diff --git a/.gitignore b/.gitignore
index 2b9c215a..02493d24 100644
--- a/.gitignore
+++ b/.gitignore
@@ -6,7 +6,7 @@ cliproxy
 # Configuration
 config.yaml
 .env
-
+.mcp.json
 # Generated content
 bin/*
 logs/*
diff --git a/internal/runtime/executor/github_copilot_executor.go b/internal/runtime/executor/github_copilot_executor.go
index 3681faf8..af83ad0c 100644
--- a/internal/runtime/executor/github_copilot_executor.go
+++ b/internal/runtime/executor/github_copilot_executor.go
@@ -110,7 +110,7 @@ func (e *GitHubCopilotExecutor) Execute(ctx context.Context, auth *cliproxyauth.
 	defer reporter.trackFailure(ctx, &err)
 
 	from := opts.SourceFormat
-	useResponses := useGitHubCopilotResponsesEndpoint(from)
+	useResponses := useGitHubCopilotResponsesEndpoint(from, req.Model)
 	to := sdktranslator.FromString("openai")
 	if useResponses {
 		to = sdktranslator.FromString("openai-response")
@@ -123,6 +123,12 @@ func (e *GitHubCopilotExecutor) Execute(ctx context.Context, auth *cliproxyauth.
 	body := sdktranslator.TranslateRequest(from, to, req.Model, bytes.Clone(req.Payload), false)
 	body = e.normalizeModel(req.Model, body)
 	body = flattenAssistantContent(body)
+	if useResponses {
+		body = normalizeGitHubCopilotResponsesInput(body)
+		body = normalizeGitHubCopilotResponsesTools(body)
+	} else {
+		body = normalizeGitHubCopilotChatTools(body)
+	}
 	requestedModel := payloadRequestedModel(opts, req.Model)
 	body = applyPayloadConfigWithRoot(e.cfg, req.Model, to.String(), "", body, originalTranslated, requestedModel)
 	body, _ = sjson.SetBytes(body, "stream", false)
@@ -199,7 +205,12 @@ func (e *GitHubCopilotExecutor) Execute(ctx context.Context, auth *cliproxyauth.
 	}
 
 	var param any
-	converted := sdktranslator.TranslateNonStream(ctx, to, from, req.Model, bytes.Clone(opts.OriginalRequest), body, data, &param)
+	converted := ""
+	if useResponses && from.String() == "claude" {
+		converted = translateGitHubCopilotResponsesNonStreamToClaude(data)
+	} else {
+		converted = sdktranslator.TranslateNonStream(ctx, to, from, req.Model, bytes.Clone(opts.OriginalRequest), body, data, &param)
+	}
 	resp = cliproxyexecutor.Response{Payload: []byte(converted)}
 	reporter.ensurePublished(ctx)
 	return resp, nil
@@ -216,7 +227,7 @@ func (e *GitHubCopilotExecutor) ExecuteStream(ctx context.Context, auth *cliprox
 	defer reporter.trackFailure(ctx, &err)
 
 	from := opts.SourceFormat
-	useResponses := useGitHubCopilotResponsesEndpoint(from)
+	useResponses := useGitHubCopilotResponsesEndpoint(from, req.Model)
 	to := sdktranslator.FromString("openai")
 	if useResponses {
 		to = sdktranslator.FromString("openai-response")
@@ -229,6 +240,12 @@ func (e *GitHubCopilotExecutor) ExecuteStream(ctx context.Context, auth *cliprox
 	body := sdktranslator.TranslateRequest(from, to, req.Model, bytes.Clone(req.Payload), true)
 	body = e.normalizeModel(req.Model, body)
 	body = flattenAssistantContent(body)
+	if useResponses {
+		body = normalizeGitHubCopilotResponsesInput(body)
+		body = normalizeGitHubCopilotResponsesTools(body)
+	} else {
+		body = normalizeGitHubCopilotChatTools(body)
+	}
 	requestedModel := payloadRequestedModel(opts, req.Model)
 	body = applyPayloadConfigWithRoot(e.cfg, req.Model, to.String(), "", body, originalTranslated, requestedModel)
 	body, _ = sjson.SetBytes(body, "stream", true)
