feat(provider): add support for azure openai provider (#1422)

* Add support for azure openai provider * Add checks for deployment model name * Apply suggestion from @Copilot Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com> * Addressing @Copilot suggestion to remove the init() function which seemed redundant * Fix readme * Fix linting checks --------- Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
2026-06-12 18:08:54 +00:00 · 2026-03-14 20:22:34 +05:30
parent 0f700a6bf0
commit 5fb4b3bedf
16 changed files with 1446 additions and 323 deletions
@@ -991,6 +991,7 @@ Cette conception permet également le **support multi-agent** avec une sélectio
 | **BytePlus**        | `byteplus/`       | `https://ark.ap-southeast.bytepluses.com/api/v3`    | OpenAI    | [Obtenir Clé](https://www.byteplus.com/)                    |
 | **LongCat**         | `longcat/`        | `https://api.longcat.chat/openai`                   | OpenAI    | [Obtenir une clé](https://longcat.chat/platform)                 |
 | **ModelScope (魔搭)**| `modelscope/`    | `https://api-inference.modelscope.cn/v1`            | OpenAI    | [Obtenir un Token](https://modelscope.cn/my/tokens)              |
+| **Azure OpenAI**    | `azure/`          | `https://{resource}.openai.azure.com`               | Azure     | [Obtenir Clé](https://portal.azure.com)                          |
 | **Antigravity** | `antigravity/` | Google Cloud | Custom | OAuth uniquement |
 | **GitHub Copilot** | `github-copilot/` | `localhost:4321` | gRPC | - |

@@ -935,6 +935,7 @@ HEARTBEAT_OK 応答         ユーザーが直接結果を受け取る
 | **BytePlus**        | `byteplus/`       | `https://ark.ap-southeast.bytepluses.com/api/v3`    | OpenAI    | [キーを取得](https://www.byteplus.com)                     |
 | **LongCat**         | `longcat/`        | `https://api.longcat.chat/openai`                   | OpenAI    | [キーを取得](https://longcat.chat/platform)                      |
 | **ModelScope (魔搭)**| `modelscope/`    | `https://api-inference.modelscope.cn/v1`            | OpenAI    | [トークンを取得](https://modelscope.cn/my/tokens)                 |
+| **Azure OpenAI**    | `azure/`          | `https://{resource}.openai.azure.com`               | Azure     | [キーを取得](https://portal.azure.com)                            |
 | **Antigravity** | `antigravity/` | Google Cloud | カスタム | OAuthのみ |
 | **GitHub Copilot** | `github-copilot/` | `localhost:4321` | gRPC | - |

@@ -1006,6 +1006,7 @@ The subagent has access to tools (message, web_search, etc.) and can communicate
 | `groq`       | LLM + **Voice transcription** (Whisper) | [console.groq.com](https://console.groq.com)                 |
 | `cerebras`   | LLM (Cerebras direct)                   | [cerebras.ai](https://cerebras.ai)                           |
 | `vivgrid`    | LLM (Vivgrid direct)                    | [vivgrid.com](https://vivgrid.com)                           |
+| `azure`      | LLM (Azure OpenAI)                      | [portal.azure.com](https://portal.azure.com)                 |

 ### Model Configuration (model_list)

@@ -1042,6 +1043,7 @@ This design also enables **multi-agent support** with flexible provider selectio
 | **Vivgrid**         | `vivgrid/`        | `https://api.vivgrid.com/v1`                        | OpenAI    | [Get Key](https://vivgrid.com)                                   |
 | **LongCat**         | `longcat/`        | `https://api.longcat.chat/openai`                   | OpenAI    | [Get Key](https://longcat.chat/platform)                         |
 | **ModelScope (魔搭)**| `modelscope/`    | `https://api-inference.modelscope.cn/v1`            | OpenAI    | [Get Token](https://modelscope.cn/my/tokens)                     |
+| **Azure OpenAI**    | `azure/`          | `https://{resource}.openai.azure.com`               | Azure     | [Get Key](https://portal.azure.com)                              |
 | **Antigravity**     | `antigravity/`    | Google Cloud                                        | Custom    | OAuth only                                                       |
 | **GitHub Copilot**  | `github-copilot/` | `localhost:4321`                                    | gRPC      | -                                                                |

@@ -987,6 +987,7 @@ Este design também possibilita o **suporte multi-agent** com seleção flexíve
 | **BytePlus**        | `byteplus/`       | `https://ark.ap-southeast.bytepluses.com/api/v3`    | OpenAI    | [Obter Chave](https://www.byteplus.com)                    |
 | **LongCat**         | `longcat/`        | `https://api.longcat.chat/openai`                   | OpenAI    | [Obter Chave](https://longcat.chat/platform)                     |
 | **ModelScope (魔搭)**| `modelscope/`    | `https://api-inference.modelscope.cn/v1`            | OpenAI    | [Obter Token](https://modelscope.cn/my/tokens)                   |
+| **Azure OpenAI**    | `azure/`          | `https://{resource}.openai.azure.com`               | Azure     | [Obter Chave](https://portal.azure.com)                          |
 | **Antigravity** | `antigravity/` | Google Cloud | Custom | Apenas OAuth |
 | **GitHub Copilot** | `github-copilot/` | `localhost:4321` | gRPC | - |

@@ -956,6 +956,7 @@ Thiết kế này cũng cho phép **hỗ trợ đa tác nhân** với lựa ch
 | **BytePlus**        | `byteplus/`       | `https://ark.ap-southeast.bytepluses.com/api/v3`    | OpenAI    | [Lấy Khóa](https://www.byteplus.com)                      |
 | **LongCat**         | `longcat/`        | `https://api.longcat.chat/openai`                   | OpenAI    | [Lấy Key](https://longcat.chat/platform)                        |
 | **ModelScope (魔搭)**| `modelscope/`    | `https://api-inference.modelscope.cn/v1`            | OpenAI    | [Lấy Token](https://modelscope.cn/my/tokens)                    |
+| **Azure OpenAI**    | `azure/`          | `https://{resource}.openai.azure.com`               | Azure     | [Lấy Khóa](https://portal.azure.com)                             |
 | **Antigravity** | `antigravity/` | Google Cloud | Tùy chỉnh | Chỉ OAuth |
 | **GitHub Copilot** | `github-copilot/` | `localhost:4321` | gRPC | - |

@@ -528,6 +528,7 @@ Agent 读取 HEARTBEAT.md
 | **BytePlus**        | `byteplus/`       | `https://ark.ap-southeast.bytepluses.com/api/v3`    | OpenAI    | [获取密钥](https://www.byteplus.com)                        |
 | **LongCat**         | `longcat/`        | `https://api.longcat.chat/openai`                   | OpenAI    | [获取密钥](https://longcat.chat/platform)                        |
 | **ModelScope (魔搭)**| `modelscope/`    | `https://api-inference.modelscope.cn/v1`            | OpenAI    | [获取 Token](https://modelscope.cn/my/tokens)                    |
+| **Azure OpenAI**    | `azure/`          | `https://{resource}.openai.azure.com`               | Azure     | [获取密钥](https://portal.azure.com)                              |
 | **Antigravity**     | `antigravity/`    | Google Cloud                                        | 自定义    | 仅 OAuth                                                          |
 | **GitHub Copilot**  | `github-copilot/` | `localhost:4321`                                    | gRPC      | -                                                                 |

