fix(gemini): harden dedicated provider compatibility

pkg/providers/factory_provider.go

@@ -114,7 +114,7 @@ func ResolveAPIBase(cfg *config.ModelConfig) string {
 
 // CreateProviderFromConfig creates a provider based on the ModelConfig.
 // It uses the protocol prefix in the Model field to determine which provider to create.
-// Supported protocol families include OpenAI-compatible prefixes (e.g., openai, openrouter, groq, gemini),
+// Supported protocol families include OpenAI-compatible prefixes (e.g., openai, openrouter, groq),
 // Azure OpenAI, Amazon Bedrock, Anthropic (including messages), and various CLI/compatibility shims.
 // See the switch on protocol in this function for the authoritative list.
 // Returns the provider, the model ID (without protocol prefix), and any error.
@@ -218,7 +218,7 @@ func CreateProviderFromConfig(cfg *config.ModelConfig) (LLMProvider, string, err
 		}
 		return provider, modelID, nil
 
-	case "litellm", "lmstudio", "openrouter", "groq", "zhipu", "gemini", "nvidia", "venice",
+	case "litellm", "lmstudio", "openrouter", "groq", "zhipu", "nvidia", "venice",
 		"ollama", "moonshot", "shengsuanyun", "deepseek", "cerebras",
 		"vivgrid", "volcengine", "vllm", "qwen", "qwen-intl", "qwen-international", "dashscope-intl",
 		"qwen-us", "dashscope-us", "mistral", "avian", "longcat", "modelscope", "novita",
@@ -242,6 +242,24 @@ func CreateProviderFromConfig(cfg *config.ModelConfig) (LLMProvider, string, err
 			cfg.CustomHeaders,
 		), modelID, nil
 
+	case "gemini":
+		if cfg.APIKey() == "" && cfg.APIBase == "" {
+			return nil, "", fmt.Errorf("api_key or api_base is required for gemini protocol (model: %s)", cfg.Model)
+		}
+		apiBase := cfg.APIBase
+		if apiBase == "" {
+			apiBase = getDefaultAPIBase(protocol)
+		}
+		return NewGeminiProvider(
+			cfg.APIKey(),
+			apiBase,
+			cfg.Proxy,
+			userAgent,
+			cfg.RequestTimeout,
+			cfg.ExtraBody,
+			cfg.CustomHeaders,
+		), modelID, nil
+
 	case "minimax":
 		// Minimax requires reasoning_split: true in the request body
 		if cfg.APIKey() == "" && cfg.APIBase == "" {

pkg/providers/factory_provider_test.go

@@ -434,6 +434,62 @@ func TestCreateProviderFromConfig_Antigravity(t *testing.T) {
 	}
 }
 
+func TestCreateProviderFromConfig_Gemini(t *testing.T) {
+	cfg := &config.ModelConfig{
+		ModelName: "test-gemini",
+		Model:     "gemini/gemini-2.5-flash",
+	}
+	cfg.SetAPIKey("test-key")
+
+	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 != "gemini-2.5-flash" {
+		t.Errorf("modelID = %q, want %q", modelID, "gemini-2.5-flash")
+	}
+	if _, ok := provider.(*GeminiProvider); !ok {
+		t.Fatalf("expected *GeminiProvider, got %T", provider)
+	}
+}
+
+func TestCreateProviderFromConfig_GeminiMissingAPIKey(t *testing.T) {
+	cfg := &config.ModelConfig{
+		ModelName: "test-gemini-no-key",
+		Model:     "gemini/gemini-2.5-flash",
+	}
+
+	_, _, err := CreateProviderFromConfig(cfg)
+	if err == nil {
+		t.Fatal("CreateProviderFromConfig() expected error for missing gemini API key")
+	}
+}
+
+func TestCreateProviderFromConfig_GeminiCustomAPIBaseWithoutKey(t *testing.T) {
+	cfg := &config.ModelConfig{
+		ModelName: "test-gemini-custom-base",
+		Model:     "gemini/gemini-2.5-flash",
+		APIBase:   "https://proxy.example.com/v1beta",
+	}
+
+	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 != "gemini-2.5-flash" {
+		t.Errorf("modelID = %q, want %q", modelID, "gemini-2.5-flash")
+	}
+	if _, ok := provider.(*GeminiProvider); !ok {
+		t.Fatalf("expected *GeminiProvider, got %T", provider)
+	}
+}
+
 func TestCreateProviderFromConfig_ClaudeCLI(t *testing.T) {
 	cfg := &config.ModelConfig{
 		ModelName: "test-claude-cli",