@@ -329,7 +346,12 @@ func (e *GitHubCopilotExecutor) ExecuteStream(ctx context.Context, auth *cliprox
 				}
 			}
 
-			chunks := sdktranslator.TranslateStream(ctx, to, from, req.Model, bytes.Clone(opts.OriginalRequest), body, bytes.Clone(line), &param)
+			var chunks []string
+			if useResponses && from.String() == "claude" {
+				chunks = translateGitHubCopilotResponsesStreamToClaude(bytes.Clone(line), &param)
+			} else {
+				chunks = sdktranslator.TranslateStream(ctx, to, from, req.Model, bytes.Clone(opts.OriginalRequest), body, bytes.Clone(line), &param)
+			}
 			for i := range chunks {
 				out <- cliproxyexecutor.StreamChunk{Payload: []byte(chunks[i])}
 			}
@@ -483,8 +505,12 @@ func (e *GitHubCopilotExecutor) normalizeModel(model string, body []byte) []byte
 	return body
 }
 
-func useGitHubCopilotResponsesEndpoint(sourceFormat sdktranslator.Format) bool {
-	return sourceFormat.String() == "openai-response"
+func useGitHubCopilotResponsesEndpoint(sourceFormat sdktranslator.Format, model string) bool {
+	if sourceFormat.String() == "openai-response" {
+		return true
+	}
+	baseModel := strings.ToLower(thinking.ParseSuffix(model).ModelName)
+	return strings.Contains(baseModel, "codex")
 }
 
 // flattenAssistantContent converts assistant message content from array format
@@ -519,6 +545,411 @@ func flattenAssistantContent(body []byte) []byte {
 	return result
 }
 
+func normalizeGitHubCopilotChatTools(body []byte) []byte {
+	tools := gjson.GetBytes(body, "tools")
+	if tools.Exists() {
+		filtered := "[]"
+		if tools.IsArray() {
+			for _, tool := range tools.Array() {
+				if tool.Get("type").String() != "function" {
+					continue
+				}
+				filtered, _ = sjson.SetRaw(filtered, "-1", tool.Raw)
+			}
+		}
+		body, _ = sjson.SetRawBytes(body, "tools", []byte(filtered))
+	}
+
+	toolChoice := gjson.GetBytes(body, "tool_choice")
+	if !toolChoice.Exists() {
+		return body
+	}
+	if toolChoice.Type == gjson.String {
+		switch toolChoice.String() {
+		case "auto", "none", "required":
+			return body
+		}
+	}
+	body, _ = sjson.SetBytes(body, "tool_choice", "auto")
+	return body
+}
+
+func normalizeGitHubCopilotResponsesInput(body []byte) []byte {
+	input := gjson.GetBytes(body, "input")
+	if input.Exists() {
+		if input.Type == gjson.String {
+			return body
+		}
+		inputString := input.Raw
+		if input.Type != gjson.JSON {
+			inputString = input.String()
+		}
+		body, _ = sjson.SetBytes(body, "input", inputString)
+		return body
+	}
+
+	var parts []string
+	if system := gjson.GetBytes(body, "system"); system.Exists() {
+		if text := strings.TrimSpace(collectTextFromNode(system)); text != "" {
+			parts = append(parts, text)
+		}
+	}
+	if messages := gjson.GetBytes(body, "messages"); messages.Exists() && messages.IsArray() {
+		for _, msg := range messages.Array() {
+			if text := strings.TrimSpace(collectTextFromNode(msg.Get("content"))); text != "" {
+				parts = append(parts, text)
+			}
+		}
+	}
+	body, _ = sjson.SetBytes(body, "input", strings.Join(parts, "\n"))
+	return body
+}
+
+func normalizeGitHubCopilotResponsesTools(body []byte) []byte {
+	tools := gjson.GetBytes(body, "tools")
+	if tools.Exists() {
+		filtered := "[]"
+		if tools.IsArray() {
+			for _, tool := range tools.Array() {
+				toolType := tool.Get("type").String()
+				// Accept OpenAI format (type="function") and Claude format
+				// (no type field, but has top-level name + input_schema).
