feat: note history modal with restore, diff comparison, and dynamic UI updates

- Complete rewrite of note-history-modal: version list with inline restore/delete,
  split diff view with synced scrolling, rich preview for markdown/richtext/checklist
- Fix restore not updating editor: use key={id-updatedAt} on NoteInlineEditor to
  force remount on restore, and add sync useEffect to reset local state on prop changes
- Add sync useEffect in NoteEditor for external note updates
- Add historyEnabled to NOTE_LIST_SELECT (no more 'Activer' on every modal open)
- Replace browser confirm() with shadcn AlertDialog for delete confirmation
- Add i18n keys: currentVersion, compareVersions, diffTitle, diffSelectHint, deleteVersionDesc
- Install diff + @types/diff for visual line diffing
- Fix MasonryGrid render-phase sync to preserve local sizes
- Update notes-tabs-view merge logic for restored note propagation
- Remove debug console.log from restoreNoteVersion

memento-note/components/home-client.tsx

@@ -156,6 +156,7 @@ export function HomeClient({ initialNotes, initialSettings }: HomeClientProps) {
     setNotes((prev) => prev.map((n) => (n.id === restored.id ? { ...n, ...restored } : n)))
     setPinnedNotes((prev) => prev.map((n) => (n.id === restored.id ? { ...n, ...restored } : n)))
     setEditingNote((prev) => (prev?.note.id === restored.id ? { ...prev, note: restored } : prev))
+    setHistoryNote((prev) => (prev?.id === restored.id ? { ...prev, ...restored } : prev))
   }, [])
 
   const handleSizeChange = useCallback((noteId: string, size: 'small' | 'medium' | 'large') => {

memento-note/components/masonry-grid.tsx

@@ -181,20 +181,14 @@ export function MasonryGrid({
 
   // Local notes state for optimistic size/order updates
   const [localNotes, setLocalNotes] = useState<Note[]>(notes);
+  const prevNotesRef = useRef<Note[]>(notes);
 
-  useEffect(() => {
-    setLocalNotes(prev => {
-      const prevIds = prev.map(n => n.id).join(',')
-      const incomingIds = notes.map(n => n.id).join(',')
-      if (prevIds === incomingIds) {
-        const localSizeMap = new Map(prev.map(n => [n.id, n.size]))
-        return notes.map(n => ({ ...n, size: localSizeMap.get(n.id) ?? n.size }))
-      }
-      // Notes added/removed: full sync but preserve local sizes
-      const localSizeMap = new Map(prev.map(n => [n.id, n.size]))
-      return notes.map(n => ({ ...n, size: localSizeMap.get(n.id) ?? n.size }))
-    })
-  }, [notes]);
+  if (notes !== prevNotesRef.current) {
+    const localSizeMap = new Map(localNotes.map(n => [n.id, n.size]));
+    const newLocalNotes = notes.map(n => ({ ...n, size: localSizeMap.get(n.id) ?? n.size }));
+    setLocalNotes(newLocalNotes);
+    prevNotesRef.current = notes;
+  }
 
   const pinnedNotes = useMemo(() => localNotes.filter(n => n.isPinned), [localNotes]);
   const othersNotes = useMemo(() => localNotes.filter(n => !n.isPinned), [localNotes]);

memento-note/components/note-card.tsx

@@ -535,7 +535,7 @@ export const NoteCard = memo(function NoteCard({
       )}
 
       {/* Fusion Badge */}
-      {optimisticNote.aiProvider === 'fusion' && (
+      {note.aiProvider === 'fusion' && optimisticNote.autoGenerated !== null && (
         <div className="px-1.5 py-0.5 rounded text-[10px] font-medium bg-purple-100 dark:bg-purple-900/30 text-purple-700 dark:text-purple-400 border border-purple-200 dark:border-purple-800 flex items-center gap-1 group/badge relative mb-2 w-fit">
           <Link2 className="h-2.5 w-2.5" />
           {t('memoryEcho.fused')}
@@ -550,28 +550,28 @@ export const NoteCard = memo(function NoteCard({
       )}
 
       {/* Title */}
-      {optimisticNote.title && (
+      {note.title && (
         <h3 dir="auto" className="text-lg font-heading font-semibold mb-2 pr-20 text-foreground leading-tight tracking-tight flex items-center gap-2">
           {(() => {
-            const TypeIcon = NOTE_TYPE_ICONS[optimisticNote.type] || AlignLeft
+            const TypeIcon = NOTE_TYPE_ICONS[note.type] || AlignLeft
             return <TypeIcon className="h-4 w-4 shrink-0 text-muted-foreground/50" />
           })()}
-          <span className="min-w-0 truncate">{optimisticNote.title}</span>
+          <span className="min-w-0 truncate">{note.title}</span>
         </h3>
       )}
 
       {/* Search Match Type Badge */}
-      {optimisticNote.matchType && (
+      {note.matchType && (
         <Badge
-          variant={optimisticNote.matchType === 'exact' ? 'default' : 'secondary'}
+          variant={note.matchType === 'exact' ? 'default' : 'secondary'}
           className={cn(
             'mb-2 text-xs',
-            optimisticNote.matchType === 'exact'
+            note.matchType === 'exact'
               ? 'bg-green-100 text-green-800 border-green-200 dark:bg-green-900/30 dark:text-green-300 dark:border-green-800'
               : 'bg-primary/10 text-primary border-primary/20 dark:bg-primary/20 dark:text-primary-foreground'
           )}
         >
-          {t(`semanticSearch.${optimisticNote.matchType === 'exact' ? 'exactMatch' : 'related'}`)}
+          {t(`semanticSearch.${note.matchType === 'exact' ? 'exactMatch' : 'related'}`)}
         </Badge>
       )}
 