pkg/providers/gemini_provider.go

@@ -0,0 +1,758 @@
+package providers
+
+import (
+	"bufio"
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+	"time"
+
+	"github.com/sipeed/picoclaw/pkg/providers/common"
+)
+
+const (
+	geminiDefaultAPIBase = "https://generativelanguage.googleapis.com/v1beta"
+	geminiDefaultModel   = "gemini-2.0-flash"
+)
+
+type GeminiProvider struct {
+	apiKey        string
+	apiBase       string
+	httpClient    *http.Client
+	extraBody     map[string]any
+	customHeaders map[string]string
+	userAgent     string
+}
+
+func NewGeminiProvider(
+	apiKey string,
+	apiBase string,
+	proxy string,
+	userAgent string,
+	requestTimeoutSeconds int,
+	extraBody map[string]any,
+	customHeaders map[string]string,
+) *GeminiProvider {
+	if strings.TrimSpace(apiBase) == "" {
+		apiBase = geminiDefaultAPIBase
+	}
+	client := common.NewHTTPClient(proxy)
+	if requestTimeoutSeconds > 0 {
+		client.Timeout = time.Duration(requestTimeoutSeconds) * time.Second
+	}
+
+	return &GeminiProvider{
+		apiKey:        strings.TrimSpace(apiKey),
+		apiBase:       strings.TrimRight(strings.TrimSpace(apiBase), "/"),
+		httpClient:    client,
+		extraBody:     cloneAnyMap(extraBody),
+		customHeaders: cloneStringMap(customHeaders),
+		userAgent:     strings.TrimSpace(userAgent),
+	}
+}
+
+func (p *GeminiProvider) GetDefaultModel() string {
+	return geminiDefaultModel
+}
+
+func (p *GeminiProvider) SupportsThinking() bool {
+	return true
+}
+
+func (p *GeminiProvider) Chat(
+	ctx context.Context,
+	messages []Message,
+	tools []ToolDefinition,
+	model string,
+	options map[string]any,
+) (*LLMResponse, error) {
+	if p.apiBase == "" {
+		return nil, fmt.Errorf("API base not configured")
+	}
+
+	model = normalizeGeminiModel(model)
+	requestBody := p.buildRequestBody(messages, tools, model, options)
+	jsonData, err := json.Marshal(requestBody)
+	if err != nil {
+		return nil, fmt.Errorf("failed to marshal request: %w", err)
+	}
+
+	url := fmt.Sprintf("%s/models/%s:generateContent", p.apiBase, model)
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewReader(jsonData))
+	if err != nil {
+		return nil, fmt.Errorf("failed to create request: %w", err)
+	}
+
+	p.applyHeaders(req)
+
+	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)
+	}
+
+	var apiResp geminiGenerateContentResponse
+	if err := json.NewDecoder(resp.Body).Decode(&apiResp); err != nil {
+		return nil, fmt.Errorf("failed to decode response: %w", err)
+	}
+
+	return parseGeminiResponse(&apiResp), nil
+}
+
+func (p *GeminiProvider) ChatStream(
+	ctx context.Context,
+	messages []Message,
+	tools []ToolDefinition,
+	model string,
+	options map[string]any,
+	onChunk func(accumulated string),
+) (*LLMResponse, error) {
+	if p.apiBase == "" {
+		return nil, fmt.Errorf("API base not configured")
+	}
+
+	model = normalizeGeminiModel(model)
+	requestBody := p.buildRequestBody(messages, tools, model, options)
+	jsonData, err := json.Marshal(requestBody)
+	if err != nil {
+		return nil, fmt.Errorf("failed to marshal request: %w", err)
+	}
+
+	url := fmt.Sprintf("%s/models/%s:streamGenerateContent?alt=sse", p.apiBase, model)
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewReader(jsonData))
+	if err != nil {
+		return nil, fmt.Errorf("failed to create request: %w", err)
+	}
+
+	p.applyHeaders(req)
+	req.Header.Set("Accept", "text/event-stream")
+
+	// Streaming should not use a whole-request timeout; context cancellation is the guard.
+	streamClient := &http.Client{Transport: p.httpClient.Transport}
+	resp, err := streamClient.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 parseGeminiStreamResponse(ctx, resp.Body, onChunk)
+}
+
+func (p *GeminiProvider) applyHeaders(req *http.Request) {
+	req.Header.Set("Content-Type", "application/json")
+	if p.apiKey != "" {
+		req.Header.Set("x-goog-api-key", p.apiKey)
+	}
+	if p.userAgent != "" {
+		req.Header.Set("User-Agent", p.userAgent)
+	}
+	for k, v := range p.customHeaders {
+		if strings.TrimSpace(k) == "" {
+			continue
+		}
+		req.Header.Set(k, v)
+	}
+}
+
+func (p *GeminiProvider) buildRequestBody(
+	messages []Message,
+	tools []ToolDefinition,
+	model string,
+	options map[string]any,
+) map[string]any {
+	contents := make([]geminiContent, 0, len(messages))
+	toolCallNames := make(map[string]string)
+	var systemInstruction *geminiContent
+
+	for _, msg := range messages {
+		switch msg.Role {
+		case "system":
+			if strings.TrimSpace(msg.Content) != "" {
+				systemInstruction = &geminiContent{Parts: []geminiPart{{Text: msg.Content}}}
+			}
+
+		case "user":
+			if msg.ToolCallID != "" {
+				toolName := resolveToolResponseName(msg.ToolCallID, toolCallNames)
+				contents = append(contents, geminiContent{
+					Role: "user",
+					Parts: []geminiPart{{
+						FunctionResponse: buildGeminiFunctionResponse(toolName, msg.ToolCallID, msg.Content, msg.Media),
+					}},
+				})
+				continue
+			}
+
+			parts := make([]geminiPart, 0, 1+len(msg.Media))
+			if strings.TrimSpace(msg.Content) != "" {
+				parts = append(parts, geminiPart{Text: msg.Content})
