Merge pull request #3156 from loafoe/feat/session-token-usage

feat(pico): emit per-turn LLM token usage on finalized message

pkg/channels/manager.go

@@ -699,18 +699,34 @@ func setStreamerModelName(streamer any, modelName string) {
 	setter.SetModelName(modelName)
 }
 
+type turnUsageStreamer interface {
+	SetTurnUsage(inputTokens, outputTokens int)
+}
+
+// setStreamerTurnUsage forwards real per-turn token usage to a streamer that
+// supports it, transparently unwrapping the manager's streamer wrappers.
+func setStreamerTurnUsage(streamer any, inputTokens, outputTokens int) {
+	setter, ok := streamer.(turnUsageStreamer)
+	if !ok {
+		return
+	}
+	setter.SetTurnUsage(inputTokens, outputTokens)
+}
+
 // splitMarkerStreamer turns accumulated streaming text containing
 // MessageSplitMarker into separate channel stream messages.
 type splitMarkerStreamer struct {
-	mu             sync.Mutex
-	current        bus.Streamer
-	reasoning      bus.ReasoningStreamer
-	begin          func(context.Context) (bus.Streamer, error)
-	completedParts int
-	finalized      bool
-	onFinalize     func(context.Context, string)
-	clearMarker    func()
-	modelName      string
+	mu               sync.Mutex
+	current          bus.Streamer
+	reasoning        bus.ReasoningStreamer
+	begin            func(context.Context) (bus.Streamer, error)
+	completedParts   int
+	finalized        bool
+	onFinalize       func(context.Context, string)
+	clearMarker      func()
+	modelName        string
+	turnInputTokens  int
+	turnOutputTokens int
 }
 
 func (s *splitMarkerStreamer) Update(ctx context.Context, content string) error {
@@ -761,6 +777,14 @@ func (s *splitMarkerStreamer) SetModelName(modelName string) {
 	setStreamerModelName(s.reasoning, s.modelName)
 }
 
+func (s *splitMarkerStreamer) SetTurnUsage(inputTokens, outputTokens int) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	s.turnInputTokens = inputTokens
+	s.turnOutputTokens = outputTokens
+	setStreamerTurnUsage(s.current, s.turnInputTokens, s.turnOutputTokens)
+}
+
 func (s *splitMarkerStreamer) Cancel(ctx context.Context) {
 	s.mu.Lock()
 	defer s.mu.Unlock()
@@ -840,6 +864,7 @@ func (s *splitMarkerStreamer) ensureCurrentLocked(ctx context.Context) error {
 	}
 	s.current = streamer
 	setStreamerModelName(s.current, s.modelName)
+	setStreamerTurnUsage(s.current, s.turnInputTokens, s.turnOutputTokens)
 	return nil
 }
 
@@ -928,6 +953,10 @@ func (s *finalizeHookStreamer) SetModelName(modelName string) {
 	setStreamerModelName(s.Streamer, strings.TrimSpace(modelName))
 }
 
+func (s *finalizeHookStreamer) SetTurnUsage(inputTokens, outputTokens int) {
+	setStreamerTurnUsage(s.Streamer, inputTokens, outputTokens)
+}
+
 func (s *finalizeHookStreamer) runFinalizeHook(ctx context.Context, content string) {
 	if s.onFinalize != nil {
 		s.onFinalize(ctx, content)

