diff --git a/client/src/App.css b/client/src/App.css
index 68a251b..ca73dc8 100644
--- a/client/src/App.css
+++ b/client/src/App.css
@@ -1799,6 +1799,22 @@ html.scheme-dark .themed-select-option.is-selected {
   gap: 24px;
 }
 
+.logbook-card-select {
+  flex: 1;
+  min-width: 0;
+  display: flex;
+  align-items: flex-start;
+  gap: 16px;
+  padding: 0;
+  margin: 0;
+  border: none;
+  background: transparent;
+  color: inherit;
+  font: inherit;
+  text-align: left;
+  cursor: pointer;
+}
+
 .logbook-card {
   background: var(--app-surface-alt);
   backdrop-filter: var(--app-backdrop);
@@ -1809,18 +1825,61 @@ html.scheme-dark .themed-select-option.is-selected {
   display: flex;
   align-items: flex-start;
   gap: 16px;
-  cursor: pointer;
   position: relative;
   transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
 }
 
-.logbook-card:hover {
+.logbook-card:hover,
+.logbook-card:focus-within {
   transform: translateY(-2px);
   border-color: var(--app-border);
   box-shadow: var(--app-card-shadow);
   background: var(--app-surface-hover);
 }
 
+.sync-conflict-banner {
+  display: flex;
+  gap: 12px;
+  align-items: flex-start;
+  margin: 0 0 16px;
+  padding: 16px;
+  border-radius: var(--app-radius-card);
+  border: 1px solid var(--app-warning-border, #f59e0b);
+  background: var(--app-warning-bg, rgba(245, 158, 11, 0.12));
+  color: var(--app-text);
+}
+
+.sync-conflict-banner__body p {
+  margin: 4px 0 12px;
+  font-size: 14px;
+  color: var(--app-text-muted);
+}
+
+.sync-conflict-banner__actions {
+  display: flex;
+  flex-wrap: wrap;
+  gap: 8px;
+}
+
+.storage-persist-hint {
+  display: flex;
+  flex-wrap: wrap;
+  align-items: center;
+  justify-content: space-between;
+  gap: 12px;
+  margin: 0 0 16px;
+  padding: 12px 16px;
+  border-radius: var(--app-radius-card);
+}
+
+.storage-persist-hint p {
+  margin: 0;
+  flex: 1;
+  min-width: 200px;
+  font-size: 14px;
+  color: var(--app-text-muted);
+}
+
 .logbook-card--shared {
   border-left: 3px solid #38bdf8;
 }
@@ -2130,9 +2189,65 @@ html.scheme-dark .themed-select-option.is-selected {
   align-items: start;
 }
 
+.app-bottom-nav {
+  display: none;
+}
+
 @media (max-width: 768px) {
   .app-body {
     grid-template-columns: minmax(0, 1fr);
+    padding-bottom: calc(72px + env(safe-area-inset-bottom, 0px));
+  }
+
+  .app-sidebar {
+    display: none;
+  }
+
+  .app-bottom-nav {
+    display: flex;
+    position: fixed;
+    bottom: 0;
+    left: 0;
+    right: 0;
+    z-index: 100;
+    justify-content: space-around;
+    align-items: stretch;
+    gap: 4px;
+    padding: 8px 8px calc(8px + env(safe-area-inset-bottom, 0px));
+    background: var(--app-surface-alt);
+    backdrop-filter: var(--app-backdrop);
+    border-top: 1px solid var(--app-border-subtle);
+    box-sizing: border-box;
+  }
+
+  .bottom-nav-btn {
+    flex: 1;
+    min-width: 0;
+    display: flex;
+    flex-direction: column;
+    align-items: center;
+    justify-content: center;
+    gap: 4px;
+    padding: 6px 4px;
+    border: none;
+    border-radius: 8px;
+    background: transparent;
+    color: var(--app-text-muted);
+    font-size: 10px;
+    font-weight: 500;
+    cursor: pointer;
+  }
+
+  .bottom-nav-btn span {
+    overflow: hidden;
+    text-overflow: ellipsis;
+    white-space: nowrap;
+    max-width: 100%;
+  }
+
+  .bottom-nav-btn.active {
+    background: var(--app-sidebar-active-bg);
+    color: var(--app-sidebar-active-text);
   }
 }
 
diff --git a/client/src/App.tsx b/client/src/App.tsx
index 070fda1..76f2666 100644
--- a/client/src/App.tsx
+++ b/client/src/App.tsx
@@ -53,6 +53,8 @@ import {
 } from './services/demoLogbook.js'
 import { fetchLogbooks, parseCollaborationRole } from './services/logbook.js'
 import { ensurePushSubscriptionIfEnabled } from './services/pushNotifications.js'
+import SyncConflictBanner from './components/SyncConflictBanner.tsx'
+import { requestPersistentStorage } from './utils/storagePersist.js'
 
 const PENDING_PUSH_LOGBOOK_KEY = 'pending_push_logbook_id'
 
@@ -71,6 +73,7 @@ function App() {
   const [isSyncing, setIsSyncing] = useState(false)
   const [isAcceptingInvite, setIsAcceptingInvite] = useState(false)
   const [showUserProfile, setShowUserProfile] = useState(false)
+  const [storagePersistHint, setStoragePersistHint] = useState(false)
   const tourLogbookRef = useRef<{ id: string; title: string } | null>(null)
   const activeLogbookRef = useRef<{ id: string | null; title: string | null }>({
     id: activeLogbookId,
@@ -428,10 +431,19 @@ function App() {
     return () => navigator.serviceWorker.removeEventListener('message', onSwMessage)
   }, [isAuthenticated, openLogbookById])
 