@@ -597,12 +597,12 @@ export const NoteCard = memo(function NoteCard({
       )}
 
       {/* Images Component */}
-      <NoteImages images={optimisticNote.images || []} title={optimisticNote.title} />
+      <NoteImages images={note.images || []} title={note.title} />
 
       {/* Link Previews */}
-      {Array.isArray(optimisticNote.links) && optimisticNote.links.length > 0 && (
+      {Array.isArray(note.links) && note.links.length > 0 && (
         <div className="flex flex-col gap-2 mb-2">
-          {optimisticNote.links.map((link, idx) => (
+          {note.links.map((link: any, idx: number) => (
             <a
               key={idx}
               href={link.url}
@@ -627,26 +627,26 @@ export const NoteCard = memo(function NoteCard({
       )}
 
       {/* Content */}
-      {optimisticNote.type === 'checklist' ? (
+      {note.type === 'checklist' ? (
         <NoteChecklist
-          items={localCheckItems || optimisticNote.checkItems || []}
+          items={localCheckItems || optimisticNote.checkItems || note.checkItems || []}
           onToggleItem={handleCheckItem}
         />
-      ) : optimisticNote.type === 'richtext' ? (
-        <div className="text-sm text-foreground line-clamp-10 rt-preview" dangerouslySetInnerHTML={{ __html: optimisticNote.content || '' }} />
+      ) : note.type === 'richtext' ? (
+        <div className="text-sm text-foreground line-clamp-10 rt-preview" dangerouslySetInnerHTML={{ __html: note.content || '' }} />
       ) : (
         <div className="text-sm text-foreground line-clamp-10">
           <MarkdownContent 
-            content={optimisticNote.content} 
+            content={note.content} 
             className="prose-h1:text-xl prose-h1:font-semibold prose-h1:leading-snug prose-h1:mt-1 prose-h1:mb-2 prose-h2:text-lg prose-h2:font-medium prose-h3:text-base prose-p:text-sm prose-p:leading-relaxed"
           />
         </div>
       )}
 
       {/* Labels - using shared LabelBadge component */}
-      {optimisticNote.notebookId && Array.isArray(optimisticNote.labels) && optimisticNote.labels.length > 0 && (
+      {note.notebookId && Array.isArray(note.labels) && note.labels.length > 0 && (
         <div className="flex flex-wrap gap-1 mt-3">
-          {optimisticNote.labels.map((label) => (
+          {note.labels.map((label: string) => (
             <LabelBadge key={label} label={label} />
           ))}
         </div>
@@ -691,7 +691,7 @@ export const NoteCard = memo(function NoteCard({
           onRestore={handleRestore}
           onPermanentDelete={handlePermanentDelete}
           onOpenHistory={() => onOpenHistory?.(note)}
-          historyEnabled={noteHistoryEnabled}
+          historyEnabled={!!note.historyEnabled}
           noteId={note.id}
           currentReminder={reminderDate}
           onUpdateReminder={handleUpdateReminder}

memento-note/components/note-editor.tsx

@@ -92,6 +92,24 @@ export function NoteEditor({ note, readOnly = false, onClose }: NoteEditorProps)
   const [showMarkdownPreview, setShowMarkdownPreview] = useState(note.type === 'markdown')
   const fileInputRef = useRef<HTMLInputElement>(null)
 
+  const prevNoteRef = useRef(note)
+  useEffect(() => {
+    if (note.id !== prevNoteRef.current.id || note.content !== prevNoteRef.current.content || note.title !== prevNoteRef.current.title) {
+      setTitle(note.title || '')
+      setContent(note.content)
+      setCheckItems(note.checkItems || [])
+      setLabels(note.labels || [])
+      setImages(note.images || [])
+      setLinks(note.links || [])
+      setColor(note.color)
+      setSize(note.size || 'small')
+      setNoteType(note.type)
+      setShowMarkdownPreview(note.type === 'markdown')
+      setCurrentReminder(note.reminder ? new Date(note.reminder as unknown as string) : null)
+    }
+    prevNoteRef.current = note
+  }, [note])
+
   // Update context notebookId when note changes
   useEffect(() => {
     setContextNotebookId(note.notebookId || null)

memento-note/components/note-history-modal.tsx

@@ -1,21 +1,25 @@
 'use client'
 
-import { useEffect, useMemo, useState, useTransition } from 'react'
-import { formatDistanceToNow } from 'date-fns'
+import { useCallback, useEffect, useMemo, useRef, useState, useTransition } from 'react'
+import { format } from 'date-fns'
 import { fr } from 'date-fns/locale/fr'
 import { enUS } from 'date-fns/locale/en-US'
-import { History, Loader2, RotateCcw, Trash2, GitBranchPlus, Check } from 'lucide-react'
+import * as Diff from 'diff'
+import {
+  History, Loader2, RotateCcw, Trash2, GitBranchPlus, Check, GitCompare, X,
+} from 'lucide-react'
 import { toast } from 'sonner'
-import { getNoteHistory, restoreNoteVersion, deleteNoteHistoryEntry } from '@/app/actions/notes'
+import {
+  getNoteHistory, restoreNoteVersion, deleteNoteHistoryEntry,
+} from '@/app/actions/notes'
 import { Button } from '@/components/ui/button'
 import {
-  Dialog,
-  DialogContent,
-  DialogDescription,
-  DialogFooter,
-  DialogHeader,
-  DialogTitle,
+  AlertDialog, AlertDialogAction, AlertDialogCancel, AlertDialogContent, AlertDialogDescription, AlertDialogFooter, AlertDialogHeader, AlertDialogTitle,
+} from '@/components/ui/alert-dialog'
+import {
+  Dialog, DialogContent, DialogDescription, DialogHeader, DialogTitle,
 } from '@/components/ui/dialog'
+import { MarkdownContent } from '@/components/markdown-content'
 import { useLanguage } from '@/lib/i18n'
 import type { Note, NoteHistoryEntry } from '@/lib/types'
 import { cn } from '@/lib/utils'
@@ -29,29 +33,147 @@ interface NoteHistoryModalProps {
   onRestored: (note: Note) => void
 }
 
