Replace model-router and model-mapper with Go implementation (#3317)

2026-03-17 00:40:48 +08:00 · 2026-01-13 20:14:29 +08:00
parent 032a69556f
commit e23ab3ca7c
14 changed files with 1418 additions and 0 deletions
--- a/plugins/wasm-go/extensions/model-mapper/Makefile
+++ b/plugins/wasm-go/extensions/model-mapper/Makefile
@@ -0,0 +1,2 @@
+build-go:
+	GOOS=wasip1 GOARCH=wasm go build -buildmode=c-shared -o main.wasm main.go
--- a/plugins/wasm-go/extensions/model-mapper/README.md
+++ b/plugins/wasm-go/extensions/model-mapper/README.md
@@ -0,0 +1,61 @@
+# 功能说明
+`model-mapper`插件实现了基于LLM协议中的model参数路由的功能
+
+# 配置字段
+
+| 名称                 | 数据类型        | 填写要求                | 默认值                   | 描述                                                                                                                                                                                                                                                         |
+| -----------          | --------------- | ----------------------- | ------                   | -------------------------------------------                                                                                                                                                                                                                  |
+| `modelKey`           | string          | 选填                    | model                    | 请求body中model参数的位置                                                                                                                                                                                                                                    |
+| `modelMapping`       | map of string   | 选填                    | -                        | AI 模型映射表，用于将请求中的模型名称映射为服务提供商支持模型名称。<br/>1. 支持前缀匹配。例如用 "gpt-3-*" 匹配所有名称以“gpt-3-”开头的模型；<br/>2. 支持使用 "*" 为键来配置通用兜底映射关系；<br/>3. 如果映射的目标名称为空字符串 ""，则表示保留原模型名称。 |
+| `enableOnPathSuffix` | array of string | 选填                    | ["/completions","/embeddings","/images/generations","/audio/speech","/fine_tuning/jobs","/moderations","/image-synthesis","/video-synthesis","/rerank","/messages"] | 只对这些特定路径后缀的请求生效                                                                                                                                                                                                                               |
+
+
+## 效果说明
+
+如下配置
+
+```yaml
+modelMapping:
+  'gpt-4-*': "qwen-max"
+  'gpt-4o': "qwen-vl-plus"
+  '*': "qwen-turbo"
+```
+
+开启后，`gpt-4-` 开头的模型参数会被改写为 `qwen-max`, `gpt-4o` 会被改写为 `qwen-vl-plus`，其他所有模型会被改写为 `qwen-turbo`
+
+例如原本的请求是：
+
+```json
+{
+    "model": "gpt-4o",
+    "frequency_penalty": 0,
+    "max_tokens": 800,
+    "stream": false,
+    "messages": [{
+        "role": "user",
+        "content": "higress项目主仓库的github地址是什么"
+    }],
+    "presence_penalty": 0,
+    "temperature": 0.7,
+    "top_p": 0.95
+}
+```
+
+
+经过这个插件后，原始的 LLM 请求体将被改成：
+
+```json
+{
+    "model": "qwen-vl-plus",
+    "frequency_penalty": 0,
+    "max_tokens": 800,
+    "stream": false,
+    "messages": [{
+        "role": "user",
+        "content": "higress项目主仓库的github地址是什么"
+    }],
+    "presence_penalty": 0,
+    "temperature": 0.7,
+    "top_p": 0.95
+}
+```
--- a/plugins/wasm-go/extensions/model-mapper/README_EN.md
+++ b/plugins/wasm-go/extensions/model-mapper/README_EN.md
@@ -0,0 +1,61 @@
+# Function Description
+The `model-mapper` plugin implements model parameter mapping functionality based on the LLM protocol.