+  useEffect(() => {
+    if (!isAuthenticated) return
+    if (sessionStorage.getItem('storage_persist_hint_dismissed')) return
+    void requestPersistentStorage().then(({ persisted, supported }) => {
+      if (supported && !persisted) setStoragePersistHint(true)
+    })
+  }, [isAuthenticated])
+
   const handleAuthenticated = async () => {
     setIsAuthenticated(true)
     trackPlausibleEvent(PlausibleEvents.LOGGED_IN)
     void ensurePushSubscriptionIfEnabled()
+    void requestPersistentStorage()
 
     try {
       const demo = await seedDemoLogbookIfNeeded()
@@ -606,7 +618,7 @@ function App() {
               <p className="app-subtitle">
                 {activeAccessRole && activeAccessRole !== 'OWNER'
                   ? t('dashboard.section_shared_hint')
-                  : `${t('app.name')} / ${activeLogbookId?.substring(0, 8)}...`}
+                  : t('app.tagline')}
               </p>
             </div>
           </div>
@@ -646,10 +658,28 @@ function App() {
           </div>
         </header>
 
+        <SyncConflictBanner logbookId={activeLogbookId} />
+
+        {storagePersistHint && (
+          <div className="storage-persist-hint glass" role="status">
+            <p>{t('pwa.storage_persist_hint')}</p>
+            <button
+              type="button"
+              className="btn secondary"
+              onClick={() => {
+                sessionStorage.setItem('storage_persist_hint_dismissed', '1')
+                setStoragePersistHint(false)
+              }}
+            >
+              {t('pwa.later')}
+            </button>
+          </div>
+        )}
+
       {/* Active Workspace */}
       <div className="app-body">
         {/* Navigation Sidebar */}
-        <aside className="app-sidebar">
+        <aside className="app-sidebar" aria-label={t('nav.dashboard')}>
           <button
             className={`sidebar-btn ${activeTab === 'logs' ? 'active' : ''}`}
             onClick={() => void handleTabChange('logs')}
@@ -746,6 +776,53 @@ function App() {
             />
           )}
         </main>
+
+        <nav className="app-bottom-nav" aria-label={t('nav.dashboard')}>
+          <button
+            type="button"
+            className={`bottom-nav-btn ${activeTab === 'logs' ? 'active' : ''}`}
+            onClick={() => void handleTabChange('logs')}
+            data-tour="nav-logs"
+          >
+            <FileText size={20} />
+            <span>{t('nav.logs')}</span>
+          </button>
+          <button
+            type="button"
+            className={`bottom-nav-btn ${activeTab === 'vessel' ? 'active' : ''}`}
+            onClick={() => void handleTabChange('vessel')}
+            data-tour="nav-vessel"
+          >
+            <Ship size={20} />
+            <span>{t('nav.vessel')}</span>
+          </button>
+          <button
+            type="button"
+            className={`bottom-nav-btn ${activeTab === 'crew' ? 'active' : ''}`}
+            onClick={() => void handleTabChange('crew')}
+            data-tour="nav-crew"
+          >
+            <Users size={20} />
+            <span>{t('nav.crew')}</span>
+          </button>
+          <button
+            type="button"
+            className={`bottom-nav-btn ${activeTab === 'stats' ? 'active' : ''}`}
+            onClick={() => void handleTabChange('stats')}
+            data-tour="nav-stats"
+          >
+            <BarChart2 size={20} />
+            <span>{t('nav.stats')}</span>
+          </button>
+          <button
+            type="button"
+            className={`bottom-nav-btn ${activeTab === 'settings' ? 'active' : ''}`}
+            onClick={() => void handleTabChange('settings')}
+          >
+            <Settings size={20} />
+            <span>{t('nav.settings')}</span>
+          </button>
+        </nav>
       </div>
     </div>
   </div>
diff --git a/client/src/components/LogEntriesList.tsx b/client/src/components/LogEntriesList.tsx
index d0b2870..afb1354 100644
--- a/client/src/components/LogEntriesList.tsx
+++ b/client/src/components/LogEntriesList.tsx
@@ -8,6 +8,7 @@ import { syncLogbook } from '../services/sync.js'
 import { downloadCsv, shareCsv } from '../services/csvExport.js'
 import { downloadLogbookPagePdf } from '../services/pdfExport.js'
 import { PlausibleEvents, trackPlausibleEvent } from '../services/analytics.js'
+import { getErrorMessage } from '../utils/errors.js'
 import LogEntryEditor from './LogEntryEditor.tsx'
 import LiveLogView from './LiveLogView.tsx'
 import EntrySkipperSignBadge from './EntrySkipperSignBadge.tsx'
@@ -142,7 +143,7 @@ export default function LogEntriesList({
       setEntries(list)
     } catch (err: any) {
       console.error('Failed to load log entries:', err)
-      setError(err.message || 'Decryption failed. Could not load journal list.')
+      setError(getErrorMessage(err, t('errors.load_failed')))
     } finally {
       setLoading(false)
     }
@@ -176,7 +177,7 @@ export default function LogEntriesList({
       trackPlausibleEvent(PlausibleEvents.CSV_EXPORTED)
     } catch (err: any) {
       console.error('Failed to download CSV:', err)
-      setError(err.message || 'Failed to generate CSV export.')
+      setError(getErrorMessage(err, t('errors.export_failed')))
     } finally {
       setExporting(false)
     }
@@ -204,7 +205,7 @@ export default function LogEntriesList({
         setError(t('logs.share_unsupported'))
       } else {
         console.error('Failed to share CSV:', err)
-        setError(err.message || 'Failed to share CSV export.')
+        setError(getErrorMessage(err, t('errors.export_failed')))
       }
     } finally {
       setExporting(false)
@@ -225,7 +226,7 @@ export default function LogEntriesList({
       trackPlausibleEvent(PlausibleEvents.PDF_EXPORTED, { scope: 'entry' })
     } catch (err: any) {
       console.error('Failed to download PDF:', err)
-      setError(err.message || 'Failed to generate PDF export.')
+      setError(getErrorMessage(err, t('errors.export_failed')))
     } finally {
       setExporting(false)
     }
@@ -317,7 +318,7 @@ export default function LogEntriesList({
       syncLogbook(logbookId).catch((err) => console.warn('Background sync failed:', err))
     } catch (err: any) {
       console.error('Failed to create entry:', err)
-      setError(err.message || 'Failed to create new log entry.')
+      setError(getErrorMessage(err, t('errors.save_failed')))
     } finally {
       setLoading(false)
     }
@@ -347,7 +348,7 @@ export default function LogEntriesList({
         syncLogbook(logbookId).catch((err) => console.warn('Background sync failed:', err))
       } catch (err: any) {
         console.error('Failed to delete log entry:', err)
-        setError(err.message || 'Failed to delete log entry.')
+        setError(getErrorMessage(err, t('errors.delete_failed')))
       }
     }
   }
@@ -460,8 +461,12 @@ export default function LogEntriesList({
               key={item.id}
               className="logbook-card glass"
               data-tour={tourFirstEntryId === item.id ? 'entry-first' : undefined}
-              onClick={() => setSelectedEntryId(item.id)}
             >
+              <button
+                type="button"
+                className="logbook-card-select"
+                onClick={() => setSelectedEntryId(item.id)}
+              >
               <div className="card-icon">
                 <FileText size={24} />
               </div>
@@ -483,6 +488,9 @@ export default function LogEntriesList({
                 </div>
               </div>
 
