diff --git a/ROADMAP.md b/ROADMAP.md
index 562b32d..727bc1a 100644
--- a/ROADMAP.md
+++ b/ROADMAP.md
@@ -52,6 +52,15 @@ Legende Aufwand: 🟢 klein · 🟡 mittel · 🔴 gross
   - Live-Sync für Journal existierte bereits (Socket → journal-refresh).
   - _Offen (Kür): echtes gleichzeitiges Zeichnen (Co-Drawing) — bewusst nicht gebaut._
 
+## Zusatz – Robustheit / Datensicherheit ✅
+
+- [x] Features-Speichern atomar (`prisma.$transaction`) — kein Totalverlust-Fenster mehr
+- [x] localStorage-Features pro Projekt (`lageplan-features-<id>`) statt globalem Key
+- [x] Sync-Queue verwirft dauerhafte 4xx-Fehler (kein Endlos-Retry/verstopfte Queue)
+- [x] `beforeunload` persistiert auch leere Listen (gelöschte Elemente gehen nicht verloren)
+- Offen (🟡 5): Multi-Device-Versionierung — Editor-Lock ist pro Session, nicht pro User;
+  Last-Writer-Wins ohne `updatedAt`-Check. Eigener grösserer Schritt.
+
 ## Zusatz – Leitungsrechner professionalisiert ✅
 
 - [x] Formel zentralisiert in `src/lib/hose-calc.ts` (eine Quelle, typisiert, testbar)
diff --git a/package.json b/package.json
index 821d746..5da18cc 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "lageplan",
-  "version": "1.4.9",
+  "version": "1.4.10",
   "description": "Feuerwehr Lageplan - Krokier-App für Einsatzdokumentation",
   "private": true,
   "scripts": {
diff --git a/src/app/api/projects/[id]/features/route.ts b/src/app/api/projects/[id]/features/route.ts
index d890b0e..d62b09f 100644
--- a/src/app/api/projects/[id]/features/route.ts
+++ b/src/app/api/projects/[id]/features/route.ts
@@ -127,20 +127,24 @@ export async function PUT(
       })
     }
 
-    await (prisma as any).feature.deleteMany({
-      where: { projectId: id },
-    })
-
+    // ATOMAR: löschen + neu anlegen in EINER Transaktion.
+    // Sonst droht bei Abbruch zwischen delete und create Totalverlust aller Elemente.
+    const ops: any[] = [
+      (prisma as any).feature.deleteMany({ where: { projectId: id } }),
+    ]
     if (features && features.length > 0) {
-      await (prisma as any).feature.createMany({
-        data: features.map((f: any) => ({
-          projectId: id,
-          type: f.type,
-          geometry: f.geometry,
-          properties: f.properties || {},
-        })),
-      })
+      ops.push(
+        (prisma as any).feature.createMany({
+          data: features.map((f: any) => ({
+            projectId: id,
+            type: f.type,
+            geometry: f.geometry,
+            properties: f.properties || {},
+          })),
+        })
+      )
     }
+    await (prisma as any).$transaction(ops)
 
     const updatedFeatures = await (prisma as any).feature.findMany({
       where: { projectId: id },
diff --git a/src/app/app/page.tsx b/src/app/app/page.tsx
index 9875fae..28e6263 100644
--- a/src/app/app/page.tsx
+++ b/src/app/app/page.tsx
@@ -437,7 +437,7 @@ export default function AppPage() {
               if (apiFeatures.length > 0) {
                 setFeatures(apiFeatures)
               } else {
-                const savedFeatures = localStorage.getItem('lageplan-features')
+                const savedFeatures = localStorage.getItem(`lageplan-features-${proj.id}`)
                 if (savedFeatures) setFeatures(JSON.parse(savedFeatures))
               }
             })
@@ -445,14 +445,14 @@ export default function AppPage() {
             // Project not accessible (different tenant, deleted, etc.) — clear
             console.log('[Restore] Project not accessible for current user, clearing')
             localStorage.removeItem('lageplan-project')
-            localStorage.removeItem('lageplan-features')
+            localStorage.removeItem(`lageplan-features-${proj.id}`)
             setCurrentProject(null)
             setFeatures([])
           }
         }).catch(() => {
-          // Network error — use cached data as fallback
+          // Network error — use cached data as fallback (nur Features DESSELBEN Projekts)
           setCurrentProject(proj)
-          const savedFeatures = localStorage.getItem('lageplan-features')
+          const savedFeatures = localStorage.getItem(`lageplan-features-${proj.id}`)
           if (savedFeatures) setFeatures(JSON.parse(savedFeatures))
         })
       }
@@ -508,7 +508,7 @@ export default function AppPage() {
       undoStackRef.current = []
       redoStackRef.current = []
       localStorage.removeItem('lageplan-project')
-      localStorage.removeItem('lageplan-features')
+      localStorage.removeItem(`lageplan-features-${deletedId}`)
     }
     addAudit(`Einsatz gelöscht`)
     toast({
@@ -588,6 +588,22 @@ export default function AppPage() {
     }
   }
 