+type ViewMode = 'preview' | 'diff'
+
 function getDateLocale(language: string) {
-  if (language === 'fr') return fr
-  return enUS
+  return language === 'fr' ? fr : enUS
+}
+
+function fmtDate(date: Date | string, language: string): string {
+  const d = typeof date === 'string' ? new Date(date) : date
+  return format(d, 'd MMM yyyy HH:mm', { locale: getDateLocale(language) })
+}
+
+function VersionPreview({ entry, language }: { entry: NoteHistoryEntry; language: string }) {
+  const isMd = entry.type === 'markdown' || entry.isMarkdown
+  const isCl = entry.type === 'checklist'
+  const isRt = entry.type === 'richtext'
+
+  return (
+    <div className="space-y-4">
+      <div>
+        <p className="text-[11px] font-semibold uppercase tracking-wider text-muted-foreground mb-1">
+          {language === 'fr' ? 'Titre' : 'Title'}
+        </p>
+        <p className="text-sm text-foreground font-medium">
+          {entry.title || (language === 'fr' ? 'Sans titre' : 'Untitled')}
+        </p>
+      </div>
+      <div>
+        <p className="text-[11px] font-semibold uppercase tracking-wider text-muted-foreground mb-1">
+          {language === 'fr' ? 'Contenu' : 'Content'}
+        </p>
+        <div className="rounded-md border border-border/70 bg-muted/30 p-3 text-sm text-foreground overflow-auto max-h-[48vh]">
+          {isCl && entry.checkItems ? (
+            <div className="space-y-1">
+              {entry.checkItems.map((item, i) => (
+                <div key={i} className="flex items-center gap-2">
+                  <span className={cn(
+                    'flex h-3.5 w-3.5 shrink-0 items-center justify-center rounded border text-[10px]',
+                    item.checked ? 'border-primary bg-primary/20 text-primary' : 'border-border'
+                  )}>{item.checked && '✓'}</span>
+                  <span className={cn(item.checked && 'line-through text-muted-foreground')}>{item.text}</span>
+                </div>
+              ))}
+            </div>
+          ) : isMd ? (
+            <div className="prose prose-sm dark:prose-invert max-w-none">
+              <MarkdownContent content={entry.content || ''} />
+            </div>
+          ) : isRt ? (
+            <div dangerouslySetInnerHTML={{ __html: entry.content || '' }} />
+          ) : (
+            <pre className="whitespace-pre-wrap font-sans">{entry.content || ''}</pre>
+          )}
+        </div>
+      </div>
+    </div>
+  )
+}
+
+interface DiffLine { type: 'added' | 'removed' | 'unchanged'; value: string }
+
+function computeLineDiff(oldText: string, newText: string) {
+  const changes = Diff.diffLines(oldText || '', newText || '')
+  const left: DiffLine[] = []
+  const right: DiffLine[] = []
+  for (const change of changes) {
+    const lines = change.value.replace(/\n$/, '').split('\n')
+    if (change.added) {
+      for (const line of lines) { right.push({ type: 'added', value: line }); left.push({ type: 'unchanged', value: '' }) }
+    } else if (change.removed) {
+      for (const line of lines) { left.push({ type: 'removed', value: line }); right.push({ type: 'unchanged', value: '' }) }
+    } else {
+      for (const line of lines) { left.push({ type: 'unchanged', value: line }); right.push({ type: 'unchanged', value: line }) }
+    }
+  }
+  return { left, right }
+}
+
+function DiffPanel({ lines, label, scrollRef, onScroll }: {
+  lines: DiffLine[]; label: string
+  scrollRef: React.RefObject<HTMLDivElement | null>
+  onScroll: () => void
+}) {
+  return (
+    <div className="flex-1 min-w-0 flex flex-col">
+      <p className="text-[11px] font-semibold text-muted-foreground mb-1.5 shrink-0">{label}</p>
+      <div
+        ref={scrollRef}
+        onScroll={onScroll}
+        className="rounded-md border border-border/70 bg-muted/30 overflow-auto max-h-[48vh] text-xs font-mono leading-relaxed flex-1"
+      >
+        {lines.map((line, i) => (
+          <div
+            key={i}
+            className={cn(
+              'px-2.5 py-px min-h-[1.4em]',
+              line.type === 'added' && 'bg-emerald-500/15 text-emerald-700 dark:text-emerald-300',
+              line.type === 'removed' && 'bg-red-500/15 text-red-700 dark:text-red-300'
+            )}
+          >
+            {line.value || '\u00A0'}
+          </div>
+        ))}
+      </div>
+    </div>
+  )
 }
 
 export function NoteHistoryModal({
-  open,
-  onOpenChange,
-  note,
-  enabled,
-  onEnableHistory,
-  onRestored,
+  open, onOpenChange, note, enabled, onEnableHistory, onRestored,
 }: NoteHistoryModalProps) {
   const { t, language } = useLanguage()
   const [entries, setEntries] = useState<NoteHistoryEntry[]>([])
   const [selectedId, setSelectedId] = useState<string | null>(null)
   const [isLoading, setIsLoading] = useState(false)
-  const [isRestoring, startRestoring] = useTransition()
-  const [isEnabling, startEnabling] = useTransition()
-  const [justEnabled, setJustEnabled] = useState(false)
+  const [isRestoring, setIsRestoring] = useState(false)
+  const [isEnabling, startEnableTx] = useTransition()
+  const [viewMode, setViewMode] = useState<ViewMode>('preview')
+  const [diffLeftId, setDiffLeftId] = useState<string | null>(null)
+  const [diffRightId, setDiffRightId] = useState<string | null>(null)
+  const [deleteTargetId, setDeleteTargetId] = useState<string | null>(null)
+  const [currentEntryId, setCurrentEntryId] = useState<string | null>(null)
+  const leftScrollRef = useRef<HTMLDivElement>(null)
+  const rightScrollRef = useRef<HTMLDivElement>(null)
+  const isScrollSyncing = useRef(false)
 