+				if toolType != "" && toolType != "function" {
+					continue
+				}
+				name := tool.Get("name").String()
+				if name == "" {
+					name = tool.Get("function.name").String()
+				}
+				if name == "" {
+					continue
+				}
+				normalized := `{"type":"function","name":""}`
+				normalized, _ = sjson.Set(normalized, "name", name)
+				if desc := tool.Get("description").String(); desc != "" {
+					normalized, _ = sjson.Set(normalized, "description", desc)
+				} else if desc = tool.Get("function.description").String(); desc != "" {
+					normalized, _ = sjson.Set(normalized, "description", desc)
+				}
+				if params := tool.Get("parameters"); params.Exists() {
+					normalized, _ = sjson.SetRaw(normalized, "parameters", params.Raw)
+				} else if params = tool.Get("function.parameters"); params.Exists() {
+					normalized, _ = sjson.SetRaw(normalized, "parameters", params.Raw)
+				} else if params = tool.Get("input_schema"); params.Exists() {
+					normalized, _ = sjson.SetRaw(normalized, "parameters", params.Raw)
+				}
+				filtered, _ = sjson.SetRaw(filtered, "-1", normalized)
+			}
+		}
+		body, _ = sjson.SetRawBytes(body, "tools", []byte(filtered))
+	}
+
+	toolChoice := gjson.GetBytes(body, "tool_choice")
+	if !toolChoice.Exists() {
+		return body
+	}
+	if toolChoice.Type == gjson.String {
+		switch toolChoice.String() {
+		case "auto", "none", "required":
+			return body
+		default:
+			body, _ = sjson.SetBytes(body, "tool_choice", "auto")
+			return body
+		}
+	}
+	if toolChoice.Type == gjson.JSON {
+		choiceType := toolChoice.Get("type").String()
+		if choiceType == "function" {
+			name := toolChoice.Get("name").String()
+			if name == "" {
+				name = toolChoice.Get("function.name").String()
+			}
+			if name != "" {
+				normalized := `{"type":"function","name":""}`
+				normalized, _ = sjson.Set(normalized, "name", name)
+				body, _ = sjson.SetRawBytes(body, "tool_choice", []byte(normalized))
+				return body
+			}
+		}
+	}
+	body, _ = sjson.SetBytes(body, "tool_choice", "auto")
+	return body
+}
+
+func collectTextFromNode(node gjson.Result) string {
+	if !node.Exists() {
+		return ""
+	}
+	if node.Type == gjson.String {
+		return node.String()
+	}
+	if node.IsArray() {
+		var parts []string
+		for _, item := range node.Array() {
+			if item.Type == gjson.String {
+				if text := item.String(); text != "" {
+					parts = append(parts, text)
+				}
+				continue
+			}
+			if text := item.Get("text").String(); text != "" {
+				parts = append(parts, text)
+				continue
+			}
+			if nested := collectTextFromNode(item.Get("content")); nested != "" {
+				parts = append(parts, nested)
+			}
+		}
+		return strings.Join(parts, "\n")
+	}
+	if node.Type == gjson.JSON {
+		if text := node.Get("text").String(); text != "" {
+			return text
+		}
+		if nested := collectTextFromNode(node.Get("content")); nested != "" {
+			return nested
+		}
+		return node.Raw
+	}
+	return node.String()
+}
+
+type githubCopilotResponsesStreamToolState struct {
+	Index int
+	ID    string
+	Name  string
+}
+
+type githubCopilotResponsesStreamState struct {
+	MessageStarted    bool
+	MessageStopSent   bool
+	TextBlockStarted  bool
+	TextBlockIndex    int
+	NextContentIndex  int
+	HasToolUse        bool
+	OutputIndexToTool map[int]*githubCopilotResponsesStreamToolState
+	ItemIDToTool      map[string]*githubCopilotResponsesStreamToolState
+}
+
+func translateGitHubCopilotResponsesNonStreamToClaude(data []byte) string {
+	root := gjson.ParseBytes(data)
+	out := `{"id":"","type":"message","role":"assistant","model":"","content":[],"stop_reason":null,"stop_sequence":null,"usage":{"input_tokens":0,"output_tokens":0}}`
+	out, _ = sjson.Set(out, "id", root.Get("id").String())
+	out, _ = sjson.Set(out, "model", root.Get("model").String())
+
+	hasToolUse := false
+	if output := root.Get("output"); output.Exists() && output.IsArray() {
+		for _, item := range output.Array() {
+			switch item.Get("type").String() {
+			case "message":
+				if content := item.Get("content"); content.Exists() && content.IsArray() {
