fix(chat): keep tool-call summary and assistant output in sync (#2449)

* fix(chat): keep tool summaries and assistant output together

* fix(pico): stream assistant text between tool calls

* fix(pico): avoid duplicate final websocket message

* fix(review): align tool feedback reconstruction with runtime behavior

* style(lint): satisfy gci and golines for review fixes

* fix(agent): gate pico interim publish for internal turns

pkg/agent/loop.go

@@ -88,6 +88,7 @@ type processOptions struct {
 	DefaultResponse         string              // Response when LLM returns empty
 	EnableSummary           bool                // Whether to trigger summarization
 	SendResponse            bool                // Whether to send response via bus
+	AllowInterimPicoPublish bool                // Whether pico tool-call interim text can be published when SendResponse is false
 	SuppressToolFeedback    bool                // Whether to suppress inline tool feedback messages
 	NoHistory               bool                // If true, don't load session history (for heartbeat)
 	SkipInitialSteeringPoll bool                // If true, skip the steering poll at loop start (used by Continue)
@@ -1398,18 +1399,19 @@ func (al *AgentLoop) processMessage(ctx context.Context, msg bus.InboundMessage)
 		})
 
 	opts := processOptions{
-		SessionKey:        sessionKey,
-		Channel:           msg.Channel,
-		ChatID:            msg.ChatID,
-		MessageID:         msg.MessageID,
-		ReplyToMessageID:  inboundMetadata(msg, metadataKeyReplyToMessage),
-		SenderID:          msg.SenderID,
-		SenderDisplayName: msg.Sender.DisplayName,
-		UserMessage:       msg.Content,
-		Media:             msg.Media,
-		DefaultResponse:   defaultResponse,
-		EnableSummary:     true,
-		SendResponse:      false,
+		SessionKey:              sessionKey,
+		Channel:                 msg.Channel,
+		ChatID:                  msg.ChatID,
+		MessageID:               msg.MessageID,
+		ReplyToMessageID:        inboundMetadata(msg, metadataKeyReplyToMessage),
+		SenderID:                msg.SenderID,
+		SenderDisplayName:       msg.Sender.DisplayName,
+		UserMessage:             msg.Content,
+		Media:                   msg.Media,
+		DefaultResponse:         defaultResponse,
+		EnableSummary:           true,
+		SendResponse:            false,
+		AllowInterimPicoPublish: true,
 	}
 
 	// context-dependent commands check their own Runtime fields and report
@@ -2253,6 +2255,26 @@ turnLoop:
 		}
 		logger.DebugCF("agent", "LLM response", llmResponseFields)
 
+		if al.bus != nil && ts.channel == "pico" && len(response.ToolCalls) > 0 && ts.opts.AllowInterimPicoPublish {
+			if strings.TrimSpace(response.Content) != "" {
+				outCtx, outCancel := context.WithTimeout(turnCtx, 3*time.Second)
+				err := al.bus.PublishOutbound(outCtx, bus.OutboundMessage{
+					Channel: ts.channel,
+					ChatID:  ts.chatID,
+					Content: response.Content,
+				})
+				outCancel()
+				if err != nil {
+					logger.WarnCF("agent", "Failed to publish pico interim tool-call content", map[string]any{
+						"error":     err.Error(),
+						"channel":   ts.channel,
+						"chat_id":   ts.chatID,
+						"iteration": iteration,
+					})
+				}
+			}
+		}
+
 		if len(response.ToolCalls) == 0 || gracefulTerminal {
 			responseContent := response.Content
 			if responseContent == "" && response.ReasoningContent != "" {
@@ -2390,7 +2412,7 @@ turnLoop:
 								string(argsJSON),
 								al.cfg.Agents.Defaults.GetToolFeedbackMaxArgsLength(),
 							)
-							feedbackMsg := fmt.Sprintf("\U0001f527 `%s`\n```\n%s\n```", toolName, feedbackPreview)
+							feedbackMsg := utils.FormatToolFeedbackMessage(toolName, feedbackPreview)
 							fbCtx, fbCancel := context.WithTimeout(turnCtx, 3*time.Second)
 							_ = al.bus.PublishOutbound(fbCtx, bus.OutboundMessage{
 								Channel: ts.channel,
@@ -2672,7 +2694,7 @@ turnLoop:
 					string(argsJSON),
 					al.cfg.Agents.Defaults.GetToolFeedbackMaxArgsLength(),
 				)
-				feedbackMsg := fmt.Sprintf("\U0001f527 `%s`\n```\n%s\n```", tc.Name, feedbackPreview)
+				feedbackMsg := utils.FormatToolFeedbackMessage(tc.Name, feedbackPreview)
 				fbCtx, fbCancel := context.WithTimeout(turnCtx, 3*time.Second)
 				_ = al.bus.PublishOutbound(fbCtx, bus.OutboundMessage{
 					Channel: ts.channel,