+  // Reset state when modal closes or note changes
+  const prevNoteId = useRef<string | null>(null)
   useEffect(() => {
-    if (!open || !note || !enabled) return
+    if (!open) {
+      setEntries([])
+      setSelectedId(null)
+      setViewMode('preview')
+      setDiffLeftId(null)
+      setDiffRightId(null)
+      setCurrentEntryId(null)
+      setIsLoading(false)
+      return
+    }
+    if (!note) return
+    if (note.id === prevNoteId.current && entries.length > 0) return
+    prevNoteId.current = note.id
 
     let cancelled = false
     setIsLoading(true)
@@ -60,220 +182,358 @@ export function NoteHistoryModal({
         if (cancelled) return
         setEntries(result)
         setSelectedId(result[0]?.id ?? null)
+        setCurrentEntryId(result[0]?.id ?? null)
       })
-      .catch((error) => {
-        console.error('Failed to load note history:', error)
-        toast.error(t('general.error'))
-      })
-      .finally(() => {
-        if (!cancelled) setIsLoading(false)
-      })
+      .catch(() => toast.error(t('general.error')))
+      .finally(() => { if (!cancelled) setIsLoading(false) })
 
-    return () => {
-      cancelled = true
-    }
-  }, [open, note, enabled, t])
+    return () => { cancelled = true }
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [open, note?.id])
 
-  const selectedEntry = useMemo(
-    () => entries.find((entry) => entry.id === selectedId) ?? null,
-    [entries, selectedId]
+  // Separate effect: fetch when enabled flips to true for this note
+  useEffect(() => {
+    if (!open || !note || !enabled) return
+    if (entries.length > 0) return
+
+    let cancelled = false
+    setIsLoading(true)
+    getNoteHistory(note.id, 50)
+      .then((result) => {
+        if (cancelled) return
+        setEntries(result)
+        setSelectedId(result[0]?.id ?? null)
+        setCurrentEntryId(result[0]?.id ?? null)
+      })
+      .catch(() => toast.error(t('general.error')))
+      .finally(() => { if (!cancelled) setIsLoading(false) })
+
+    return () => { cancelled = true }
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [enabled])
+
+  const currentVersion = useMemo(
+    () => entries.find((e) => e.id === currentEntryId) ?? null,
+    [entries, currentEntryId]
   )
 
-  const handleRestore = () => {
-    if (!note || !selectedEntry) return
-    startRestoring(async () => {
-      try {
-        const restored = await restoreNoteVersion(note.id, selectedEntry.id)
-        onRestored(restored)
-        toast.success(t('notes.historyRestored') || 'Version restaurée')
-      } catch (error) {
-        console.error('Failed to restore history entry:', error)
-        toast.error(t('general.error'))
-      }
-    })
-  }
+  const selectedEntry = useMemo(
+    () => entries.find((e) => e.id === selectedId) ?? null,
+    [entries, selectedId]
+  )
+  const diffLeftEntry = useMemo(() => entries.find((e) => e.id === diffLeftId) ?? null, [entries, diffLeftId])
+  const diffRightEntry = useMemo(() => entries.find((e) => e.id === diffRightId) ?? null, [entries, diffRightId])
+
+  const diffResult = useMemo(() => {
+    if (!diffLeftEntry || !diffRightEntry) return null
+    return computeLineDiff(diffLeftEntry.content, diffRightEntry.content)
+  }, [diffLeftEntry, diffRightEntry])
+
+  const isDiffReady = !!(diffLeftId && diffRightId && diffLeftId !== diffRightId)
+
+  const handleRestore = useCallback(async (entryId: string) => {
+    if (!note) return
+    const entry = entries.find((e) => e.id === entryId)
+    if (!entry) return
+    setIsRestoring(true)
+    try {
+      const restored = await restoreNoteVersion(note.id, entryId)
+      setCurrentEntryId(entryId)
+      toast.success(t('notes.historyRestored') || 'Version restaurée')
+      onOpenChange(false)
+      onRestored(restored)
+    } catch {
+      toast.error(t('general.error'))
+    } finally {
+      setIsRestoring(false)
+    }
+  }, [note, entries, onOpenChange, t, onRestored])
+
+  const handleDelete = useCallback((entryId: string) => {
+    setDeleteTargetId(entryId)
+  }, [])
+
+  const confirmDelete = useCallback(async () => {
+    if (!note || !deleteTargetId) return
+    const entryId = deleteTargetId
+    setDeleteTargetId(null)
+    setIsRestoring(true)
+    try {
+      await deleteNoteHistoryEntry(note.id, entryId)
+      setEntries((prev) => prev.filter((e) => e.id !== entryId))
+      if (selectedId === entryId) setSelectedId(entries[0]?.id ?? null)
+      if (diffLeftId === entryId) setDiffLeftId(null)
+      if (diffRightId === entryId) setDiffRightId(null)
+      toast.success(t('notes.versionDeleted') || 'Version supprimée')
+    } catch {
+      toast.error(t('general.error'))
+    } finally {
+      setIsRestoring(false)
+    }
+  }, [note, entries, selectedId, diffLeftId, diffRightId, deleteTargetId, t])
 
   const handleEnable = () => {
-    startEnabling(async () => {
+    startEnableTx(async () => {
       try {
         await onEnableHistory()
-        setJustEnabled(true)
-        toast.success(t('notes.historyEnabled') || 'History activé')
-      } catch (error) {
-        console.error('Failed to enable history:', error)
+        toast.success(t('notes.historyEnabled') || 'Historique activé')
+      } catch {
         toast.error(t('general.error'))
       }
     })
   }
 