+			}
+			parts = append(parts, buildInlineMediaParts(msg.Media)...)
+			if len(parts) > 0 {
+				contents = append(contents, geminiContent{Role: "user", Parts: parts})
+			}
+
+		case "assistant":
+			content := geminiContent{Role: "model"}
+			if strings.TrimSpace(msg.Content) != "" {
+				content.Parts = append(content.Parts, geminiPart{Text: msg.Content})
+			}
+			for _, tc := range msg.ToolCalls {
+				toolName, toolArgs, thoughtSignature := normalizeStoredToolCall(tc)
+				if toolName == "" {
+					continue
+				}
+				if tc.ID != "" {
+					toolCallNames[tc.ID] = toolName
+				}
+				part := geminiPart{
+					FunctionCall: &geminiFunctionCall{
+						Name: toolName,
+						Args: toolArgs,
+						ID:   tc.ID,
+					},
+				}
+				if thoughtSignature != "" {
+					part.ThoughtSignature = thoughtSignature
+					part.ThoughtSignatureSnake = thoughtSignature
+				}
+				content.Parts = append(content.Parts, part)
+			}
+			if len(content.Parts) > 0 {
+				contents = append(contents, content)
+			}
+
+		case "tool":
+			toolName := resolveToolResponseName(msg.ToolCallID, toolCallNames)
+			contents = append(contents, geminiContent{
+				Role: "user",
+				Parts: []geminiPart{{
+					FunctionResponse: buildGeminiFunctionResponse(toolName, msg.ToolCallID, msg.Content, msg.Media),
+				}},
+			})
+		}
+	}
+
+	body := map[string]any{
+		"contents": contents,
+	}
+	if systemInstruction != nil {
+		body["systemInstruction"] = systemInstruction
+	}
+
+	if len(tools) > 0 {
+		funcDecls := make([]geminiFunctionDeclaration, 0, len(tools))
+		for _, t := range tools {
+			if t.Type != "function" {
+				continue
+			}
+			funcDecls = append(funcDecls, geminiFunctionDeclaration{
+				Name:        t.Function.Name,
+				Description: t.Function.Description,
+				Parameters:  sanitizeSchemaForGemini(t.Function.Parameters),
+			})
+		}
+		if len(funcDecls) > 0 {
+			body["tools"] = []geminiTool{{FunctionDeclarations: funcDecls}}
+		}
+	}
+
+	generationConfig := make(map[string]any)
+	if val, ok := options["max_tokens"]; ok {
+		if maxTokens, ok := val.(int); ok && maxTokens > 0 {
+			generationConfig["maxOutputTokens"] = maxTokens
+		} else if maxTokens, ok := val.(float64); ok && maxTokens > 0 {
+			generationConfig["maxOutputTokens"] = int(maxTokens)
+		}
+	}
+	if temp, ok := options["temperature"].(float64); ok {
+		generationConfig["temperature"] = temp
+	}
+
+	if thinkingConfig := buildGeminiThinkingConfig(model, options); len(thinkingConfig) > 0 {
+		generationConfig["thinkingConfig"] = thinkingConfig
+	}
+
+	if len(generationConfig) > 0 {
+		body["generationConfig"] = generationConfig
+	}
+
+	for k, v := range p.extraBody {
+		body[k] = v
+	}
+
+	return body
+}
+
+func normalizeGeminiModel(model string) string {
+	model = strings.TrimSpace(model)
+	model = strings.TrimPrefix(model, "models/")
+	if strings.Contains(model, "/") {
+		_, modelID := ExtractProtocol(model)
+		if modelID != "" {
+			return modelID
+		}
+	}
+	if model == "" {
+		return geminiDefaultModel
+	}
+	return model
+}
+
+func mapGeminiThinkingLevel(level string) string {
+	switch strings.ToLower(strings.TrimSpace(level)) {
+	case "minimal", "off":
+		return "minimal"
+	case "low":
+		return "low"
+	case "medium":
+		return "medium"
+	case "high", "xhigh", "adaptive":
+		return "high"
+	default:
+		return ""
+	}
+}
+
+func buildGeminiThinkingConfig(model string, options map[string]any) map[string]any {
+	if !geminiModelSupportsThinkingConfig(model) {
+		return nil
+	}
+
+	config := map[string]any{"includeThoughts": true}
+	rawLevel, _ := options["thinking_level"].(string)
+	rawLevel = strings.ToLower(strings.TrimSpace(rawLevel))
+
+	if isGemini25Model(model) {
+		if budget, ok := mapGeminiThinkingBudget(rawLevel, model); ok {
+			config["thinkingBudget"] = budget
+		}
+		return config
+	}
+
+	if thinkingLevel := mapGeminiThinkingLevel(rawLevel); thinkingLevel != "" {
+		config["thinkingLevel"] = thinkingLevel
+	}
+	return config
+}
+
+func geminiModelSupportsThinkingConfig(model string) bool {
+	lowerModel := strings.ToLower(strings.TrimSpace(model))
+	return strings.Contains(lowerModel, "gemini-3") || isGemini25Model(lowerModel)
+}
+
+func isGemini25Model(model string) bool {
+	lowerModel := strings.ToLower(strings.TrimSpace(model))
+	return strings.Contains(lowerModel, "gemini-2.5") || strings.Contains(lowerModel, "gemini-25")
+}
+
+func mapGeminiThinkingBudget(level string, model string) (int, bool) {
+	level = strings.ToLower(strings.TrimSpace(level))
+	if level == "" {
+		return 0, false
+	}
+
+	switch level {
+	case "adaptive":
+		return -1, true
+	case "minimal":
+		if strings.Contains(strings.ToLower(model), "pro") {
+			return 128, true
+		}
+		return 0, true
+	case "off":
+		if strings.Contains(strings.ToLower(model), "pro") {
+			// Gemini 2.5 Pro cannot disable thinking; use the lowest supported budget.
+			return 128, true
+		}
+		return 0, true
+	case "low":
+		return 1024, true
+	case "medium":
+		return 4096, true
+	case "high":
+		return 8192, true