+					for _, part := range content.Array() {
+						if part.Get("type").String() != "output_text" {
+							continue
+						}
+						text := part.Get("text").String()
+						if text == "" {
+							continue
+						}
+						block := `{"type":"text","text":""}`
+						block, _ = sjson.Set(block, "text", text)
+						out, _ = sjson.SetRaw(out, "content.-1", block)
+					}
+				}
+			case "function_call":
+				hasToolUse = true
+				toolUse := `{"type":"tool_use","id":"","name":"","input":{}}`
+				toolID := item.Get("call_id").String()
+				if toolID == "" {
+					toolID = item.Get("id").String()
+				}
+				toolUse, _ = sjson.Set(toolUse, "id", toolID)
+				toolUse, _ = sjson.Set(toolUse, "name", item.Get("name").String())
+				if args := item.Get("arguments").String(); args != "" && gjson.Valid(args) {
+					argObj := gjson.Parse(args)
+					if argObj.IsObject() {
+						toolUse, _ = sjson.SetRaw(toolUse, "input", argObj.Raw)
+					}
+				}
+				out, _ = sjson.SetRaw(out, "content.-1", toolUse)
+			}
+		}
+	}
+
+	inputTokens := root.Get("usage.input_tokens").Int()
+	outputTokens := root.Get("usage.output_tokens").Int()
+	out, _ = sjson.Set(out, "usage.input_tokens", inputTokens)
+	out, _ = sjson.Set(out, "usage.output_tokens", outputTokens)
+	if hasToolUse {
+		out, _ = sjson.Set(out, "stop_reason", "tool_use")
+	} else {
+		out, _ = sjson.Set(out, "stop_reason", "end_turn")
+	}
+	return out
+}
+
+func translateGitHubCopilotResponsesStreamToClaude(line []byte, param *any) []string {
+	if *param == nil {
+		*param = &githubCopilotResponsesStreamState{
+			TextBlockIndex:    -1,
+			OutputIndexToTool: make(map[int]*githubCopilotResponsesStreamToolState),
+			ItemIDToTool:      make(map[string]*githubCopilotResponsesStreamToolState),
+		}
+	}
+	state := (*param).(*githubCopilotResponsesStreamState)
+
+	if !bytes.HasPrefix(line, dataTag) {
+		return nil
+	}
+	payload := bytes.TrimSpace(line[5:])
+	if bytes.Equal(payload, []byte("[DONE]")) {
+		return nil
+	}
+	if !gjson.ValidBytes(payload) {
+		return nil
+	}
+
+	event := gjson.GetBytes(payload, "type").String()
+	results := make([]string, 0, 4)
+	ensureMessageStart := func() {
+		if state.MessageStarted {
+			return
+		}
+		messageStart := `{"type":"message_start","message":{"id":"","type":"message","role":"assistant","model":"","content":[],"stop_reason":null,"stop_sequence":null,"usage":{"input_tokens":0,"output_tokens":0}}}`
+		messageStart, _ = sjson.Set(messageStart, "message.id", gjson.GetBytes(payload, "response.id").String())
+		messageStart, _ = sjson.Set(messageStart, "message.model", gjson.GetBytes(payload, "response.model").String())
+		results = append(results, "event: message_start\ndata: "+messageStart+"\n\n")
+		state.MessageStarted = true
+	}
+	startTextBlockIfNeeded := func() {
+		if state.TextBlockStarted {
+			return
+		}
+		if state.TextBlockIndex < 0 {
+			state.TextBlockIndex = state.NextContentIndex
+			state.NextContentIndex++
+		}
+		contentBlockStart := `{"type":"content_block_start","index":0,"content_block":{"type":"text","text":""}}`
+		contentBlockStart, _ = sjson.Set(contentBlockStart, "index", state.TextBlockIndex)
+		results = append(results, "event: content_block_start\ndata: "+contentBlockStart+"\n\n")
+		state.TextBlockStarted = true
+	}
+	stopTextBlockIfNeeded := func() {
+		if !state.TextBlockStarted {
+			return
+		}
+		contentBlockStop := `{"type":"content_block_stop","index":0}`
+		contentBlockStop, _ = sjson.Set(contentBlockStop, "index", state.TextBlockIndex)
+		results = append(results, "event: content_block_stop\ndata: "+contentBlockStop+"\n\n")
+		state.TextBlockStarted = false
+		state.TextBlockIndex = -1
+	}
+	resolveTool := func(itemID string, outputIndex int) *githubCopilotResponsesStreamToolState {
+		if itemID != "" {
+			if tool, ok := state.ItemIDToTool[itemID]; ok {
+				return tool
+			}
+		}
+		if tool, ok := state.OutputIndexToTool[outputIndex]; ok {
+			if itemID != "" {
+				state.ItemIDToTool[itemID] = tool
+			}
+			return tool
+		}
+		return nil
+	}
+
+	switch event {