@@ -53,6 +53,12 @@
      "api_key": "your-modelscope-access-token",
      "api_base": "https://api-inference.modelscope.cn/v1"
    },
+    {
+      "model_name": "azure-gpt5",
+      "model": "azure/my-gpt5-deployment",
+      "api_key": "your-azure-api-key",
+      "api_base": "https://your-resource.openai.azure.com"
+    },
    {
      "model_name": "loadbalanced-gpt-5.4",
      "model": "openai/gpt-5.4",
@@ -384,6 +384,15 @@ func DefaultConfig() *Config {
 				APIBase:   "http://localhost:8000/v1",
 				APIKey:    "",
 			},
+
+			// Azure OpenAI - https://portal.azure.com
+			// model_name is a user-friendly alias; the model field's path after "azure/" is your deployment name
+			{
+				ModelName: "azure-gpt5",
+				Model:     "azure/my-gpt5-deployment",
+				APIBase:   "https://your-resource.openai.azure.com",
+				APIKey:    "",
+			},
 		},
 		Gateway: GatewayConfig{
 			Host: "127.0.0.1",
@@ -0,0 +1,150 @@
+package azure
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/url"
+	"strings"
+	"time"
+
+	"github.com/sipeed/picoclaw/pkg/providers/common"
+	"github.com/sipeed/picoclaw/pkg/providers/protocoltypes"
+)
+
+type (
+	LLMResponse    = protocoltypes.LLMResponse
+	Message        = protocoltypes.Message
+	ToolDefinition = protocoltypes.ToolDefinition
+)
+
+const (
+	// azureAPIVersion is the Azure OpenAI API version used for all requests.
+	azureAPIVersion       = "2024-10-21"
+	defaultRequestTimeout = common.DefaultRequestTimeout
+)
+
+// Provider implements the LLM provider interface for Azure OpenAI endpoints.
+// It handles Azure-specific authentication (api-key header), URL construction
+// (deployment-based), and request body formatting (max_completion_tokens, no model field).
+type Provider struct {
+	apiKey     string
+	apiBase    string
+	httpClient *http.Client
+}
+
+// Option configures the Azure Provider.
+type Option func(*Provider)
+
+// WithRequestTimeout sets the HTTP request timeout.
+func WithRequestTimeout(timeout time.Duration) Option {
+	return func(p *Provider) {
+		if timeout > 0 {
+			p.httpClient.Timeout = timeout
+		}
+	}
+}
+
+// NewProvider creates a new Azure OpenAI provider.
+func NewProvider(apiKey, apiBase, proxy string, opts ...Option) *Provider {
+	p := &Provider{
+		apiKey:     apiKey,
+		apiBase:    strings.TrimRight(apiBase, "/"),
+		httpClient: common.NewHTTPClient(proxy),
+	}
+
+	for _, opt := range opts {
+		if opt != nil {
+			opt(p)
+		}
+	}
+
+	return p
+}
+
+// NewProviderWithTimeout creates a new Azure OpenAI provider with a custom request timeout in seconds.
+func NewProviderWithTimeout(apiKey, apiBase, proxy string, requestTimeoutSeconds int) *Provider {
+	return NewProvider(
+		apiKey, apiBase, proxy,
+		WithRequestTimeout(time.Duration(requestTimeoutSeconds)*time.Second),
+	)
+}
+
+// Chat sends a chat completion request to the Azure OpenAI endpoint.
+// The model parameter is used as the Azure deployment name in the URL.
+func (p *Provider) Chat(
+	ctx context.Context,
+	messages []Message,
+	tools []ToolDefinition,
+	model string,
+	options map[string]any,
+) (*LLMResponse, error) {
+	if p.apiBase == "" {
+		return nil, fmt.Errorf("Azure API base not configured")
+	}
+
+	// model is the deployment name for Azure OpenAI
+	deployment := model
+
+	// Build Azure-specific URL safely using url.JoinPath and query encoding
+	// to prevent path traversal or query injection via deployment names.
+	base, err := url.JoinPath(p.apiBase, "openai/deployments", deployment, "chat/completions")
+	if err != nil {
+		return nil, fmt.Errorf("failed to build Azure request URL: %w", err)
+	}
+	requestURL := base + "?api-version=" + azureAPIVersion
+
+	// Build request body — no "model" field (Azure infers from deployment URL)
+	requestBody := map[string]any{
+		"messages": common.SerializeMessages(messages),
+	}
+
+	if len(tools) > 0 {
+		requestBody["tools"] = tools
+		requestBody["tool_choice"] = "auto"
+	}
+
+	// Azure OpenAI always uses max_completion_tokens
+	if maxTokens, ok := common.AsInt(options["max_tokens"]); ok {
+		requestBody["max_completion_tokens"] = maxTokens
+	}
+
+	if temperature, ok := common.AsFloat(options["temperature"]); ok {
+		requestBody["temperature"] = temperature
+	}
+
+	jsonData, err := json.Marshal(requestBody)
+	if err != nil {
+		return nil, fmt.Errorf("failed to marshal request: %w", err)
+	}
+
+	req, err := http.NewRequestWithContext(ctx, "POST", requestURL, bytes.NewReader(jsonData))
+	if err != nil {
+		return nil, fmt.Errorf("failed to create request: %w", err)
+	}
+
+	// Azure uses api-key header instead of Authorization: Bearer
+	req.Header.Set("Content-Type", "application/json")
+	if p.apiKey != "" {
+		req.Header.Set("api-key", p.apiKey)
+	}
+
+	resp, err := p.httpClient.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("failed to send request: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, common.HandleErrorResponse(resp, p.apiBase)
+	}
+
+	return common.ReadAndParseResponse(resp, p.apiBase)
+}
+
+// GetDefaultModel returns an empty string as Azure deployments are user-configured.
+func (p *Provider) GetDefaultModel() string {
+	return ""
+}
@@ -0,0 +1,232 @@
+package azure
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"time"
+)
+
+// writeValidResponse writes a minimal valid Azure OpenAI chat completion response.
+func writeValidResponse(w http.ResponseWriter) {
+	resp := map[string]any{
+		"choices": []map[string]any{
+			{
+				"message":       map[string]any{"content": "ok"},
+				"finish_reason": "stop",
+			},
+		},
+	}
+	w.Header().Set("Content-Type", "application/json")
+	json.NewEncoder(w).Encode(resp)
+}
+
+func TestProviderChat_AzureURLConstruction(t *testing.T) {
+	var capturedPath string
+	var capturedAPIVersion string
+
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		capturedPath = r.URL.Path
+		capturedAPIVersion = r.URL.Query().Get("api-version")
+		writeValidResponse(w)
+	}))
+	defer server.Close()
+
+	p := NewProvider("test-key", server.URL, "")
+	_, err := p.Chat(t.Context(), []Message{{Role: "user", Content: "hi"}}, nil, "my-gpt5-deployment", nil)
+	if err != nil {
+		t.Fatalf("Chat() error = %v", err)
+	}
+
+	wantPath := "/openai/deployments/my-gpt5-deployment/chat/completions"
+	if capturedPath != wantPath {
+		t.Errorf("URL path = %q, want %q", capturedPath, wantPath)
+	}
+	if capturedAPIVersion != azureAPIVersion {
+		t.Errorf("api-version = %q, want %q", capturedAPIVersion, azureAPIVersion)
+	}
+}
+
+func TestProviderChat_AzureAuthHeader(t *testing.T) {
+	var capturedAPIKey string
+	var capturedAuth string
+
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		capturedAPIKey = r.Header.Get("api-key")
+		capturedAuth = r.Header.Get("Authorization")
+		writeValidResponse(w)
+	}))
+	defer server.Close()
+
+	p := NewProvider("test-azure-key", server.URL, "")
+	_, err := p.Chat(t.Context(), []Message{{Role: "user", Content: "hi"}}, nil, "deployment", nil)
+	if err != nil {
+		t.Fatalf("Chat() error = %v", err)
+	}
+
+	if capturedAPIKey != "test-azure-key" {
+		t.Errorf("api-key header = %q, want %q", capturedAPIKey, "test-azure-key")
+	}
+	if capturedAuth != "" {
+		t.Errorf("Authorization header should be empty, got %q", capturedAuth)
+	}
+}
+
+func TestProviderChat_AzureOmitsModelFromBody(t *testing.T) {
+	var requestBody map[string]any
+
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		json.NewDecoder(r.Body).Decode(&requestBody)
+		writeValidResponse(w)
+	}))
+	defer server.Close()
+
+	p := NewProvider("test-key", server.URL, "")
+	_, err := p.Chat(t.Context(), []Message{{Role: "user", Content: "hi"}}, nil, "deployment", nil)
+	if err != nil {
+		t.Fatalf("Chat() error = %v", err)
+	}
+
+	if _, exists := requestBody["model"]; exists {
+		t.Error("request body should not contain 'model' field for Azure OpenAI")
+	}
+}
+
+func TestProviderChat_AzureUsesMaxCompletionTokens(t *testing.T) {
+	var requestBody map[string]any
+
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		json.NewDecoder(r.Body).Decode(&requestBody)
+		writeValidResponse(w)
+	}))
+	defer server.Close()
+
+	p := NewProvider("test-key", server.URL, "")
+	_, err := p.Chat(
+		t.Context(),
+		[]Message{{Role: "user", Content: "hi"}},
+		nil,
+		"deployment",
+		map[string]any{"max_tokens": 2048},
+	)
+	if err != nil {
+		t.Fatalf("Chat() error = %v", err)
+	}
+
+	if _, exists := requestBody["max_completion_tokens"]; !exists {
+		t.Error("request body should contain 'max_completion_tokens'")
+	}
+	if _, exists := requestBody["max_tokens"]; exists {
+		t.Error("request body should not contain 'max_tokens'")
+	}
+}
+
+func TestProviderChat_AzureHTTPError(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		http.Error(w, `{"error":"unauthorized"}`, http.StatusUnauthorized)
+	}))
+	defer server.Close()
+
+	p := NewProvider("bad-key", server.URL, "")
+	_, err := p.Chat(t.Context(), []Message{{Role: "user", Content: "hi"}}, nil, "deployment", nil)
+	if err == nil {
+		t.Fatal("expected error, got nil")
+	}
+}
+
+func TestProviderChat_AzureParseToolCalls(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		resp := map[string]any{
+			"choices": []map[string]any{
+				{
+					"message": map[string]any{
+						"content": "",
+						"tool_calls": []map[string]any{
+							{
+								"id":   "call_1",
+								"type": "function",
+								"function": map[string]any{
+									"name":      "get_weather",
+									"arguments": `{"city":"Seattle"}`,
+								},
+							},
+						},
+					},
+					"finish_reason": "tool_calls",
+				},
+			},
+		}
+		w.Header().Set("Content-Type", "application/json")
+		json.NewEncoder(w).Encode(resp)
+	}))
+	defer server.Close()
+
+	p := NewProvider("test-key", server.URL, "")
+	out, err := p.Chat(t.Context(), []Message{{Role: "user", Content: "weather?"}}, nil, "deployment", nil)
+	if err != nil {
+		t.Fatalf("Chat() error = %v", err)
+	}
+
+	if len(out.ToolCalls) != 1 {
+		t.Fatalf("len(ToolCalls) = %d, want 1", len(out.ToolCalls))
+	}
+	if out.ToolCalls[0].Name != "get_weather" {
+		t.Errorf("ToolCalls[0].Name = %q, want %q", out.ToolCalls[0].Name, "get_weather")
+	}
+}
+
+func TestProvider_AzureEmptyAPIBase(t *testing.T) {
+	p := NewProvider("test-key", "", "")
+	_, err := p.Chat(t.Context(), []Message{{Role: "user", Content: "hi"}}, nil, "deployment", nil)
+	if err == nil {
+		t.Fatal("expected error for empty API base")
+	}
+}
+
+func TestProvider_AzureRequestTimeoutDefault(t *testing.T) {
+	p := NewProvider("test-key", "https://example.com", "")
+	if p.httpClient.Timeout != defaultRequestTimeout {
+		t.Errorf("timeout = %v, want %v", p.httpClient.Timeout, defaultRequestTimeout)
+	}
+}
+
+func TestProvider_AzureRequestTimeoutOverride(t *testing.T) {
+	p := NewProvider("test-key", "https://example.com", "", WithRequestTimeout(300*time.Second))
+	if p.httpClient.Timeout != 300*time.Second {
+		t.Errorf("timeout = %v, want %v", p.httpClient.Timeout, 300*time.Second)
+	}
+}
+
+func TestProvider_AzureNewProviderWithTimeout(t *testing.T) {
+	p := NewProviderWithTimeout("test-key", "https://example.com", "", 180)
+	if p.httpClient.Timeout != 180*time.Second {
+		t.Errorf("timeout = %v, want %v", p.httpClient.Timeout, 180*time.Second)
+	}
+}
+
+func TestProviderChat_AzureDeploymentNameEscaped(t *testing.T) {
+	var capturedPath string
+
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		capturedPath = r.URL.RawPath // use RawPath to see percent-encoding
+		if capturedPath == "" {
+			capturedPath = r.URL.Path
+		}
+		writeValidResponse(w)
+	}))
+	defer server.Close()
+
+	p := NewProvider("test-key", server.URL, "")
+
+	// Deployment name with characters that could cause path injection
+	_, err := p.Chat(t.Context(), []Message{{Role: "user", Content: "hi"}}, nil, "my deploy/../../admin", nil)
+	if err != nil {
+		t.Fatalf("Chat() error = %v", err)
+	}
+
+	// The slash and special chars in the deployment name must be escaped, not treated as path separators
+	if capturedPath == "/openai/deployments/my deploy/../../admin/chat/completions" {
+		t.Fatal("deployment name was interpolated without escaping — path injection possible")
+	}
+}
@@ -0,0 +1,380 @@
+// PicoClaw - Ultra-lightweight personal AI agent
+// License: MIT
+//
+// Copyright (c) 2026 PicoClaw contributors
+
+// Package common provides shared utilities used by multiple LLM provider
+// implementations (openai_compat, azure, etc.).
+package common
+
+import (
+	"bufio"
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"log"
+	"net/http"
+	"net/url"
+	"strings"
+	"time"
+
+	"github.com/sipeed/picoclaw/pkg/providers/protocoltypes"
+)
+
+// Re-export protocol types used across providers.
+type (
+	ToolCall               = protocoltypes.ToolCall
+	FunctionCall           = protocoltypes.FunctionCall
+	LLMResponse            = protocoltypes.LLMResponse
+	UsageInfo              = protocoltypes.UsageInfo
+	Message                = protocoltypes.Message
+	ToolDefinition         = protocoltypes.ToolDefinition
+	ToolFunctionDefinition = protocoltypes.ToolFunctionDefinition
+	ExtraContent           = protocoltypes.ExtraContent
+	GoogleExtra            = protocoltypes.GoogleExtra
+	ReasoningDetail        = protocoltypes.ReasoningDetail
+)
+
+const DefaultRequestTimeout = 120 * time.Second
+
