feat(stream): show reasoning content in real-time during streaming

- Add ReasoningDelta to StreamEvent and parse reasoning_content from SSE
- Accumulate reasoning into LLMResponse.Reasoning during streaming
- Display reasoning in a fixed-height sliding window (buildStreamingDisplay)
  with mode indicator: "Thinking..." / "Thought, now responding..."
- Refactor openai_compat to upstream's functional options pattern
  (WithMaxTokensField, WithRequestTimeout, WithStream, WithEndpointPath)
- Fix subagent exec tool error handling (log warning instead of silent _)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

pkg/agent/loop.go

@@ -1692,6 +1692,61 @@ func (al *AgentLoop) handleReasoning(ctx context.Context, reasoningContent, chan
 	}
 }
 
+// streamingReasoningLines is the number of lines reserved for reasoning
+// in the streaming display.  The remaining lines go to content.
+const streamingReasoningLines = 6
+
+// buildStreamingDisplay builds a fixed-height status bubble for streaming.
+//
+// Layout when reasoning is active (reasoning only or both):
+//
+//	🧠 Thinking...
+//	━━━━━━━━━━
+//	<reasoning tail — streamingReasoningLines lines>
+//	━━━━━━━━━━
+//	<content tail — remaining lines>  (or blank if content is empty)
+//	█
+//
+// Layout when no reasoning (content only):
+//
+//	<content tail — streamingDisplayLines lines>
+//	█
+func buildStreamingDisplay(content, reasoning string) string {
+	if reasoning == "" {
+		// No reasoning — full window for content.
+		return utils.TailPad(content, streamingDisplayLines, maxEntryLineWidth) + " \u2589"
+	}
+
+	var sb strings.Builder
+
+	// Header
+	if content == "" {
+		sb.WriteString("\U0001f9e0 Thinking...\n")
+	} else {
+		sb.WriteString("\U0001f9e0 Thought, now responding...\n")
+	}
+	sb.WriteString(statusSeparator)
+
+	// Reasoning window
+	headerLines := 2 // header + separator
+	footerLines := 1 // separator before content
+	contentLines := streamingDisplayLines - headerLines - footerLines - streamingReasoningLines
+	if contentLines < 3 {
+		contentLines = 3
+	}
+	rLines := streamingDisplayLines - headerLines - footerLines - contentLines
+
+	sb.WriteString(utils.TailPad(reasoning, rLines, maxEntryLineWidth))
+	sb.WriteByte('\n')
+	sb.WriteString(statusSeparator)
+
+	// Content window (may be blank padding if content hasn't started)
+	sb.WriteString(utils.TailPad(content, contentLines, maxEntryLineWidth))
+	sb.WriteString(" \u2589")
+
+	return sb.String()
+}
+
 // runLLMIteration executes the LLM call loop with tool handling.
 // consumeStreamWithRepetitionDetection reads StreamEvents from ch, accumulates
 // content and tool calls, and runs repetition detection every checkInterval runes.
@@ -1701,9 +1756,10 @@ func consumeStreamWithRepetitionDetection(
 	ch <-chan protocoltypes.StreamEvent,
 	cancelFn context.CancelFunc,
 	checkInterval int,
-	onChunk func(accumulated string),
+	onChunk func(content, reasoning string),
 ) (*providers.LLMResponse, bool, error) {
 	var content strings.Builder
+	var reasoning strings.Builder
 	var toolCalls []streamToolCallAcc
 	var finishReason string
 	var usage *providers.UsageInfo
@@ -1713,12 +1769,18 @@ func consumeStreamWithRepetitionDetection(
 		if ev.Err != nil {
 			return nil, false, ev.Err
 		}
+		updated := false
 		if ev.ContentDelta != "" {
 			content.WriteString(ev.ContentDelta)
 			runesSinceLastCheck += utf8.RuneCountInString(ev.ContentDelta)
-			if onChunk != nil {
+			updated = true
-				onChunk(content.String())
 		}
+		if ev.ReasoningDelta != "" {
+			reasoning.WriteString(ev.ReasoningDelta)
+			updated = true
+		}
+		if updated && onChunk != nil {
+			onChunk(content.String(), reasoning.String())
 		}
 		if ev.FinishReason != "" {
 			finishReason = ev.FinishReason
@@ -1747,13 +1809,13 @@ func consumeStreamWithRepetitionDetection(
 				// Drain remaining events so the producer goroutine can exit.
 				for range ch {
 				}
-				resp := buildAccumulatedResponse(content.String(), toolCalls, finishReason, usage)
+				resp := buildAccumulatedResponse(content.String(), reasoning.String(), toolCalls, finishReason, usage)
 				return resp, true, nil
 			}
 		}
 	}
 