+	case "response.created":
+		ensureMessageStart()
+	case "response.output_text.delta":
+		ensureMessageStart()
+		startTextBlockIfNeeded()
+		delta := gjson.GetBytes(payload, "delta").String()
+		if delta != "" {
+			contentDelta := `{"type":"content_block_delta","index":0,"delta":{"type":"text_delta","text":""}}`
+			contentDelta, _ = sjson.Set(contentDelta, "index", state.TextBlockIndex)
+			contentDelta, _ = sjson.Set(contentDelta, "delta.text", delta)
+			results = append(results, "event: content_block_delta\ndata: "+contentDelta+"\n\n")
+		}
+	case "response.output_item.added":
+		if gjson.GetBytes(payload, "item.type").String() != "function_call" {
+			break
+		}
+		ensureMessageStart()
+		stopTextBlockIfNeeded()
+		state.HasToolUse = true
+		tool := &githubCopilotResponsesStreamToolState{
+			Index: state.NextContentIndex,
+			ID:    gjson.GetBytes(payload, "item.call_id").String(),
+			Name:  gjson.GetBytes(payload, "item.name").String(),
+		}
+		if tool.ID == "" {
+			tool.ID = gjson.GetBytes(payload, "item.id").String()
+		}
+		state.NextContentIndex++
+		outputIndex := int(gjson.GetBytes(payload, "output_index").Int())
+		state.OutputIndexToTool[outputIndex] = tool
+		if itemID := gjson.GetBytes(payload, "item.id").String(); itemID != "" {
+			state.ItemIDToTool[itemID] = tool
+		}
+		contentBlockStart := `{"type":"content_block_start","index":0,"content_block":{"type":"tool_use","id":"","name":"","input":{}}}`
+		contentBlockStart, _ = sjson.Set(contentBlockStart, "index", tool.Index)
+		contentBlockStart, _ = sjson.Set(contentBlockStart, "content_block.id", tool.ID)
+		contentBlockStart, _ = sjson.Set(contentBlockStart, "content_block.name", tool.Name)
+		results = append(results, "event: content_block_start\ndata: "+contentBlockStart+"\n\n")
+	case "response.output_item.delta":
+		item := gjson.GetBytes(payload, "item")
+		if item.Get("type").String() != "function_call" {
+			break
+		}
+		tool := resolveTool(item.Get("id").String(), int(gjson.GetBytes(payload, "output_index").Int()))
+		if tool == nil {
+			break
+		}
+		partial := gjson.GetBytes(payload, "delta").String()
+		if partial == "" {
+			partial = item.Get("arguments").String()
+		}
+		if partial == "" {
+			break
+		}
+		inputDelta := `{"type":"content_block_delta","index":0,"delta":{"type":"input_json_delta","partial_json":""}}`
+		inputDelta, _ = sjson.Set(inputDelta, "index", tool.Index)
+		inputDelta, _ = sjson.Set(inputDelta, "delta.partial_json", partial)
+		results = append(results, "event: content_block_delta\ndata: "+inputDelta+"\n\n")
+	case "response.output_item.done":
+		if gjson.GetBytes(payload, "item.type").String() != "function_call" {
+			break
+		}
+		tool := resolveTool(gjson.GetBytes(payload, "item.id").String(), int(gjson.GetBytes(payload, "output_index").Int()))
+		if tool == nil {
+			break
+		}
+		contentBlockStop := `{"type":"content_block_stop","index":0}`
+		contentBlockStop, _ = sjson.Set(contentBlockStop, "index", tool.Index)
+		results = append(results, "event: content_block_stop\ndata: "+contentBlockStop+"\n\n")
+	case "response.completed":
+		ensureMessageStart()
+		stopTextBlockIfNeeded()
+		if !state.MessageStopSent {
+			stopReason := "end_turn"
+			if state.HasToolUse {
+				stopReason = "tool_use"
+			}
+			messageDelta := `{"type":"message_delta","delta":{"stop_reason":"","stop_sequence":null},"usage":{"input_tokens":0,"output_tokens":0}}`
+			messageDelta, _ = sjson.Set(messageDelta, "delta.stop_reason", stopReason)
+			messageDelta, _ = sjson.Set(messageDelta, "usage.input_tokens", gjson.GetBytes(payload, "response.usage.input_tokens").Int())
+			messageDelta, _ = sjson.Set(messageDelta, "usage.output_tokens", gjson.GetBytes(payload, "response.usage.output_tokens").Int())
+			results = append(results, "event: message_delta\ndata: "+messageDelta+"\n\n")
+			results = append(results, "event: message_stop\ndata: {\"type\":\"message_stop\"}\n\n")
+			state.MessageStopSent = true
+		}
+	}
+
+	return results
+}
+
 // isHTTPSuccess checks if the status code indicates success (2xx).