+// NewHTTPClient creates an *http.Client with an optional proxy and the default timeout.
+func NewHTTPClient(proxy string) *http.Client {
+	client := &http.Client{
+		Timeout: DefaultRequestTimeout,
+	}
+	if proxy != "" {
+		parsed, err := url.Parse(proxy)
+		if err == nil {
+			// Preserve http.DefaultTransport settings (TLS, HTTP/2, timeouts, etc.)
+			if base, ok := http.DefaultTransport.(*http.Transport); ok {
+				tr := base.Clone()
+				tr.Proxy = http.ProxyURL(parsed)
+				client.Transport = tr
+			} else {
+				// Fallback: minimal transport if DefaultTransport is not *http.Transport.
+				client.Transport = &http.Transport{
+					Proxy: http.ProxyURL(parsed),
+				}
+			}
+		} else {
+			log.Printf("common: invalid proxy URL %q: %v", proxy, err)
+		}
+	}
+	return client
+}
+
+// --- Message serialization ---
+
+// openaiMessage is the wire-format message for OpenAI-compatible APIs.
+// It mirrors protocoltypes.Message but omits SystemParts, which is an
+// internal field that would be unknown to third-party endpoints.
+type openaiMessage struct {
+	Role             string     `json:"role"`
+	Content          string     `json:"content"`
+	ReasoningContent string     `json:"reasoning_content,omitempty"`
+	ToolCalls        []ToolCall `json:"tool_calls,omitempty"`
+	ToolCallID       string     `json:"tool_call_id,omitempty"`
+}
+
+// SerializeMessages converts internal Message structs to the OpenAI wire format.
+//   - Strips SystemParts (unknown to third-party endpoints)
+//   - Converts messages with Media to multipart content format (text + image_url parts)
+//   - Preserves ToolCallID, ToolCalls, and ReasoningContent for all messages
+func SerializeMessages(messages []Message) []any {
+	out := make([]any, 0, len(messages))
+	for _, m := range messages {
+		if len(m.Media) == 0 {
+			out = append(out, openaiMessage{
+				Role:             m.Role,
+				Content:          m.Content,
+				ReasoningContent: m.ReasoningContent,
+				ToolCalls:        m.ToolCalls,
+				ToolCallID:       m.ToolCallID,
+			})
+			continue
+		}
+
+		// Multipart content format for messages with media
+		parts := make([]map[string]any, 0, 1+len(m.Media))
+		if m.Content != "" {
+			parts = append(parts, map[string]any{
+				"type": "text",
+				"text": m.Content,
+			})
+		}
+		for _, mediaURL := range m.Media {
+			if strings.HasPrefix(mediaURL, "data:image/") {
+				parts = append(parts, map[string]any{
+					"type": "image_url",
+					"image_url": map[string]any{
+						"url": mediaURL,
+					},
+				})
+			}
+		}
+
+		msg := map[string]any{
+			"role":    m.Role,
+			"content": parts,
+		}
+		if m.ToolCallID != "" {
+			msg["tool_call_id"] = m.ToolCallID
+		}
+		if len(m.ToolCalls) > 0 {
+			msg["tool_calls"] = m.ToolCalls
+		}
+		if m.ReasoningContent != "" {
+			msg["reasoning_content"] = m.ReasoningContent
+		}
+		out = append(out, msg)
+	}
+	return out
+}
+
+// --- Response parsing ---
+
+// ParseResponse parses a JSON chat completion response body into an LLMResponse.
+func ParseResponse(body io.Reader) (*LLMResponse, error) {
+	var apiResponse struct {
+		Choices []struct {
+			Message struct {
+				Content          string            `json:"content"`
+				ReasoningContent string            `json:"reasoning_content"`
+				Reasoning        string            `json:"reasoning"`
+				ReasoningDetails []ReasoningDetail `json:"reasoning_details"`
+				ToolCalls        []struct {
+					ID       string `json:"id"`
+					Type     string `json:"type"`
+					Function *struct {
+						Name      string          `json:"name"`
+						Arguments json.RawMessage `json:"arguments"`
+					} `json:"function"`
+					ExtraContent *struct {
+						Google *struct {
+							ThoughtSignature string `json:"thought_signature"`
+						} `json:"google"`
+					} `json:"extra_content"`
+				} `json:"tool_calls"`
+			} `json:"message"`
+			FinishReason string `json:"finish_reason"`
+		} `json:"choices"`
+		Usage *UsageInfo `json:"usage"`
+	}
+
+	if err := json.NewDecoder(body).Decode(&apiResponse); err != nil {
+		return nil, fmt.Errorf("failed to decode response: %w", err)
+	}
+
+	if len(apiResponse.Choices) == 0 {
+		return &LLMResponse{
+			Content:      "",
+			FinishReason: "stop",
+		}, nil
+	}
+
+	choice := apiResponse.Choices[0]
+	toolCalls := make([]ToolCall, 0, len(choice.Message.ToolCalls))
+	for _, tc := range choice.Message.ToolCalls {
+		arguments := make(map[string]any)
+		name := ""
+
+		// Extract thought_signature from Gemini/Google-specific extra content
+		thoughtSignature := ""
+		if tc.ExtraContent != nil && tc.ExtraContent.Google != nil {
+			thoughtSignature = tc.ExtraContent.Google.ThoughtSignature
+		}
+
+		if tc.Function != nil {
+			name = tc.Function.Name
+			arguments = DecodeToolCallArguments(tc.Function.Arguments, name)
+		}
+
+		toolCall := ToolCall{
+			ID:               tc.ID,
+			Name:             name,
+			Arguments:        arguments,
+			ThoughtSignature: thoughtSignature,
+		}
+
+		if thoughtSignature != "" {
+			toolCall.ExtraContent = &ExtraContent{
+				Google: &GoogleExtra{
+					ThoughtSignature: thoughtSignature,
+				},
+			}
+		}
+
+		toolCalls = append(toolCalls, toolCall)
+	}
+
+	return &LLMResponse{
+		Content:          choice.Message.Content,
+		ReasoningContent: choice.Message.ReasoningContent,
+		Reasoning:        choice.Message.Reasoning,
+		ReasoningDetails: choice.Message.ReasoningDetails,
+		ToolCalls:        toolCalls,
+		FinishReason:     choice.FinishReason,
+		Usage:            apiResponse.Usage,
+	}, nil
+}
+
+// DecodeToolCallArguments decodes a tool call's arguments from raw JSON.
+func DecodeToolCallArguments(raw json.RawMessage, name string) map[string]any {
+	arguments := make(map[string]any)
+	raw = bytes.TrimSpace(raw)
+	if len(raw) == 0 || bytes.Equal(raw, []byte("null")) {
+		return arguments
+	}
+
+	var decoded any
+	if err := json.Unmarshal(raw, &decoded); err != nil {
+		log.Printf("common: failed to decode tool call arguments payload for %q: %v", name, err)
+		arguments["raw"] = string(raw)
+		return arguments
+	}
+
+	switch v := decoded.(type) {
+	case string:
+		if strings.TrimSpace(v) == "" {
+			return arguments
+		}
+		if err := json.Unmarshal([]byte(v), &arguments); err != nil {
+			log.Printf("common: failed to decode tool call arguments for %q: %v", name, err)
+			arguments["raw"] = v
+		}
+		return arguments
+	case map[string]any:
+		return v
+	default:
+		log.Printf("common: unsupported tool call arguments type for %q: %T", name, decoded)
+		arguments["raw"] = string(raw)
+		return arguments
+	}
+}
+
+// --- HTTP response helpers ---
+
+// HandleErrorResponse reads a non-200 response body and returns an appropriate error.
+func HandleErrorResponse(resp *http.Response, apiBase string) error {
+	contentType := resp.Header.Get("Content-Type")
+	body, readErr := io.ReadAll(io.LimitReader(resp.Body, 256))
+	if readErr != nil {
+		return fmt.Errorf("failed to read response: %w", readErr)
+	}
+	if LooksLikeHTML(body, contentType) {
+		return WrapHTMLResponseError(resp.StatusCode, body, contentType, apiBase)
+	}
+	return fmt.Errorf(
+		"API request failed:\n  Status: %d\n  Body:   %s",
+		resp.StatusCode,
+		ResponsePreview(body, 128),
+	)
+}
+
+// ReadAndParseResponse peeks at the response body to detect HTML errors,
+// then parses the JSON response into an LLMResponse.
+func ReadAndParseResponse(resp *http.Response, apiBase string) (*LLMResponse, error) {
+	contentType := resp.Header.Get("Content-Type")
+	reader := bufio.NewReader(resp.Body)
+	prefix, err := reader.Peek(256)
+	if err != nil && err != io.EOF && err != bufio.ErrBufferFull {
+		return nil, fmt.Errorf("failed to inspect response: %w", err)
+	}
+	if LooksLikeHTML(prefix, contentType) {
+		return nil, WrapHTMLResponseError(resp.StatusCode, prefix, contentType, apiBase)
+	}
+	out, err := ParseResponse(reader)
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse JSON response: %w", err)
+	}
+	return out, nil
+}
+
+// LooksLikeHTML checks if the response body appears to be HTML.
+func LooksLikeHTML(body []byte, contentType string) bool {
+	contentType = strings.ToLower(strings.TrimSpace(contentType))
+	if strings.Contains(contentType, "text/html") || strings.Contains(contentType, "application/xhtml+xml") {
+		return true
+	}
+	prefix := bytes.ToLower(leadingTrimmedPrefix(body, 128))
+	return bytes.HasPrefix(prefix, []byte("<!doctype html")) ||
+		bytes.HasPrefix(prefix, []byte("<html")) ||
+		bytes.HasPrefix(prefix, []byte("<head")) ||
+		bytes.HasPrefix(prefix, []byte("<body"))
+}
+
+// WrapHTMLResponseError creates a descriptive error for HTML responses.
+func WrapHTMLResponseError(statusCode int, body []byte, contentType, apiBase string) error {
+	respPreview := ResponsePreview(body, 128)
+	return fmt.Errorf(
+		"API request failed: %s returned HTML instead of JSON (content-type: %s); check api_base or proxy configuration.\n  Status: %d\n  Body:   %s",
+		apiBase,
+		contentType,
+		statusCode,
+		respPreview,
+	)
+}
+
+// ResponsePreview returns a truncated preview of response body for error messages.
+func ResponsePreview(body []byte, maxLen int) string {
+	trimmed := bytes.TrimSpace(body)
+	if len(trimmed) == 0 {
+		return "<empty>"
+	}
+	if len(trimmed) <= maxLen {
+		return string(trimmed)
+	}
+	return string(trimmed[:maxLen]) + "..."
+}
+
+func leadingTrimmedPrefix(body []byte, maxLen int) []byte {
+	i := 0
+	for i < len(body) {
+		switch body[i] {
+		case ' ', '\t', '\n', '\r', '\f', '\v':
+			i++
+		default:
+			end := i + maxLen
+			if end > len(body) {
+				end = len(body)
+			}
+			return body[i:end]
+		}
+	}
+	return nil
+}
+
+// --- Numeric helpers ---
+
+// AsInt converts various numeric types to int.
+func AsInt(v any) (int, bool) {
+	switch val := v.(type) {
+	case int:
+		return val, true
+	case int64:
+		return int(val), true
+	case float64:
+		return int(val), true
+	case float32:
+		return int(val), true
+	default:
+		return 0, false
+	}
+}
+
+// AsFloat converts various numeric types to float64.
+func AsFloat(v any) (float64, bool) {
+	switch val := v.(type) {
+	case float64:
+		return val, true
+	case float32:
+		return float64(val), true
+	case int:
+		return float64(val), true
+	case int64:
+		return float64(val), true
+	default:
+		return 0, false
+	}
+}
@@ -0,0 +1,558 @@
+package common
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"strings"
+	"testing"
+
+	"github.com/sipeed/picoclaw/pkg/providers/protocoltypes"
+)
+
+// --- NewHTTPClient tests ---
+
+func TestNewHTTPClient_DefaultTimeout(t *testing.T) {
+	client := NewHTTPClient("")
+	if client.Timeout != DefaultRequestTimeout {
+		t.Errorf("timeout = %v, want %v", client.Timeout, DefaultRequestTimeout)
+	}
+}
+
+func TestNewHTTPClient_WithProxy(t *testing.T) {
+	client := NewHTTPClient("http://127.0.0.1:8080")
+	transport, ok := client.Transport.(*http.Transport)
+	if !ok || transport == nil {
+		t.Fatalf("expected http.Transport with proxy, got %T", client.Transport)
+	}
+	req := &http.Request{URL: &url.URL{Scheme: "https", Host: "api.example.com"}}
+	gotProxy, err := transport.Proxy(req)
+	if err != nil {
+		t.Fatalf("proxy function error: %v", err)
+	}
+	if gotProxy == nil || gotProxy.String() != "http://127.0.0.1:8080" {
+		t.Errorf("proxy = %v, want http://127.0.0.1:8080", gotProxy)
+	}
+}
+
+func TestNewHTTPClient_NoProxy(t *testing.T) {
+	client := NewHTTPClient("")
+	if client.Transport != nil {
+		t.Errorf("expected nil transport without proxy, got %T", client.Transport)
+	}
+}
+
+func TestNewHTTPClient_InvalidProxy(t *testing.T) {
+	// Should not panic, just log and return client without proxy
+	client := NewHTTPClient("://bad-url")
+	if client == nil {
+		t.Fatal("expected non-nil client even with invalid proxy")
+	}
+}
+
+// --- SerializeMessages tests ---
+
+func TestSerializeMessages_PlainText(t *testing.T) {
+	messages := []Message{
+		{Role: "user", Content: "hello"},
+		{Role: "assistant", Content: "hi", ReasoningContent: "thinking..."},
+	}
+	result := SerializeMessages(messages)
+
+	data, _ := json.Marshal(result)
+	var msgs []map[string]any
+	json.Unmarshal(data, &msgs)
+
+	if msgs[0]["content"] != "hello" {
+		t.Errorf("expected plain string content, got %v", msgs[0]["content"])
+	}
+	if msgs[1]["reasoning_content"] != "thinking..." {
+		t.Errorf("reasoning_content not preserved, got %v", msgs[1]["reasoning_content"])
+	}
+}
+
+func TestSerializeMessages_WithMedia(t *testing.T) {
+	messages := []Message{
+		{Role: "user", Content: "describe this", Media: []string{"data:image/png;base64,abc123"}},
+	}
+	result := SerializeMessages(messages)
+
+	data, _ := json.Marshal(result)
+	var msgs []map[string]any
+	json.Unmarshal(data, &msgs)
+
+	content, ok := msgs[0]["content"].([]any)
+	if !ok {
+		t.Fatalf("expected array content for media message, got %T", msgs[0]["content"])
+	}
+	if len(content) != 2 {
+		t.Fatalf("expected 2 content parts, got %d", len(content))
+	}
+}
+
+func TestSerializeMessages_MediaWithToolCallID(t *testing.T) {
+	messages := []Message{
+		{Role: "tool", Content: "result", Media: []string{"data:image/png;base64,xyz"}, ToolCallID: "call_1"},
+	}
+	result := SerializeMessages(messages)
+
+	data, _ := json.Marshal(result)
+	var msgs []map[string]any