+              <ChevronRight size={18} style={{ color: '#475569', marginLeft: 'auto' }} aria-hidden />
+              </button>
+
               <button className="btn-pdf" onClick={(e) => handleDownloadPdf(item.id, item.date, e)} title={t('logs.export_pdf')} disabled={exporting}>
                 <Download size={18} />
               </button>
@@ -492,8 +500,6 @@ export default function LogEntriesList({
                   <Trash2 size={18} />
                 </button>
               )}
-              
-              <ChevronRight size={18} style={{ color: '#475569', marginLeft: 'auto' }} />
             </div>
           ))}
         </div>
diff --git a/client/src/components/LogEntryEditor.tsx b/client/src/components/LogEntryEditor.tsx
index 639bf24..d588a8c 100644
--- a/client/src/components/LogEntryEditor.tsx
+++ b/client/src/components/LogEntryEditor.tsx
@@ -5,6 +5,8 @@ import { getActiveMasterKey } from '../services/auth.js'
 import { getLogbookKey } from '../services/logbookKeys.js'
 import { encryptJson, decryptJson } from '../services/crypto.js'
 import { syncLogbook } from '../services/sync.js'
+import { saveEntryDraft, clearEntryDraft } from '../services/entryDraft.js'
+import { getErrorMessage } from '../utils/errors.js'
 import { downloadLogbookPagePdf } from '../services/pdfExport.js'
 import { FileText, Save, ChevronLeft, Check, Compass, Plus, Trash2, MapPin, CloudSun, Clock, Download, Upload, Pencil, X, ChevronDown, ChevronUp } from 'lucide-react'
 import PhotoCapture from './PhotoCapture.tsx'
@@ -288,6 +290,14 @@ export default function LogEntryEditor({
     events
   ])
 
+  useEffect(() => {
+    if (readOnly || loading || !date) return
+    const timer = window.setTimeout(() => {
+      void saveEntryDraft(logbookId, entryId, buildPayloadForSigning())
+    }, 4000)
+    return () => window.clearTimeout(timer)
+  }, [readOnly, loading, logbookId, entryId, buildPayloadForSigning, date])
+
   const fuelPerMotorHour = useMemo(
     () => computeFuelPerMotorHour(parseFloat(fuelConsumption) || 0, parseFloat(motorHours) || 0),
     [fuelConsumption, motorHours]
@@ -1208,15 +1218,17 @@ export default function LogEntryEditor({
         ...signaturesForSave
       })
 
+      await clearEntryDraft(logbookId, entryId)
+
       setSuccess(true)
       trackPlausibleEvent(PlausibleEvents.TRAVEL_DAY_SAVED)
       setTimeout(() => {
         setSuccess(false)
         onBack()
       }, 1500)
-    } catch (err: any) {
+    } catch (err: unknown) {
       console.error('Failed to save entry details:', err)
-      setError(err.message || 'Failed to save entry details.')
+      setError(getErrorMessage(err, t('errors.save_failed')))
     } finally {
       setSaving(false)
     }
diff --git a/client/src/components/LogbookDashboard.tsx b/client/src/components/LogbookDashboard.tsx
index 69dae7c..3a2bb73 100644
--- a/client/src/components/LogbookDashboard.tsx
+++ b/client/src/components/LogbookDashboard.tsx
@@ -6,6 +6,7 @@ import { fetchLogbooks, createLogbook, deleteLogbook, updateLogbookTitle, type D
 import LogbookRoleBadge from './LogbookRoleBadge.tsx'
 import BetaBadge from './BetaBadge.tsx'
 import { PlausibleEvents, trackPlausibleEvent } from '../services/analytics.js'
+import { getErrorMessage } from '../utils/errors.js'
 import { logoutUser } from '../services/auth.js'
 import { useDialog } from './ModalDialog.tsx'
 import { BookOpen, Plus, Trash2, LogOut, Languages, RefreshCw, Ship, Wifi, WifiOff, Search, X, CalendarDays, CaseSensitive, ArrowUp, ArrowDown } from 'lucide-react'
@@ -102,8 +103,8 @@ export default function LogbookDashboard({ onSelectLogbook, onLogout, onOpenProf
     try {
       const data = await fetchLogbooks()
       setLogbooks(data)
-    } catch (err: any) {
-      setError(err.message || 'Failed to load logbooks')
+    } catch (err: unknown) {
+      setError(getErrorMessage(err, t('errors.load_failed')))
     } finally {
       setLoading(false)
       setRefreshing(false)
@@ -121,8 +122,8 @@ export default function LogbookDashboard({ onSelectLogbook, onLogout, onOpenProf
       setLogbooks((prev) => [created, ...prev])
       setNewTitle('')
       trackPlausibleEvent(PlausibleEvents.LOGBOOK_CREATED)
-    } catch (err: any) {
-      setError(err.message || 'Failed to create logbook')
+    } catch (err: unknown) {
+      setError(getErrorMessage(err, t('errors.save_failed')))
     } finally {
       setLoading(false)
     }
@@ -138,7 +139,7 @@ export default function LogbookDashboard({ onSelectLogbook, onLogout, onOpenProf
         await deleteLogbook(id)
         setLogbooks((prev) => prev.filter((lb) => lb.id !== id))
       } catch (err: any) {
-        setError(err.message || 'Failed to delete logbook')
+        setError(getErrorMessage(err, t('errors.delete_failed')))
       } finally {
         setLoading(false)
       }
@@ -182,7 +183,7 @@ export default function LogbookDashboard({ onSelectLogbook, onLogout, onOpenProf
         )
       )
     } catch (err: any) {
-      setError(err.message || 'Failed to update logbook title')
+      setError(getErrorMessage(err, t('errors.save_failed')))
     } finally {
       setLoading(false)
     }
@@ -226,8 +227,12 @@ export default function LogbookDashboard({ onSelectLogbook, onLogout, onOpenProf
     <div
       key={lb.id}
       className={`logbook-card glass${lb.isShared ? ' logbook-card--shared' : ''}`}
-      onClick={() => onSelectLogbook(lb.id, lb.title)}
     >
+      <button
+        type="button"
+        className="logbook-card-select"
+        onClick={() => onSelectLogbook(lb.id, lb.title)}
+      >
       <div className="card-icon">
         <BookOpen size={24} />
       </div>
@@ -282,6 +287,7 @@ export default function LogbookDashboard({ onSelectLogbook, onLogout, onOpenProf
           </span>
         </div>
       </div>
+      </button>
 