 func isHTTPSuccess(statusCode int) bool {
 	return statusCode >= 200 && statusCode < 300
diff --git a/internal/runtime/executor/github_copilot_executor_test.go b/internal/runtime/executor/github_copilot_executor_test.go
index ef077fd6..2895c8a7 100644
--- a/internal/runtime/executor/github_copilot_executor_test.go
+++ b/internal/runtime/executor/github_copilot_executor_test.go
@@ -1,8 +1,10 @@
 package executor
 
 import (
+	"strings"
 	"testing"
 
+	sdktranslator "github.com/router-for-me/CLIProxyAPI/v6/sdk/translator"
 	"github.com/tidwall/gjson"
 )
 
@@ -52,3 +54,189 @@ func TestGitHubCopilotNormalizeModel_StripsSuffix(t *testing.T) {
 		})
 	}
 }
+
+func TestUseGitHubCopilotResponsesEndpoint_OpenAIResponseSource(t *testing.T) {
+	t.Parallel()
+	if !useGitHubCopilotResponsesEndpoint(sdktranslator.FromString("openai-response"), "claude-3-5-sonnet") {
+		t.Fatal("expected openai-response source to use /responses")
+	}
+}
+
+func TestUseGitHubCopilotResponsesEndpoint_CodexModel(t *testing.T) {
+	t.Parallel()
+	if !useGitHubCopilotResponsesEndpoint(sdktranslator.FromString("openai"), "gpt-5-codex") {
+		t.Fatal("expected codex model to use /responses")
+	}
+}
+
+func TestUseGitHubCopilotResponsesEndpoint_DefaultChat(t *testing.T) {
+	t.Parallel()
+	if useGitHubCopilotResponsesEndpoint(sdktranslator.FromString("openai"), "claude-3-5-sonnet") {
+		t.Fatal("expected default openai source with non-codex model to use /chat/completions")
+	}
+}
+
+func TestNormalizeGitHubCopilotChatTools_KeepFunctionOnly(t *testing.T) {
+	t.Parallel()
+	body := []byte(`{"tools":[{"type":"function","function":{"name":"ok"}},{"type":"code_interpreter"}],"tool_choice":"auto"}`)
+	got := normalizeGitHubCopilotChatTools(body)
+	tools := gjson.GetBytes(got, "tools").Array()
+	if len(tools) != 1 {
+		t.Fatalf("tools len = %d, want 1", len(tools))
+	}
+	if tools[0].Get("type").String() != "function" {
+		t.Fatalf("tool type = %q, want function", tools[0].Get("type").String())
+	}
+}
+
+func TestNormalizeGitHubCopilotChatTools_InvalidToolChoiceDowngradeToAuto(t *testing.T) {
+	t.Parallel()
+	body := []byte(`{"tools":[],"tool_choice":{"type":"function","function":{"name":"x"}}}`)
+	got := normalizeGitHubCopilotChatTools(body)
+	if gjson.GetBytes(got, "tool_choice").String() != "auto" {
+		t.Fatalf("tool_choice = %s, want auto", gjson.GetBytes(got, "tool_choice").Raw)
+	}
+}
+
+func TestNormalizeGitHubCopilotResponsesInput_MissingInputExtractedFromSystemAndMessages(t *testing.T) {
+	t.Parallel()
+	body := []byte(`{"system":"sys text","messages":[{"role":"user","content":"user text"},{"role":"assistant","content":[{"type":"text","text":"assistant text"}]}]}`)
+	got := normalizeGitHubCopilotResponsesInput(body)
+	in := gjson.GetBytes(got, "input")
+	if in.Type != gjson.String {
+		t.Fatalf("input type = %v, want string", in.Type)
+	}
+	if !strings.Contains(in.String(), "sys text") || !strings.Contains(in.String(), "user text") || !strings.Contains(in.String(), "assistant text") {
+		t.Fatalf("input = %q, want merged text", in.String())
+	}
+}
+
+func TestNormalizeGitHubCopilotResponsesInput_NonStringInputStringified(t *testing.T) {
