feat: storage watchdog — USB disconnect detection, auto-stop, safe eject, auto-reconnect (v0.17.0)

New storage watchdog monitors registered storage paths every 5s. On disconnect
(3 consecutive probe failures), auto-stops affected apps, lazy-unmounts stale
VFS entries, fires alerts/notifications/hub report. On reconnect (UUID detected),
auto-remounts via fstab, cleans stale restic locks, offers app restart.

Safe disconnect UI for USB drives: confirmation dialog, stop apps, sync, unmount.
Disconnected state visible across all pages (dashboard, settings, backups, monitoring)
with hatched red bars and badges. Backup guards skip disconnected drives.

22 files changed (1 new: monitor/watchdog.go), ~1500 lines added.

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

controller/internal/web/handlers.go

@@ -22,17 +22,26 @@ import (
 
 // StorageBarInfo holds data for rendering a storage usage bar on dashboard/monitoring.
 type StorageBarInfo struct {
-	Label   string  // e.g., "USB HDD 1TB", "SYS Storage 350G"
-	Path    string  // e.g., "/mnt/hdd_1"
-	TotalGB float64
-	UsedGB  float64
-	Percent float64
+	Label        string  // e.g., "USB HDD 1TB", "SYS Storage 350G"
+	Path         string  // e.g., "/mnt/hdd_1"
+	TotalGB      float64
+	UsedGB       float64
+	Percent      float64
+	Disconnected bool
 }
 
 // buildStorageBars returns usage bars for all registered storage paths.
 func (s *Server) buildStorageBars() []StorageBarInfo {
 	var bars []StorageBarInfo
 	for _, sp := range s.settings.GetStoragePaths() {
+		if sp.Disconnected {
+			bars = append(bars, StorageBarInfo{
+				Label:        sp.Label,
+				Path:         sp.Path,
+				Disconnected: true,
+			})
+			continue
+		}
 		di := system.GetDiskUsage(sp.Path)
 		if di == nil {
 			continue
@@ -65,11 +74,13 @@ type StorageAppDetail struct {
 // StoragePathView extends StoragePath with display data for the settings page.
 type StoragePathView struct {
 	settings.StoragePath
-	DiskInfo   *system.DiskUsageInfo
-	AppCount   int
-	IsMounted  bool
-	AppDetails []StorageAppDetail
-	FSInfo     *system.FSInfo
+	DiskInfo    *system.DiskUsageInfo
+	AppCount    int
+	IsMounted   bool
+	AppDetails  []StorageAppDetail
+	FSInfo      *system.FSInfo
+	IsUSB       bool     // true if this is a USB-attached device (safe disconnect available)
+	StoppedApps []string // stacks auto-stopped due to disconnect (for restart UI)
 }
 
 func (s *Server) baseData(page, title string) map[string]interface{} {
@@ -659,6 +670,9 @@ type AppBackupRow struct {
 	Tier2SizeHuman   string
 	Tier2Browsable   bool // true for rsync (plain files), false for restic
 
+	// Drive disconnected — app's home drive is currently disconnected
+	DriveDisconnected bool
+
 	// Warnings accumulated for this app
 	Warnings []string
 }
@@ -700,10 +714,32 @@ func (s *Server) buildAppBackupRows(
 		}
 	}
 
+	// Build disconnected paths set for drive-disconnected detection
+	disconnectedPaths := make(map[string]bool)
+	for _, dp := range s.settings.GetDisconnectedPaths() {
+		disconnectedPaths[dp.Path] = true
+	}
+
 	var rows []AppBackupRow
 	for _, app := range status.AppDataInfo {
 		hasDB := dbStacks[app.StackName] || app.HasDBDump
 
+		// Check if this app's home drive is disconnected
+		driveDisconnected := false
+		if app.HasHDDData && len(app.HDDPaths) > 0 {
+			for dp := range disconnectedPaths {
+				for _, hp := range app.HDDPaths {
+					if strings.HasPrefix(hp.HostPath, dp+"/") || hp.HostPath == dp {
+						driveDisconnected = true
+						break
+					}
+				}
+				if driveDisconnected {
+					break
+				}
+			}
+		}
+
 		// Build backup contents label
 		var parts []string
 		if hasDB {
@@ -716,10 +752,11 @@ func (s *Server) buildAppBackupRows(
 		contents := strings.Join(parts, " + ")
 
 		row := AppBackupRow{
-			StackName:      app.StackName,
-			DisplayName:    app.DisplayName,
-			HasHDDData:     app.HasHDDData,
-			HasDB:          hasDB,
+			StackName:         app.StackName,
+			DisplayName:       app.DisplayName,
+			HasHDDData:        app.HasHDDData,
+			HasDB:             hasDB,
+			DriveDisconnected: driveDisconnected,
 			StorageLabel:   app.StorageLabel,
 			HDDSizeHuman:   app.HDDSizeHuman,
 			BackupContents: contents,
@@ -933,13 +970,23 @@ func (s *Server) settingsData() map[string]interface{} {
 	for _, sp := range storagePaths {
 		view := StoragePathView{
 			StoragePath: sp,
-			IsMounted:   system.IsMountPoint(sp.Path),
-			AppDetails:  s.appDetailsForPath(sp.Path),
-			FSInfo:      system.GetFSInfo(sp.Path),
+			StoppedApps: sp.StoppedStacks,
 		}
-		view.AppCount = len(view.AppDetails)
-		if di := system.GetDiskUsage(sp.Path); di != nil {
-			view.DiskInfo = di
+		if sp.Disconnected {
+			// Skip I/O calls on disconnected drives — they'd hang or fail
+			view.IsMounted = false
+		} else {
+			view.IsMounted = system.IsMountPoint(sp.Path)
+			view.AppDetails = s.appDetailsForPath(sp.Path)
+			view.FSInfo = system.GetFSInfo(sp.Path)
+			view.AppCount = len(view.AppDetails)
+			if di := system.GetDiskUsage(sp.Path); di != nil {
+				view.DiskInfo = di
+			}
+			// Detect USB for safe disconnect button
+			if view.FSInfo != nil && view.FSInfo.Device != "" {
+				view.IsUSB = system.IsUSBDevice(view.FSInfo.Device)
+			}
 		}
 		storageViews = append(storageViews, view)
 	}