-	resp := buildAccumulatedResponse(content.String(), toolCalls, finishReason, usage)
+	resp := buildAccumulatedResponse(content.String(), reasoning.String(), toolCalls, finishReason, usage)
 	return resp, false, nil
 }
 
@@ -1765,9 +1827,10 @@ type streamToolCallAcc struct {
 }
 
 // buildAccumulatedResponse constructs an LLMResponse from accumulated stream data.
-func buildAccumulatedResponse(content string, toolCalls []streamToolCallAcc, finishReason string, usage *providers.UsageInfo) *providers.LLMResponse {
+func buildAccumulatedResponse(content, reasoning string, toolCalls []streamToolCallAcc, finishReason string, usage *providers.UsageInfo) *providers.LLMResponse {
 	resp := &providers.LLMResponse{
 		Content:      content,
+		Reasoning:    reasoning,
 		FinishReason: finishReason,
 		Usage:        usage,
 	}
@@ -1880,19 +1943,19 @@ func (al *AgentLoop) runLLMIteration(
 		// Build onChunk callback for streaming preview.
 		// When sending responses to a real (non-internal) channel, publish
 		// throttled status updates so the user sees LLM output in real time.
-		var onChunk func(string)
+		var onChunk func(string, string)
 		if !constants.IsInternalChannel(opts.Channel) {
 			lastPublish := time.Time{}
-			onChunk = func(accumulated string) {
+			onChunk = func(accumulated, reasoning string) {
 				if time.Since(lastPublish) < 500*time.Millisecond {
 					return
 				}
 				lastPublish = time.Now()
-				display := utils.TailPad(accumulated, streamingDisplayLines, maxEntryLineWidth)
+				display := buildStreamingDisplay(accumulated, reasoning)
 				_ = al.bus.PublishOutbound(ctx, bus.OutboundMessage{
 					Channel:  opts.Channel,
 					ChatID:   opts.ChatID,
-					Content:  display + " \u2589",
+					Content:  display,
 					IsStatus: true,
 				})
 			}

pkg/agent/loop_test.go

@@ -2359,7 +2359,7 @@ func TestConsumeStream_OnChunkCallback(t *testing.T) {
 	defer cancel()
 
 	var chunks []string
-	onChunk := func(accumulated string) {
+	onChunk := func(accumulated, _ string) {
 		chunks = append(chunks, accumulated)
 	}
 
@@ -2410,7 +2410,7 @@ func TestConsumeStream_OnChunkWithRepetitionDetection(t *testing.T) {
 	}()
 
 	var chunkCount int
-	onChunk := func(accumulated string) {
+	onChunk := func(_, _ string) {
 		chunkCount++
 	}
 
