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
@@ -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")
+	}
+}