-  useEffect(() => {
-    if (!justEnabled) return
-    const timer = setTimeout(() => setJustEnabled(false), 1800)
-    return () => clearTimeout(timer)
-  }, [justEnabled])
-
-  const handleDeleteEntry = (entryId: string) => {
-    if (!note) return
-    if (!confirm(t('notes.deleteVersionConfirm') || 'Supprimer cette version définitivement ?')) return
-    startRestoring(async () => {
-      try {
-        await deleteNoteHistoryEntry(note.id, entryId)
-        setEntries((prev) => prev.filter((e) => e.id !== entryId))
-        if (selectedId === entryId) {
-          setSelectedId(null)
-        }
-        toast.success(t('notes.versionDeleted') || 'Version supprimée')
-      } catch (error) {
-        console.error('Failed to delete history entry:', error)
-        toast.error(t('general.error'))
-      }
-    })
+  const handleSyncScroll = (source: 'left' | 'right') => {
+    if (isScrollSyncing.current) return
+    isScrollSyncing.current = true
+    const src = source === 'left' ? leftScrollRef.current : rightScrollRef.current
+    const tgt = source === 'left' ? rightScrollRef.current : leftScrollRef.current
+    if (src && tgt) {
+      const ratio = src.scrollTop / (src.scrollHeight - src.clientHeight || 1)
+      tgt.scrollTop = ratio * (tgt.scrollHeight - tgt.clientHeight)
+    }
+    requestAnimationFrame(() => { isScrollSyncing.current = false })
   }
 
+  const noteTitle = note?.title || t('notes.untitled') || 'Sans titre'
+
   return (
     <Dialog open={open} onOpenChange={onOpenChange}>
-      <DialogContent className="max-w-5xl p-0">
-        <DialogHeader className="border-b border-border/60 px-6 py-4">
-          <DialogTitle className="flex items-center gap-2">
+      <DialogContent
+        className={cn(
+          'p-0 gap-0 sm:!max-w-none',
+          viewMode === 'diff' && isDiffReady ? 'w-[92vw] max-w-[1500px]' : 'w-auto min-w-[500px] max-w-[800px]'
+        )}
+      >
+        {/* ── Header ── */}
+        <div className="border-b border-border/60 px-5 py-3 pr-10">
+          <DialogTitle className="flex items-center gap-2 text-sm">
             <History className="h-4 w-4 text-primary" />
             {t('notes.history') || 'Historique'}
           </DialogTitle>
-          <DialogDescription>
-            {note?.title || t('notes.untitled') || 'Sans titre'}
+          <DialogDescription className="text-xs text-muted-foreground mt-0.5 truncate">
+            {noteTitle}
           </DialogDescription>
-        </DialogHeader>
+        </div>
 