pkg/agent/loop_test.go

@@ -1069,6 +1069,40 @@ func (m *toolFeedbackProvider) GetDefaultModel() string {
 	return "heartbeat-tool-feedback-model"
 }
 
+type picoInterleavedContentProvider struct {
+	calls int
+}
+
+func (m *picoInterleavedContentProvider) Chat(
+	ctx context.Context,
+	messages []providers.Message,
+	tools []providers.ToolDefinition,
+	model string,
+	opts map[string]any,
+) (*providers.LLMResponse, error) {
+	m.calls++
+	if m.calls == 1 {
+		return &providers.LLMResponse{
+			Content: "intermediate model text",
+			ToolCalls: []providers.ToolCall{{
+				ID:        "call_tool_limit_test",
+				Type:      "function",
+				Name:      "tool_limit_test_tool",
+				Arguments: map[string]any{"value": "x"},
+			}},
+		}, nil
+	}
+
+	return &providers.LLMResponse{
+		Content:   "final model text",
+		ToolCalls: []providers.ToolCall{},
+	}, nil
+}
+
+func (m *picoInterleavedContentProvider) GetDefaultModel() string {
+	return "pico-interleaved-content-model"
+}
+
 type toolLimitOnlyProvider struct{}
 
 func (m *toolLimitOnlyProvider) Chat(
@@ -2732,6 +2766,133 @@ func TestProcessMessage_PublishesToolFeedbackWhenEnabled(t *testing.T) {
 	}
 }
 