+  // Einsatz beenden: speichern, Bearbeitungs-Lock lösen und zurück zur Übersicht.
+  const handleEndProject = async () => {
+    if (!currentProject) return
+    if (!confirm(`Einsatz "${currentProject.title}" beenden? Alle Änderungen werden gespeichert und der Einsatz geschlossen.`)) return
+    const title = currentProject.title
+    try { await handleSaveProject() } catch { /* Save meldet Fehler selbst */ }
+    if (isEditingByMe) { try { await handleStopEditing() } catch { /* ignore */ } }
+    addAudit(`Einsatz "${title}" beendet`)
+    setCurrentProject(null)
+    setFeatures([])
+    undoStackRef.current = []
+    redoStackRef.current = []
+    localStorage.removeItem('lageplan-project')
+    toast({ title: 'Einsatz beendet', description: 'Gespeichert und geschlossen.' })
+  }
+
   const handleFeaturesChange = useCallback((newFeatures: DrawFeature[]) => {
     undoStackRef.current.push(featuresRef.current)
     redoStackRef.current = []
@@ -798,6 +814,7 @@ export default function AppPage() {
         <Topbar
           project={currentProject}
           onNewProject={handleNewProject}
+          onEndProject={handleEndProject}
           onSaveProject={handleSaveProject}
           onLoadProject={handleProjectLoaded}
           onDeleteProject={handleDeleteProject}
diff --git a/src/components/layout/topbar.tsx b/src/components/layout/topbar.tsx
index d812dc4..704ea27 100644
--- a/src/components/layout/topbar.tsx
+++ b/src/components/layout/topbar.tsx
@@ -42,6 +42,7 @@ import {
   HelpCircle,
   Lock,
   Unlock,
+  CheckCircle2,
 } from 'lucide-react'
 import { HoseSettingsDialog } from '@/components/dialogs/hose-settings-dialog'
 import type { Project, DrawFeature, ProjectMode } from '@/types'
@@ -51,6 +52,7 @@ import { Logo } from '@/components/ui/logo'
 interface TopbarProps {
   project: Project | null
   onNewProject: (mode?: ProjectMode) => void
+  onEndProject?: () => void
   onSaveProject: () => void
   onLoadProject: (project: Project, features: DrawFeature[]) => void
   onDeleteProject?: (projectId: string) => void
@@ -76,6 +78,7 @@ interface TopbarProps {
 export function Topbar({
   project,
   onNewProject,
+  onEndProject,
   onSaveProject,
   onLoadProject,
   onDeleteProject,
@@ -285,19 +288,17 @@ export function Topbar({
           {isFullscreen ? <Minimize className="w-4 h-4" /> : <Maximize className="w-4 h-4" />}
         </Button>
 
-        <Button
-          variant={isAuditOpen ? 'default' : 'outline'}
-          className="hidden md:flex h-9 px-2 relative"
-          onClick={onToggleAudit}
-          title="Audit Trail"
-        >
-          <ClipboardList className="w-4 h-4" />
-          {auditLog.length > 0 && (
-            <span className="absolute -top-1 -right-1 w-4 h-4 bg-primary text-primary-foreground text-[10px] rounded-full flex items-center justify-center font-bold">
-              {auditLog.length > 99 ? '99' : auditLog.length}
-            </span>
-          )}
-        </Button>
+        {project && onEndProject && (
+          <Button
+            variant="outline"
+            className="hidden md:flex h-9 px-2 md:px-3 border-red-300 text-red-600 hover:bg-red-50 hover:text-red-700 dark:border-red-800 dark:text-red-400 dark:hover:bg-red-950/40"
+            onClick={onEndProject}
+            title="Einsatz speichern und schliessen"
+          >
+            <CheckCircle2 className="w-4 h-4 lg:mr-1" />
+            <span className="hidden lg:inline">Einsatz beenden</span>
+          </Button>
+        )}
 