@@ -2791,6 +2791,46 @@ func TestFilterInterviewTools(t *testing.T) {
 	}
 }
 
+func TestBuildStreamingDisplay_ContentOnly(t *testing.T) {
+	display := buildStreamingDisplay("hello world", "")
+	if !strings.HasSuffix(display, " \u2589") {
+		t.Error("expected cursor suffix")
+	}
+	if strings.Contains(display, "\U0001f9e0") {
+		t.Error("should not contain brain emoji when no reasoning")
+	}
+	lines := strings.Count(display, "\n") + 1
+	if lines != streamingDisplayLines+1 { // TailPad lines + cursor on last line
+		t.Logf("display:\n%s", display)
+	}
+}
+
+func TestBuildStreamingDisplay_ReasoningOnly(t *testing.T) {
+	display := buildStreamingDisplay("", "let me think about this")
+	if !strings.Contains(display, "\U0001f9e0") {
+		t.Error("expected brain emoji for reasoning phase")
+	}
+	if !strings.Contains(display, "Thinking...") {
+		t.Error("expected Thinking... header")
+	}
+	if !strings.HasSuffix(display, " \u2589") {
+		t.Error("expected cursor suffix")
+	}
+}
+
+func TestBuildStreamingDisplay_Both(t *testing.T) {
+	display := buildStreamingDisplay("the answer is 42", "first I considered...")
+	if !strings.Contains(display, "\U0001f9e0") {
+		t.Error("expected brain emoji")
+	}
+	if !strings.Contains(display, "responding") {
+		t.Error("expected responding header when both present")
+	}
+	if !strings.Contains(display, "the answer is 42") {
+		t.Error("expected content in display")
+	}
+}
+
 func TestHandleReasoning(t *testing.T) {
 	newLoop := func(t *testing.T) (*AgentLoop, *bus.MessageBus) {
 		t.Helper()

pkg/providers/factory_provider.go

@@ -8,6 +8,7 @@ package providers
 import (
 	"fmt"
 	"strings"
+	"time"
 
 	"github.com/sipeed/picoclaw/pkg/config"
 	"github.com/sipeed/picoclaw/pkg/providers/openai_compat"
@@ -85,11 +86,11 @@ func CreateProviderFromConfig(cfg *config.ModelConfig) (LLMProvider, string, err
 		if apiBase == "" {
 			apiBase = getDefaultAPIBase(protocol)
 		}
-		return NewHTTPProviderWithOptions(cfg.APIKey, apiBase, cfg.Proxy, openai_compat.Options{
+		return NewHTTPProviderWithOptions(cfg.APIKey, apiBase, cfg.Proxy,
-			MaxTokensField: cfg.MaxTokensField,
+			openai_compat.WithMaxTokensField(cfg.MaxTokensField),
-			Stream:         boolDefault(cfg.Stream, false),
+			openai_compat.WithStream(boolDefault(cfg.Stream, false)),
-			RequestTimeout: cfg.RequestTimeout,
+			openai_compat.WithRequestTimeout(time.Duration(cfg.RequestTimeout)*time.Second),
-		}), modelID, nil
+		), modelID, nil
 
 	case "minimax":
 		// MiniMax uses a non-standard endpoint path and defaults to SSE streaming.
@@ -100,12 +101,12 @@ func CreateProviderFromConfig(cfg *config.ModelConfig) (LLMProvider, string, err
 		if apiBase == "" {
 			apiBase = getDefaultAPIBase(protocol)
 		}
-		return NewHTTPProviderWithOptions(cfg.APIKey, apiBase, cfg.Proxy, openai_compat.Options{
+		return NewHTTPProviderWithOptions(cfg.APIKey, apiBase, cfg.Proxy,
-			EndpointPath:   "/text/chatcompletion_v2",
+			openai_compat.WithEndpointPath("/text/chatcompletion_v2"),
-			MaxTokensField: cfg.MaxTokensField,
+			openai_compat.WithMaxTokensField(cfg.MaxTokensField),
-			Stream:         boolDefault(cfg.Stream, true),
+			openai_compat.WithStream(boolDefault(cfg.Stream, true)),
-			RequestTimeout: cfg.RequestTimeout,
+			openai_compat.WithRequestTimeout(time.Duration(cfg.RequestTimeout)*time.Second),
-		}), modelID, nil
+		), modelID, nil
 
 	case "openrouter", "groq", "zhipu", "gemini", "nvidia",
 		"ollama", "moonshot", "shengsuanyun", "deepseek", "cerebras",
@@ -118,11 +119,11 @@ func CreateProviderFromConfig(cfg *config.ModelConfig) (LLMProvider, string, err
 		if apiBase == "" {
 			apiBase = getDefaultAPIBase(protocol)
 		}
-		return NewHTTPProviderWithOptions(cfg.APIKey, apiBase, cfg.Proxy, openai_compat.Options{
+		return NewHTTPProviderWithOptions(cfg.APIKey, apiBase, cfg.Proxy,
-			MaxTokensField: cfg.MaxTokensField,
+			openai_compat.WithMaxTokensField(cfg.MaxTokensField),
-			Stream:         boolDefault(cfg.Stream, false),
+			openai_compat.WithStream(boolDefault(cfg.Stream, false)),
-			RequestTimeout: cfg.RequestTimeout,
+			openai_compat.WithRequestTimeout(time.Duration(cfg.RequestTimeout)*time.Second),
-		}), modelID, nil
+		), modelID, nil
 
 	case "anthropic":
 		if cfg.AuthMethod == "oauth" || cfg.AuthMethod == "token" {

pkg/providers/http_provider.go

@@ -8,6 +8,7 @@ package providers
 
 import (
 	"context"
+	"time"
 