pkg/channels/manager_test.go

@@ -3383,3 +3383,56 @@ func TestManager_SendPlaceholder(t *testing.T) {
 		t.Error("expected SendPlaceholder to fail for unknown channel")
 	}
 }
+
+// turnUsageTrackingStreamer is a mockStreamer that records SetTurnUsage calls,
+// used to verify the manager's streamer wrappers forward per-turn token usage
+// to the inner streamer (regression: the wrappers previously dropped it because
+// SetTurnUsage is not part of the bus.Streamer interface).
+type turnUsageTrackingStreamer struct {
+	mockStreamer
+	inputTokens  int
+	outputTokens int
+	usageCalls   int
+}
+
+func (m *turnUsageTrackingStreamer) SetTurnUsage(inputTokens, outputTokens int) {
+	m.usageCalls++
+	m.inputTokens = inputTokens
+	m.outputTokens = outputTokens
+}
+
+func TestFinalizeHookStreamerForwardsTurnUsage(t *testing.T) {
+	inner := &turnUsageTrackingStreamer{}
+	wrapper := &finalizeHookStreamer{Streamer: inner}
+
+	setter, ok := any(wrapper).(turnUsageStreamer)
+	if !ok {
+		t.Fatal("finalizeHookStreamer does not satisfy turnUsageStreamer")
+	}
+	setter.SetTurnUsage(1234, 567)
+
+	if inner.usageCalls != 1 {
+		t.Fatalf("inner SetTurnUsage calls = %d, want 1", inner.usageCalls)
+	}
+	if inner.inputTokens != 1234 || inner.outputTokens != 567 {
+		t.Errorf("inner usage = (%d, %d), want (1234, 567)", inner.inputTokens, inner.outputTokens)
+	}
+}
+
+func TestSplitMarkerStreamerForwardsTurnUsage(t *testing.T) {
+	inner := &turnUsageTrackingStreamer{}
+	wrapper := &splitMarkerStreamer{current: inner}
+
+	setter, ok := any(wrapper).(turnUsageStreamer)
+	if !ok {
+		t.Fatal("splitMarkerStreamer does not satisfy turnUsageStreamer")
+	}
+	setter.SetTurnUsage(1234, 567)
+
+	if inner.usageCalls != 1 {
+		t.Fatalf("inner SetTurnUsage calls = %d, want 1", inner.usageCalls)
+	}
+	if inner.inputTokens != 1234 || inner.outputTokens != 567 {
+		t.Errorf("inner usage = (%d, %d), want (1234, 567)", inner.inputTokens, inner.outputTokens)
+	}
+}

pkg/channels/pico/pico.go

@@ -105,6 +105,8 @@ type PicoChannel struct {
 	cancel             context.CancelFunc
 	progress           *channels.ToolFeedbackAnimator
 	deleteMessageFn    func(context.Context, string, string) error
+	// broadcastFn lets tests intercept outbound broadcasts. nil → broadcastToSession.
+	broadcastFn func(chatID string, msg PicoMessage) error
 }
 
 // NewPicoChannel creates a new Pico Protocol channel.
@@ -531,6 +533,8 @@ type picoStreamer struct {
 	channel          *PicoChannel
 	chatID           string
 	modelName        string
+	turnInputTokens  int
+	turnOutputTokens int
 	messageID        string
 	reasoningID      string
 	throttleInterval time.Duration
@@ -553,6 +557,17 @@ func (s *picoStreamer) SetModelName(modelName string) {
 	s.modelName = strings.TrimSpace(modelName)
 }
 
+// SetTurnUsage records the real per-turn LLM token usage to emit on finalize.
+func (s *picoStreamer) SetTurnUsage(inputTokens, outputTokens int) {
+	if s == nil {
+		return
+	}
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	s.turnInputTokens = inputTokens
+	s.turnOutputTokens = outputTokens
+}
+
 func (s *picoStreamer) Update(ctx context.Context, content string) error {
 	s.mu.Lock()
 	defer s.mu.Unlock()
@@ -661,8 +676,9 @@ func (s *picoStreamer) sendLocked(ctx context.Context, content string, contextUs
 			payload[PayloadKeyModelName] = s.modelName
 		}
 		setContextUsagePayload(payload, contextUsage)
+		setTurnUsagePayload(payload, s.turnInputTokens, s.turnOutputTokens)
 		outMsg := newMessage(TypeMessageCreate, payload)
-		if err := s.channel.broadcastToSession(s.chatID, outMsg); err != nil {
+		if err := s.channel.broadcast(s.chatID, outMsg); err != nil {
 			return err
 		}
 	} else if content != s.lastContent || contextUsage != nil {
@@ -673,6 +689,7 @@ func (s *picoStreamer) sendLocked(ctx context.Context, content string, contextUs
 		if s.modelName != "" {
 			payload[PayloadKeyModelName] = s.modelName
 		}
+		setTurnUsagePayload(payload, s.turnInputTokens, s.turnOutputTokens)
 		if err := s.channel.editMessagePayload(ctx, s.chatID, s.messageID, payload, contextUsage); err != nil {
 			return err
 		}
@@ -932,6 +949,14 @@ func (c *PicoChannel) handleMediaDownload(w http.ResponseWriter, r *http.Request
 	http.ServeContent(w, r, filename, info.ModTime(), file)
 }
 
