if !okSet {
+		return okEnvelope(pluginapi.PayloadResponse{Body: body})
+	}
+	return okEnvelope(pluginapi.PayloadResponse{Body: updated})
+}
+
+func shouldSetPriorityServiceTier(req pluginapi.RequestTransformRequest) bool {
+	if !fastEnabled.Load() {
+		return false
+	}
+	if !strings.EqualFold(req.ToFormat, "codex") {
+		return false
+	}
+	return req.Model == "gpt-5.5"
+}
+
+func decodeFastConfig(configYAML []byte) (bool, error) {
+	var cfg pluginConfig
+	if errUnmarshal := yaml.Unmarshal(configYAML, &cfg); errUnmarshal != nil {
+		return false, errUnmarshal
+	}
+	return cfg.Fast, nil
+}
+
+func setPriorityServiceTier(body []byte) ([]byte, bool) {
+	updated, errSet := sjson.SetBytes(body, "service_tier", "priority")
+	if errSet != nil {
+		return nil, false
+	}
+	return updated, true
+}
+
+func okEnvelope(v any) ([]byte, error) {
+	raw, errMarshal := json.Marshal(v)
+	if errMarshal != nil {
+		return nil, errMarshal
+	}
+	return json.Marshal(envelope{OK: true, Result: raw})
+}
+
+func errorEnvelope(code, message string) []byte {
+	raw, _ := json.Marshal(envelope{OK: false, Error: &envelopeError{Code: code, Message: message}})
+	return raw
+}
+
+func writeResponse(response *C.cliproxy_buffer, raw []byte) {
+	if response == nil || len(raw) == 0 {
+		return
+	}
+	ptr := C.CBytes(raw)
+	if ptr == nil {
+		return
+	}
+	response.ptr = ptr
+	response.len = C.size_t(len(raw))
+}