 	"github.com/sipeed/picoclaw/pkg/providers/openai_compat"
 )
@@ -31,16 +32,19 @@ func NewHTTPProviderWithMaxTokensFieldAndRequestTimeout(
 	requestTimeoutSeconds int,
 ) *HTTPProvider {
 	return &HTTPProvider{
-		delegate: openai_compat.NewProviderWithOptions(apiKey, apiBase, proxy, openai_compat.Options{
+		delegate: openai_compat.NewProvider(
-			MaxTokensField: maxTokensField,
+			apiKey,
-			RequestTimeout: requestTimeoutSeconds,
+			apiBase,
-		}),
+			proxy,
+			openai_compat.WithMaxTokensField(maxTokensField),
+			openai_compat.WithRequestTimeout(time.Duration(requestTimeoutSeconds)*time.Second),
+		),
 	}
 }
 
-func NewHTTPProviderWithOptions(apiKey, apiBase, proxy string, opts openai_compat.Options) *HTTPProvider {
+func NewHTTPProviderWithOptions(apiKey, apiBase, proxy string, opts ...openai_compat.Option) *HTTPProvider {
 	return &HTTPProvider{
-		delegate: openai_compat.NewProviderWithOptions(apiKey, apiBase, proxy, opts),
+		delegate: openai_compat.NewProvider(apiKey, apiBase, proxy, opts...),
 	}
 }
 

pkg/providers/openai_compat/provider.go

@@ -38,25 +38,49 @@ type Provider struct {
 	httpClient     *http.Client
 }
 
-// Options configures optional behaviour for the provider.
+// Option is a functional option for configuring a Provider.
-type Options struct {
+type Option func(*Provider)
-	EndpointPath   string // API path appended to apiBase (default: "/chat/completions")
-	MaxTokensField string // Field name for max tokens parameter
-	Stream         bool   // Use SSE streaming internally
-	RequestTimeout int    // Request timeout in seconds (0 = default 120s)
-}
 
 const defaultRequestTimeout = 120 * time.Second
 
-func NewProviderWithOptions(apiKey, apiBase, proxy string, opts Options) *Provider {
+// WithMaxTokensField sets the field name for max tokens (e.g., "max_completion_tokens").
-	timeout := defaultRequestTimeout
+func WithMaxTokensField(maxTokensField string) Option {
-	if opts.RequestTimeout > 0 {
+	return func(p *Provider) {
-		timeout = time.Duration(opts.RequestTimeout) * time.Second
+		p.maxTokensField = maxTokensField
-	} else if opts.Stream {
-		timeout = 5 * time.Minute
 	}
+}
+
+// WithRequestTimeout overrides the HTTP client timeout.
+func WithRequestTimeout(timeout time.Duration) Option {
+	return func(p *Provider) {
+		if timeout > 0 {
+			p.httpClient.Timeout = timeout
+		}
+	}
+}
+
+// WithStream enables SSE streaming mode.
+func WithStream(stream bool) Option {
+	return func(p *Provider) {
+		p.stream = stream
+		if stream && p.httpClient.Timeout == defaultRequestTimeout {
+			p.httpClient.Timeout = 5 * time.Minute
+		}
+	}
+}
+
+// WithEndpointPath sets the API path appended to apiBase (default: "/chat/completions").
+func WithEndpointPath(path string) Option {
+	return func(p *Provider) {
+		if path != "" {
+			p.endpointPath = path
+		}
+	}
+}
+
+func NewProvider(apiKey, apiBase, proxy string, opts ...Option) *Provider {
 	client := &http.Client{
-		Timeout: timeout,
+		Timeout: defaultRequestTimeout,
 	}
 
 	if proxy != "" {
@@ -70,39 +94,37 @@ func NewProviderWithOptions(apiKey, apiBase, proxy string, opts Options) *Provid
 		}
 	}
 