+
+# Configuration Fields
+
+| Name                 | Type            | Requirement             | Default Value            | Description |
+| --- | --- | --- | --- | --- |
+| `modelKey`           | string          | Optional                | model                    | The position of the model parameter in the request body. |
+| `modelMapping`       | map of string   | Optional                | -                        | AI model mapping table, used to map the model name in the request to the model name supported by the service provider.<br/>1. Supports prefix matching. For example, use "gpt-3-*" to match all names starting with "gpt-3-";<br/>2. Supports using "*" as a key to configure a generic fallback mapping;<br/>3. If the target mapping name is an empty string "", it indicates keeping the original model name. |
+| `enableOnPathSuffix` | array of string | Optional                | ["/completions","/embeddings","/images/generations","/audio/speech","/fine_tuning/jobs","/moderations","/image-synthesis","/video-synthesis","/rerank","/messages"] | Only effective for requests with these specific path suffixes. |
+
+
+## Effect Description
+
+Configuration example:
+
+```yaml
+modelMapping:
+  'gpt-4-*': "qwen-max"
+  'gpt-4o': "qwen-vl-plus"
+  '*': "qwen-turbo"
+```
+
+After enabling, model parameters starting with `gpt-4-` will be replaced with `qwen-max`, `gpt-4o` will be replaced with `qwen-vl-plus`, and all other models will be replaced with `qwen-turbo`.
+
+For example, the original request is:
+
+```json
+{
+    "model": "gpt-4o",
+    "frequency_penalty": 0,
+    "max_tokens": 800,
+    "stream": false,
+    "messages": [{
+        "role": "user",
+        "content": "What is the github address of the main repository of the higress project"
+    }],
+    "presence_penalty": 0,
+    "temperature": 0.7,
+    "top_p": 0.95
+}
+```
+
+
+After processing by this plugin, the original LLM request body will be modified to:
+
+```json
+{
+    "model": "qwen-vl-plus",
+    "frequency_penalty": 0,
+    "max_tokens": 800,
+    "stream": false,
+    "messages": [{
+        "role": "user",
+        "content": "What is the github address of the main repository of the higress project"
+    }],
+    "presence_penalty": 0,
+    "temperature": 0.7,
+    "top_p": 0.95
+}
+```
--- a/plugins/wasm-go/extensions/model-mapper/go.mod
+++ b/plugins/wasm-go/extensions/model-mapper/go.mod
@@ -0,0 +1,24 @@
+module github.com/alibaba/higress/plugins/wasm-go/extensions/model-mapper
+
+go 1.24.1
+
+toolchain go1.24.7
+
+require (
+	github.com/higress-group/proxy-wasm-go-sdk v0.0.0-20251103120604-77e9cce339d2
+	github.com/higress-group/wasm-go v1.0.7-0.20251209122854-7e766df5675c
+	github.com/stretchr/testify v1.9.0
+	github.com/tidwall/gjson v1.18.0
+	github.com/tidwall/sjson v1.2.5
+)
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/google/uuid v1.6.0 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/tetratelabs/wazero v1.7.2 // indirect
+	github.com/tidwall/match v1.1.1 // indirect
+	github.com/tidwall/pretty v1.2.1 // indirect
+	github.com/tidwall/resp v0.1.1 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)
--- a/plugins/wasm-go/extensions/model-mapper/go.sum