+	json.Unmarshal(data, &msgs)
+
+	if msgs[0]["tool_call_id"] != "call_1" {
+		t.Errorf("tool_call_id not preserved, got %v", msgs[0]["tool_call_id"])
+	}
+}
+
+func TestSerializeMessages_StripsSystemParts(t *testing.T) {
+	messages := []Message{
+		{
+			Role:    "system",
+			Content: "you are helpful",
+			SystemParts: []protocoltypes.ContentBlock{
+				{Type: "text", Text: "you are helpful"},
+			},
+		},
+	}
+	result := SerializeMessages(messages)
+
+	data, _ := json.Marshal(result)
+	if strings.Contains(string(data), "system_parts") {
+		t.Error("system_parts should not appear in serialized output")
+	}
+}
+
+// --- ParseResponse tests ---
+
+func TestParseResponse_BasicContent(t *testing.T) {
+	body := `{"choices":[{"message":{"content":"hello world"},"finish_reason":"stop"}]}`
+	out, err := ParseResponse(strings.NewReader(body))
+	if err != nil {
+		t.Fatalf("ParseResponse() error = %v", err)
+	}
+	if out.Content != "hello world" {
+		t.Errorf("Content = %q, want %q", out.Content, "hello world")
+	}
+	if out.FinishReason != "stop" {
+		t.Errorf("FinishReason = %q, want %q", out.FinishReason, "stop")
+	}
+}
+
+func TestParseResponse_EmptyChoices(t *testing.T) {
+	body := `{"choices":[]}`
+	out, err := ParseResponse(strings.NewReader(body))
+	if err != nil {
+		t.Fatalf("ParseResponse() error = %v", err)
+	}
+	if out.Content != "" {
+		t.Errorf("Content = %q, want empty", out.Content)
+	}
+	if out.FinishReason != "stop" {
+		t.Errorf("FinishReason = %q, want %q", out.FinishReason, "stop")
+	}
+}
+
+func TestParseResponse_WithToolCalls(t *testing.T) {
+	body := `{"choices":[{"message":{"content":"","tool_calls":[{"id":"call_1","type":"function","function":{"name":"get_weather","arguments":"{\"city\":\"SF\"}"}}]},"finish_reason":"tool_calls"}]}`
+	out, err := ParseResponse(strings.NewReader(body))
+	if err != nil {
+		t.Fatalf("ParseResponse() error = %v", err)
+	}
+	if len(out.ToolCalls) != 1 {
+		t.Fatalf("len(ToolCalls) = %d, want 1", len(out.ToolCalls))
+	}
+	if out.ToolCalls[0].Name != "get_weather" {
+		t.Errorf("ToolCalls[0].Name = %q, want %q", out.ToolCalls[0].Name, "get_weather")
+	}
+	if out.ToolCalls[0].Arguments["city"] != "SF" {
+		t.Errorf("ToolCalls[0].Arguments[city] = %v, want SF", out.ToolCalls[0].Arguments["city"])
+	}
+}
+
+func TestParseResponse_WithUsage(t *testing.T) {
+	body := `{"choices":[{"message":{"content":"ok"},"finish_reason":"stop"}],"usage":{"prompt_tokens":10,"completion_tokens":5,"total_tokens":15}}`
+	out, err := ParseResponse(strings.NewReader(body))
+	if err != nil {
+		t.Fatalf("ParseResponse() error = %v", err)
+	}
+	if out.Usage == nil {
+		t.Fatal("Usage is nil")
+	}
+	if out.Usage.PromptTokens != 10 {
+		t.Errorf("PromptTokens = %d, want 10", out.Usage.PromptTokens)
+	}
+}
+
+func TestParseResponse_WithReasoningContent(t *testing.T) {
+	body := `{"choices":[{"message":{"content":"2","reasoning_content":"Let me think... 1+1=2"},"finish_reason":"stop"}]}`
+	out, err := ParseResponse(strings.NewReader(body))
+	if err != nil {
+		t.Fatalf("ParseResponse() error = %v", err)
+	}
+	if out.ReasoningContent != "Let me think... 1+1=2" {
+		t.Errorf("ReasoningContent = %q, want %q", out.ReasoningContent, "Let me think... 1+1=2")
+	}
+}
+
+func TestParseResponse_InvalidJSON(t *testing.T) {
+	_, err := ParseResponse(strings.NewReader("not json"))
+	if err == nil {
+		t.Fatal("expected error for invalid JSON")
+	}
+}
+
+// --- DecodeToolCallArguments tests ---
+
+func TestDecodeToolCallArguments_ObjectJSON(t *testing.T) {
+	raw := json.RawMessage(`{"city":"Seattle","units":"metric"}`)
+	args := DecodeToolCallArguments(raw, "test")
+	if args["city"] != "Seattle" {
+		t.Errorf("city = %v, want Seattle", args["city"])
+	}
+	if args["units"] != "metric" {
+		t.Errorf("units = %v, want metric", args["units"])
+	}
+}
+
+func TestDecodeToolCallArguments_StringJSON(t *testing.T) {
+	raw := json.RawMessage(`"{\"city\":\"SF\"}"`)
+	args := DecodeToolCallArguments(raw, "test")
+	if args["city"] != "SF" {
+		t.Errorf("city = %v, want SF", args["city"])
+	}
+}
+
+func TestDecodeToolCallArguments_EmptyInput(t *testing.T) {
+	args := DecodeToolCallArguments(nil, "test")
+	if len(args) != 0 {
+		t.Errorf("expected empty map, got %v", args)
+	}
+}
+
+func TestDecodeToolCallArguments_NullInput(t *testing.T) {
+	args := DecodeToolCallArguments(json.RawMessage(`null`), "test")
+	if len(args) != 0 {
+		t.Errorf("expected empty map, got %v", args)
+	}
+}
+
+func TestDecodeToolCallArguments_InvalidJSON(t *testing.T) {
+	args := DecodeToolCallArguments(json.RawMessage(`not-json`), "test")
+	if _, ok := args["raw"]; !ok {
+		t.Error("expected 'raw' fallback key for invalid JSON")
+	}
+}
+
+func TestDecodeToolCallArguments_EmptyStringJSON(t *testing.T) {
+	args := DecodeToolCallArguments(json.RawMessage(`"  "`), "test")
+	if len(args) != 0 {
+		t.Errorf("expected empty map for whitespace string, got %v", args)
+	}
+}
+
+// --- HandleErrorResponse tests ---
+
+func TestHandleErrorResponse_JSONError(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		w.WriteHeader(http.StatusBadRequest)
+		w.Write([]byte(`{"error":"bad request"}`))
+	}))
+	defer server.Close()
+
+	resp, err := http.Get(server.URL)
+	if err != nil {
+		t.Fatalf("http.Get() error = %v", err)
+	}
+	defer resp.Body.Close()
+	err = HandleErrorResponse(resp, server.URL)
+	if err == nil {
+		t.Fatal("expected error")
+	}
+	if !strings.Contains(err.Error(), "400") {
+		t.Errorf("error should contain status code, got %v", err)
+	}
+	if strings.Contains(err.Error(), "HTML") {
+		t.Errorf("should not mention HTML for JSON error, got %v", err)
+	}
+}
+
+func TestHandleErrorResponse_HTMLError(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "text/html")
+		w.WriteHeader(http.StatusBadGateway)
+		w.Write([]byte("<!DOCTYPE html><html><body>bad gateway</body></html>"))
+	}))
+	defer server.Close()
+
+	resp, err := http.Get(server.URL)
+	if err != nil {
+		t.Fatalf("http.Get() error = %v", err)
+	}
+	defer resp.Body.Close()
+	err = HandleErrorResponse(resp, server.URL)
+	if err == nil {
+		t.Fatal("expected error")
+	}
+	if !strings.Contains(err.Error(), "HTML instead of JSON") {
+		t.Errorf("expected HTML error message, got %v", err)
+	}
+}
+
+// --- ReadAndParseResponse tests ---
+
+func TestReadAndParseResponse_ValidJSON(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		w.Write([]byte(`{"choices":[{"message":{"content":"ok"},"finish_reason":"stop"}]}`))
+	}))
+	defer server.Close()
+
+	resp, err := http.Get(server.URL)
+	if err != nil {
+		t.Fatalf("http.Get() error = %v", err)
+	}
+	defer resp.Body.Close()
+	out, err := ReadAndParseResponse(resp, server.URL)
+	if err != nil {
+		t.Fatalf("ReadAndParseResponse() error = %v", err)
+	}
+	if out.Content != "ok" {
+		t.Errorf("Content = %q, want %q", out.Content, "ok")
+	}
+}
+
+func TestReadAndParseResponse_HTMLResponse(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "text/html")
+		w.Write([]byte("<!DOCTYPE html><html><body>login page</body></html>"))
+	}))
+	defer server.Close()
+
+	resp, err := http.Get(server.URL)
+	if err != nil {
+		t.Fatalf("http.Get() error = %v", err)
+	}
+	defer resp.Body.Close()
+	_, err = ReadAndParseResponse(resp, server.URL)
+	if err == nil {
+		t.Fatal("expected error for HTML response")
+	}
+	if !strings.Contains(err.Error(), "HTML instead of JSON") {
+		t.Errorf("expected HTML error, got %v", err)
+	}
+}
+
+// --- LooksLikeHTML tests ---
+
+func TestLooksLikeHTML_ContentTypeHTML(t *testing.T) {
+	if !LooksLikeHTML(nil, "text/html; charset=utf-8") {
+		t.Error("expected true for text/html content type")
+	}
+}
+
+func TestLooksLikeHTML_ContentTypeXHTML(t *testing.T) {
+	if !LooksLikeHTML(nil, "application/xhtml+xml") {
+		t.Error("expected true for xhtml content type")
+	}
+}
+
+func TestLooksLikeHTML_BodyPrefix(t *testing.T) {
+	tests := []struct {
+		name string
+		body string
+	}{
+		{"doctype", "<!DOCTYPE html><html>"},
+		{"html tag", "<html><body>"},
+		{"head tag", "<head><title>"},
+		{"body tag", "<body>content"},
+		{"whitespace before", "  \n\t<!DOCTYPE html>"},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if !LooksLikeHTML([]byte(tt.body), "application/json") {
+				t.Errorf("expected true for body %q", tt.body)
+			}
+		})
+	}
+}
+
+func TestLooksLikeHTML_NotHTML(t *testing.T) {
+	if LooksLikeHTML([]byte(`{"error":"bad"}`), "application/json") {
+		t.Error("expected false for JSON body")
+	}
+}
+
+// --- ResponsePreview tests ---
+
+func TestResponsePreview_Short(t *testing.T) {
+	got := ResponsePreview([]byte("hello"), 128)
+	if got != "hello" {
+		t.Errorf("got %q, want %q", got, "hello")
+	}
+}
+
+func TestResponsePreview_Truncated(t *testing.T) {
+	body := strings.Repeat("a", 200)
+	got := ResponsePreview([]byte(body), 128)
+	if len(got) != 131 { // 128 + "..."
+		t.Errorf("len = %d, want 131", len(got))
+	}
+	if !strings.HasSuffix(got, "...") {
+		t.Error("expected ... suffix")
+	}
+}
+
+func TestResponsePreview_Empty(t *testing.T) {
+	got := ResponsePreview([]byte(""), 128)
+	if got != "<empty>" {
+		t.Errorf("got %q, want %q", got, "<empty>")
+	}
+}
+
+func TestResponsePreview_Whitespace(t *testing.T) {
+	got := ResponsePreview([]byte("  \n\t  "), 128)
+	if got != "<empty>" {
+		t.Errorf("got %q, want %q for whitespace-only body", got, "<empty>")
+	}
+}
+
+// --- AsInt tests ---
+
+func TestAsInt(t *testing.T) {
+	tests := []struct {
+		name string
+		val  any
+		want int
+		ok   bool
+	}{
+		{"int", 42, 42, true},
+		{"int64", int64(99), 99, true},
+		{"float64", float64(512), 512, true},
+		{"float32", float32(256), 256, true},
+		{"string", "nope", 0, false},
+		{"nil", nil, 0, false},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, ok := AsInt(tt.val)
+			if ok != tt.ok || got != tt.want {
+				t.Errorf("AsInt(%v) = (%d, %v), want (%d, %v)", tt.val, got, ok, tt.want, tt.ok)
+			}
+		})
+	}
+}
+
+// --- AsFloat tests ---
+
+func TestAsFloat(t *testing.T) {
+	tests := []struct {
+		name string
+		val  any
+		want float64
+		ok   bool
+	}{
+		{"float64", float64(0.7), 0.7, true},
+		{"float32", float32(0.5), float64(float32(0.5)), true},
+		{"int", 1, 1.0, true},
+		{"int64", int64(100), 100.0, true},
+		{"string", "nope", 0, false},
+		{"nil", nil, 0, false},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, ok := AsFloat(tt.val)
+			if ok != tt.ok || got != tt.want {
+				t.Errorf("AsFloat(%v) = (%f, %v), want (%f, %v)", tt.val, got, ok, tt.want, tt.ok)
+			}
+		})
+	}
+}
+
+// --- WrapHTMLResponseError tests ---
+
+func TestWrapHTMLResponseError(t *testing.T) {
+	err := WrapHTMLResponseError(502, []byte("<html>bad</html>"), "text/html", "https://api.example.com")
+	if err == nil {
+		t.Fatal("expected error")
+	}
+	msg := err.Error()
+	if !strings.Contains(msg, "502") {
+		t.Errorf("expected status code in error, got %v", msg)
+	}
+	if !strings.Contains(msg, "https://api.example.com") {
+		t.Errorf("expected api base in error, got %v", msg)
+	}
+	if !strings.Contains(msg, "HTML instead of JSON") {
+		t.Errorf("expected HTML mention in error, got %v", msg)
+	}
+}
+
+// --- HandleErrorResponse with read failure ---
+
+func TestHandleErrorResponse_EmptyBody(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		w.WriteHeader(http.StatusInternalServerError)
+		// empty body
+	}))
+	defer server.Close()
+
+	resp, err := http.Get(server.URL)
+	if err != nil {
+		t.Fatalf("http.Get() error = %v", err)
+	}
+	defer resp.Body.Close()
+	err = HandleErrorResponse(resp, server.URL)
+	if err == nil {
+		t.Fatal("expected error")
+	}
+	if !strings.Contains(err.Error(), "500") {
+		t.Errorf("expected status code, got %v", err)
+	}
+}
+
+// --- ReadAndParseResponse with invalid JSON ---
+
+func TestReadAndParseResponse_InvalidJSON(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		w.Write([]byte("not valid json"))
+	}))
+	defer server.Close()
+
+	resp, err := http.Get(server.URL)
+	if err != nil {
+		t.Fatalf("http.Get() error = %v", err)
+	}
+	defer resp.Body.Close()
+	_, err = ReadAndParseResponse(resp, server.URL)
+	if err == nil {
+		t.Fatal("expected error for invalid JSON")
+	}
+}
+
+// --- ParseResponse with thought_signature (Google/Gemini) ---
+
+func TestParseResponse_WithThoughtSignature(t *testing.T) {
+	body := `{"choices":[{"message":{"content":"","tool_calls":[{"id":"call_1","type":"function","function":{"name":"test_tool","arguments":"{}"},"extra_content":{"google":{"thought_signature":"sig123"}}}]},"finish_reason":"tool_calls"}]}`
+	out, err := ParseResponse(strings.NewReader(body))
+	if err != nil {
+		t.Fatalf("ParseResponse() error = %v", err)
+	}
+	if len(out.ToolCalls) != 1 {
+		t.Fatalf("len(ToolCalls) = %d, want 1", len(out.ToolCalls))
+	}
+	if out.ToolCalls[0].ThoughtSignature != "sig123" {
+		t.Errorf("ThoughtSignature = %q, want %q", out.ToolCalls[0].ThoughtSignature, "sig123")
+	}
+	if out.ToolCalls[0].ExtraContent == nil || out.ToolCalls[0].ExtraContent.Google == nil {
+		t.Fatal("ExtraContent.Google is nil")
+	}
+	if out.ToolCalls[0].ExtraContent.Google.ThoughtSignature != "sig123" {
+		t.Errorf("ExtraContent.Google.ThoughtSignature = %q, want %q",
+			out.ToolCalls[0].ExtraContent.Google.ThoughtSignature, "sig123")
+	}
+}
@@ -11,6 +11,7 @@ import (

