fix: replace premature media file cleanup with background MediaCleaner

Channel handlers delete downloaded media files via defer os.Remove()
before the async agent loop consumer can read them, causing silent
failures in voice/image/document processing.

Remove the immediate defer cleanup from telegram, line, slack, and
onebot handlers. Introduce a background MediaCleaner goroutine that
periodically removes files older than 30 minutes from the temp media
directory, preventing unbounded accumulation.

discord.go is unchanged because it processes files synchronously.

Closes #619

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

cmd/picoclaw/cmd_gateway.go

@@ -25,6 +25,7 @@ import (
 	"github.com/sipeed/picoclaw/pkg/providers"
 	"github.com/sipeed/picoclaw/pkg/state"
 	"github.com/sipeed/picoclaw/pkg/tools"
+	"github.com/sipeed/picoclaw/pkg/utils"
 	"github.com/sipeed/picoclaw/pkg/voice"
 )
 
@@ -192,6 +193,9 @@ func gatewayCmd() {
 		fmt.Println("✓ Device event service started")
 	}
 
+	mediaCleaner := utils.NewMediaCleaner()
+	mediaCleaner.Start()
+
 	if err := channelManager.StartAll(ctx); err != nil {
 		fmt.Printf("Error starting channels: %v\n", err)
 	}
@@ -216,6 +220,7 @@ func gatewayCmd() {
 	deviceService.Stop()
 	heartbeatService.Stop()
 	cronService.Stop()
+	mediaCleaner.Stop()
 	agentLoop.Stop()
 	channelManager.StopAll(ctx)
 	fmt.Println("✓ Gateway stopped")

pkg/channels/line.go

@@ -10,7 +10,6 @@ import (
 	"fmt"
 	"io"
 	"net/http"
-	"os"
 	"strings"
 	"sync"
 	"time"
@@ -307,18 +306,6 @@ func (c *LINEChannel) processEvent(event lineEvent) {
 
 	var content string
 	var mediaPaths []string
-	localFiles := []string{}
-
-	defer func() {
-		for _, file := range localFiles {
-			if err := os.Remove(file); err != nil {
-				logger.DebugCF("line", "Failed to cleanup temp file", map[string]any{
-					"file":  file,
-					"error": err.Error(),
-				})
-			}
-		}
-	}()
 
 	switch msg.Type {
 	case "text":
@@ -330,21 +317,18 @@ func (c *LINEChannel) processEvent(event lineEvent) {
 	case "image":
 		localPath := c.downloadContent(msg.ID, "image.jpg")
 		if localPath != "" {
-			localFiles = append(localFiles, localPath)
 		mediaPaths = append(mediaPaths, localPath)
 			content = "[image]"
 		}
 	case "audio":
 		localPath := c.downloadContent(msg.ID, "audio.m4a")
 		if localPath != "" {
-			localFiles = append(localFiles, localPath)
 		mediaPaths = append(mediaPaths, localPath)
 			content = "[audio]"
 		}
 	case "video":
 		localPath := c.downloadContent(msg.ID, "video.mp4")
 		if localPath != "" {
-			localFiles = append(localFiles, localPath)
 		mediaPaths = append(mediaPaths, localPath)
 			content = "[video]"
 		}

pkg/channels/onebot.go

@@ -4,7 +4,6 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
-	"os"
 	"strconv"
 	"strings"
 	"sync"
@@ -571,7 +570,6 @@ type parseMessageResult struct {
 	Text           string
 	IsBotMentioned bool
 	Media          []string
-	LocalFiles     []string
 	ReplyTo        string
 }
 
@@ -603,7 +601,6 @@ func (c *OneBotChannel) parseMessageSegments(raw json.RawMessage, selfID int64)
 	mentioned := false
 	selfIDStr := strconv.FormatInt(selfID, 10)
 	var media []string
-	var localFiles []string
 	var replyTo string
 
 	for _, seg := range segments {
@@ -642,7 +639,6 @@ func (c *OneBotChannel) parseMessageSegments(raw json.RawMessage, selfID int64)
 					})
 					if localPath != "" {
 						media = append(media, localPath)
-						localFiles = append(localFiles, localPath)
 						textParts = append(textParts, fmt.Sprintf("[%s]", segType))
 					}
 				}
@@ -656,7 +652,6 @@ func (c *OneBotChannel) parseMessageSegments(raw json.RawMessage, selfID int64)
 						LoggerPrefix: "onebot",
 					})
 					if localPath != "" {
-						localFiles = append(localFiles, localPath)
 						if c.transcriber != nil && c.transcriber.IsAvailable() {
 							tctx, tcancel := context.WithTimeout(c.ctx, 30*time.Second)
 							result, err := c.transcriber.Transcribe(tctx, localPath)
@@ -703,7 +698,6 @@ func (c *OneBotChannel) parseMessageSegments(raw json.RawMessage, selfID int64)
 		Text:           strings.TrimSpace(strings.Join(textParts, "")),
 		IsBotMentioned: mentioned,
 		Media:          media,
-		LocalFiles:     localFiles,
 		ReplyTo:        replyTo,
 	}
 }
@@ -824,20 +818,6 @@ func (c *OneBotChannel) handleMessage(raw *oneBotRawEvent) {
 		}
 	}
 