+++ b/plugins/wasm-go/extensions/model-mapper/go.sum
@@ -0,0 +1,30 @@
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
+github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
+github.com/higress-group/proxy-wasm-go-sdk v0.0.0-20251103120604-77e9cce339d2 h1:NY33OrWCJJ+DFiLc+lsBY4Ywor2Ik61ssk6qkGF8Ypo=
+github.com/higress-group/proxy-wasm-go-sdk v0.0.0-20251103120604-77e9cce339d2/go.mod h1:tRI2LfMudSkKHhyv1uex3BWzcice2s/l8Ah8axporfA=
+github.com/higress-group/wasm-go v1.0.7-0.20251209122854-7e766df5675c h1:DdVPyaMHSYBqO5jwB9Wl3PqsBGIf4u29BHMI0uIVB1Y=
+github.com/higress-group/wasm-go v1.0.7-0.20251209122854-7e766df5675c/go.mod h1:uKVYICbRaxTlKqdm8E0dpjbysxM8uCPb9LV26hF3Km8=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
+github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
+github.com/tetratelabs/wazero v1.7.2 h1:1+z5nXJNwMLPAWaTePFi49SSTL0IMx/i3Fg8Yc25GDc=
+github.com/tetratelabs/wazero v1.7.2/go.mod h1:ytl6Zuh20R/eROuyDaGPkp82O9C/DJfXAwJfQ3X6/7Y=
+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/go.mod h1:ITEVvHYasfjBbM0u2Pg8T2nJnzm8xPwvNhhsoaGGjNU=
+github.com/tidwall/pretty v1.2.1 h1:qjsOFOWWQl+N3RsoF5/ssm1pHmJJwhjlSbZ51I6wMl4=
+github.com/tidwall/pretty v1.2.1/go.mod h1:ITEVvHYasfjBbM0u2Pg8T2nJnzm8xPwvNhhsoaGGjNU=
+github.com/tidwall/resp v0.1.1 h1:Ly20wkhqKTmDUPlyM1S7pWo5kk0tDu8OoC/vFArXmwE=
+github.com/tidwall/resp v0.1.1/go.mod h1:3/FrruOBAxPTPtundW0VXgmsQ4ZBA0Aw714lVYgwFa0=
+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=
--- a/plugins/wasm-go/extensions/model-mapper/main.go
+++ b/plugins/wasm-go/extensions/model-mapper/main.go
@@ -0,0 +1,192 @@
+package main
+
+import (
+	"errors"
+	"sort"
+	"strings"
+
+	"github.com/higress-group/proxy-wasm-go-sdk/proxywasm"
+	"github.com/higress-group/proxy-wasm-go-sdk/proxywasm/types"
+	"github.com/higress-group/wasm-go/pkg/log"
+	"github.com/higress-group/wasm-go/pkg/wrapper"
+	"github.com/tidwall/gjson"
+	"github.com/tidwall/sjson"
+)
+
+const (
+	DefaultMaxBodyBytes = 100 * 1024 * 1024 // 100MB
+)
+
+func main() {}
+
+func init() {
+	wrapper.SetCtx(
+		"model-mapper",
+		wrapper.ParseConfig(parseConfig),
+		wrapper.ProcessRequestHeaders(onHttpRequestHeaders),
+		wrapper.ProcessRequestBody(onHttpRequestBody),
+		wrapper.WithRebuildAfterRequests[Config](1000),
+		wrapper.WithRebuildMaxMemBytes[Config](200*1024*1024),
+	)
+}
+
+type ModelMapping struct {
+	Prefix string
+	Target string
+}
+
+type Config struct {
+	modelKey           string
+	exactModelMapping  map[string]string
+	prefixModelMapping []ModelMapping
+	defaultModel       string
+	enableOnPathSuffix []string
+}
+
+func parseConfig(json gjson.Result, config *Config) error {
+	config.modelKey = json.Get("modelKey").String()
+	if config.modelKey == "" {
+		config.modelKey = "model"
+	}
+
+	modelMapping := json.Get("modelMapping")
+	if modelMapping.Exists() && !modelMapping.IsObject() {
+		return errors.New("modelMapping must be an object")
+	}
+
+	config.exactModelMapping = make(map[string]string)
+	config.prefixModelMapping = make([]ModelMapping, 0)
+
+	// To replicate C++ behavior (nlohmann::json iterates keys alphabetically),
+	// we collect entries and sort them by key.