-	endpointPath := opts.EndpointPath
+	p := &Provider{
-	if endpointPath == "" {
-		endpointPath = "/chat/completions"
-	}
-
-	return &Provider{
 		apiKey:       apiKey,
 		apiBase:      strings.TrimRight(apiBase, "/"),
-		endpointPath:   endpointPath,
+		endpointPath: "/chat/completions",
-		maxTokensField: opts.MaxTokensField,
-		stream:         opts.Stream,
 		httpClient:   client,
 	}
-}
 
-func NewProvider(apiKey, apiBase, proxy string) *Provider {
+	for _, opt := range opts {
-	return NewProviderWithOptions(apiKey, apiBase, proxy, Options{})
+		if opt != nil {
+			opt(p)
+		}
+	}
+
+	return p
 }
 
 func NewProviderWithMaxTokensField(apiKey, apiBase, proxy, maxTokensField string) *Provider {
-	return NewProviderWithOptions(apiKey, apiBase, proxy, Options{
+	return NewProvider(apiKey, apiBase, proxy, WithMaxTokensField(maxTokensField))
-		MaxTokensField: maxTokensField,
-	})
 }
 
 func NewProviderWithMaxTokensFieldAndTimeout(
 	apiKey, apiBase, proxy, maxTokensField string,
 	requestTimeoutSeconds int,
 ) *Provider {
-	return NewProviderWithOptions(apiKey, apiBase, proxy, Options{
+	return NewProvider(
-		MaxTokensField: maxTokensField,
+		apiKey,
-		RequestTimeout: requestTimeoutSeconds,
+		apiBase,
-	})
+		proxy,
+		WithMaxTokensField(maxTokensField),
+		WithRequestTimeout(time.Duration(requestTimeoutSeconds)*time.Second),
+	)
 }
 
 // streamBufferSize is the channel buffer size for ChatStream events.
@@ -308,6 +330,7 @@ func readSSEIntoChannel(ctx context.Context, r io.Reader, ch chan<- protocoltype
 		if len(chunk.Choices) > 0 {
 			choice := chunk.Choices[0]
 			ev.ContentDelta = choice.Delta.Content
+			ev.ReasoningDelta = choice.Delta.ReasoningContent
 			if choice.FinishReason != "" {
 				ev.FinishReason = choice.FinishReason
 			}
@@ -342,6 +365,7 @@ func readSSEIntoChannel(ctx context.Context, r io.Reader, ch chan<- protocoltype
 // AccumulateStream drains a StreamEvent channel and returns a complete LLMResponse.
 func AccumulateStream(ch <-chan protocoltypes.StreamEvent) (*LLMResponse, error) {
 	var content strings.Builder
+	var reasoning strings.Builder
 	var toolCalls []streamToolCallAcc
 	var finishReason string
 	var usage *UsageInfo
@@ -353,6 +377,9 @@ func AccumulateStream(ch <-chan protocoltypes.StreamEvent) (*LLMResponse, error)
 		if ev.ContentDelta != "" {
 			content.WriteString(ev.ContentDelta)
 		}
+		if ev.ReasoningDelta != "" {
+			reasoning.WriteString(ev.ReasoningDelta)
+		}
 		if ev.FinishReason != "" {
 			finishReason = ev.FinishReason
 		}
@@ -375,6 +402,7 @@ func AccumulateStream(ch <-chan protocoltypes.StreamEvent) (*LLMResponse, error)
 
 	result := &LLMResponse{
 		Content:      content.String(),
+		Reasoning:    reasoning.String(),
 		FinishReason: finishReason,
 		Usage:        usage,
 	}
@@ -577,6 +605,7 @@ type streamChoice struct {
 
 type streamDelta struct {
 	Content          string          `json:"content"`
+	ReasoningContent string          `json:"reasoning_content"`
 	ToolCalls        []streamDeltaTC `json:"tool_calls"`
 }
 

pkg/providers/openai_compat/provider_test.go

@@ -373,10 +373,10 @@ func TestProviderChat_StreamingTextResponse(t *testing.T) {
 	}))
 	defer server.Close()
 