       {!lb.isShared && (
         <div className="logbook-card-actions">
diff --git a/client/src/components/ModalDialog.tsx b/client/src/components/ModalDialog.tsx
index 8594a23..3e9e2f1 100644
--- a/client/src/components/ModalDialog.tsx
+++ b/client/src/components/ModalDialog.tsx
@@ -1,4 +1,14 @@
-import React, { createContext, useContext, useState, useRef, useCallback, useMemo } from 'react'
+import React, {
+  createContext,
+  useContext,
+  useState,
+  useRef,
+  useCallback,
+  useMemo,
+  useEffect,
+  useId
+} from 'react'
+import { useTranslation } from 'react-i18next'
 
 interface DialogContextType {
   showAlert: (message: string, title?: string, confirmText?: string) => Promise<void>
@@ -16,6 +26,11 @@ export function useDialog() {
 }
 
 export function DialogProvider({ children }: { children: React.ReactNode }) {
+  const { t } = useTranslation()
+  const titleId = useId()
+  const messageId = useId()
+  const confirmRef = useRef<HTMLButtonElement>(null)
+
   const [isOpen, setIsOpen] = useState(false)
   const [title, setTitle] = useState('')
   const [message, setMessage] = useState('')
@@ -23,19 +38,20 @@ export function DialogProvider({ children }: { children: React.ReactNode }) {
   const [confirmLabel, setConfirmLabel] = useState('OK')
   const [cancelLabel, setCancelLabel] = useState('Cancel')
 
-  const resolveRef = useRef<((val: any) => void) | null>(null)
+  const alertResolveRef = useRef<(() => void) | null>(null)
+  const confirmResolveRef = useRef<((val: boolean) => void) | null>(null)
 
   const showAlert = useCallback((msg: string, headerTitle?: string, btnText?: string): Promise<void> => {
     setMessage(msg)
     setTitle(headerTitle || '')
     setType('alert')
-    setConfirmLabel(btnText || 'OK')
+    setConfirmLabel(btnText || t('dialog.ok'))
     setIsOpen(true)
 
     return new Promise<void>((resolve) => {
-      resolveRef.current = resolve
+      alertResolveRef.current = resolve
     })
-  }, [])
+  }, [t])
 
   const showConfirm = useCallback((
     msg: string,
@@ -46,31 +62,47 @@ export function DialogProvider({ children }: { children: React.ReactNode }) {
     setMessage(msg)
     setTitle(headerTitle || '')
     setType('confirm')
-    setConfirmLabel(btnConfirm || 'Yes')
-    setCancelLabel(btnCancel || 'No')
+    setConfirmLabel(btnConfirm || t('dialog.yes'))
+    setCancelLabel(btnCancel || t('dialog.no'))
     setIsOpen(true)
 
     return new Promise<boolean>((resolve) => {
-      resolveRef.current = resolve
+      confirmResolveRef.current = resolve
     })
-  }, [])
+  }, [t])
 
   const handleConfirm = useCallback(() => {
     setIsOpen(false)
-    if (resolveRef.current) {
-      resolveRef.current(type === 'confirm' ? true : undefined)
-      resolveRef.current = null
+    if (type === 'confirm' && confirmResolveRef.current) {
+      confirmResolveRef.current(true)
+      confirmResolveRef.current = null
+    } else if (alertResolveRef.current) {
+      alertResolveRef.current()
+      alertResolveRef.current = null
     }
   }, [type])
 
   const handleCancel = useCallback(() => {
     setIsOpen(false)
-    if (resolveRef.current) {
-      resolveRef.current(false)
-      resolveRef.current = null
+    if (confirmResolveRef.current) {
+      confirmResolveRef.current(false)
+      confirmResolveRef.current = null
     }
   }, [])
 