 	"github.com/sipeed/picoclaw/pkg/config"
 	anthropicmessages "github.com/sipeed/picoclaw/pkg/providers/anthropic_messages"
+	"github.com/sipeed/picoclaw/pkg/providers/azure"
 )

 // createClaudeAuthProvider creates a Claude provider using OAuth credentials from auth store.
@@ -94,6 +95,24 @@ func CreateProviderFromConfig(cfg *config.ModelConfig) (LLMProvider, string, err
 			cfg.RequestTimeout,
 		), modelID, nil

+	case "azure", "azure-openai":
+		// Azure OpenAI uses deployment-based URLs, api-key header auth,
+		// and always sends max_completion_tokens.
+		if cfg.APIKey == "" {
+			return nil, "", fmt.Errorf("api_key is required for azure protocol")
+		}
+		if cfg.APIBase == "" {
+			return nil, "", fmt.Errorf(
+				"api_base is required for azure protocol (e.g., https://your-resource.openai.azure.com)",
+			)
+		}
+		return azure.NewProviderWithTimeout(
+			cfg.APIKey,
+			cfg.APIBase,
+			cfg.Proxy,
+			cfg.RequestTimeout,
+		), modelID, nil
+
 	case "litellm", "openrouter", "groq", "zhipu", "gemini", "nvidia",
 		"ollama", "moonshot", "shengsuanyun", "deepseek", "cerebras",
 		"vivgrid", "volcengine", "vllm", "qwen", "mistral", "avian",
@@ -64,6 +64,12 @@ func TestExtractProtocol(t *testing.T) {
 			wantProtocol: "nvidia",
 			wantModelID:  "meta/llama-3.1-8b",
 		},
+		{
+			name:         "azure with prefix",
+			model:        "azure/my-gpt5-deployment",
+			wantProtocol: "azure",
+			wantModelID:  "my-gpt5-deployment",
+		},
 	}