+	case "xhigh":
+		return 16384, true
+	default:
+		return 0, false
+	}
+}
+
+func parseGeminiResponse(resp *geminiGenerateContentResponse) *LLMResponse {
+	contentParts := make([]string, 0)
+	reasoningParts := make([]string, 0)
+	toolCalls := make([]ToolCall, 0)
+	finishReason := ""
+
+	for _, candidate := range resp.Candidates {
+		for _, part := range candidate.Content.Parts {
+			if part.Text != "" {
+				if part.Thought {
+					reasoningParts = append(reasoningParts, part.Text)
+				} else {
+					contentParts = append(contentParts, part.Text)
+				}
+			}
+			if part.FunctionCall != nil {
+				toolCalls = append(toolCalls, buildGeminiToolCall(part))
+			}
+		}
+		if candidate.FinishReason != "" {
+			finishReason = candidate.FinishReason
+		}
+	}
+
+	var usage *UsageInfo
+	if resp.UsageMetadata.TotalTokenCount > 0 {
+		usage = &UsageInfo{
+			PromptTokens:     resp.UsageMetadata.PromptTokenCount,
+			CompletionTokens: resp.UsageMetadata.CandidatesTokenCount,
+			TotalTokens:      resp.UsageMetadata.TotalTokenCount,
+		}
+	}
+
+	return &LLMResponse{
+		Content:          strings.Join(contentParts, ""),
+		ReasoningContent: strings.Join(reasoningParts, ""),
+		ToolCalls:        toolCalls,
+		FinishReason:     normalizeGeminiFinishReason(finishReason, len(toolCalls)),
+		Usage:            usage,
+	}
+}
+
+func parseGeminiStreamResponse(
+	ctx context.Context,
+	reader io.Reader,
+	onChunk func(accumulated string),
+) (*LLMResponse, error) {
+	var contentBuilder strings.Builder
+	var reasoningBuilder strings.Builder
+	var finishReason string
+	var usage *UsageInfo
+
+	toolCallsByID := make(map[string]ToolCall)
+	toolCallOrder := make([]string, 0)
+	fallbackIndex := 0
+
+	scanner := bufio.NewScanner(reader)
+	scanner.Buffer(make([]byte, 0, 1024*1024), 10*1024*1024)
+	for scanner.Scan() {
+		if err := ctx.Err(); err != nil {
+			return nil, err
+		}
+
+		line := scanner.Text()
+		if !strings.HasPrefix(line, "data: ") {
+			continue
+		}
+		data := strings.TrimPrefix(line, "data: ")
+		if data == "[DONE]" {
+			break
+		}
+
+		var chunk geminiGenerateContentResponse
+		if err := json.Unmarshal([]byte(data), &chunk); err != nil {
+			continue
+		}
+
+		for _, candidate := range chunk.Candidates {
+			for _, part := range candidate.Content.Parts {
+				if part.Text != "" {
+					if part.Thought {
+						reasoningBuilder.WriteString(part.Text)
+					} else {
+						contentBuilder.WriteString(part.Text)
+						if onChunk != nil {
+							onChunk(contentBuilder.String())
+						}
+					}
+				}
+				if part.FunctionCall != nil {
+					tc := buildGeminiToolCall(part)
+					key := tc.ID
+					if strings.TrimSpace(key) == "" {
+						fallbackIndex++
+						key = fmt.Sprintf("%s#%d", tc.Name, fallbackIndex)
+						tc.ID = key
+					}
+					if _, exists := toolCallsByID[key]; !exists {
+						toolCallOrder = append(toolCallOrder, key)
+					}
+					toolCallsByID[key] = tc
+				}
+			}
+			if candidate.FinishReason != "" {
+				finishReason = candidate.FinishReason
+			}
+		}
+
+		if chunk.UsageMetadata.TotalTokenCount > 0 {
+			usage = &UsageInfo{
+				PromptTokens:     chunk.UsageMetadata.PromptTokenCount,
+				CompletionTokens: chunk.UsageMetadata.CandidatesTokenCount,
+				TotalTokens:      chunk.UsageMetadata.TotalTokenCount,
+			}
+		}
+	}
+
+	if err := scanner.Err(); err != nil {
+		return nil, fmt.Errorf("streaming read error: %w", err)
+	}
+
+	toolCalls := make([]ToolCall, 0, len(toolCallOrder))
+	for _, key := range toolCallOrder {
+		toolCalls = append(toolCalls, toolCallsByID[key])
+	}
+
+	return &LLMResponse{
+		Content:          contentBuilder.String(),
+		ReasoningContent: reasoningBuilder.String(),
+		ToolCalls:        toolCalls,
+		FinishReason:     normalizeGeminiFinishReason(finishReason, len(toolCalls)),
+		Usage:            usage,
+	}, nil
+}
+
+func normalizeGeminiFinishReason(reason string, toolCalls int) string {
+	if toolCalls > 0 {
+		return "tool_calls"
+	}
+
+	switch strings.ToUpper(strings.TrimSpace(reason)) {
+	case "MAX_TOKENS":
+		return "length"
+	case "", "STOP":
+		return "stop"
+	default:
+		return strings.ToLower(strings.TrimSpace(reason))
+	}
+}
+
+func buildGeminiToolCall(part geminiPart) ToolCall {
+	if part.FunctionCall == nil {
+		return ToolCall{}
+	}
+
+	args := part.FunctionCall.Args
+	if args == nil {
+		args = make(map[string]any)
+	}
+	argsJSON, _ := json.Marshal(args)
+	thoughtSignature := extractPartThoughtSignature(part.ThoughtSignature, part.ThoughtSignatureSnake)
+
+	toolCall := ToolCall{
+		ID:               part.FunctionCall.ID,
+		Name:             part.FunctionCall.Name,
+		Arguments:        args,
+		ThoughtSignature: thoughtSignature,
+		Function: &FunctionCall{
+			Name:             part.FunctionCall.Name,
+			Arguments:        string(argsJSON),
+			ThoughtSignature: thoughtSignature,
+		},
+	}
+
+	if thoughtSignature != "" {
+		toolCall.ExtraContent = &ExtraContent{
+			Google: &GoogleExtra{ThoughtSignature: thoughtSignature},
+		}
+	}
+	if strings.TrimSpace(toolCall.ID) == "" {