+  useEffect(() => {
+    if (!isOpen) return
+    confirmRef.current?.focus()
+    const onKeyDown = (e: KeyboardEvent) => {
+      if (e.key === 'Escape') {
+        if (type === 'confirm') handleCancel()
+        else handleConfirm()
+      }
+    }
+    window.addEventListener('keydown', onKeyDown)
+    return () => window.removeEventListener('keydown', onKeyDown)
+  }, [isOpen, type, handleCancel, handleConfirm])
+
   const contextValue = useMemo(
     () => ({ showAlert, showConfirm }),
     [showAlert, showConfirm]
@@ -80,17 +112,44 @@ export function DialogProvider({ children }: { children: React.ReactNode }) {
     <DialogContext.Provider value={contextValue}>
       {children}
       {isOpen && (
-        <div className="custom-dialog-overlay" onClick={type === 'alert' ? handleConfirm : undefined}>
-          <div className="custom-dialog-card glass scale-in" onClick={(e) => e.stopPropagation()}>
-            {title && <h3 className="custom-dialog-title">{title}</h3>}
-            <p className="custom-dialog-message">{message}</p>
+        <div
+          className="custom-dialog-overlay"
+          onClick={type === 'confirm' ? handleCancel : handleConfirm}
+        >
+          <div
+            className="custom-dialog-card glass scale-in"
+            role="dialog"
+            aria-modal="true"
+            aria-labelledby={title ? titleId : undefined}
+            aria-describedby={messageId}
+            onClick={(e) => e.stopPropagation()}
+          >
+            {title && (
+              <h3 id={titleId} className="custom-dialog-title">
+                {title}
+              </h3>
+            )}
+            <p id={messageId} className="custom-dialog-message">
+              {message}
+            </p>
             <div className="custom-dialog-actions">
               {type === 'confirm' && (
-                <button type="button" className="btn secondary" onClick={handleCancel} style={{ width: 'auto', padding: '8px 20px', margin: 0 }}>
+                <button
+                  type="button"
+                  className="btn secondary"
+                  onClick={handleCancel}
+                  style={{ width: 'auto', padding: '8px 20px', margin: 0 }}
+                >
                   {cancelLabel}
                 </button>
               )}
-              <button type="button" className="btn primary" onClick={handleConfirm} style={{ width: 'auto', minWidth: '80px', padding: '8px 20px', margin: 0 }}>
+              <button
+                ref={confirmRef}
+                type="button"
+                className="btn primary"
+                onClick={handleConfirm}
+                style={{ width: 'auto', minWidth: '80px', padding: '8px 20px', margin: 0 }}
+              >
                 {confirmLabel}
               </button>
             </div>
diff --git a/client/src/components/SyncConflictBanner.tsx b/client/src/components/SyncConflictBanner.tsx
new file mode 100644
index 0000000..719ba91
--- /dev/null
+++ b/client/src/components/SyncConflictBanner.tsx
@@ -0,0 +1,64 @@
+import { useEffect, useState } from 'react'
+import { useTranslation } from 'react-i18next'
+import { AlertTriangle } from 'lucide-react'
+import {
+  getSyncConflicts,
+  subscribeSyncConflicts,
+  type SyncConflict
+} from '../services/syncConflicts.js'
+import {
+  resolveSyncConflictKeepLocal,
+  resolveSyncConflictUseServer
+} from '../services/sync.js'
+
+interface SyncConflictBannerProps {
+  logbookId: string | null
+}
+
+export default function SyncConflictBanner({ logbookId }: SyncConflictBannerProps) {
+  const { t } = useTranslation()
+  const [items, setItems] = useState<SyncConflict[]>([])
+
+  useEffect(() => {
+    const refresh = () => {
+      setItems(logbookId ? getSyncConflicts(logbookId) : getSyncConflicts())
+    }
+    refresh()
+    return subscribeSyncConflicts(refresh)
+  }, [logbookId])
+
+  if (items.length === 0) return null
+
+  const first = items[0]
+
+  return (
+    <div className="sync-conflict-banner" role="alert">
+      <AlertTriangle size={20} aria-hidden />
+      <div className="sync-conflict-banner__body">
+        <strong>{t('sync.conflict_title')}</strong>
+        <p>
+          {t('sync.conflict_message', {
+            count: items.length,
+            id: first.payloadId.slice(0, 8)
+          })}
+        </p>
+        <div className="sync-conflict-banner__actions">
+          <button
+            type="button"
+            className="btn secondary"
+            onClick={() => void resolveSyncConflictUseServer(first)}
+          >
+            {t('sync.conflict_use_server')}
+          </button>
+          <button
+            type="button"
+            className="btn primary"
+            onClick={() => void resolveSyncConflictKeepLocal(first)}
+          >
+            {t('sync.conflict_keep_local')}
+          </button>
+        </div>
+      </div>
+    </div>
+  )
+}
diff --git a/client/src/i18n/locales/da.json b/client/src/i18n/locales/da.json
index f9d3c4b..91e028c 100644
--- a/client/src/i18n/locales/da.json
+++ b/client/src/i18n/locales/da.json
@@ -13,6 +13,17 @@
       "sv": "Svenska",
       "nb": "Norsk"
     },
+    "dialog": {
+      "ok": "OK",
+      "yes": "Ja",
+      "no": "Nej"
+    },
+    "errors": {
+      "load_failed": "Data kunne ikke indlæses.",
+      "save_failed": "Ændringer kunne ikke gemmes.",
+      "delete_failed": "Sletning mislykkedes.",
+      "export_failed": "Eksport mislykkedes."
+    },
     "common": {
       "unsaved_changes_title": "Ikke gemte ændringer",
       "unsaved_changes_message": "Du har ændringer, der ikke er gemt. Vil du virkelig forlade siden? Dine ændringer vil gå tabt.",
@@ -92,13 +103,18 @@
       "update_title": "Opdatering tilgængelig",
       "update_desc": "En ny version af Kapteins Daagbok er klar. Opdater venligst for at få de seneste ændringer.",
       "update_now": "Opdater nu",
-      "update_reloading": "Indlæser..."
+      "update_reloading": "Indlæser...",
+      "storage_persist_hint": "Browseren kan slette offline-data. Tillad permanent lagring, så din logbog forbliver beskyttet."
     },
     "sync": {
       "status_synced": "Synkroniseret",
       "status_syncing": "Synkroniser...",
       "status_offline": "Offline-cache",
-      "status_unsynced": "Usynkroniserede ændringer"
+      "status_unsynced": "Usynkroniserede ændringer",
+      "conflict_title": "Synkroniseringskonflikt",
+      "conflict_message": "{{count}} ændring(er) kunne ikke synkroniseres (post {{id}}…). Vælg hvilken version der skal gælde.",
+      "conflict_use_server": "Brug serverversion",
+      "conflict_keep_local": "Behold min version"
     },
     "vessel": {
       "title": "Skibets stamdata",
diff --git a/client/src/i18n/locales/de.json b/client/src/i18n/locales/de.json
index 4c0bec2..404d958 100644
--- a/client/src/i18n/locales/de.json
+++ b/client/src/i18n/locales/de.json
@@ -13,6 +13,17 @@
       "sv": "Svenska",
       "nb": "Norsk"
     },
+    "dialog": {
+      "ok": "OK",
+      "yes": "Ja",
+      "no": "Nein"
+    },
+    "errors": {
+      "load_failed": "Daten konnten nicht geladen werden.",