-	// Clean up temp files when done
-	if len(parsed.LocalFiles) > 0 {
-		defer func() {
-			for _, f := range parsed.LocalFiles {
-				if err := os.Remove(f); err != nil {
-					logger.DebugCF("onebot", "Failed to remove temp file", map[string]any{
-						"path":  f,
-						"error": err.Error(),
-					})
-				}
-			}
-		}()
-	}
-
 	if c.isDuplicate(messageID) {
 		logger.DebugCF("onebot", "Duplicate message, skipping", map[string]any{
 			"message_id": messageID,

pkg/channels/slack.go

@@ -3,7 +3,6 @@ package channels
 import (
 	"context"
 	"fmt"
-	"os"
 	"strings"
 	"sync"
 	"time"
@@ -232,19 +231,6 @@ func (c *SlackChannel) handleMessageEvent(ev *slackevents.MessageEvent) {
 	content = c.stripBotMention(content)
 
 	var mediaPaths []string
-	localFiles := []string{} // 跟踪需要清理的本地文件
-
-	// 确保临时文件在函数返回时被清理
-	defer func() {
-		for _, file := range localFiles {
-			if err := os.Remove(file); err != nil {
-				logger.DebugCF("slack", "Failed to cleanup temp file", map[string]any{
-					"file":  file,
-					"error": err.Error(),
-				})
-			}
-		}
-	}()
 
 	if ev.Message != nil && len(ev.Message.Files) > 0 {
 		for _, file := range ev.Message.Files {
@@ -252,7 +238,6 @@ func (c *SlackChannel) handleMessageEvent(ev *slackevents.MessageEvent) {
 			if localPath == "" {
 				continue
 			}
-			localFiles = append(localFiles, localPath)
 		mediaPaths = append(mediaPaths, localPath)
 
 			if utils.IsAudioFile(file.Name, file.Mimetype) && c.transcriber != nil && c.transcriber.IsAvailable() {

pkg/channels/telegram.go

@@ -221,19 +221,6 @@ func (c *TelegramChannel) handleMessage(ctx context.Context, message *telego.Mes
 
 	content := ""
 	mediaPaths := []string{}
-	localFiles := []string{} // 跟踪需要清理的本地文件
-
-	// 确保临时文件在函数返回时被清理
-	defer func() {
-		for _, file := range localFiles {
-			if err := os.Remove(file); err != nil {
-				logger.DebugCF("telegram", "Failed to cleanup temp file", map[string]any{
-					"file":  file,
-					"error": err.Error(),
-				})
-			}
-		}
-	}()
 
 	if message.Text != "" {
 		content += message.Text
@@ -250,7 +237,6 @@ func (c *TelegramChannel) handleMessage(ctx context.Context, message *telego.Mes
 		photo := message.Photo[len(message.Photo)-1]
 		photoPath := c.downloadPhoto(ctx, photo.FileID)
 		if photoPath != "" {
-			localFiles = append(localFiles, photoPath)
 		mediaPaths = append(mediaPaths, photoPath)
 			if content != "" {
 				content += "\n"
@@ -262,7 +248,6 @@ func (c *TelegramChannel) handleMessage(ctx context.Context, message *telego.Mes
 	if message.Voice != nil {
 		voicePath := c.downloadFile(ctx, message.Voice.FileID, ".ogg")
 		if voicePath != "" {
-			localFiles = append(localFiles, voicePath)
 		mediaPaths = append(mediaPaths, voicePath)
 
 			transcribedText := ""
@@ -297,7 +282,6 @@ func (c *TelegramChannel) handleMessage(ctx context.Context, message *telego.Mes
 	if message.Audio != nil {
 		audioPath := c.downloadFile(ctx, message.Audio.FileID, ".mp3")
 		if audioPath != "" {
-			localFiles = append(localFiles, audioPath)
 		mediaPaths = append(mediaPaths, audioPath)
 			if content != "" {
 				content += "\n"
@@ -309,7 +293,6 @@ func (c *TelegramChannel) handleMessage(ctx context.Context, message *telego.Mes
 	if message.Document != nil {
 		docPath := c.downloadFile(ctx, message.Document.FileID, "")
 		if docPath != "" {
-			localFiles = append(localFiles, docPath)
 		mediaPaths = append(mediaPaths, docPath)
 			if content != "" {
 				content += "\n"

pkg/utils/media.go

@@ -6,6 +6,7 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/google/uuid"
@@ -13,6 +14,9 @@ import (
 	"github.com/sipeed/picoclaw/pkg/logger"
 )
 
+// MediaDir is the subdirectory name under os.TempDir() where downloaded media files are stored.
+const MediaDir = "picoclaw_media"
+
 // IsAudioFile checks if a file is an audio file based on its filename extension and content type.
 func IsAudioFile(filename, contentType string) bool {
 	audioExtensions := []string{".mp3", ".wav", ".ogg", ".m4a", ".flac", ".aac", ".wma"}
@@ -65,7 +69,7 @@ func DownloadFile(url, filename string, opts DownloadOptions) string {
 		opts.LoggerPrefix = "utils"
 	}
 