-        {!enabled || justEnabled ? (
+        {/* ── Body ── */}
+        {!enabled ? (
           <div className="flex flex-col items-center justify-center px-6 py-16 text-center">
-            {justEnabled ? (
-              <>
-                <div className="flex h-16 w-16 items-center justify-center rounded-2xl bg-emerald-500/10 mb-5 animate-in zoom-in-50 duration-300">
-                  <Check className="h-8 w-8 text-emerald-500" />
-                </div>
-                <h3 className="text-base font-semibold text-foreground mb-1.5 animate-in fade-in slide-in-from-bottom-2 duration-300">
-                  {t('notes.historyEnabledTitle') || 'Historique activé !'}
-                </h3>
-                <p className="text-sm text-muted-foreground max-w-xs animate-in fade-in slide-in-from-bottom-3 duration-500 leading-relaxed">
-                  {t('notes.historyEnabledDesc') || "Les versions de cette note seront désormais enregistrées."}
-                </p>
-              </>
-            ) : (
-              <>
-                <div className="flex h-16 w-16 items-center justify-center rounded-2xl bg-primary/10 mb-5">
-                  <GitBranchPlus className="h-8 w-8 text-primary" />
-                </div>
-                <h3 className="text-base font-semibold text-foreground mb-1.5">
-                  {t('notes.historyDisabledTitle') || 'Historique des versions'}
-                </h3>
-                <p className="text-sm text-muted-foreground max-w-xs mb-6 leading-relaxed">
-                  {t('notes.historyDisabledDesc') || "Suivez les modifications de cette note au fil du temps. Activez l'historique pour commencer à enregistrer des versions."}
-                </p>
-                <Button onClick={handleEnable} disabled={isEnabling} size="lg" className="rounded-full px-8">
-                  {isEnabling && <Loader2 className="mr-2 h-4 w-4 animate-spin" />}
-                  {t('notes.enableHistory') || "Activer l'historique"}
-                </Button>
-              </>
-            )}
+            <div className="flex h-16 w-16 items-center justify-center rounded-2xl bg-primary/10 mb-5">
+              <GitBranchPlus className="h-8 w-8 text-primary" />
+            </div>
+            <h3 className="text-base font-semibold text-foreground mb-1.5">
+              {t('notes.historyDisabledTitle') || 'Historique des versions'}
+            </h3>
+            <p className="text-sm text-muted-foreground max-w-xs mb-6 leading-relaxed">
+              {t('notes.historyDisabledDesc') || "Activez l'historique pour enregistrer les versions."}
+            </p>
+            <Button onClick={handleEnable} disabled={isEnabling} size="lg" className="rounded-full px-8">
+              {isEnabling && <Loader2 className="mr-2 h-4 w-4 animate-spin" />}
+              {t('notes.enableHistory') || "Activer l'historique"}
+            </Button>
+          </div>
+        ) : isLoading ? (
+          <div className="flex items-center justify-center py-16 text-sm text-muted-foreground gap-2">
+            <Loader2 className="h-4 w-4 animate-spin" />
+            {t('general.loading')}
+          </div>
+        ) : entries.length === 0 ? (
+          <div className="flex flex-col items-center justify-center py-16 text-center">
+            <History className="h-8 w-8 text-muted-foreground/30 mb-3" />
+            <p className="text-sm text-muted-foreground">{t('notes.historyEmpty') || 'Aucune version disponible'}</p>
           </div>
         ) : (
-          <div className="grid grid-cols-[260px_1fr] gap-0">
-            <div className="max-h-[60vh] overflow-y-auto border-r border-border/60 p-3">
-              {isLoading ? (
-                <div className="flex items-center gap-2 px-2 py-3 text-sm text-muted-foreground">
-                  <Loader2 className="h-4 w-4 animate-spin" />
-                  {t('general.loading')}
-                </div>
-              ) : entries.length === 0 ? (
-                <p className="px-2 py-3 text-sm text-muted-foreground">
-                  {t('notes.historyEmpty') || 'Aucune version disponible'}
-                </p>
-              ) : (
-                <div className="space-y-1">
-                  {entries.map((entry) => (
-                    <div
-                      key={entry.id}
-                      className={cn(
-                        'group/entry relative w-full rounded-md border px-2.5 py-2 text-left transition-colors',
-                        selectedId === entry.id
-                          ? 'border-primary/40 bg-primary/8'
-                          : 'border-border/70 hover:bg-muted/60'
+          <div className="grid grid-cols-[210px_1fr]">
+            {/* ── Left: Version list ── */}
+            <div className="max-h-[65vh] overflow-y-auto border-r border-border/60 p-2 space-y-1">
+              {entries.map((entry) => {
+                const isCurrent = entry.version === currentVersion?.version
+                const isSelected = viewMode === 'preview' && selectedId === entry.id
+                const isDL = entry.id === diffLeftId
+                const isDR = entry.id === diffRightId
+                const isDiffSel = viewMode === 'diff' && (isDL || isDR)
+
+                return (
+                  <div
+                    key={entry.id}
+                    onClick={() => {
+                      if (viewMode === 'diff') {
+                        if (!diffLeftId) { setDiffLeftId(entry.id) }
+                        else if (!diffRightId && entry.id !== diffLeftId) { setDiffRightId(entry.id) }
+                        else { setDiffLeftId(entry.id); setDiffRightId(null) }
+                      } else {
+                        setSelectedId(entry.id)
+                      }
+                    }}
+                    className={cn(
+                      'group/entry relative rounded-md border px-2.5 py-1.5 cursor-pointer transition-colors',
+                      isDiffSel
+                        ? isDL ? 'border-red-400/50 bg-red-500/10' : 'border-emerald-400/50 bg-emerald-500/10'
+                        : isSelected ? 'border-primary/40 bg-primary/8' : 'border-transparent hover:bg-muted/60'
+                    )}
+                  >
+                    <div className="flex items-center gap-1.5 pr-10">
+                      <span className="text-xs font-semibold text-foreground">v{entry.version}</span>
+                      {isCurrent && (
+                        <span className="rounded bg-primary/15 px-1.5 py-px text-[10px] font-medium text-primary whitespace-nowrap">
+                          {t('notes.currentVersion') || 'actuelle'}
+                        </span>
+                      )}
+                    </div>
+                    <p className="text-[11px] text-muted-foreground" suppressHydrationWarning>
+                      {fmtDate(entry.createdAt, language)}
+                    </p>
+
+                    <div className={cn(
+                      'absolute right-1 top-1/2 -translate-y-1/2 flex items-center gap-0.5',
+                      isSelected || isDiffSel ? 'opacity-100' : 'opacity-0 group-hover/entry:opacity-100'
+                    )}>
+                      {viewMode === 'preview' && (
+                        <button
+                          type="button" onClick={(e) => { e.stopPropagation(); handleRestore(entry.id) }}
+                          disabled={isRestoring}
+                          className="rounded p-1 text-muted-foreground/60 hover:text-primary hover:bg-primary/10"
+                          title={t('notes.restore') || 'Restaurer'}
+                        >
+                          {isRestoring ? <Loader2 className="h-3 w-3 animate-spin" /> : <RotateCcw className="h-3 w-3" />}
+                        </button>
                       )}
-                    >
                       <button
-                        type="button"
-                        onClick={() => setSelectedId(entry.id)}
-                        className="w-full text-left"
-                      >
-                        <p className="text-xs font-semibold text-foreground">
-                          v{entry.version}
-                        </p>
-                        <p className="text-[11px] text-muted-foreground" suppressHydrationWarning>
-                          {formatDistanceToNow(new Date(entry.createdAt), {
-                            addSuffix: true,
-                            locale: getDateLocale(language),
-                          })}
-                        </p>
-                        {entry.reason && (
-                          <p className="mt-1 line-clamp-1 text-[11px] text-muted-foreground">
-                            {entry.reason}
-                          </p>
-                        )}
-                      </button>
-                      <button
-                        type="button"
-                        onClick={(e) => { e.stopPropagation(); handleDeleteEntry(entry.id) }}
-                        className="absolute right-1.5 top-1.5 rounded p-0.5 text-muted-foreground/40 opacity-0 transition-opacity hover:text-red-500 group-hover/entry:opacity-100"
+                        type="button" onClick={(e) => { e.stopPropagation(); handleDelete(entry.id) }}
+                        className="rounded p-1 text-muted-foreground/60 hover:text-red-500 hover:bg-red-500/10"
                         title={t('notes.deleteVersion') || 'Supprimer'}
                       >
                         <Trash2 className="h-3 w-3" />
                       </button>
                     </div>
-                  ))}
+                  </div>
+                )
+              })}
+
+              {viewMode === 'diff' && entries.length >= 2 && (
+                <div className="mt-2 border-t border-border/40 pt-2 px-1">
+                  <p className="text-[10px] text-muted-foreground mb-1.5">
+                    {t('notes.diffSelectHint') || 'Cliquez sur 2 versions pour comparer'}
+                  </p>
+                  <div className="flex items-center gap-2 text-[11px]">
+                    <span className="flex items-center gap-1">
+                      <span className="h-2 w-2 rounded-full bg-red-400 inline-block" />
+                      {diffLeftEntry ? `v${diffLeftEntry.version}` : '—'}
+                    </span>
+                    <span className="text-muted-foreground">→</span>
+                    <span className="flex items-center gap-1">
+                      <span className="h-2 w-2 rounded-full bg-emerald-400 inline-block" />
+                      {diffRightEntry ? `v${diffRightEntry.version}` : '—'}
+                    </span>
+                    {isDiffReady && (
+                      <button
+                        type="button"
+                        onClick={() => { setDiffLeftId(null); setDiffRightId(null) }}
+                        className="ml-auto p-0.5 text-muted-foreground hover:text-foreground"
+                      >
+                        <X className="h-3 w-3" />
+                      </button>
+                    )}
+                  </div>
                 </div>
               )}
             </div>
 