+      "save_failed": "Änderungen konnten nicht gespeichert werden.",
+      "delete_failed": "Löschen fehlgeschlagen.",
+      "export_failed": "Export fehlgeschlagen."
+    },
     "common": {
       "unsaved_changes_title": "Ungespeicherte Änderungen",
       "unsaved_changes_message": "Du hast ungespeicherte Änderungen. Möchtest du die Seite wirklich verlassen? Deine Änderungen gehen verloren.",
@@ -92,13 +103,18 @@
       "update_title": "Update verfügbar",
       "update_desc": "Eine neue Version von Kapteins Daagbok ist bereit. Bitte aktualisieren, um die neuesten Änderungen zu erhalten.",
       "update_now": "Jetzt aktualisieren",
-      "update_reloading": "Wird geladen…"
+      "update_reloading": "Wird geladen…",
+      "storage_persist_hint": "Der Browser kann Offline-Daten löschen. Erlaube dauerhafte Speicherung, damit dein Logbuch geschützt bleibt (in den Browser-Einstellungen oder beim nächsten Hinweis)."
     },
     "sync": {
       "status_synced": "Synchronisiert",
       "status_syncing": "Synchronisiere…",
       "status_offline": "Offline-Cache",
-      "status_unsynced": "Unsynchronisierte Änderungen"
+      "status_unsynced": "Unsynchronisierte Änderungen",
+      "conflict_title": "Synchronisationskonflikt",
+      "conflict_message": "{{count}} Änderung(en) konnten nicht synchronisiert werden (Eintrag {{id}}…). Bitte wähle, welche Version gelten soll.",
+      "conflict_use_server": "Server-Version übernehmen",
+      "conflict_keep_local": "Meine Version behalten"
     },
     "vessel": {
       "title": "Schiffs-Stammdaten",
diff --git a/client/src/i18n/locales/en.json b/client/src/i18n/locales/en.json
index 89bc4c0..644fb25 100644
--- a/client/src/i18n/locales/en.json
+++ b/client/src/i18n/locales/en.json
@@ -13,6 +13,17 @@
       "sv": "Svenska",
       "nb": "Norsk"
     },
+    "dialog": {
+      "ok": "OK",
+      "yes": "Yes",
+      "no": "No"
+    },
+    "errors": {
+      "load_failed": "Could not load data.",
+      "save_failed": "Could not save changes.",
+      "delete_failed": "Could not delete.",
+      "export_failed": "Export failed."
+    },
     "common": {
       "unsaved_changes_title": "Unsaved changes",
       "unsaved_changes_message": "You have unsaved changes. Leave this page anyway? Your changes will be lost.",
@@ -92,13 +103,18 @@
       "update_title": "Update available",
       "update_desc": "A new version of Kapteins Daagbok is ready. Reload to get the latest changes.",
       "update_now": "Reload now",
-      "update_reloading": "Reloading…"
+      "update_reloading": "Reloading…",
+      "storage_persist_hint": "Your browser may delete offline data. Allow persistent storage to keep your logbook safe (browser settings or when prompted)."
     },
     "sync": {
       "status_synced": "Synced",
       "status_syncing": "Syncing…",
       "status_offline": "Offline Cache",
-      "status_unsynced": "Unsynced changes"
+      "status_unsynced": "Unsynced changes",
+      "conflict_title": "Sync conflict",
+      "conflict_message": "{{count}} change(s) could not be synced (entry {{id}}…). Choose which version to keep.",
+      "conflict_use_server": "Use server version",
+      "conflict_keep_local": "Keep my version"
     },
     "vessel": {
       "title": "Vessel Master Data",
diff --git a/client/src/i18n/locales/nb.json b/client/src/i18n/locales/nb.json
index 65a717f..ddf2a23 100644
--- a/client/src/i18n/locales/nb.json
+++ b/client/src/i18n/locales/nb.json
@@ -13,6 +13,17 @@
       "sv": "Svenska",
       "nb": "Norsk"
     },
+    "dialog": {
+      "ok": "OK",
+      "yes": "Ja",
+      "no": "Nei"
+    },
+    "errors": {
+      "load_failed": "Data kunne ikke lastes.",
+      "save_failed": "Endringer kunne ikke lagres.",
+      "delete_failed": "Sletting mislyktes.",
+      "export_failed": "Eksport mislyktes."
+    },
     "common": {
       "unsaved_changes_title": "Ikke-lagrede endringer",
       "unsaved_changes_message": "Du har endringer som ikke er lagret. Vil du virkelig forlate siden? Endringene dine vil gå tapt.",
@@ -92,13 +103,18 @@
       "update_title": "Oppdatering tilgjengelig",
       "update_desc": "En ny versjon av Kapteins Daagbok er klar. Oppdater for å få med de siste endringene.",
       "update_now": "Oppdater nå",
-      "update_reloading": "Laster..."
+      "update_reloading": "Laster...",
+      "storage_persist_hint": "Nettleseren kan slette offlinedata. Tillat permanent lagring slik at loggboken din forblir beskyttet."
     },
     "sync": {
       "status_synced": "Synkronisert",
       "status_syncing": "Synkroniser...",
       "status_offline": "Frakoblet hurtigbuffer",
-      "status_unsynced": "Usynkroniserte endringer"
+      "status_unsynced": "Usynkroniserte endringer",
+      "conflict_title": "Synkroniseringskonflikt",
+      "conflict_message": "{{count}} endring(er) kunne ikke synkroniseres (post {{id}}…). Velg hvilken versjon som skal gjelde.",
+      "conflict_use_server": "Bruk serverversjon",
+      "conflict_keep_local": "Behold min versjon"
     },
     "vessel": {
       "title": "Stamdata for skip",
diff --git a/client/src/i18n/locales/sv.json b/client/src/i18n/locales/sv.json
index 19cfdad..cd251d4 100644
--- a/client/src/i18n/locales/sv.json
+++ b/client/src/i18n/locales/sv.json
@@ -13,6 +13,17 @@
       "sv": "Svenska",
       "nb": "Norsk"
     },
+    "dialog": {
+      "ok": "OK",
+      "yes": "Ja",
+      "no": "Nej"
+    },
+    "errors": {
+      "load_failed": "Data kunde inte laddas.",
+      "save_failed": "Ändringar kunde inte sparas.",
+      "delete_failed": "Radering misslyckades.",
+      "export_failed": "Export misslyckades."
+    },
     "common": {
       "unsaved_changes_title": "Osparade ändringar",
       "unsaved_changes_message": "Du har ändringar som inte sparats. Vill du verkligen lämna sidan? Dina ändringar kommer att gå förlorade.",
@@ -92,13 +103,18 @@
       "update_title": "Uppdatering tillgänglig",
       "update_desc": "En ny version av Kapteins Daagbok är klar. Uppdatera för att få de senaste ändringarna.",
       "update_now": "Uppdatering nu",
-      "update_reloading": "Laddar..."
+      "update_reloading": "Laddar...",
+      "storage_persist_hint": "Webbläsaren kan radera offlinedata. Tillåt permanent lagring så att din loggbok förblir skyddad."
     },
     "sync": {
       "status_synced": "Synkroniserad",
       "status_syncing": "Synkronisera...",
       "status_offline": "Offline-cache",
-      "status_unsynced": "Osynkroniserade förändringar"
+      "status_unsynced": "Osynkroniserade förändringar",
+      "conflict_title": "Synkroniseringskonflikt",
+      "conflict_message": "{{count}} ändring(ar) kunde inte synkas (post {{id}}…). Välj vilken version som ska gälla.",
+      "conflict_use_server": "Använd serverversion",
+      "conflict_keep_local": "Behåll min version"
     },
     "vessel": {
       "title": "Masterdata för fartyg",
diff --git a/client/src/services/db.ts b/client/src/services/db.ts
index 8ef4dcc..d6f9fab 100644
--- a/client/src/services/db.ts
+++ b/client/src/services/db.ts
@@ -90,6 +90,15 @@ export interface SyncQueueItem {
   updatedAt: string
 }
 