+func TestRun_PicoPublishesAssistantContentDuringToolCallsWithoutFinalDuplicate(t *testing.T) {
+	tmpDir := t.TempDir()
+
+	cfg := &config.Config{
+		Agents: config.AgentsConfig{
+			Defaults: config.AgentDefaults{
+				Workspace:         tmpDir,
+				ModelName:         "test-model",
+				MaxTokens:         4096,
+				MaxToolIterations: 10,
+			},
+		},
+	}
+
+	msgBus := bus.NewMessageBus()
+	provider := &picoInterleavedContentProvider{}
+	al := NewAgentLoop(cfg, msgBus, provider)
+
+	agent := al.GetRegistry().GetDefaultAgent()
+	if agent == nil {
+		t.Fatal("expected default agent")
+	}
+	agent.Tools.Register(&toolLimitTestTool{})
+
+	runCtx, runCancel := context.WithCancel(context.Background())
+	defer runCancel()
+
+	runDone := make(chan error, 1)
+	go func() {
+		runDone <- al.Run(runCtx)
+	}()
+
+	if err := msgBus.PublishInbound(context.Background(), bus.InboundMessage{
+		Channel:  "pico",
+		SenderID: "user-1",
+		ChatID:   "session-1",
+		Content:  "run with tools",
+	}); err != nil {
+		t.Fatalf("PublishInbound() error = %v", err)
+	}
+
+	outputs := make([]string, 0, 2)
+	deadline := time.After(2 * time.Second)
+	for len(outputs) < 2 {
+		select {
+		case outbound := <-msgBus.OutboundChan():
+			outputs = append(outputs, outbound.Content)
+		case <-deadline:
+			t.Fatalf("timed out waiting for pico outputs, got %v", outputs)
+		}
+	}
+
+	if outputs[0] != "intermediate model text" {
+		t.Fatalf("first outbound content = %q, want %q", outputs[0], "intermediate model text")
+	}
+	if outputs[1] != "final model text" {
+		t.Fatalf("second outbound content = %q, want %q", outputs[1], "final model text")
+	}
+
+	runCancel()
+	select {
+	case err := <-runDone:
+		if err != nil {
+			t.Fatalf("Run() error = %v", err)
+		}
+	case <-time.After(2 * time.Second):
+		t.Fatal("timed out waiting for Run() to exit")
+	}
+
+	select {
+	case outbound := <-msgBus.OutboundChan():
+		if outbound.Content == "final model text" {
+			t.Fatalf("unexpected duplicate final pico output: %+v", outbound)
+		}
+	case <-time.After(200 * time.Millisecond):
+	}
+}
+
+func TestRunAgentLoop_PicoSkipsInterimPublishWhenNotAllowed(t *testing.T) {
+	tmpDir := t.TempDir()
+
+	cfg := &config.Config{
+		Agents: config.AgentsConfig{
+			Defaults: config.AgentDefaults{
+				Workspace:         tmpDir,
+				ModelName:         "test-model",
+				MaxTokens:         4096,
+				MaxToolIterations: 10,
+			},
+		},
+	}
+
+	msgBus := bus.NewMessageBus()
+	provider := &picoInterleavedContentProvider{}
+	al := NewAgentLoop(cfg, msgBus, provider)
+
+	agent := al.GetRegistry().GetDefaultAgent()
+	if agent == nil {
+		t.Fatal("expected default agent")
+	}
+	agent.Tools.Register(&toolLimitTestTool{})
+
+	response, err := al.runAgentLoop(context.Background(), agent, processOptions{
+		SessionKey:              "agent:main:pico:session-1",
+		Channel:                 "pico",
+		ChatID:                  "session-1",
+		UserMessage:             "run with tools",
+		DefaultResponse:         defaultResponse,
+		EnableSummary:           false,
+		SendResponse:            false,
+		AllowInterimPicoPublish: false,
+		SuppressToolFeedback:    true,
+	})
+	if err != nil {
+		t.Fatalf("runAgentLoop() error = %v", err)
+	}
+	if response != "final model text" {
+		t.Fatalf("runAgentLoop() response = %q, want %q", response, "final model text")
+	}
+
+	select {
+	case outbound := <-msgBus.OutboundChan():
+		t.Fatalf("unexpected outbound message when interim publish disabled: %+v", outbound)
+	case <-time.After(200 * time.Millisecond):
+	}
+}
+
 func TestResolveMediaRefs_ResolvesToBase64(t *testing.T) {
 	store := media.NewFileMediaStore()
 	dir := t.TempDir()

pkg/utils/tool_feedback.go

@@ -0,0 +1,9 @@
+package utils
+
+import "fmt"
+
+// FormatToolFeedbackMessage renders the tool name and arguments preview in the
+// same markdown shape used by live tool feedback and session reconstruction.
+func FormatToolFeedbackMessage(toolName, argsPreview string) string {
+	return fmt.Sprintf("\U0001f527 `%s`\n```\n%s\n```", toolName, argsPreview)
+}

pkg/utils/tool_feedback_test.go

@@ -0,0 +1,11 @@
+package utils
+
+import "testing"
+
+func TestFormatToolFeedbackMessage(t *testing.T) {
+	got := FormatToolFeedbackMessage("read_file", "{\"path\":\"README.md\"}")
+	want := "\U0001f527 `read_file`\n```\n{\"path\":\"README.md\"}\n```"
+	if got != want {
+		t.Fatalf("FormatToolFeedbackMessage() = %q, want %q", got, want)
+	}
+}

web/backend/api/session.go

@@ -14,6 +14,7 @@ import (
 
 	"github.com/sipeed/picoclaw/pkg/config"
 	"github.com/sipeed/picoclaw/pkg/providers"
+	"github.com/sipeed/picoclaw/pkg/utils"
 )
 