-	mediaDir := filepath.Join(os.TempDir(), "picoclaw_media")
+	mediaDir := filepath.Join(os.TempDir(), MediaDir)
 	if err := os.MkdirAll(mediaDir, 0o700); err != nil {
 		logger.ErrorCF(opts.LoggerPrefix, "Failed to create media directory", map[string]any{
 			"error": err.Error(),
@@ -141,3 +145,83 @@ func DownloadFileSimple(url, filename string) string {
 		LoggerPrefix: "media",
 	})
 }
+
+// MediaCleaner periodically removes old files from the media temp directory.
+type MediaCleaner struct {
+	interval time.Duration
+	maxAge   time.Duration
+	stop     chan struct{}
+	once     sync.Once
+}
+
+// NewMediaCleaner creates a new MediaCleaner with default settings
+// (scan every 5 minutes, remove files older than 30 minutes).
+func NewMediaCleaner() *MediaCleaner {
+	return &MediaCleaner{
+		interval: 5 * time.Minute,
+		maxAge:   30 * time.Minute,
+		stop:     make(chan struct{}),
+	}
+}
+
+// Start begins the background cleanup goroutine. Safe to call multiple times.
+func (mc *MediaCleaner) Start() {
+	mc.once.Do(func() {
+		go mc.loop()
+		logger.InfoC("media", "Media cleaner started")
+	})
+}
+
+// Stop signals the cleanup goroutine to exit. Safe to call multiple times.
+func (mc *MediaCleaner) Stop() {
+	select {
+	case <-mc.stop:
+	default:
+		close(mc.stop)
+		logger.InfoC("media", "Media cleaner stopped")
+	}
+}
+
+func (mc *MediaCleaner) loop() {
+	ticker := time.NewTicker(mc.interval)
+	defer ticker.Stop()
+	for {
+		select {
+		case <-mc.stop:
+			return
+		case <-ticker.C:
+			mc.cleanup()
+		}
+	}
+}
+
+func (mc *MediaCleaner) cleanup() {
+	mediaDir := filepath.Join(os.TempDir(), MediaDir)
+	entries, err := os.ReadDir(mediaDir)
+	if err != nil {
+		return
+	}
+
+	now := time.Now()
+	removed := 0
+	for _, entry := range entries {
+		if entry.IsDir() {
+			continue
+		}
+		info, err := entry.Info()
+		if err != nil {
+			continue
+		}
+		if now.Sub(info.ModTime()) > mc.maxAge {
+			path := filepath.Join(mediaDir, entry.Name())
+			if err := os.Remove(path); err == nil {
+				removed++
+			}
+		}
+	}
+	if removed > 0 {
+		logger.DebugCF("media", "Cleaned up old media files", map[string]any{
+			"removed": removed,
+		})
+	}
+}

pkg/utils/media_test.go

@@ -0,0 +1,66 @@
+package utils
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+)
+
+func TestMediaCleanerRemovesOldFiles(t *testing.T) {
+	// Setup: create a temp media directory with old and new files
+	mediaDir := filepath.Join(os.TempDir(), MediaDir)
+	if err := os.MkdirAll(mediaDir, 0700); err != nil {
+		t.Fatalf("failed to create media dir: %v", err)
+	}
+
+	// Create an "old" file and backdate its modification time
+	oldFile := filepath.Join(mediaDir, "test_old_file.jpg")
+	if err := os.WriteFile(oldFile, []byte("old"), 0600); err != nil {
+		t.Fatalf("failed to create old file: %v", err)
+	}
+	oldTime := time.Now().Add(-1 * time.Hour)
+	if err := os.Chtimes(oldFile, oldTime, oldTime); err != nil {
+		t.Fatalf("failed to set old file time: %v", err)
+	}
+
+	// Create a "new" file (just created, so modtime is now)
+	newFile := filepath.Join(mediaDir, "test_new_file.jpg")
+	if err := os.WriteFile(newFile, []byte("new"), 0600); err != nil {
+		t.Fatalf("failed to create new file: %v", err)
+	}
+
+	// Cleanup test files at end
+	defer os.Remove(oldFile)
+	defer os.Remove(newFile)
+
+	// Run cleanup directly
+	mc := NewMediaCleaner()
+	mc.cleanup()
+
+	// Old file should be gone
+	if _, err := os.Stat(oldFile); !os.IsNotExist(err) {
+		t.Errorf("expected old file to be removed, but it still exists")
+	}
+
+	// New file should still exist
+	if _, err := os.Stat(newFile); err != nil {
+		t.Errorf("expected new file to still exist, got error: %v", err)
+	}
+}
+
+func TestMediaCleanerStartStop(t *testing.T) {
+	mc := NewMediaCleaner()
+
+	// Start should not panic
+	mc.Start()
+
+	// Second Start should be idempotent (sync.Once)
+	mc.Start()
+
+	// Stop should not panic
+	mc.Stop()
+
+	// Second Stop should be idempotent
+	mc.Stop()
+}