+export interface EntryDraftRecord {
+  logbookId: string
+  entryId: string
+  encryptedData: string
+  iv: string
+  tag: string
+  updatedAt: string
+}
+
 class DaagboxDatabase extends Dexie {
   logbooks!: Table<LocalLogbook>
   yachts!: Table<LocalYacht>
@@ -101,6 +110,7 @@ class DaagboxDatabase extends Dexie {
   nmeaArchives!: Table<LocalNmeaArchive>
   logbookKeys!: Table<LocalLogbookKey>
   syncQueue!: Table<SyncQueueItem>
+  entryDrafts!: Table<EntryDraftRecord, [string, string]>
 
   constructor() {
     super('DaagboxDatabase')
@@ -167,6 +177,19 @@ class DaagboxDatabase extends Dexie {
       nmeaArchives: 'entryId, logbookId, updatedAt',
       logbookKeys: 'logbookId'
     })
+    this.version(7).stores({
+      logbooks: 'id, encryptedTitle, updatedAt, isSynced, isShared, isDemo',
+      yachts: 'logbookId, updatedAt',
+      crews: 'payloadId, logbookId, updatedAt',
+      deviations: 'logbookId, updatedAt',
+      entries: 'payloadId, logbookId, updatedAt',
+      syncQueue: '++id, action, type, payloadId, logbookId',
+      photos: 'payloadId, entryId, logbookId, updatedAt',
+      gpsTracks: 'entryId, logbookId, updatedAt',
+      nmeaArchives: 'entryId, logbookId, updatedAt',
+      logbookKeys: 'logbookId',
+      entryDrafts: '[logbookId+entryId], updatedAt'
+    })
   }
 }
 
diff --git a/client/src/services/entryDraft.ts b/client/src/services/entryDraft.ts
new file mode 100644
index 0000000..24e34bc
--- /dev/null
+++ b/client/src/services/entryDraft.ts
@@ -0,0 +1,53 @@
+import { db } from './db.js'
+import { encryptJson, decryptJson } from './crypto.js'
+import { getActiveMasterKey } from './auth.js'
+
+export interface EntryDraftRecord {
+  logbookId: string
+  entryId: string
+  encryptedData: string
+  iv: string
+  tag: string
+  updatedAt: string
+}
+
+export async function saveEntryDraft(
+  logbookId: string,
+  entryId: string,
+  payload: unknown
+): Promise<void> {
+  const masterKey = getActiveMasterKey()
+  if (!masterKey) return
+
+  const { ciphertext, iv, tag } = await encryptJson(payload, masterKey)
+  await db.entryDrafts.put({
+    logbookId,
+    entryId,
+    encryptedData: ciphertext,
+    iv,
+    tag,
+    updatedAt: new Date().toISOString()
+  })
+}
+
+export async function loadEntryDraft<T = unknown>(
+  logbookId: string,
+  entryId: string
+): Promise<T | null> {
+  const masterKey = getActiveMasterKey()
+  if (!masterKey) return null
+
+  const row = await db.entryDrafts.get([logbookId, entryId])
+  if (!row) return null
+
+  try {
+    return (await decryptJson(row.encryptedData, row.iv, row.tag, masterKey)) as T
+  } catch {
+    await db.entryDrafts.delete([logbookId, entryId])
+    return null
+  }
+}
+
+export async function clearEntryDraft(logbookId: string, entryId: string): Promise<void> {
+  await db.entryDrafts.delete([logbookId, entryId])
+}
diff --git a/client/src/services/sync.ts b/client/src/services/sync.ts
index 8449aa7..cabe948 100644
--- a/client/src/services/sync.ts
+++ b/client/src/services/sync.ts
@@ -2,6 +2,11 @@ import { db, type SyncQueueItem } from './db.js'
 import { getActiveMasterKey } from './auth.js'
 import { apiFetch } from './api.js'
 import { getLogbookAccess } from './logbookAccess.js'
+import {
+  clearSyncConflict,
+  reportSyncConflict,
+  type SyncConflict
+} from './syncConflicts.js'
 
 const API_BASE = '/api/sync'
 const syncingLogbooks = new Set<string>()
@@ -177,10 +182,19 @@ async function pushChanges(logbookId: string): Promise<boolean> {
       const queueItem = pending[i]
       if (!queueItem) continue
 