 // registerSessionRoutes binds session list and detail endpoints to the ServeMux.
@@ -76,6 +77,11 @@ const (
 	handledToolResponseSummaryText = "Requested output delivered via tool attachment."
 )
 
+func defaultToolFeedbackMaxArgsLength() int {
+	defaults := config.AgentDefaults{}
+	return defaults.GetToolFeedbackMaxArgsLength()
+}
+
 // extractPicoSessionID extracts the session UUID from a full session key.
 // Returns the UUID and true if the key matches the Pico session pattern.
 func extractPicoSessionID(key string) (string, bool) {
@@ -202,7 +208,7 @@ func (h *Handler) readJSONLSession(dir, sessionID string) (sessionFile, error) {
 	}, nil
 }
 
-func buildSessionListItem(sessionID string, sess sessionFile) sessionListItem {
+func buildSessionListItem(sessionID string, sess sessionFile, toolFeedbackMaxArgsLength int) sessionListItem {
 	preview := ""
 	for _, msg := range sess.Messages {
 		if msg.Role == "user" {
@@ -219,7 +225,7 @@ func buildSessionListItem(sessionID string, sess sessionFile) sessionListItem {
 	}
 	title := preview
 
-	validMessageCount := len(visibleSessionMessages(sess.Messages))
+	validMessageCount := len(visibleSessionMessages(sess.Messages, toolFeedbackMaxArgsLength))
 
 	return sessionListItem{
 		ID:           sessionID,
@@ -260,7 +266,7 @@ func sessionMessagePreview(msg providers.Message) string {
 	return ""
 }
 
-func visibleSessionMessages(messages []providers.Message) []sessionChatMessage {
+func visibleSessionMessages(messages []providers.Message, toolFeedbackMaxArgsLength int) []sessionChatMessage {
 	transcript := make([]sessionChatMessage, 0, len(messages))
 
 	for _, msg := range messages {
@@ -275,6 +281,11 @@ func visibleSessionMessages(messages []providers.Message) []sessionChatMessage {
 			}
 
 		case "assistant":
+			toolSummaryMessages := visibleAssistantToolSummaryMessages(msg.ToolCalls, toolFeedbackMaxArgsLength)
+			if len(toolSummaryMessages) > 0 {
+				transcript = append(transcript, toolSummaryMessages...)
+			}
+
 			visibleToolMessages := visibleAssistantToolMessages(msg.ToolCalls)
 			if len(visibleToolMessages) > 0 {
 				transcript = append(transcript, visibleToolMessages...)
@@ -283,7 +294,7 @@ func visibleSessionMessages(messages []providers.Message) []sessionChatMessage {
 			// Pico web chat can persist both visible `message` tool output and a
 			// later plain assistant reply in the same turn. Hide only the fixed
 			// internal summary that marks handled tool delivery.
-			if len(visibleToolMessages) > 0 || !sessionMessageVisible(msg) || assistantMessageInternalOnly(msg) {
+			if !sessionMessageVisible(msg) || assistantMessageInternalOnly(msg) {
 				continue
 			}
 
@@ -302,6 +313,52 @@ func assistantMessageInternalOnly(msg providers.Message) bool {
 	return strings.TrimSpace(msg.Content) == handledToolResponseSummaryText
 }
 