+	type mappingEntry struct {
+		key   string
+		value string
+	}
+	var entries []mappingEntry
+	modelMapping.ForEach(func(key, value gjson.Result) bool {
+		entries = append(entries, mappingEntry{
+			key:   key.String(),
+			value: value.String(),
+		})
+		return true
+	})
+	sort.Slice(entries, func(i, j int) bool {
+		return entries[i].key < entries[j].key
+	})
+
+	for _, entry := range entries {
+		key := entry.key
+		value := entry.value
+		if key == "*" {
+			config.defaultModel = value
+		} else if strings.HasSuffix(key, "*") {
+			prefix := strings.TrimSuffix(key, "*")
+			config.prefixModelMapping = append(config.prefixModelMapping, ModelMapping{
+				Prefix: prefix,
+				Target: value,
+			})
+		} else {
+			config.exactModelMapping[key] = value
+		}
+	}
+
+	enableOnPathSuffix := json.Get("enableOnPathSuffix")
+	if enableOnPathSuffix.Exists() {
+		if !enableOnPathSuffix.IsArray() {
+			return errors.New("enableOnPathSuffix must be an array")
+		}
+		for _, item := range enableOnPathSuffix.Array() {
+			config.enableOnPathSuffix = append(config.enableOnPathSuffix, item.String())
+		}
+	} else {
+		config.enableOnPathSuffix = []string{
+			"/completions",
+			"/embeddings",
+			"/images/generations",
+			"/audio/speech",
+			"/fine_tuning/jobs",
+			"/moderations",
+			"/image-synthesis",
+			"/video-synthesis",
+			"/rerank",
+			"/messages",
+		}
+	}
+
+	return nil
+}
+
+func onHttpRequestHeaders(ctx wrapper.HttpContext, config Config) types.Action {
+	// Check path suffix
+	path, err := proxywasm.GetHttpRequestHeader(":path")
+	if err != nil {
+		return types.ActionContinue
+	}
+
+	// Strip query parameters
+	if idx := strings.Index(path, "?"); idx != -1 {
+		path = path[:idx]
+	}
+
+	matched := false
+	for _, suffix := range config.enableOnPathSuffix {
+		if strings.HasSuffix(path, suffix) {
+			matched = true
+			break
+		}
+	}
+	if !matched {
+		return types.ActionContinue
+	}
+
+	if !ctx.HasRequestBody() {
+		ctx.DontReadRequestBody()
+		return types.ActionContinue
+	}
+
+	// Prepare for body processing
+	proxywasm.RemoveHttpRequestHeader("content-length")
+	// 100MB buffer limit
+	ctx.SetRequestBodyBufferLimit(DefaultMaxBodyBytes)
+
+	return types.HeaderStopIteration
+}
+
+func onHttpRequestBody(ctx wrapper.HttpContext, config Config, body []byte) types.Action {
+	if len(body) == 0 {
+		return types.ActionContinue
+	}
+
+	oldModel := gjson.GetBytes(body, config.modelKey).String()
+
+	newModel := config.defaultModel
+	if newModel == "" {
+		newModel = oldModel
+	}
+
+	// Exact match
+	if target, ok := config.exactModelMapping[oldModel]; ok {
+		newModel = target
+	} else {
+		// Prefix match
+		for _, mapping := range config.prefixModelMapping {
+			if strings.HasPrefix(oldModel, mapping.Prefix) {
+				newModel = mapping.Target
+				break
+			}
+		}
+	}
+
+	if newModel != "" && newModel != oldModel {
+		newBody, err := sjson.SetBytes(body, config.modelKey, newModel)
+		if err != nil {
+			log.Errorf("failed to update model: %v", err)
+			return types.ActionContinue
+		}
+		proxywasm.ReplaceHttpRequestBody(newBody)
+		log.Debugf("model mapped, before: %s, after: %s", oldModel, newModel)
+	}
+
+	return types.ActionContinue
+}
--- a/plugins/wasm-go/extensions/model-mapper/main_test.go
+++ b/plugins/wasm-go/extensions/model-mapper/main_test.go
@@ -0,0 +1,250 @@
+package main
+
+import (
+	"encoding/json"
+	"strings"
+	"testing"
+
+	"github.com/higress-group/proxy-wasm-go-sdk/proxywasm/types"
+	"github.com/higress-group/wasm-go/pkg/test"
+	"github.com/stretchr/testify/require"
+	"github.com/tidwall/gjson"
+)
+
+// Basic configs for wasm test host
+var (
+	basicConfig = func() json.RawMessage {