-            <div className="max-h-[60vh] overflow-y-auto px-6 py-4">
-              {selectedEntry ? (
-                <div className="space-y-4">
-                  <div>
-                    <p className="text-xs font-semibold uppercase tracking-wider text-muted-foreground">
-                      {t('notes.title') || 'Titre'}
-                    </p>
-                    <p className="mt-1 text-sm text-foreground">
-                      {selectedEntry.title || t('notes.untitled') || 'Sans titre'}
-                    </p>
-                  </div>
-
-                  <div>
-                    <p className="text-xs font-semibold uppercase tracking-wider text-muted-foreground">
-                      {t('notes.content') || 'Contenu'}
-                    </p>
-                    <pre className="mt-1 whitespace-pre-wrap rounded-md border border-border/70 bg-muted/30 p-3 text-sm text-foreground">
-                      {selectedEntry.content || ''}
-                    </pre>
+            {/* ── Right: Preview / Diff ── */}
+            <div className="max-h-[65vh] overflow-y-auto px-5 py-4">
+              {viewMode === 'preview' ? (
+                selectedEntry ? (
+                  <VersionPreview entry={selectedEntry} language={language} />
+                ) : (
+                  <p className="text-sm text-muted-foreground py-8 text-center">
+                    {t('notes.historySelectVersion') || 'Sélectionnez une version pour la prévisualiser'}
+                  </p>
+                )
+              ) : isDiffReady && diffResult ? (
+                <div className="space-y-3">
+                  <p className="text-xs font-semibold text-muted-foreground">
+                    {t('notes.diffTitle') || 'Comparaison'} : v{diffLeftEntry!.version} → v{diffRightEntry!.version}
+                  </p>
+                  <div className="flex gap-3">
+                    <DiffPanel
+                      lines={diffResult.left}
+                      label={`v${diffLeftEntry!.version} — ${fmtDate(diffLeftEntry!.createdAt, language)}`}
+                      scrollRef={leftScrollRef}
+                      onScroll={() => handleSyncScroll('left')}
+                    />
+                    <DiffPanel
+                      lines={diffResult.right}
+                      label={`v${diffRightEntry!.version} — ${fmtDate(diffRightEntry!.createdAt, language)}`}
+                      scrollRef={rightScrollRef}
+                      onScroll={() => handleSyncScroll('right')}
+                    />
                   </div>
                 </div>
               ) : (
-                <p className="text-sm text-muted-foreground">
-                  {t('notes.historySelectVersion') || 'Sélectionnez une version pour prévisualiser son contenu'}
-                </p>
+                <div className="flex flex-col items-center justify-center py-12 text-center">
+                  <GitCompare className="h-8 w-8 text-muted-foreground/30 mb-3" />
+                  <p className="text-sm text-muted-foreground">
+                    {t('notes.diffSelectHint') || 'Cliquez sur 2 versions pour comparer'}
+                  </p>
+                </div>
               )}
             </div>
           </div>
         )}
 