+	t.Parallel()
+	body := []byte(`{"input":{"foo":"bar"}}`)
+	got := normalizeGitHubCopilotResponsesInput(body)
+	in := gjson.GetBytes(got, "input")
+	if in.Type != gjson.String {
+		t.Fatalf("input type = %v, want string", in.Type)
+	}
+	if !strings.Contains(in.String(), "foo") {
+		t.Fatalf("input = %q, want stringified object", in.String())
+	}
+}
+
+func TestNormalizeGitHubCopilotResponsesTools_FlattenFunctionTools(t *testing.T) {
+	t.Parallel()
+	body := []byte(`{"tools":[{"type":"function","function":{"name":"sum","description":"d","parameters":{"type":"object"}}},{"type":"web_search"}]}`)
+	got := normalizeGitHubCopilotResponsesTools(body)
+	tools := gjson.GetBytes(got, "tools").Array()
+	if len(tools) != 1 {
+		t.Fatalf("tools len = %d, want 1", len(tools))
+	}
+	if tools[0].Get("name").String() != "sum" {
+		t.Fatalf("tools[0].name = %q, want sum", tools[0].Get("name").String())
+	}
+	if !tools[0].Get("parameters").Exists() {
+		t.Fatal("expected parameters to be preserved")
+	}
+}
+
+func TestNormalizeGitHubCopilotResponsesTools_ClaudeFormatTools(t *testing.T) {
+	t.Parallel()
+	body := []byte(`{"tools":[{"name":"Bash","description":"Run commands","input_schema":{"type":"object","properties":{"command":{"type":"string"}},"required":["command"]}},{"name":"Read","description":"Read files","input_schema":{"type":"object","properties":{"path":{"type":"string"}}}}]}`)
+	got := normalizeGitHubCopilotResponsesTools(body)
+	tools := gjson.GetBytes(got, "tools").Array()
+	if len(tools) != 2 {
+		t.Fatalf("tools len = %d, want 2", len(tools))
+	}
+	if tools[0].Get("type").String() != "function" {
+		t.Fatalf("tools[0].type = %q, want function", tools[0].Get("type").String())
+	}
+	if tools[0].Get("name").String() != "Bash" {
+		t.Fatalf("tools[0].name = %q, want Bash", tools[0].Get("name").String())
+	}
+	if tools[0].Get("description").String() != "Run commands" {
+		t.Fatalf("tools[0].description = %q, want 'Run commands'", tools[0].Get("description").String())
+	}
+	if !tools[0].Get("parameters").Exists() {
+		t.Fatal("expected parameters to be set from input_schema")
+	}
+	if tools[0].Get("parameters.properties.command").Exists() != true {
+		t.Fatal("expected parameters.properties.command to exist")
+	}
+	if tools[1].Get("name").String() != "Read" {
+		t.Fatalf("tools[1].name = %q, want Read", tools[1].Get("name").String())
+	}
+}
+
+func TestNormalizeGitHubCopilotResponsesTools_FlattenToolChoiceFunctionObject(t *testing.T) {
+	t.Parallel()
+	body := []byte(`{"tool_choice":{"type":"function","function":{"name":"sum"}}}`)
+	got := normalizeGitHubCopilotResponsesTools(body)
+	if gjson.GetBytes(got, "tool_choice.type").String() != "function" {
+		t.Fatalf("tool_choice.type = %q, want function", gjson.GetBytes(got, "tool_choice.type").String())
+	}
+	if gjson.GetBytes(got, "tool_choice.name").String() != "sum" {
+		t.Fatalf("tool_choice.name = %q, want sum", gjson.GetBytes(got, "tool_choice.name").String())
+	}
+}
+
+func TestNormalizeGitHubCopilotResponsesTools_InvalidToolChoiceDowngradeToAuto(t *testing.T) {
+	t.Parallel()