+func visibleAssistantToolSummaryMessages(
+	toolCalls []providers.ToolCall,
+	toolFeedbackMaxArgsLength int,
+) []sessionChatMessage {
+	if len(toolCalls) == 0 {
+		return nil
+	}
+	if toolFeedbackMaxArgsLength <= 0 {
+		toolFeedbackMaxArgsLength = defaultToolFeedbackMaxArgsLength()
+	}
+
+	messages := make([]sessionChatMessage, 0, len(toolCalls))
+	for _, tc := range toolCalls {
+		name := tc.Name
+		argsJSON := ""
+		if tc.Function != nil {
+			if name == "" {
+				name = tc.Function.Name
+			}
+			argsJSON = tc.Function.Arguments
+		}
+
+		if strings.TrimSpace(name) == "" {
+			continue
+		}
+
+		if strings.TrimSpace(argsJSON) == "" && len(tc.Arguments) > 0 {
+			if encodedArgs, err := json.Marshal(tc.Arguments); err == nil {
+				argsJSON = string(encodedArgs)
+			}
+		}
+
+		argsPreview := strings.TrimSpace(argsJSON)
+		if argsPreview == "" {
+			argsPreview = "{}"
+		}
+
+		messages = append(messages, sessionChatMessage{
+			Role:    "assistant",
+			Content: utils.FormatToolFeedbackMessage(name, utils.Truncate(argsPreview, toolFeedbackMaxArgsLength)),
+		})
+	}
+
+	return messages
+}
+
 func visibleAssistantToolMessages(toolCalls []providers.ToolCall) []sessionChatMessage {
 	if len(toolCalls) == 0 {
 		return nil
@@ -347,7 +404,19 @@ func (h *Handler) sessionsDir() (string, error) {
 		return "", err
 	}
 
-	workspace := cfg.Agents.Defaults.Workspace
+	return resolveSessionsDir(cfg.Agents.Defaults.Workspace), nil
+}
+
+func (h *Handler) sessionRuntimeSettings() (string, int, error) {
+	cfg, err := config.LoadConfig(h.configPath)
+	if err != nil {
+		return "", 0, err
+	}
+
+	return resolveSessionsDir(cfg.Agents.Defaults.Workspace), cfg.Agents.Defaults.GetToolFeedbackMaxArgsLength(), nil
+}
+
+func resolveSessionsDir(workspace string) string {
 	if workspace == "" {
 		home, _ := os.UserHomeDir()
 		workspace = filepath.Join(home, ".picoclaw", "workspace")
@@ -363,14 +432,14 @@ func (h *Handler) sessionsDir() (string, error) {
 		}
 	}
 
-	return filepath.Join(workspace, "sessions"), nil
+	return filepath.Join(workspace, "sessions")
 }
 
 // handleListSessions returns a list of Pico session summaries.
 //
 //	GET /api/sessions
 func (h *Handler) handleListSessions(w http.ResponseWriter, r *http.Request) {
-	dir, err := h.sessionsDir()
+	dir, toolFeedbackMaxArgsLength, err := h.sessionRuntimeSettings()
 	if err != nil {
 		http.Error(w, "failed to resolve sessions directory", http.StatusInternalServerError)
 		return
@@ -454,7 +523,7 @@ func (h *Handler) handleListSessions(w http.ResponseWriter, r *http.Request) {
 		}
 
 		seen[sessionID] = struct{}{}
-		items = append(items, buildSessionListItem(sessionID, sess))
+		items = append(items, buildSessionListItem(sessionID, sess, toolFeedbackMaxArgsLength))
 	}
 
 	// Sort by updated descending (most recent first)
@@ -502,7 +571,7 @@ func (h *Handler) handleGetSession(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	dir, err := h.sessionsDir()
+	dir, toolFeedbackMaxArgsLength, err := h.sessionRuntimeSettings()
 	if err != nil {
 		http.Error(w, "failed to resolve sessions directory", http.StatusInternalServerError)
 		return
@@ -529,7 +598,7 @@ func (h *Handler) handleGetSession(w http.ResponseWriter, r *http.Request) {
 		}
 	}
 