+		data, _ := json.Marshal(map[string]interface{}{
+			"modelKey": "model",
+			"modelMapping": map[string]string{
+				"gpt-3.5-turbo": "gpt-4",
+			},
+			"enableOnPathSuffix": []string{
+				"/v1/chat/completions",
+			},
+		})
+		return data
+	}()
+
+	customConfig = func() json.RawMessage {
+		data, _ := json.Marshal(map[string]interface{}{
+			"modelKey": "request.model",
+			"modelMapping": map[string]string{
+				"*":          "gpt-4o",
+				"gpt-3.5*":   "gpt-4-mini",
+				"gpt-3.5-t":  "gpt-4-turbo",
+				"gpt-3.5-t1": "gpt-4-turbo-1",
+			},
+			"enableOnPathSuffix": []string{
+				"/v1/chat/completions",
+				"/v1/embeddings",
+			},
+		})
+		return data
+	}()
+)
+
+func TestParseConfig(t *testing.T) {
+	test.RunGoTest(t, func(t *testing.T) {
+		t.Run("basic config with defaults", func(t *testing.T) {
+			var cfg Config
+			jsonData := []byte(`{
+				"modelMapping": {
+					"gpt-3.5-turbo": "gpt-4",
+					"gpt-4*": "gpt-4o-mini",
+					"*": "gpt-4o"
+				}
+			}`)
+			err := parseConfig(gjson.ParseBytes(jsonData), &cfg)
+			require.NoError(t, err)
+
+			// default modelKey
+			require.Equal(t, "model", cfg.modelKey)
+			// exact mapping
+			require.Equal(t, "gpt-4", cfg.exactModelMapping["gpt-3.5-turbo"])
+			// prefix mapping
+			require.Len(t, cfg.prefixModelMapping, 1)
+			require.Equal(t, "gpt-4", cfg.prefixModelMapping[0].Prefix)
+			// default model
+			require.Equal(t, "gpt-4o", cfg.defaultModel)
+			// default enabled path suffixes
+			require.Contains(t, cfg.enableOnPathSuffix, "/completions")
+			require.Contains(t, cfg.enableOnPathSuffix, "/embeddings")
+		})
+
+		t.Run("custom modelKey and enableOnPathSuffix", func(t *testing.T) {
+			var cfg Config
+			jsonData := []byte(`{
+				"modelKey": "request.model",
+				"modelMapping": {
+					"gpt-3.5-turbo": "gpt-4",
+					"gpt-3.5*": "gpt-4-mini"
+				},
+				"enableOnPathSuffix": ["/v1/chat/completions", "/v1/embeddings"]
+			}`)
+			err := parseConfig(gjson.ParseBytes(jsonData), &cfg)
+			require.NoError(t, err)
+
+			require.Equal(t, "request.model", cfg.modelKey)
+			require.Equal(t, "gpt-4", cfg.exactModelMapping["gpt-3.5-turbo"])
+			require.Len(t, cfg.prefixModelMapping, 1)
+			require.Equal(t, "gpt-3.5", cfg.prefixModelMapping[0].Prefix)
+			require.Equal(t, "gpt-4-mini", cfg.prefixModelMapping[0].Target)
+			require.Equal(t, 2, len(cfg.enableOnPathSuffix))
+			require.Contains(t, cfg.enableOnPathSuffix, "/v1/chat/completions")
+			require.Contains(t, cfg.enableOnPathSuffix, "/v1/embeddings")
+		})
+
+		t.Run("modelMapping must be object", func(t *testing.T) {
+			var cfg Config
+			jsonData := []byte(`{
+				"modelMapping": "invalid"
+			}`)
+			err := parseConfig(gjson.ParseBytes(jsonData), &cfg)
+			require.Error(t, err)
+		})
+
+		t.Run("enableOnPathSuffix must be array", func(t *testing.T) {
+			var cfg Config
+			jsonData := []byte(`{
+				"enableOnPathSuffix": "not-array"
+			}`)
+			err := parseConfig(gjson.ParseBytes(jsonData), &cfg)
+			require.Error(t, err)
+		})
+	})
+}
+
+func TestOnHttpRequestHeaders(t *testing.T) {
+	test.RunTest(t, func(t *testing.T) {
+		t.Run("skip when path not matched", func(t *testing.T) {
+			host, status := test.NewTestHost(basicConfig)
+			defer host.Reset()
+			require.Equal(t, types.OnPluginStartStatusOK, status)
+
+			originalHeaders := [][2]string{
+				{":authority", "example.com"},
+				{":path", "/v1/other"},
+				{":method", "POST"},
+				{"content-type", "application/json"},
+				{"content-length", "123"},
+			}
+			action := host.CallOnHttpRequestHeaders(originalHeaders)
+			require.Equal(t, types.ActionContinue, action)
+