+		toolCall.ID = fmt.Sprintf("call_%s_%d", toolCall.Name, time.Now().UnixNano())
+	}
+
+	return toolCall
+}
+
+func buildInlineMediaParts(media []string) []geminiPart {
+	parts := make([]geminiPart, 0, len(media))
+	for _, mediaURL := range media {
+		mimeType, data, ok := parseBase64DataURL(mediaURL)
+		if !ok {
+			continue
+		}
+		parts = append(parts, geminiPart{
+			InlineData: &geminiInlineData{
+				MIMEType: mimeType,
+				Data:     data,
+			},
+		})
+	}
+	return parts
+}
+
+func buildGeminiFunctionResponse(
+	toolName string,
+	toolCallID string,
+	result string,
+	media []string,
+) *geminiFunctionResponse {
+	response := &geminiFunctionResponse{
+		ID:   toolCallID,
+		Name: toolName,
+		Response: map[string]any{
+			"result": result,
+		},
+	}
+
+	if parts := buildFunctionResponseMediaParts(media); len(parts) > 0 {
+		response.Parts = parts
+	}
+
+	return response
+}
+
+func buildFunctionResponseMediaParts(media []string) []geminiFunctionResponsePart {
+	parts := make([]geminiFunctionResponsePart, 0, len(media))
+	for i, mediaURL := range media {
+		mimeType, data, ok := parseBase64DataURL(mediaURL)
+		if !ok {
+			continue
+		}
+		parts = append(parts, geminiFunctionResponsePart{
+			InlineData: &geminiInlineData{
+				MIMEType:    mimeType,
+				Data:        data,
+				DisplayName: defaultFunctionResponseDisplayName(mimeType, i+1),
+			},
+		})
+	}
+	return parts
+}
+
+func defaultFunctionResponseDisplayName(mimeType string, index int) string {
+	suffix := "bin"
+	switch strings.ToLower(strings.TrimSpace(mimeType)) {
+	case "image/png":
+		suffix = "png"
+	case "image/jpeg":
+		suffix = "jpg"
+	case "image/webp":
+		suffix = "webp"
+	case "application/pdf":
+		suffix = "pdf"
+	case "text/plain":
+		suffix = "txt"
+	}
+	return fmt.Sprintf("attachment-%d.%s", index, suffix)
+}
+
+func parseBase64DataURL(mediaURL string) (mimeType string, data string, ok bool) {
+	if !strings.HasPrefix(mediaURL, "data:") {
+		return "", "", false
+	}
+
+	payload := strings.TrimPrefix(mediaURL, "data:")
+	header, data, found := strings.Cut(payload, ",")
+	if !found {
+		return "", "", false
+	}
+	mimeType, params, _ := strings.Cut(header, ";")
+	mimeType = strings.TrimSpace(mimeType)
+	data = strings.TrimSpace(data)
+	if mimeType == "" || data == "" {
+		return "", "", false
+	}
+	if !strings.Contains(strings.ToLower(params), "base64") {
+		return "", "", false
+	}
+	return mimeType, data, true
+}
+
+func cloneAnyMap(in map[string]any) map[string]any {
+	if len(in) == 0 {
+		return nil
+	}
+	out := make(map[string]any, len(in))
+	for k, v := range in {
+		out[k] = v
+	}
+	return out
+}
+
+func cloneStringMap(in map[string]string) map[string]string {
+	if len(in) == 0 {
+		return nil
+	}
+	out := make(map[string]string, len(in))
+	for k, v := range in {
+		out[k] = v
+	}
+	return out
+}
+
+type geminiGenerateContentResponse struct {
+	Candidates []struct {
+		Content struct {
+			Role  string       `json:"role"`
+			Parts []geminiPart `json:"parts"`
+		} `json:"content"`
+		FinishReason string `json:"finishReason"`
+	} `json:"candidates"`
+	UsageMetadata struct {
+		PromptTokenCount     int `json:"promptTokenCount"`
+		CandidatesTokenCount int `json:"candidatesTokenCount"`
+		TotalTokenCount      int `json:"totalTokenCount"`
+	} `json:"usageMetadata"`
+}
+
+type geminiContent struct {
+	Role  string       `json:"role,omitempty"`
+	Parts []geminiPart `json:"parts"`
+}
+
+type geminiPart struct {
+	Text                  string                  `json:"text,omitempty"`
+	Thought               bool                    `json:"thought,omitempty"`
+	ThoughtSignature      string                  `json:"thoughtSignature,omitempty"`
+	ThoughtSignatureSnake string                  `json:"thought_signature,omitempty"`
+	InlineData            *geminiInlineData       `json:"inlineData,omitempty"`
+	FunctionCall          *geminiFunctionCall     `json:"functionCall,omitempty"`
+	FunctionResponse      *geminiFunctionResponse `json:"functionResponse,omitempty"`
+}
+
+type geminiInlineData struct {
+	MIMEType    string `json:"mimeType"`
+	Data        string `json:"data"`
+	DisplayName string `json:"displayName,omitempty"`
+}
+
+type geminiFunctionCall struct {
+	ID   string         `json:"id,omitempty"`
+	Name string         `json:"name"`
+	Args map[string]any `json:"args,omitempty"`
+}
+
+type geminiFunctionResponse struct {
+	ID       string                       `json:"id,omitempty"`
+	Name     string                       `json:"name"`
+	Response map[string]any               `json:"response"`
+	Parts    []geminiFunctionResponsePart `json:"parts,omitempty"`
+}
+
+type geminiFunctionResponsePart struct {
+	InlineData *geminiInlineData `json:"inlineData,omitempty"`
+}
+
+type geminiTool struct {
+	FunctionDeclarations []geminiFunctionDeclaration `json:"functionDeclarations"`
+}
+
+type geminiFunctionDeclaration struct {
+	Name        string `json:"name"`
+	Description string `json:"description,omitempty"`
+	Parameters  any    `json:"parameters,omitempty"`
+}