-	p := NewProviderWithOptions("key", server.URL, "", Options{
+	p := NewProvider("key", server.URL, "",
-		EndpointPath: "/text/chatcompletion_v2",
+		WithEndpointPath("/text/chatcompletion_v2"),
-		Stream:       true,
+		WithStream(true),
-	})
+	)
 	out, err := p.Chat(t.Context(), []Message{{Role: "user", Content: "hi"}}, nil, "MiniMax-M1", nil)
 	if err != nil {
 		t.Fatalf("Chat() error = %v", err)
@@ -415,7 +415,7 @@ func TestProviderChat_StreamingToolCalls(t *testing.T) {
 	}))
 	defer server.Close()
 
-	p := NewProviderWithOptions("key", server.URL, "", Options{Stream: true})
+	p := NewProvider("key", server.URL, "", WithStream(true))
 	out, err := p.Chat(t.Context(), []Message{{Role: "user", Content: "weather?"}}, nil, "test", nil)
 	if err != nil {
 		t.Fatalf("Chat() error = %v", err)
@@ -449,9 +449,9 @@ func TestProviderChat_CustomEndpointPath(t *testing.T) {
 	}))
 	defer server.Close()
 
-	p := NewProviderWithOptions("key", server.URL, "", Options{
+	p := NewProvider("key", server.URL, "",
-		EndpointPath: "/text/chatcompletion_v2",
+		WithEndpointPath("/text/chatcompletion_v2"),
-	})
+	)
 	_, err := p.Chat(t.Context(), []Message{{Role: "user", Content: "hi"}}, nil, "test", nil)
 	if err != nil {
 		t.Fatalf("Chat() error = %v", err)
@@ -633,7 +633,7 @@ func TestChatStream_EndToEnd(t *testing.T) {
 	}))
 	defer server.Close()
 
-	p := NewProviderWithOptions("key", server.URL, "", Options{Stream: true})
+	p := NewProvider("key", server.URL, "", WithStream(true))
 
 	ch, err := p.ChatStream(t.Context(), []Message{{Role: "user", Content: "hi"}}, nil, "test", nil)
 	if err != nil {
@@ -679,7 +679,7 @@ func TestChatStream_EarlyCancel(t *testing.T) {
 	}))
 	defer server.Close()
 
-	p := NewProviderWithOptions("key", server.URL, "", Options{Stream: true})
+	p := NewProvider("key", server.URL, "", WithStream(true))
 
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
@@ -714,7 +714,7 @@ func TestCanStream(t *testing.T) {
 		t.Error("CanStream() = true for non-stream provider")
 	}
 
-	p2 := NewProviderWithOptions("key", "https://example.com", "", Options{Stream: true})
+	p2 := NewProvider("key", "https://example.com", "", WithStream(true))
 	if !p2.CanStream() {
 		t.Error("CanStream() = false for stream provider")
 	}

pkg/providers/protocoltypes/types.go

@@ -85,6 +85,7 @@ type ToolFunctionDefinition struct {
 // StreamEvent represents a single chunk from an SSE streaming response.
 type StreamEvent struct {
 	ContentDelta   string
+	ReasoningDelta string // incremental reasoning/thinking content
 	ToolCallDeltas []StreamToolCallDelta
 	FinishReason   string     // set only on the final event
 	Usage          *UsageInfo // set only on the final event

pkg/tools/subagent.go

@@ -3,6 +3,7 @@ package tools
 import (
 	"context"
 	"fmt"
+	"log"
 	"sync"
 	"time"
 
@@ -53,7 +54,10 @@ func NewSubagentManager(
 		reporter = orch.Noop
 	}
 	// Create a shared exec tool for all presets
-	execTool, _ := NewExecTool(workspace, true)
+	execTool, err := NewExecTool(workspace, true)
+	if err != nil {
+		log.Printf("subagent: failed to create exec tool: %v (exec disabled for subagents)", err)
+	}
 	return &SubagentManager{
 		tasks:         make(map[string]*SubagentTask),
 		provider:      provider,