+	body := []byte(`{"tool_choice":{"type":"function"}}`)
+	got := normalizeGitHubCopilotResponsesTools(body)
+	if gjson.GetBytes(got, "tool_choice").String() != "auto" {
+		t.Fatalf("tool_choice = %s, want auto", gjson.GetBytes(got, "tool_choice").Raw)
+	}
+}
+
+func TestTranslateGitHubCopilotResponsesNonStreamToClaude_TextMapping(t *testing.T) {
+	t.Parallel()
+	resp := []byte(`{"id":"resp_1","model":"gpt-5-codex","output":[{"type":"message","content":[{"type":"output_text","text":"hello"}]}],"usage":{"input_tokens":3,"output_tokens":5}}`)
+	out := translateGitHubCopilotResponsesNonStreamToClaude(resp)
+	if gjson.Get(out, "type").String() != "message" {
+		t.Fatalf("type = %q, want message", gjson.Get(out, "type").String())
+	}
+	if gjson.Get(out, "content.0.type").String() != "text" {
+		t.Fatalf("content.0.type = %q, want text", gjson.Get(out, "content.0.type").String())
+	}
+	if gjson.Get(out, "content.0.text").String() != "hello" {
+		t.Fatalf("content.0.text = %q, want hello", gjson.Get(out, "content.0.text").String())
+	}
+}
+
+func TestTranslateGitHubCopilotResponsesNonStreamToClaude_ToolUseMapping(t *testing.T) {
+	t.Parallel()
+	resp := []byte(`{"id":"resp_2","model":"gpt-5-codex","output":[{"type":"function_call","id":"fc_1","call_id":"call_1","name":"sum","arguments":"{\"a\":1}"}],"usage":{"input_tokens":1,"output_tokens":2}}`)
+	out := translateGitHubCopilotResponsesNonStreamToClaude(resp)
+	if gjson.Get(out, "content.0.type").String() != "tool_use" {
+		t.Fatalf("content.0.type = %q, want tool_use", gjson.Get(out, "content.0.type").String())
+	}
+	if gjson.Get(out, "content.0.name").String() != "sum" {
+		t.Fatalf("content.0.name = %q, want sum", gjson.Get(out, "content.0.name").String())
+	}
+	if gjson.Get(out, "stop_reason").String() != "tool_use" {
+		t.Fatalf("stop_reason = %q, want tool_use", gjson.Get(out, "stop_reason").String())
+	}
+}
+
+func TestTranslateGitHubCopilotResponsesStreamToClaude_TextLifecycle(t *testing.T) {
+	t.Parallel()
+	var param any
+
+	created := translateGitHubCopilotResponsesStreamToClaude([]byte(`data: {"type":"response.created","response":{"id":"resp_1","model":"gpt-5-codex"}}`), &param)
+	if len(created) == 0 || !strings.Contains(created[0], "message_start") {
+		t.Fatalf("created events = %#v, want message_start", created)
+	}
+
+	delta := translateGitHubCopilotResponsesStreamToClaude([]byte(`data: {"type":"response.output_text.delta","delta":"he"}`), &param)
+	joinedDelta := strings.Join(delta, "")
+	if !strings.Contains(joinedDelta, "content_block_start") || !strings.Contains(joinedDelta, "text_delta") {
+		t.Fatalf("delta events = %#v, want content_block_start + text_delta", delta)
+	}
+
+	completed := translateGitHubCopilotResponsesStreamToClaude([]byte(`data: {"type":"response.completed","response":{"usage":{"input_tokens":7,"output_tokens":9}}}`), &param)
+	joinedCompleted := strings.Join(completed, "")
+	if !strings.Contains(joinedCompleted, "message_delta") || !strings.Contains(joinedCompleted, "message_stop") {
+		t.Fatalf("completed events = %#v, want message_delta + message_stop", completed)
+	}
+}