 	for _, tt := range tests {
@@ -371,3 +377,69 @@ func TestCreateProviderFromConfig_RequestTimeoutPropagation(t *testing.T) {
 		t.Fatalf("Chat() error = %q, want timeout-related error", errMsg)
 	}
 }
+
+func TestCreateProviderFromConfig_Azure(t *testing.T) {
+	cfg := &config.ModelConfig{
+		ModelName: "azure-gpt5",
+		Model:     "azure/my-gpt5-deployment",
+		APIKey:    "test-azure-key",
+		APIBase:   "https://my-resource.openai.azure.com",
+	}
+
+	provider, modelID, err := CreateProviderFromConfig(cfg)
+	if err != nil {
+		t.Fatalf("CreateProviderFromConfig() error = %v", err)
+	}
+	if provider == nil {
+		t.Fatal("CreateProviderFromConfig() returned nil provider")
+	}
+	if modelID != "my-gpt5-deployment" {
+		t.Errorf("modelID = %q, want %q", modelID, "my-gpt5-deployment")
+	}
+}
+
+func TestCreateProviderFromConfig_AzureOpenAIAlias(t *testing.T) {
+	cfg := &config.ModelConfig{
+		ModelName: "azure-gpt4",
+		Model:     "azure-openai/my-deployment",
+		APIKey:    "test-azure-key",
+		APIBase:   "https://my-resource.openai.azure.com",
+	}
+
+	provider, modelID, err := CreateProviderFromConfig(cfg)
+	if err != nil {
+		t.Fatalf("CreateProviderFromConfig() error = %v", err)
+	}
+	if provider == nil {
+		t.Fatal("CreateProviderFromConfig() returned nil provider")
+	}
+	if modelID != "my-deployment" {
+		t.Errorf("modelID = %q, want %q", modelID, "my-deployment")
+	}
+}
+
+func TestCreateProviderFromConfig_AzureMissingAPIKey(t *testing.T) {
+	cfg := &config.ModelConfig{
+		ModelName: "azure-gpt5",
+		Model:     "azure/my-gpt5-deployment",
+		APIBase:   "https://my-resource.openai.azure.com",
+	}
+
+	_, _, err := CreateProviderFromConfig(cfg)
+	if err == nil {
+		t.Fatal("CreateProviderFromConfig() expected error for missing API key")
+	}
+}
+
+func TestCreateProviderFromConfig_AzureMissingAPIBase(t *testing.T) {
+	cfg := &config.ModelConfig{
+		ModelName: "azure-gpt5",
+		Model:     "azure/my-gpt5-deployment",
+		APIKey:    "test-azure-key",
+	}
+
+	_, _, err := CreateProviderFromConfig(cfg)
+	if err == nil {
+		t.Fatal("CreateProviderFromConfig() expected error for missing API base")
+	}
+}
@@ -1,18 +1,16 @@
 package openai_compat