-      if (res.status === 'success' || res.status === 'conflict') {
+      if (res.status === 'success') {
         if (queueItem.id !== undefined) {
           await db.syncQueue.delete(queueItem.id)
         }
+        clearSyncConflict(logbookId, res.payloadId ?? queueItem.payloadId, queueItem.type)
+      } else if (res.status === 'conflict') {
+        reportSyncConflict({
+          logbookId,
+          payloadId: res.payloadId ?? queueItem.payloadId,
+          type: queueItem.type,
+          reason: typeof res.reason === 'string' ? res.reason : 'Server version is newer',
+          queueItemId: queueItem.id
+        })
       } else {
         console.error(`Sync failed for item ${res.payloadId}:`, res.error)
       }
@@ -525,3 +539,43 @@ export function stopBackgroundSync() {
     syncIntervalId = null
   }
 }
+
+/** Accept server version: pull latest and drop the conflicting queue item. */
+export async function resolveSyncConflictUseServer(conflict: SyncConflict): Promise<void> {
+  if (conflict.queueItemId !== undefined) {
+    await db.syncQueue.delete(conflict.queueItemId)
+  } else {
+    const pending = await db.syncQueue
+      .where({ logbookId: conflict.logbookId })
+      .filter(
+        (item) => item.payloadId === conflict.payloadId && item.type === conflict.type
+      )
+      .toArray()
+    const ids = pending.map((p) => p.id).filter((id): id is number => id !== undefined)
+    if (ids.length > 0) await db.syncQueue.bulkDelete(ids)
+  }
+  clearSyncConflict(conflict.logbookId, conflict.payloadId, conflict.type)
+  await pullChanges(conflict.logbookId)
+}
+
+/** Keep local version: bump queue timestamp and retry push. */
+export async function resolveSyncConflictKeepLocal(conflict: SyncConflict): Promise<void> {
+  const bump = new Date(Date.now() + 1000).toISOString()
+  if (conflict.queueItemId !== undefined) {
+    await db.syncQueue.update(conflict.queueItemId, { updatedAt: bump })
+  } else {
+    const pending = await db.syncQueue
+      .where({ logbookId: conflict.logbookId })
+      .filter(
+        (item) => item.payloadId === conflict.payloadId && item.type === conflict.type
+      )
+      .toArray()
+    for (const item of pending) {
+      if (item.id !== undefined) {
+        await db.syncQueue.update(item.id, { updatedAt: bump })
+      }
+    }
+  }
+  clearSyncConflict(conflict.logbookId, conflict.payloadId, conflict.type)
+  await flushPushQueue(conflict.logbookId)
+}
diff --git a/client/src/services/syncConflicts.ts b/client/src/services/syncConflicts.ts
new file mode 100644
index 0000000..7f042cc
--- /dev/null
+++ b/client/src/services/syncConflicts.ts
@@ -0,0 +1,48 @@
+export interface SyncConflict {
+  logbookId: string
+  payloadId: string
+  type: string
+  reason: string
+  queueItemId?: number
+  detectedAt: string
+}
+
+const conflicts = new Map<string, SyncConflict>()
+const listeners = new Set<() => void>()
+
+function conflictKey(logbookId: string, payloadId: string, type: string): string {
+  return `${logbookId}:${type}:${payloadId}`
+}
+
+export function getSyncConflicts(logbookId?: string): SyncConflict[] {
+  const all = Array.from(conflicts.values())
+  if (!logbookId) return all
+  return all.filter((c) => c.logbookId === logbookId)
+}
+
+export function hasSyncConflicts(logbookId?: string): boolean {
+  return getSyncConflicts(logbookId).length > 0
+}
+
+export function reportSyncConflict(conflict: Omit<SyncConflict, 'detectedAt'>): void {
+  const key = conflictKey(conflict.logbookId, conflict.payloadId, conflict.type)
+  conflicts.set(key, { ...conflict, detectedAt: new Date().toISOString() })
+  listeners.forEach((l) => l())
+}
+
+export function clearSyncConflict(logbookId: string, payloadId: string, type: string): void {
+  conflicts.delete(conflictKey(logbookId, payloadId, type))
+  listeners.forEach((l) => l())
+}
+
+export function clearSyncConflictsForLogbook(logbookId: string): void {
+  for (const key of conflicts.keys()) {
+    if (key.startsWith(`${logbookId}:`)) conflicts.delete(key)
+  }
+  listeners.forEach((l) => l())
+}
+
+export function subscribeSyncConflicts(listener: () => void): () => void {
+  listeners.add(listener)
+  return () => listeners.delete(listener)
+}
diff --git a/client/src/utils/errors.ts b/client/src/utils/errors.ts
new file mode 100644
index 0000000..3017f78
--- /dev/null
+++ b/client/src/utils/errors.ts
@@ -0,0 +1,10 @@
+/** Map unknown errors to a user-facing message (i18n key or fallback). */
+export function getErrorMessage(err: unknown, fallback: string): string {
+  if (err instanceof Error && err.message.trim()) {
+    return err.message
+  }
+  if (typeof err === 'string' && err.trim()) {
+    return err
+  }
+  return fallback
+}
diff --git a/client/src/utils/storagePersist.ts b/client/src/utils/storagePersist.ts
new file mode 100644
index 0000000..0bc3b6d
--- /dev/null
+++ b/client/src/utils/storagePersist.ts
@@ -0,0 +1,17 @@
+/** Request durable IndexedDB storage (important on iOS Safari). */
+export async function requestPersistentStorage(): Promise<{
+  persisted: boolean
+  supported: boolean
+}> {
+  if (!('storage' in navigator) || !navigator.storage.persist) {
+    return { persisted: false, supported: false }
+  }
+  try {
+    const persisted = await navigator.storage.persisted()
+    if (persisted) return { persisted: true, supported: true }
+    const granted = await navigator.storage.persist()
+    return { persisted: granted, supported: true }
+  } catch {
+    return { persisted: false, supported: true }
+  }
+}