pkg/providers/gemini_provider_test.go

@@ -0,0 +1,440 @@
+package providers
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+)
+
+func TestGeminiProvider_ChatSeparatesThoughtAndToolCall(t *testing.T) {
+	var capturedBody map[string]any
+
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodPost {
+			t.Fatalf("method = %s, want POST", r.Method)
+		}
+		if !strings.Contains(r.URL.Path, ":generateContent") {
+			t.Fatalf("path = %s, expected generateContent endpoint", r.URL.Path)
+		}
+		if got := r.Header.Get("x-goog-api-key"); got != "test-key" {
+			t.Fatalf("x-goog-api-key = %q, want %q", got, "test-key")
+		}
+		if err := json.NewDecoder(r.Body).Decode(&capturedBody); err != nil {
+			t.Fatalf("decode request body: %v", err)
+		}
+
+		w.Header().Set("Content-Type", "application/json")
+		_ = json.NewEncoder(w).Encode(map[string]any{
+			"candidates": []any{
+				map[string]any{
+					"content": map[string]any{
+						"role": "model",
+						"parts": []any{
+							map[string]any{"text": "hidden", "thought": true},
+							map[string]any{"text": "visible"},
+							map[string]any{
+								"functionCall": map[string]any{
+									"id":   "call_1",
+									"name": "search",
+									"args": map[string]any{"q": "hi"},
+								},
+								"thoughtSignature": "sig-1",
+							},
+						},
+					},
+					"finishReason": "STOP",
+				},
+			},
+			"usageMetadata": map[string]any{
+				"promptTokenCount":     2,
+				"candidatesTokenCount": 3,
+				"totalTokenCount":      5,
+			},
+		})
+	}))
+	defer server.Close()
+
+	provider := NewGeminiProvider("test-key", server.URL, "", "picoclaw-test", 0, nil, nil)
+	resp, err := provider.Chat(
+		t.Context(),
+		[]Message{{Role: "user", Content: "hello"}},
+		nil,
+		"gemini-3-flash-preview",
+		map[string]any{"thinking_level": "high"},
+	)
+	if err != nil {
+		t.Fatalf("Chat() error = %v", err)
+	}
+	if resp.Content != "visible" {
+		t.Fatalf("Content = %q, want %q", resp.Content, "visible")
+	}
+	if resp.ReasoningContent != "hidden" {
+		t.Fatalf("ReasoningContent = %q, want %q", resp.ReasoningContent, "hidden")
+	}
+	if resp.FinishReason != "tool_calls" {
+		t.Fatalf("FinishReason = %q, want %q", resp.FinishReason, "tool_calls")
+	}
+	if resp.Usage == nil || resp.Usage.TotalTokens != 5 {
+		t.Fatalf("Usage = %#v, expected total tokens = 5", resp.Usage)
+	}
+	if len(resp.ToolCalls) != 1 {
+		t.Fatalf("ToolCalls len = %d, want 1", len(resp.ToolCalls))
+	}
+	if resp.ToolCalls[0].ID != "call_1" {
+		t.Fatalf("ToolCall ID = %q, want %q", resp.ToolCalls[0].ID, "call_1")
+	}
+	if resp.ToolCalls[0].Name != "search" {
+		t.Fatalf("ToolCall Name = %q, want %q", resp.ToolCalls[0].Name, "search")
+	}
+	if resp.ToolCalls[0].ThoughtSignature != "sig-1" {
+		t.Fatalf("ToolCall ThoughtSignature = %q, want %q", resp.ToolCalls[0].ThoughtSignature, "sig-1")
+	}
+	if resp.ToolCalls[0].Function == nil || !strings.Contains(resp.ToolCalls[0].Function.Arguments, `"q":"hi"`) {
+		t.Fatalf("ToolCall Function arguments = %#v, want q=hi", resp.ToolCalls[0].Function)
+	}
+
+	generationConfig, ok := capturedBody["generationConfig"].(map[string]any)
+	if !ok {
+		t.Fatalf("request missing generationConfig: %#v", capturedBody)
+	}
+	thinkingConfig, ok := generationConfig["thinkingConfig"].(map[string]any)
+	if !ok {
+		t.Fatalf("request missing thinkingConfig: %#v", generationConfig)
+	}
+	if includeThoughts, ok := thinkingConfig["includeThoughts"].(bool); !ok || !includeThoughts {
+		t.Fatalf("thinkingConfig.includeThoughts = %#v, want true", thinkingConfig["includeThoughts"])
+	}
+	if got := thinkingConfig["thinkingLevel"]; got != "high" {
+		t.Fatalf("thinkingConfig.thinkingLevel = %#v, want %q", got, "high")
+	}
+}
+
+func TestGeminiProvider_ChatStreamParsesThoughtTextAndToolCalls(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if !strings.Contains(r.URL.Path, ":streamGenerateContent") {
+			t.Fatalf("path = %s, expected streamGenerateContent endpoint", r.URL.Path)
+		}
+		if got := r.URL.Query().Get("alt"); got != "sse" {
+			t.Fatalf("alt query = %q, want %q", got, "sse")
+		}
+
+		w.Header().Set("Content-Type", "text/event-stream")
+		flusher, ok := w.(http.Flusher)
+		if !ok {
+			t.Fatal("response writer is not flushable")
+		}
+
+		chunks := []map[string]any{
+			{
+				"candidates": []any{map[string]any{
+					"content": map[string]any{
+						"parts": []any{
+							map[string]any{"text": "think ", "thought": true},
+							map[string]any{"text": "Hello "},
+						},
+					},
+				}},
+			},
+			{
+				"candidates": []any{map[string]any{
+					"content": map[string]any{
+						"parts": []any{
+							map[string]any{"text": "World"},
+							map[string]any{
+								"functionCall": map[string]any{
+									"id":   "call_stream",
+									"name": "search",
+									"args": map[string]any{"q": "stream"},
+								},
+							},
+						},
+					},
+					"finishReason": "STOP",
+				}},
+				"usageMetadata": map[string]any{
+					"promptTokenCount":     1,
+					"candidatesTokenCount": 2,
+					"totalTokenCount":      3,
+				},
+			},
+		}
+
+		for _, chunk := range chunks {
+			raw, err := json.Marshal(chunk)
+			if err != nil {
+				t.Fatalf("marshal chunk: %v", err)
+			}
+			if _, err := fmt.Fprintf(w, "data: %s\n\n", raw); err != nil {
+				t.Fatalf("write chunk: %v", err)
+			}
+			flusher.Flush()
+		}
+		_, _ = fmt.Fprint(w, "data: [DONE]\n\n")
+		flusher.Flush()
+	}))
+	defer server.Close()
+
+	provider := NewGeminiProvider("test-key", server.URL, "", "", 0, nil, nil)
+	updates := make([]string, 0)
+	resp, err := provider.ChatStream(
+		t.Context(),
+		[]Message{{Role: "user", Content: "hello"}},
+		nil,
+		"gemini-2.5-flash",
+		nil,
+		func(accumulated string) {
+			updates = append(updates, accumulated)
+		},
+	)
+	if err != nil {
+		t.Fatalf("ChatStream() error = %v", err)
+	}
+	if resp.Content != "Hello World" {
+		t.Fatalf("Content = %q, want %q", resp.Content, "Hello World")
+	}
+	if resp.ReasoningContent != "think " {
+		t.Fatalf("ReasoningContent = %q, want %q", resp.ReasoningContent, "think ")
+	}
+	if len(resp.ToolCalls) != 1 || resp.ToolCalls[0].ID != "call_stream" {
+		t.Fatalf("ToolCalls = %#v, want single call_stream", resp.ToolCalls)
+	}
+	if resp.FinishReason != "tool_calls" {
+		t.Fatalf("FinishReason = %q, want %q", resp.FinishReason, "tool_calls")
+	}
+	if resp.Usage == nil || resp.Usage.TotalTokens != 3 {
+		t.Fatalf("Usage = %#v, expected total tokens = 3", resp.Usage)
+	}
+	if len(updates) < 2 || updates[len(updates)-1] != "Hello World" {
+		t.Fatalf("stream updates = %#v, expected final accumulated text", updates)
+	}
+}
+
+func TestGeminiProvider_BuildRequestBodyIncludesMediaAndThinkingConfig(t *testing.T) {
+	provider := NewGeminiProvider("test-key", "https://example.com/v1beta", "", "", 0, nil, nil)