+// broadcast routes through broadcastFn when set (tests), else broadcastToSession.
+func (c *PicoChannel) broadcast(chatID string, msg PicoMessage) error {
+	if c.broadcastFn != nil {
+		return c.broadcastFn(chatID, msg)
+	}
+	return c.broadcastToSession(chatID, msg)
+}
+
 // broadcastToSession sends a message to all connections with a matching session.
 func (c *PicoChannel) broadcastToSession(chatID string, msg PicoMessage) error {
 	// chatID format: "pico:<sessionID>"
@@ -1403,6 +1428,20 @@ func setContextUsagePayload(payload map[string]any, u *bus.ContextUsage) {
 	}
 }
 
+// setTurnUsagePayload attaches real per-turn LLM token usage to the payload.
+// Input and output are kept separate (billed at different rates); total is a
+// convenience sum. Omitted entirely when both counts are zero.
+func setTurnUsagePayload(payload map[string]any, inputTokens, outputTokens int) {
+	if inputTokens <= 0 && outputTokens <= 0 {
+		return
+	}
+	payload[PayloadKeyUsage] = map[string]any{
+		"input_tokens":  inputTokens,
+		"output_tokens": outputTokens,
+		"total_tokens":  inputTokens + outputTokens,
+	}
+}
+
 func picoToolCallsPayload(msg bus.OutboundMessage) ([]utils.VisibleToolCall, bool) {
 	raw := strings.TrimSpace(msg.Context.Raw[PayloadKeyToolCalls])
 	if raw == "" {

pkg/channels/pico/pico_usage_test.go

@@ -0,0 +1,69 @@
+package pico
+
+import (
+	"context"
+	"testing"
+)
+
+func TestSetTurnUsagePayload(t *testing.T) {
+	t.Run("populates usage block when counts present", func(t *testing.T) {
+		payload := map[string]any{PayloadKeyContent: "hi"}
+		setTurnUsagePayload(payload, 1234, 567)
+
+		raw, ok := payload[PayloadKeyUsage]
+		if !ok {
+			t.Fatalf("expected %q key in payload", PayloadKeyUsage)
+		}
+		usage, ok := raw.(map[string]any)
+		if !ok {
+			t.Fatalf("usage block is not a map: %T", raw)
+		}
+		if usage["input_tokens"] != 1234 {
+			t.Errorf("input_tokens = %v, want 1234", usage["input_tokens"])
+		}
+		if usage["output_tokens"] != 567 {
+			t.Errorf("output_tokens = %v, want 567", usage["output_tokens"])
+		}
+		if usage["total_tokens"] != 1801 {
+			t.Errorf("total_tokens = %v, want 1801", usage["total_tokens"])
+		}
+	})
+
+	t.Run("omits usage block when both counts zero", func(t *testing.T) {
+		payload := map[string]any{PayloadKeyContent: "hi"}
+		setTurnUsagePayload(payload, 0, 0)
+		if _, ok := payload[PayloadKeyUsage]; ok {
+			t.Errorf("expected no %q key when counts are zero", PayloadKeyUsage)
+		}
+	})
+}
+
+// newCaptureStreamer returns a streamer whose broadcasts are captured into the
+// returned map pointer, so tests need no live websocket.
+func newCaptureStreamer() (*picoStreamer, *map[string]any) {
+	var last map[string]any
+	ch := &PicoChannel{}
+	ch.broadcastFn = func(chatID string, msg PicoMessage) error {
+		last = msg.Payload
+		return nil
+	}
+	s := &picoStreamer{channel: ch, chatID: "c1"}
+	return s, &last
+}
+
+func TestStreamerEmitsUsageOnFinalize(t *testing.T) {
+	s, last := newCaptureStreamer()
+	s.SetTurnUsage(100, 40)
+
+	// sendLocked with empty messageID takes the create branch, which attaches
+	// usage from the streamer's stored counts.
+	s.mu.Lock()
+	err := s.sendLocked(context.Background(), "answer", nil)
+	s.mu.Unlock()
+	if err != nil {
+		t.Fatalf("sendLocked: %v", err)
+	}
+	if _, ok := (*last)[PayloadKeyUsage]; !ok {
+		t.Fatalf("expected usage in payload, got %+v", *last)
+	}
+}

pkg/channels/pico/protocol.go

@@ -28,6 +28,7 @@ const (
 	PayloadKeyPlaceholder = "placeholder"
 	PayloadKeyToolCalls   = "tool_calls"
 	PayloadKeyModelName   = "model_name"
+	PayloadKeyUsage       = "usage"
 
 	MessageKindThought   = "thought"
 	MessageKindToolCalls = "tool_calls"