 import (
-	"bufio"
 	"bytes"
 	"context"
 	"encoding/json"
 	"fmt"
-	"io"
-	"log"
 	"net/http"
 	"net/url"
 	"strings"
 	"time"

+	"github.com/sipeed/picoclaw/pkg/providers/common"
 	"github.com/sipeed/picoclaw/pkg/providers/protocoltypes"
 )

@@ -38,7 +36,7 @@ type Provider struct {

 type Option func(*Provider)

-const defaultRequestTimeout = 120 * time.Second
+const defaultRequestTimeout = common.DefaultRequestTimeout

 func WithMaxTokensField(maxTokensField string) Option {
 	return func(p *Provider) {
@@ -55,25 +53,10 @@ func WithRequestTimeout(timeout time.Duration) Option {
 }

 func NewProvider(apiKey, apiBase, proxy string, opts ...Option) *Provider {
-	client := &http.Client{
-		Timeout: defaultRequestTimeout,
-	}
-
-	if proxy != "" {
-		parsed, err := url.Parse(proxy)
-		if err == nil {
-			client.Transport = &http.Transport{
-				Proxy: http.ProxyURL(parsed),
-			}
-		} else {
-			log.Printf("openai_compat: invalid proxy URL %q: %v", proxy, err)
-		}
-	}
-
 	p := &Provider{
 		apiKey:     apiKey,
 		apiBase:    strings.TrimRight(apiBase, "/"),
-		httpClient: client,
+		httpClient: common.NewHTTPClient(proxy),
 	}

 	for _, opt := range opts {
@@ -117,7 +100,7 @@ func (p *Provider) Chat(

 	requestBody := map[string]any{
 		"model":    model,
-		"messages": serializeMessages(messages),
+		"messages": common.SerializeMessages(messages),
 	}

 	if len(tools) > 0 {
@@ -125,7 +108,7 @@ func (p *Provider) Chat(
 		requestBody["tool_choice"] = "auto"
 	}

-	if maxTokens, ok := asInt(options["max_tokens"]); ok {
+	if maxTokens, ok := common.AsInt(options["max_tokens"]); ok {
 		// Use configured maxTokensField if specified, otherwise fallback to model-based detection
 		fieldName := p.maxTokensField
 		if fieldName == "" {
@@ -141,7 +124,7 @@ func (p *Provider) Chat(
 		requestBody[fieldName] = maxTokens
 	}

-	if temperature, ok := asFloat(options["temperature"]); ok {
+	if temperature, ok := common.AsFloat(options["temperature"]); ok {
 		lowerModel := strings.ToLower(model)
 		// Kimi k2 models only support temperature=1.
 		if strings.Contains(lowerModel, "kimi") && strings.Contains(lowerModel, "k2") {
@@ -185,275 +168,11 @@ func (p *Provider) Chat(
 	}
 	defer resp.Body.Close()

-	contentType := resp.Header.Get("Content-Type")
-
-	// Non-200: read a prefix to tell HTML error page apart from JSON error body.
 	if resp.StatusCode != http.StatusOK {
-		body, readErr := io.ReadAll(io.LimitReader(resp.Body, 256))
-		if readErr != nil {
-			return nil, fmt.Errorf("failed to read response: %w", readErr)
-		}
-		if looksLikeHTML(body, contentType) {
-			return nil, wrapHTMLResponseError(resp.StatusCode, body, contentType, p.apiBase)
-		}
-		return nil, fmt.Errorf(
-			"API request failed:\n  Status: %d\n  Body:   %s",
-			resp.StatusCode,
-			responsePreview(body, 128),
-		)
+		return nil, common.HandleErrorResponse(resp, p.apiBase)
 	}