+
+	body := provider.buildRequestBody(
+		[]Message{{
+			Role:    "user",
+			Content: "analyze attachments",
+			Media: []string{
+				"data:application/pdf;base64,UEZERGF0YQ==",
+				"data:image/png;base64,aW1hZ2VEYXRh",
+			},
+		}},
+		nil,
+		"gemini-3-flash-preview",
+		map[string]any{
+			"thinking_level": "low",
+			"max_tokens":     128,
+			"temperature":    0.2,
+		},
+	)
+
+	contents, ok := body["contents"].([]geminiContent)
+	if !ok || len(contents) != 1 {
+		t.Fatalf("contents = %#v, want one gemini content", body["contents"])
+	}
+	parts := contents[0].Parts
+	mimeSet := map[string]bool{}
+	for _, part := range parts {
+		if part.InlineData != nil {
+			mimeSet[part.InlineData.MIMEType] = true
+		}
+	}
+	if !mimeSet["application/pdf"] {
+		t.Fatalf("inline media missing application/pdf: %#v", parts)
+	}
+	if !mimeSet["image/png"] {
+		t.Fatalf("inline media missing image/png: %#v", parts)
+	}
+
+	generationConfig, ok := body["generationConfig"].(map[string]any)
+	if !ok {
+		t.Fatalf("generationConfig = %#v, want map", body["generationConfig"])
+	}
+	if got := generationConfig["maxOutputTokens"]; got != 128 {
+		t.Fatalf("maxOutputTokens = %#v, want 128", got)
+	}
+	if got := generationConfig["temperature"]; got != 0.2 {
+		t.Fatalf("temperature = %#v, want 0.2", got)
+	}
+	thinkingConfig, ok := generationConfig["thinkingConfig"].(map[string]any)
+	if !ok {
+		t.Fatalf("thinkingConfig = %#v, want map", generationConfig["thinkingConfig"])
+	}
+	if includeThoughts, ok := thinkingConfig["includeThoughts"].(bool); !ok || !includeThoughts {
+		t.Fatalf("includeThoughts = %#v, want true", thinkingConfig["includeThoughts"])
+	}
+	if got := thinkingConfig["thinkingLevel"]; got != "low" {
+		t.Fatalf("thinkingLevel = %#v, want %q", got, "low")
+	}
+}
+
+func TestGeminiProvider_BuildRequestBody_UsesThinkingBudgetForGemini25(t *testing.T) {
+	provider := NewGeminiProvider("test-key", "https://example.com/v1beta", "", "", 0, nil, nil)
+	body := provider.buildRequestBody(
+		[]Message{{Role: "user", Content: "hello"}},
+		nil,
+		"gemini-2.5-flash",
+		map[string]any{"thinking_level": "medium"},
+	)
+
+	generationConfig, ok := body["generationConfig"].(map[string]any)
+	if !ok {
+		t.Fatalf("generationConfig = %#v, want map", body["generationConfig"])
+	}
+	thinkingConfig, ok := generationConfig["thinkingConfig"].(map[string]any)
+	if !ok {
+		t.Fatalf("thinkingConfig = %#v, want map", generationConfig["thinkingConfig"])
+	}
+	if got := thinkingConfig["thinkingBudget"]; got != 4096 {
+		t.Fatalf("thinkingBudget = %#v, want 4096", got)
+	}
+	if _, hasLevel := thinkingConfig["thinkingLevel"]; hasLevel {
+		t.Fatalf("thinkingLevel should not be set for Gemini 2.5: %#v", thinkingConfig)
+	}
+}
+
+func TestGeminiProvider_BuildRequestBody_OmitsThinkingConfigForGemini20(t *testing.T) {
+	provider := NewGeminiProvider("test-key", "https://example.com/v1beta", "", "", 0, nil, nil)
+	body := provider.buildRequestBody(
+		[]Message{{Role: "user", Content: "hello"}},
+		nil,
+		"gemini-2.0-flash-exp",
+		map[string]any{"thinking_level": "high"},
+	)
+
+	if _, ok := body["generationConfig"]; ok {
+		t.Fatalf("generationConfig should be omitted for Gemini 2.0 when only thinking_level is set: %#v", body)
+	}
+}
+
+func TestGeminiProvider_BuildRequestBody_PreservesToolResponseMedia(t *testing.T) {
+	provider := NewGeminiProvider("test-key", "https://example.com/v1beta", "", "", 0, nil, nil)
+	body := provider.buildRequestBody(
+		[]Message{
+			{
+				Role: "assistant",
+				ToolCalls: []ToolCall{{
+					ID:        "call_1",
+					Name:      "load_image",
+					Arguments: map[string]any{"path": "demo.png"},
+				}},
+			},
+			{
+				Role:       "tool",
+				ToolCallID: "call_1",
+				Content:    "tool result",
+				Media: []string{
+					"data:image/png;base64,aW1hZ2VEYXRh",
+					"data:application/pdf;base64,UEZERGF0YQ==",
+				},
+			},
+		},
+		nil,
+		"gemini-3-flash-preview",
+		nil,
+	)
+
+	contents, ok := body["contents"].([]geminiContent)
+	if !ok || len(contents) != 2 {
+		t.Fatalf("contents = %#v, want two content entries", body["contents"])
+	}
+	parts := contents[1].Parts
+	if len(parts) != 1 || parts[0].FunctionResponse == nil {
+		t.Fatalf("tool response part = %#v, want functionResponse", parts)
+	}
+	response := parts[0].FunctionResponse
+	if response.Name != "load_image" {
+		t.Fatalf("functionResponse.Name = %q, want %q", response.Name, "load_image")
+	}
+	if response.Response["result"] != "tool result" {
+		t.Fatalf("functionResponse.Response = %#v, want result=tool result", response.Response)
+	}
+	if len(response.Parts) != 2 {
+		t.Fatalf("functionResponse.Parts len = %d, want 2", len(response.Parts))
+	}
+}
+
+func TestGeminiProvider_ChatAllowsCustomAuthHeaderWithoutAPIKey(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if got := r.Header.Get("Authorization"); got != "Bearer test-token" {
+			t.Fatalf("Authorization = %q, want %q", got, "Bearer test-token")
+		}
+		if got := r.Header.Get("x-goog-api-key"); got != "" {
+			t.Fatalf("x-goog-api-key = %q, want empty", got)
+		}
+		w.Header().Set("Content-Type", "application/json")
+		_ = json.NewEncoder(w).Encode(map[string]any{
+			"candidates": []any{
+				map[string]any{
+					"content": map[string]any{
+						"parts": []any{map[string]any{"text": "ok"}},
+					},
+					"finishReason": "STOP",
+				},
+			},
+		})
+	}))
+	defer server.Close()
+
+	provider := NewGeminiProvider(
+		"",
+		server.URL,
+		"",
+		"",
+		0,
+		nil,
+		map[string]string{"Authorization": "Bearer test-token"},
+	)
+
+	resp, err := provider.Chat(
+		t.Context(),
+		[]Message{{Role: "user", Content: "hello"}},
+		nil,
+		"gemini-2.5-flash",
+		nil,
+	)
+	if err != nil {
+		t.Fatalf("Chat() error = %v", err)
+	}
+	if resp.Content != "ok" {
+		t.Fatalf("Content = %q, want %q", resp.Content, "ok")
+	}
+}
+
+func TestGeminiProvider_ChatAllowsMissingAPIKeyForCustomAPIBase(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if got := r.Header.Get("x-goog-api-key"); got != "" {
+			t.Fatalf("x-goog-api-key = %q, want empty", got)
+		}
+		w.Header().Set("Content-Type", "application/json")
+		_ = json.NewEncoder(w).Encode(map[string]any{
+			"candidates": []any{
+				map[string]any{
+					"content":      map[string]any{"parts": []any{map[string]any{"text": "ok"}}},
+					"finishReason": "STOP",
+				},
+			},
+		})
+	}))
+	defer server.Close()
+
+	provider := NewGeminiProvider("", server.URL, "", "", 0, nil, nil)
+	resp, err := provider.Chat(
+		t.Context(),
+		[]Message{{Role: "user", Content: "hello"}},
+		nil,
+		"gemini-2.5-flash",
+		nil,
+	)
+	if err != nil {
+		t.Fatalf("Chat() error = %v", err)
+	}
+	if resp.Content != "ok" {
+		t.Fatalf("Content = %q, want %q", resp.Content, "ok")
+	}
+}