-	messages := visibleSessionMessages(sess.Messages)
+	messages := visibleSessionMessages(sess.Messages, toolFeedbackMaxArgsLength)
 
 	w.Header().Set("Content-Type", "application/json")
 	json.NewEncoder(w).Encode(map[string]any{

web/backend/api/session_test.go

@@ -13,6 +13,7 @@ import (
 	"github.com/sipeed/picoclaw/pkg/memory"
 	"github.com/sipeed/picoclaw/pkg/providers"
 	"github.com/sipeed/picoclaw/pkg/session"
+	"github.com/sipeed/picoclaw/pkg/utils"
 )
 
 func sessionsTestDir(t *testing.T, configPath string) string {
@@ -273,11 +274,14 @@ func TestHandleGetSession_ReconstructsVisibleMessageToolOutput(t *testing.T) {
 	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 len(resp.Messages) != 3 {
+		t.Fatalf("len(resp.Messages) = %d, want 3", len(resp.Messages))
 	}
-	if resp.Messages[1].Role != "assistant" || resp.Messages[1].Content != "visible tool output" {
-		t.Fatalf("assistant message = %#v, want visible tool output", resp.Messages[1])
+	if !strings.Contains(resp.Messages[1].Content, "`message`") {
+		t.Fatalf("tool summary message = %#v, want message tool summary", resp.Messages[1])
+	}
+	if resp.Messages[2].Role != "assistant" || resp.Messages[2].Content != "visible tool output" {
+		t.Fatalf("assistant message = %#v, want visible tool output", resp.Messages[2])
 	}
 }
 
@@ -336,14 +340,17 @@ func TestHandleGetSession_PreservesFinalAssistantReplyAfterMessageToolOutput(t *
 	if err := json.Unmarshal(rec.Body.Bytes(), &resp); err != nil {
 		t.Fatalf("Unmarshal() error = %v", err)
 	}
-	if len(resp.Messages) != 3 {
-		t.Fatalf("len(resp.Messages) = %d, want 3", len(resp.Messages))
+	if len(resp.Messages) != 4 {
+		t.Fatalf("len(resp.Messages) = %d, want 4", len(resp.Messages))
 	}
-	if resp.Messages[1].Role != "assistant" || resp.Messages[1].Content != "visible tool output" {
-		t.Fatalf("interim assistant message = %#v, want visible tool output", resp.Messages[1])
+	if !strings.Contains(resp.Messages[1].Content, "`message`") {
+		t.Fatalf("tool summary message = %#v, want message tool summary", resp.Messages[1])
 	}
-	if resp.Messages[2].Role != "assistant" || resp.Messages[2].Content != "final assistant reply" {
-		t.Fatalf("final assistant message = %#v, want final assistant reply", resp.Messages[2])
+	if resp.Messages[2].Role != "assistant" || resp.Messages[2].Content != "visible tool output" {
+		t.Fatalf("interim assistant message = %#v, want visible tool output", resp.Messages[2])
+	}
+	if resp.Messages[3].Role != "assistant" || resp.Messages[3].Content != "final assistant reply" {
+		t.Fatalf("final assistant message = %#v, want final assistant reply", resp.Messages[3])
 	}
 }
 