-	// Peek without consuming so the full stream reaches the JSON decoder.
-	reader := bufio.NewReader(resp.Body)
-	prefix, err := reader.Peek(256) // io.EOF/ErrBufferFull are normal; only real errors abort
-	if err != nil && err != io.EOF && err != bufio.ErrBufferFull {
-		return nil, fmt.Errorf("failed to inspect response: %w", err)
-	}
-	if looksLikeHTML(prefix, contentType) {
-		return nil, wrapHTMLResponseError(resp.StatusCode, prefix, contentType, p.apiBase)
-	}
-
-	out, err := parseResponse(reader)
-	if err != nil {
-		return nil, fmt.Errorf("failed to parse JSON response: %w", err)
-	}
-
-	return out, nil
-}
-
-func wrapHTMLResponseError(statusCode int, body []byte, contentType, apiBase string) error {
-	respPreview := responsePreview(body, 128)
-	return fmt.Errorf(
-		"API request failed: %s returned HTML instead of JSON (content-type: %s); check api_base or proxy configuration.\n  Status: %d\n  Body:   %s",
-		apiBase,
-		contentType,
-		statusCode,
-		respPreview,
-	)
-}
-
-func looksLikeHTML(body []byte, contentType string) bool {
-	contentType = strings.ToLower(strings.TrimSpace(contentType))
-	if strings.Contains(contentType, "text/html") || strings.Contains(contentType, "application/xhtml+xml") {
-		return true
-	}
-	prefix := bytes.ToLower(leadingTrimmedPrefix(body, 128))
-	return bytes.HasPrefix(prefix, []byte("<!doctype html")) ||
-		bytes.HasPrefix(prefix, []byte("<html")) ||
-		bytes.HasPrefix(prefix, []byte("<head")) ||
-		bytes.HasPrefix(prefix, []byte("<body"))
-}
-
-func leadingTrimmedPrefix(body []byte, maxLen int) []byte {
-	i := 0
-	for i < len(body) {
-		switch body[i] {
-		case ' ', '\t', '\n', '\r', '\f', '\v':
-			i++
-		default:
-			end := i + maxLen
-			if end > len(body) {
-				end = len(body)
-			}
-			return body[i:end]
-		}
-	}
-	return nil
-}
-
-func responsePreview(body []byte, maxLen int) string {
-	trimmed := bytes.TrimSpace(body)
-	if len(trimmed) == 0 {
-		return "<empty>"
-	}
-	if len(trimmed) <= maxLen {
-		return string(trimmed)
-	}
-	return string(trimmed[:maxLen]) + "..."
-}
-
-func parseResponse(body io.Reader) (*LLMResponse, error) {
-	var apiResponse struct {
-		Choices []struct {
-			Message struct {
-				Content          string            `json:"content"`
-				ReasoningContent string            `json:"reasoning_content"`
-				Reasoning        string            `json:"reasoning"`
-				ReasoningDetails []ReasoningDetail `json:"reasoning_details"`
-				ToolCalls        []struct {
-					ID       string `json:"id"`
-					Type     string `json:"type"`
-					Function *struct {
-						Name      string          `json:"name"`
-						Arguments json.RawMessage `json:"arguments"`
-					} `json:"function"`
-					ExtraContent *struct {
-						Google *struct {
-							ThoughtSignature string `json:"thought_signature"`
-						} `json:"google"`
-					} `json:"extra_content"`
-				} `json:"tool_calls"`
-			} `json:"message"`
-			FinishReason string `json:"finish_reason"`
-		} `json:"choices"`
-		Usage *UsageInfo `json:"usage"`
-	}
-
-	if err := json.NewDecoder(body).Decode(&apiResponse); err != nil {
-		return nil, fmt.Errorf("failed to decode response: %w", err)
-	}
-
-	if len(apiResponse.Choices) == 0 {
-		return &LLMResponse{
-			Content:      "",
-			FinishReason: "stop",
-		}, nil
-	}
-
-	choice := apiResponse.Choices[0]
-	toolCalls := make([]ToolCall, 0, len(choice.Message.ToolCalls))
-	for _, tc := range choice.Message.ToolCalls {
-		arguments := make(map[string]any)
-		name := ""
-
-		// Extract thought_signature from Gemini/Google-specific extra content
-		thoughtSignature := ""
-		if tc.ExtraContent != nil && tc.ExtraContent.Google != nil {
-			thoughtSignature = tc.ExtraContent.Google.ThoughtSignature
-		}
-
-		if tc.Function != nil {
-			name = tc.Function.Name
-			arguments = decodeToolCallArguments(tc.Function.Arguments, name)
-		}
-
-		// Build ToolCall with ExtraContent for Gemini 3 thought_signature persistence
-		toolCall := ToolCall{
-			ID:               tc.ID,
-			Name:             name,
-			Arguments:        arguments,
-			ThoughtSignature: thoughtSignature,
-		}
-
-		if thoughtSignature != "" {
-			toolCall.ExtraContent = &ExtraContent{
-				Google: &GoogleExtra{
-					ThoughtSignature: thoughtSignature,
-				},
-			}
-		}
-
-		toolCalls = append(toolCalls, toolCall)
-	}
-
-	return &LLMResponse{
-		Content:          choice.Message.Content,
-		ReasoningContent: choice.Message.ReasoningContent,
-		Reasoning:        choice.Message.Reasoning,
-		ReasoningDetails: choice.Message.ReasoningDetails,
-		ToolCalls:        toolCalls,
-		FinishReason:     choice.FinishReason,
-		Usage:            apiResponse.Usage,
-	}, nil
-}
-
-func decodeToolCallArguments(raw json.RawMessage, name string) map[string]any {
-	arguments := make(map[string]any)
-	raw = bytes.TrimSpace(raw)
-	if len(raw) == 0 || bytes.Equal(raw, []byte("null")) {
-		return arguments
-	}
-
-	var decoded any
-	if err := json.Unmarshal(raw, &decoded); err != nil {
-		log.Printf("openai_compat: failed to decode tool call arguments payload for %q: %v", name, err)
-		arguments["raw"] = string(raw)
-		return arguments
-	}
-
-	switch v := decoded.(type) {
-	case string:
-		if strings.TrimSpace(v) == "" {
-			return arguments
-		}
-		if err := json.Unmarshal([]byte(v), &arguments); err != nil {
-			log.Printf("openai_compat: failed to decode tool call arguments for %q: %v", name, err)
-			arguments["raw"] = v
-		}
-		return arguments
-	case map[string]any:
-		return v
-	default:
-		log.Printf("openai_compat: unsupported tool call arguments type for %q: %T", name, decoded)
-		arguments["raw"] = string(raw)
-		return arguments
-	}
-}
-
-// openaiMessage is the wire-format message for OpenAI-compatible APIs.
-// It mirrors protocoltypes.Message but omits SystemParts, which is an
-// internal field that would be unknown to third-party endpoints.
-type openaiMessage struct {
-	Role             string     `json:"role"`
-	Content          string     `json:"content"`
-	ReasoningContent string     `json:"reasoning_content,omitempty"`
-	ToolCalls        []ToolCall `json:"tool_calls,omitempty"`
-	ToolCallID       string     `json:"tool_call_id,omitempty"`
-}
-
-// serializeMessages converts internal Message structs to the OpenAI wire format.
-// - Strips SystemParts (unknown to third-party endpoints)
-// - Converts messages with Media to multipart content format (text + image_url parts)
-// - Preserves ToolCallID, ToolCalls, and ReasoningContent for all messages
-func serializeMessages(messages []Message) []any {
-	out := make([]any, 0, len(messages))
-	for _, m := range messages {
-		if len(m.Media) == 0 {
-			out = append(out, openaiMessage{
-				Role:             m.Role,
-				Content:          m.Content,
-				ReasoningContent: m.ReasoningContent,
-				ToolCalls:        m.ToolCalls,
-				ToolCallID:       m.ToolCallID,
-			})
-			continue
-		}
-
-		// Multipart content format for messages with media
-		parts := make([]map[string]any, 0, 1+len(m.Media))
-		if m.Content != "" {
-			parts = append(parts, map[string]any{
-				"type": "text",
-				"text": m.Content,
-			})
-		}
-		for _, mediaURL := range m.Media {
-			if strings.HasPrefix(mediaURL, "data:image/") {
-				parts = append(parts, map[string]any{
-					"type": "image_url",
-					"image_url": map[string]any{
-						"url": mediaURL,
-					},
-				})
-			}
-		}
-
-		msg := map[string]any{
-			"role":    m.Role,
-			"content": parts,
-		}
-		if m.ToolCallID != "" {
-			msg["tool_call_id"] = m.ToolCallID
-		}
-		if len(m.ToolCalls) > 0 {
-			msg["tool_calls"] = m.ToolCalls
-		}
-		if m.ReasoningContent != "" {
-			msg["reasoning_content"] = m.ReasoningContent
-		}
-		out = append(out, msg)
-	}
-	return out
+	return common.ReadAndParseResponse(resp, p.apiBase)
 }

 func normalizeModel(model, apiBase string) string {
@@ -476,36 +195,6 @@ func normalizeModel(model, apiBase string) string {
 	}
 }

-func asInt(v any) (int, bool) {
-	switch val := v.(type) {
-	case int:
-		return val, true
-	case int64:
-		return int(val), true
-	case float64:
-		return int(val), true
-	case float32:
-		return int(val), true
-	default:
-		return 0, false
-	}
-}
-
-func asFloat(v any) (float64, bool) {
-	switch val := v.(type) {
-	case float64:
-		return val, true
-	case float32:
-		return float64(val), true
-	case int:
-		return float64(val), true
-	case int64:
-		return float64(val), true
-	default:
-		return 0, false
-	}
-}
-
 // supportsPromptCacheKey reports whether the given API base is known to
 // support the prompt_cache_key request field. Currently only OpenAI's own
 // API and Azure OpenAI support this. All other OpenAI-compatible providers
@@ -12,6 +12,7 @@ import (
 	"testing"
 	"time"

+	"github.com/sipeed/picoclaw/pkg/providers/common"
 	"github.com/sipeed/picoclaw/pkg/providers/protocoltypes"
 )

@@ -648,7 +649,7 @@ func TestSerializeMessages_PlainText(t *testing.T) {
 		{Role: "user", Content: "hello"},
 		{Role: "assistant", Content: "hi", ReasoningContent: "thinking..."},
 	}
-	result := serializeMessages(messages)
+	result := common.SerializeMessages(messages)

 	data, err := json.Marshal(result)
 	if err != nil {
@@ -670,7 +671,7 @@ func TestSerializeMessages_WithMedia(t *testing.T) {
 	messages := []protocoltypes.Message{
 		{Role: "user", Content: "describe this", Media: []string{"data:image/png;base64,abc123"}},
 	}
-	result := serializeMessages(messages)
+	result := common.SerializeMessages(messages)

 	data, _ := json.Marshal(result)
 	var msgs []map[string]any
@@ -703,7 +704,7 @@ func TestSerializeMessages_MediaWithToolCallID(t *testing.T) {
 	messages := []protocoltypes.Message{
 		{Role: "tool", Content: "image result", Media: []string{"data:image/png;base64,xyz"}, ToolCallID: "call_1"},
 	}
-	result := serializeMessages(messages)
+	result := common.SerializeMessages(messages)

 	data, _ := json.Marshal(result)
 	var msgs []map[string]any
@@ -833,7 +834,7 @@ func TestSerializeMessages_StripsSystemParts(t *testing.T) {
 			},
 		},
 	}
-	result := serializeMessages(messages)
+	result := common.SerializeMessages(messages)

 	data, _ := json.Marshal(result)
 	raw := string(data)