pkg/providers/openai_compat/provider.go

@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"io"
 	"log"
+	"maps"
 	"net/http"
 	"net/url"
 	"strings"
@@ -181,9 +182,7 @@ func (p *Provider) buildRequestBody(
 
 	// Merge extra body fields configured per-provider/model.
 	// These are injected last so they take precedence over defaults.
-	for k, v := range p.extraBody {
+	maps.Copy(requestBody, p.extraBody)
-		requestBody[k] = v
-	}
 
 	return requestBody
 }

web/backend/api/session.go

@@ -281,6 +281,12 @@ func visibleSessionMessages(messages []providers.Message, toolFeedbackMaxArgsLen
 			}
 
 		case "assistant":
+			// Reasoning-only assistant messages are transient display artifacts and
+			// should not be restored from session history.
+			if assistantMessageTransientThought(msg) {
+				continue
+			}
+
 			toolSummaryMessages := visibleAssistantToolSummaryMessages(msg.ToolCalls, toolFeedbackMaxArgsLength)
 			if len(toolSummaryMessages) > 0 {
 				transcript = append(transcript, toolSummaryMessages...)
@@ -309,6 +315,13 @@ func visibleSessionMessages(messages []providers.Message, toolFeedbackMaxArgsLen
 	return transcript
 }
 
+func assistantMessageTransientThought(msg providers.Message) bool {
+	return strings.TrimSpace(msg.Content) == "" &&
+		strings.TrimSpace(msg.ReasoningContent) != "" &&
+		len(msg.ToolCalls) == 0 &&
+		len(msg.Media) == 0
+}
+
 func assistantMessageInternalOnly(msg providers.Message) bool {
 	return strings.TrimSpace(msg.Content) == handledToolResponseSummaryText
 }

web/backend/api/session_test.go

@@ -218,6 +218,59 @@ func TestHandleGetSession_JSONLStorage(t *testing.T) {
 	}
 }
 
+func TestHandleGetSession_OmitsTransientThoughtMessages(t *testing.T) {
+	configPath, cleanup := setupOAuthTestEnv(t)
+	defer cleanup()
+
+	dir := sessionsTestDir(t, configPath)
+	store, err := memory.NewJSONLStore(dir)
+	if err != nil {
+		t.Fatalf("NewJSONLStore() error = %v", err)
+	}
+
+	sessionKey := picoSessionPrefix + "detail-transient-thought"
+	for _, msg := range []providers.Message{
+		{Role: "user", Content: "hello"},
+		{Role: "assistant", ReasoningContent: "internal chain of thought"},
+		{Role: "assistant", Content: "final visible answer"},
+	} {
+		if err := store.AddFullMessage(nil, sessionKey, msg); err != nil {
+			t.Fatalf("AddFullMessage() error = %v", err)
+		}
+	}
+
+	h := NewHandler(configPath)
+	mux := http.NewServeMux()
+	h.RegisterRoutes(mux)
+
+	rec := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodGet, "/api/sessions/detail-transient-thought", nil)
+	mux.ServeHTTP(rec, req)
+
+	if rec.Code != http.StatusOK {
+		t.Fatalf("status = %d, want %d, body=%s", rec.Code, http.StatusOK, rec.Body.String())
+	}
+
+	var resp struct {
+		Messages []struct {
+			Role    string `json:"role"`
+			Content string `json:"content"`
+		} `json:"messages"`
+	}
+	if err := json.Unmarshal(rec.Body.Bytes(), &resp); err != nil {
+		t.Fatalf("Unmarshal() error = %v", err)
+	}
+	if len(resp.Messages) != 2 {
+		t.Fatalf("len(resp.Messages) = %d, want 2", len(resp.Messages))
+	}
+	if resp.Messages[0].Role != "user" || resp.Messages[0].Content != "hello" {
+		t.Fatalf("first message = %#v, want user/hello", resp.Messages[0])
+	}
+	if resp.Messages[1].Role != "assistant" || resp.Messages[1].Content != "final visible answer" {
+		t.Fatalf("second message = %#v, want assistant/final visible answer", resp.Messages[1])
+	}
+}
+
 func TestHandleGetSession_ReconstructsVisibleMessageToolOutput(t *testing.T) {
 	configPath, cleanup := setupOAuthTestEnv(t)
 	defer cleanup()