+			newHeaders := host.GetRequestHeaders()
+			// content-length should still exist because path is not enabled
+			foundContentLength := false
+			for _, h := range newHeaders {
+				if strings.ToLower(h[0]) == "content-length" {
+					foundContentLength = true
+					break
+				}
+			}
+			require.True(t, foundContentLength)
+		})
+
+		t.Run("process when path and content-type match", func(t *testing.T) {
+			host, status := test.NewTestHost(basicConfig)
+			defer host.Reset()
+			require.Equal(t, types.OnPluginStartStatusOK, status)
+
+			originalHeaders := [][2]string{
+				{":authority", "example.com"},
+				{":path", "/v1/chat/completions"},
+				{":method", "POST"},
+				{"content-type", "application/json"},
+				{"content-length", "123"},
+			}
+			action := host.CallOnHttpRequestHeaders(originalHeaders)
+			require.Equal(t, types.HeaderStopIteration, action)
+
+			newHeaders := host.GetRequestHeaders()
+			// content-length should be removed
+			for _, h := range newHeaders {
+				require.NotEqual(t, strings.ToLower(h[0]), "content-length")
+			}
+		})
+	})
+}
+
+func TestOnHttpRequestBody_ModelMapping(t *testing.T) {
+	test.RunTest(t, func(t *testing.T) {
+		t.Run("exact mapping", func(t *testing.T) {
+			host, status := test.NewTestHost(basicConfig)
+			defer host.Reset()
+			require.Equal(t, types.OnPluginStartStatusOK, status)
+
+			host.CallOnHttpRequestHeaders([][2]string{
+				{":authority", "example.com"},
+				{":path", "/v1/chat/completions"},
+				{":method", "POST"},
+				{"content-type", "application/json"},
+			})
+
+			origBody := []byte(`{
+				"model": "gpt-3.5-turbo",
+				"messages": [{"role": "user", "content": "hello"}]
+			}`)
+			action := host.CallOnHttpRequestBody(origBody)
+			require.Equal(t, types.ActionContinue, action)
+
+			processed := host.GetRequestBody()
+			require.NotNil(t, processed)
+			require.Equal(t, "gpt-4", gjson.GetBytes(processed, "model").String())
+		})
+
+		t.Run("default model when key missing", func(t *testing.T) {
+			// use customConfig where default model is set with "*"
+			host, status := test.NewTestHost(customConfig)
+			defer host.Reset()
+			require.Equal(t, types.OnPluginStartStatusOK, status)
+
+			host.CallOnHttpRequestHeaders([][2]string{
+				{":authority", "example.com"},
+				{":path", "/v1/chat/completions"},
+				{":method", "POST"},
+				{"content-type", "application/json"},
+			})
+
+			origBody := []byte(`{
+				"request": {
+					"messages": [{"role": "user", "content": "hello"}]
+				}
+			}`)
+			action := host.CallOnHttpRequestBody(origBody)
+			require.Equal(t, types.ActionContinue, action)
+
+			processed := host.GetRequestBody()
+			require.NotNil(t, processed)
+			// default model should be set at request.model
+			require.Equal(t, "gpt-4o", gjson.GetBytes(processed, "request.model").String())
+		})
+
+		t.Run("prefix mapping takes effect", func(t *testing.T) {
+			host, status := test.NewTestHost(customConfig)
+			defer host.Reset()
+			require.Equal(t, types.OnPluginStartStatusOK, status)
+
+			host.CallOnHttpRequestHeaders([][2]string{
+				{":authority", "example.com"},
+				{":path", "/v1/chat/completions"},
+				{":method", "POST"},
+				{"content-type", "application/json"},
+			})
+
+			origBody := []byte(`{
+				"request": {
+					"model": "gpt-3.5-turbo-16k",
+					"messages": [{"role": "user", "content": "hello"}]
+				}
+			}`)
+			action := host.CallOnHttpRequestBody(origBody)
+			require.Equal(t, types.ActionContinue, action)
+
+			processed := host.GetRequestBody()
+			require.NotNil(t, processed)
+			require.Equal(t, "gpt-4-mini", gjson.GetBytes(processed, "request.model").String())
+		})
+	})
+}