@@ -400,8 +407,152 @@ func TestHandleListSessions_MessageCountUsesVisibleTranscript(t *testing.T) {
 	if len(items) != 1 {
 		t.Fatalf("len(items) = %d, want 1", len(items))
 	}
-	if items[0].MessageCount != 2 {
-		t.Fatalf("items[0].MessageCount = %d, want 2", items[0].MessageCount)
+	if items[0].MessageCount != 3 {
+		t.Fatalf("items[0].MessageCount = %d, want 3", items[0].MessageCount)
+	}
+}
+
+func TestHandleGetSession_PreservesToolSummaryAndAssistantContent(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-tool-summary-and-content"
+	for _, msg := range []providers.Message{
+		{Role: "user", Content: "check file"},
+		{
+			Role:    "assistant",
+			Content: "model final reply",
+			ToolCalls: []providers.ToolCall{
+				{
+					ID:   "call_1",
+					Type: "function",
+					Function: &providers.FunctionCall{
+						Name:      "read_file",
+						Arguments: `{"path":"README.md","start_line":1,"end_line":10}`,
+					},
+				},
+			},
+		},
+	} {
+		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-tool-summary-and-content", 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) != 3 {
+		t.Fatalf("len(resp.Messages) = %d, want 3", len(resp.Messages))
+	}
+	if resp.Messages[0].Role != "user" || resp.Messages[0].Content != "check file" {
+		t.Fatalf("first message = %#v, want user/check file", resp.Messages[0])
+	}
+	if !strings.Contains(resp.Messages[1].Content, "`read_file`") {
+		t.Fatalf("tool summary message = %#v, want read_file summary", resp.Messages[1])
+	}
+	if resp.Messages[2].Role != "assistant" || resp.Messages[2].Content != "model final reply" {
+		t.Fatalf("assistant message = %#v, want model final reply", resp.Messages[2])
+	}
+}
+
+func TestHandleGetSession_UsesConfiguredToolFeedbackMaxArgsLength(t *testing.T) {
+	configPath, cleanup := setupOAuthTestEnv(t)
+	defer cleanup()
+
+	cfg, err := config.LoadConfig(configPath)
+	if err != nil {
+		t.Fatalf("LoadConfig() error = %v", err)
+	}
+	cfg.Agents.Defaults.ToolFeedback.MaxArgsLength = 20
+	err = config.SaveConfig(configPath, cfg)
+	if err != nil {
+		t.Fatalf("SaveConfig() error = %v", err)
+	}
+
+	dir := sessionsTestDir(t, configPath)
+	store, err := memory.NewJSONLStore(dir)
+	if err != nil {
+		t.Fatalf("NewJSONLStore() error = %v", err)
+	}
+
+	argsJSON := `{"path":"README.md","start_line":1,"end_line":10,"extra":"abcdefghijklmnopqrstuvwxyz"}`
+	sessionKey := picoSessionPrefix + "detail-tool-summary-max-args"
+	err = store.AddFullMessage(nil, sessionKey, providers.Message{Role: "user", Content: "check file"})
+	if err != nil {
+		t.Fatalf("AddFullMessage(user) error = %v", err)
+	}
+	err = store.AddFullMessage(nil, sessionKey, providers.Message{
+		Role: "assistant",
+		ToolCalls: []providers.ToolCall{{
+			ID:   "call_1",
+			Type: "function",
+			Function: &providers.FunctionCall{
+				Name:      "read_file",
+				Arguments: argsJSON,
+			},
+		}},
+	})
+	if err != nil {
+		t.Fatalf("AddFullMessage(assistant) error = %v", err)
+	}
+
+	h := NewHandler(configPath)
+	mux := http.NewServeMux()
+	h.RegisterRoutes(mux)
+
+	rec := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodGet, "/api/sessions/detail-tool-summary-max-args", 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"`
+	}
+	err = json.Unmarshal(rec.Body.Bytes(), &resp)
+	if err != nil {
+		t.Fatalf("Unmarshal() error = %v", err)
+	}
+	if len(resp.Messages) < 2 {
+		t.Fatalf("len(resp.Messages) = %d, want at least 2", len(resp.Messages))
+	}
+
+	wantPreview := utils.Truncate(argsJSON, 20)
+	if !strings.Contains(resp.Messages[1].Content, wantPreview) {
+		t.Fatalf("tool summary = %q, want preview %q", resp.Messages[1].Content, wantPreview)
+	}
+	if strings.Contains(resp.Messages[1].Content, argsJSON) {
+		t.Fatalf("tool summary = %q, expected configured truncation", resp.Messages[1].Content)
 	}
 }