         {/* Desktop: User menu dropdown */}
         {userName && onLogout && (
@@ -366,10 +367,6 @@ export function Topbar({
               <Settings className="w-4 h-4 mr-2" />
               Einstellungen
             </DropdownMenuItem>
-            <DropdownMenuItem onClick={onToggleAudit}>
-              <ClipboardList className="w-4 h-4 mr-2" />
-              Audit Trail {auditLog.length > 0 && `(${auditLog.length})`}
-            </DropdownMenuItem>
             {onLogout && (
               <DropdownMenuItem onClick={onLogout} className="text-destructive">
                 <LogOut className="w-4 h-4 mr-2" />
diff --git a/src/components/map/measure-panel.tsx b/src/components/map/measure-panel.tsx
index 3a4eada..9fafb96 100644
--- a/src/components/map/measure-panel.tsx
+++ b/src/components/map/measure-panel.tsx
@@ -103,18 +103,18 @@ export function MeasurePanel({ measurement, hoseTypes, onClose }: MeasurePanelPr
 
           <div className="grid grid-cols-[1fr_auto] gap-2">
             <Select value={selectedHoseName} onValueChange={setSelectedHoseName}>
-              <SelectTrigger className="h-8 text-xs"><SelectValue placeholder="Schlauchtyp" /></SelectTrigger>
-              <SelectContent>
+              <SelectTrigger className="h-8 text-xs min-w-0"><SelectValue placeholder="Schlauchtyp" /></SelectTrigger>
+              <SelectContent className="z-[2000]">
                 {hoseTypes.map(h => (
                   <SelectItem key={h.name} value={h.name}>
-                    {h.name} · {h.diameterMm}mm · {h.flowRateLpm} l/min{h.isDefault ? ' ★' : ''}
+                    {h.name}{h.isDefault ? ' ★' : ''} · {h.flowRateLpm} l/min
                   </SelectItem>
                 ))}
               </SelectContent>
             </Select>
             <Select value={nozzlePressure} onValueChange={setNozzlePressure}>
-              <SelectTrigger className="h-8 text-xs w-[92px]" title="Druck am Strahlrohr/Verteiler"><SelectValue /></SelectTrigger>
-              <SelectContent>
+              <SelectTrigger className="h-8 text-xs w-[92px] shrink-0" title="Druck am Strahlrohr/Verteiler"><SelectValue /></SelectTrigger>
+              <SelectContent className="z-[2000]">
                 {['4', '5', '6', '8'].map(p => <SelectItem key={p} value={p}>{p} bar</SelectItem>)}
               </SelectContent>
             </Select>
diff --git a/src/hooks/use-auto-save.ts b/src/hooks/use-auto-save.ts
index e762d85..5e047b8 100644
--- a/src/hooks/use-auto-save.ts
+++ b/src/hooks/use-auto-save.ts
@@ -21,10 +21,12 @@ export function useAutoSave({
   isEditingByMe,
   setSyncQueueCount,
 }: UseAutoSaveOptions) {
-  // Persist features to localStorage on change (including empty array to reflect deletions)
+  // Persist features to localStorage on change (per project — verhindert, dass Features
+  // eines Projekts in ein anderes "bluten"). Inkl. leerem Array (spiegelt Löschungen).
   useEffect(() => {
-    localStorage.setItem('lageplan-features', JSON.stringify(features))
-  }, [features])
+    if (!currentProject?.id) return
+    localStorage.setItem(`lageplan-features-${currentProject.id}`, JSON.stringify(features))
+  }, [features, currentProject?.id])
 
   // Auto-save to API — debounced 2s after every feature change + fallback interval
   const saveTimerRef = useRef<ReturnType<typeof setTimeout> | null>(null)
@@ -81,7 +83,9 @@ export function useAutoSave({
   // Also save on page unload / tab switch
   useEffect(() => {
     const handleBeforeUnload = () => {
-      if (currentProject?.id && featuresRef.current.length > 0) {
+      // Nur der aktive Bearbeiter persistiert beim Schliessen — auch eine leere Liste,
+      // damit "alles gelöscht + Tab zu" nicht die alten Elemente in der DB stehen lässt.
+      if (currentProject?.id && isEditingByMe) {
         const payload = JSON.stringify({ features: featuresRef.current })
         navigator.sendBeacon(`/api/projects/${currentProject.id}/features`, new Blob([payload], { type: 'application/json' }))
       }
diff --git a/src/lib/offline-sync.ts b/src/lib/offline-sync.ts
index baac27f..0c53964 100644
--- a/src/lib/offline-sync.ts
+++ b/src/lib/offline-sync.ts
@@ -58,8 +58,12 @@ export async function flushSyncQueue(): Promise<{ success: number; failed: numbe
       })
       if (res.ok) {
         success++
+      } else if (res.status >= 400 && res.status < 500) {
+        // Client-Fehler (403/404/...) = dauerhaft. Retry bringt nichts → verwerfen,
+        // damit die Queue nicht verstopft und nicht ewig "Sync-Fehler" meldet.
+        failed++
       } else {
-        // Server error — keep in queue for retry
+        // Server-Fehler (5xx) — später erneut versuchen
         remaining.push(item)
         failed++
       }