fix: make WebDAV upload retry reliable

settings.go

@@ -1,6 +1,8 @@
 package main
 
 import (
+	"crypto/rand"
+	"fmt"
 	"strings"
 	"time"
 
@@ -68,6 +70,9 @@ func (a *App) putSettings(c *gin.Context) {
 	} else {
 		a.storage = nil
 	}
+	// Credentials/config changes should repair already-downloaded local files
+	// immediately instead of waiting for the periodic retry interval.
+	go a.resyncPendingUploads()
 	c.JSON(200, gin.H{"ok": true})
 }
 
@@ -77,11 +82,48 @@ func (a *App) testWebDAV(c *gin.Context) {
 		c.Status(400)
 		return
 	}
+	// An empty password means "use the saved password". The password is never
+	// returned to the browser, so this also makes a fresh settings page test
+	// the credential that is actually stored by the server.
+	if v.URL == "" {
+		v.URL = a.cfg.WebDAVURL
+	}
+	if v.User == "" {
+		v.User = a.cfg.WebDAVUser
+	}
+	if v.Pass == "" {
+		v.Pass = a.cfg.WebDAVPass
+	}
+	v.Path = strings.Trim(v.Path, "/")
+	if v.Path == "" {
+		v.Path = a.cfg.WebDAVPath
+	}
+	if v.URL == "" || v.User == "" || v.Pass == "" {
+		c.JSON(400, gin.H{"ok": false, "error": "WebDAV URL、用户名或密码未配置"})
+		return
+	}
 	client := gowebdav.NewClient(v.URL, v.User, v.Pass)
 	client.SetTimeout(20 * time.Second)
 	if err := client.Connect(); err != nil {
-		c.JSON(502, gin.H{"ok": false, "error": err.Error()})
+		c.JSON(502, gin.H{"ok": false, "error": "WebDAV authentication failed: " + err.Error()})
 		return
 	}
+	if v.Path != "" {
+		if err := client.MkdirAll(v.Path, 0755); err != nil {
+			c.JSON(502, gin.H{"ok": false, "error": "WebDAV target path is not writable: " + err.Error()})
+			return
+		}
+	}
+	var token [12]byte
+	if _, err := rand.Read(token[:]); err != nil {
+		c.JSON(500, gin.H{"ok": false, "error": "failed to create test token"})
+		return
+	}
+	testPath := strings.Trim(v.Path, "/") + "/.am-downloader-test-" + fmt.Sprintf("%x", token[:])
+	if err := client.Write(testPath, []byte("ok"), 0644); err != nil {
+		c.JSON(502, gin.H{"ok": false, "error": "WebDAV write test failed: " + err.Error()})
+		return
+	}
+	_ = client.Remove(testPath)
 	c.JSON(200, gin.H{"ok": true, "path": v.Path})
 }

user_webdav.go

@@ -112,7 +112,7 @@ func (a *App) storageForTask(t *Task) (RemoteStorage, string, bool) {
 	if a.db.First(&user, t.UserID).Error != nil {
 		return nil, "", false
 	}
-	if !a.hasPermission(user.ID, PermWebDAV) {
+	if user.Role != RoleAdmin && !a.hasPermission(user.ID, PermWebDAV) {
 		return nil, "", false
 	}
 	// Regular users use the system/global WebDAV only. They cannot override

util.go

@@ -25,6 +25,16 @@ func (a *App) fail(t *Task, err error) {
 	}
 }
 
+func (a *App) failUpload(t *Task, err error) {
+	if err == nil {
+		err = errors.New("unknown WebDAV upload error")
+	}
+	t.RemotePath = ""
+	t.Status = "upload_pending"
+	t.Error = "WebDAV 上传失败，等待自动重试: " + err.Error()
+	a.db.Save(t)
+}
+
 var bad = regexp.MustCompile(`[/\\:*?"<>|]+`)
 
 func safe(s string) string {

webdav.go

@@ -19,9 +19,8 @@ func (a *App) upload(t *Task) {
 	}
 	a.db.Model(t).Updates(map[string]any{"status": "uploading"})
 	remote := strings.TrimRight(root, "/") + "/" + safe(t.Artist) + "/" + safe(t.Album) + "/" + safe(t.Title) + "." + safe(t.Format)
-	t.RemotePath = remote
 	if err := storage.MkdirAll(filepath.ToSlash(filepath.Dir(remote))); err != nil {
-		a.fail(t, err)
+		a.failUpload(t, err)
 		return
 	}
 	if fi, err := os.Stat(t.LocalPath); err == nil {
@@ -37,9 +36,10 @@ func (a *App) upload(t *Task) {
 		}
 	}
 	if err := storage.Upload(t.LocalPath, remote); err != nil {
-		a.fail(t, err)
+		a.failUpload(t, err)
 		return
 	}
+	t.RemotePath = remote
 	if a.cfg.WebDAVVersionPolicy == "replace_lower" {
 		a.cleanupLowerQualityVersions(t, storage)
 	}

webdav_resync.go

@@ -6,7 +6,7 @@ import "time"
 // unavailable or the user's WebDAV permission was not yet configured.
 func (a *App) resyncPendingUploads() {
 	var tasks []Task
-	if err := a.db.Where("status = ? AND local_path <> ? AND (remote_path = ? OR remote_path IS NULL)", "done", "", "").Order("id asc").Limit(100).Find(&tasks).Error; err != nil {
+	if err := a.db.Where("status IN ? AND local_path <> ? AND (remote_path = ? OR remote_path IS NULL)", []string{"done", "upload_pending", "error"}, "", "").Order("id asc").Limit(100).Find(&tasks).Error; err != nil {
 		return
 	}
 	for i := range tasks {
@@ -20,7 +20,7 @@ func (a *App) resyncPendingUploads() {
 }
 
 // startWebDAVResync runs a small periodic repair loop. It is intentionally
-// conservative: only completed local tasks without a remote path are retried.
+// conservative: only tasks with a completed local file and no confirmed remote path are retried.
 func (a *App) startWebDAVResync() {
 	go func() {
 		a.resyncPendingUploads()