-        <DialogFooter className="border-t border-border/60 px-6 py-3">
-          {enabled && selectedEntry && (
-            <Button onClick={handleRestore} disabled={isRestoring}>
-              {isRestoring
-                ? <Loader2 className="mr-2 h-4 w-4 animate-spin" />
-                : <RotateCcw className="mr-2 h-4 w-4" />}
-              {t('notes.restore') || 'Restaurer'}
-            </Button>
-          )}
-        </DialogFooter>
+        {/* ── Footer: actions ── */}
+        {enabled && !isLoading && entries.length >= 2 && (
+          <div className="flex items-center justify-end border-t border-border/60 px-5 py-2.5">
+            <div className="flex items-center gap-1 rounded-lg border border-border/60 p-0.5">
+                <button
+                  type="button"
+                  onClick={() => { setViewMode('preview'); setDiffLeftId(null); setDiffRightId(null) }}
+                  className={cn(
+                    'rounded-md px-2.5 py-1 text-xs font-medium transition-colors',
+                    viewMode === 'preview' ? 'bg-primary text-primary-foreground' : 'text-muted-foreground hover:text-foreground'
+                  )}
+                >
+                  {t('notes.history') || 'Historique'}
+                </button>
+                <button
+                  type="button"
+                  onClick={() => {
+                    setViewMode('diff')
+                    if (!diffLeftId && entries.length >= 2) {
+                      setDiffLeftId(entries[1].id)
+                      setDiffRightId(entries[0].id)
+                    }
+                  }}
+                  className={cn(
+                    'rounded-md px-2.5 py-1 text-xs font-medium transition-colors inline-flex items-center gap-1',
+                    viewMode === 'diff' ? 'bg-primary text-primary-foreground' : 'text-muted-foreground hover:text-foreground'
+                  )}
+                >
+                  <GitCompare className="h-3 w-3" />
+                  {t('notes.compareVersions') || 'Comparer'}
+                </button>
+              </div>
+          </div>
+        )}
       </DialogContent>
+
+      <AlertDialog open={!!deleteTargetId} onOpenChange={(open) => { if (!open) setDeleteTargetId(null) }}>
+        <AlertDialogContent size="sm">
+          <AlertDialogHeader>
+            <AlertDialogTitle>{t('notes.deleteVersionConfirm') || 'Supprimer cette version définitivement ?'}</AlertDialogTitle>
+            <AlertDialogDescription>
+              {t('notes.deleteVersionDesc') || 'Cette action est irréversible. La version sera définitivement supprimée de l\'historique.'}
+            </AlertDialogDescription>
+          </AlertDialogHeader>
+          <AlertDialogFooter>
+            <AlertDialogCancel>{t('general.cancel') || 'Annuler'}</AlertDialogCancel>
+            <AlertDialogAction variant="destructive" onClick={confirmDelete}>
+              {t('general.delete') || 'Supprimer'}
+            </AlertDialogAction>
+          </AlertDialogFooter>
+        </AlertDialogContent>
+      </AlertDialog>
     </Dialog>
   )
 }

memento-note/components/note-inline-editor.tsx

@@ -139,6 +139,22 @@ export function NoteInlineEditor({
   const [fusionNotes, setFusionNotes] = useState<Array<Partial<Note>>>([])
   const [comparisonNotes, setComparisonNotes] = useState<Array<Partial<Note>>>([])
 
+  const noteContentRef = useRef(note.content)
+  const noteTitleRef = useRef(note.title)
+  useEffect(() => {
+    if (note.content !== noteContentRef.current || note.title !== noteTitleRef.current) {
+      clearTimeout(saveTimerRef.current)
+      setIsDirty(false)
+      setTitle(note.title || '')
+      setContent(note.content || '')
+      setCheckItems(note.checkItems || [])
+      setNoteType(note.type)
+      pendingRef.current = { title: note.title || '', content: note.content || '', checkItems: note.checkItems || [], isMarkdown: note.type === 'markdown', noteType: note.type }
+      noteContentRef.current = note.content
+      noteTitleRef.current = note.title
+    }
+  }, [note])
+
   const changeTitle = (t: string) => { setTitle(t); onChange?.(note.id, { title: t }) }
   const changeContent = (c: string) => { setContent(c); onChange?.(note.id, { content: c }) }
   const changeCheckItems = (ci: CheckItem[]) => { setCheckItems(ci); onChange?.(note.id, { checkItems: ci }) }
@@ -639,7 +655,7 @@ export function NoteInlineEditor({
                     if (note.historyEnabled) {
                       onOpenHistory(note)
                     } else if (onEnableHistory) {
-                      onEnableHistory(note.id).then(() => onOpenHistory(note))
+                      onEnableHistory(note.id).then(() => onOpenHistory({ ...note, historyEnabled: true }))
                     }
                   }}
                 >

memento-note/components/notes-tabs-view.tsx

@@ -1,6 +1,6 @@
 'use client'
 
-import { useCallback, useEffect, useMemo, useState, useTransition } from 'react'
+import { useCallback, useEffect, useMemo, useState, useTransition, useRef } from 'react'
 import { useNoteRefreshOptional } from '@/context/NoteRefreshContext'
 import {
   DndContext,
@@ -641,34 +641,48 @@ export function NotesTabsView({
   const [sortOrder, setSortOrder] = useState<SortOrder>('date-desc')
   const [sidebarOpen, setSidebarOpen] = useState(true)
 
-  useEffect(() => {
-    setItems((prev) => {
-      const prevIds = prev.map((n) => n.id).join(',')
-      const incomingIds = notes.map((n) => n.id).join(',')
-      const merge = (fresh: Note, local: Note) => {
-        const labelsChanged = JSON.stringify(fresh.labels?.sort()) !== JSON.stringify(local.labels?.sort())
-        return {
-          ...fresh,
-          title: local.title || fresh.title,
-          content: local.content,
-          checkItems: local.checkItems,
-          labels: labelsChanged ? fresh.labels : local.labels
-        }
+  const prevNotesRef = useRef<Note[]>(notes)
+
+  if (notes !== prevNotesRef.current) {
+    const prevIds = items.map((n) => n.id).join(',')
+    const incomingIds = notes.map((n) => n.id).join(',')
+    
+    const merge = (fresh: Note, local: Note, oldFresh?: Note) => {
+      const labelsChanged = JSON.stringify(fresh.labels?.sort()) !== JSON.stringify(local.labels?.sort())
+      
+      const contentChangedOnServer = oldFresh && oldFresh.content !== fresh.content
+      const titleChangedOnServer = oldFresh && oldFresh.title !== fresh.title
+      const checkItemsChangedOnServer = oldFresh && JSON.stringify(oldFresh.checkItems) !== JSON.stringify(fresh.checkItems)
+
+      return {
+        ...fresh,
+        title: titleChangedOnServer ? fresh.title : (local.title || fresh.title),
+        content: contentChangedOnServer ? fresh.content : local.content,
+        checkItems: checkItemsChangedOnServer ? fresh.checkItems : local.checkItems,
+        labels: labelsChanged ? fresh.labels : local.labels
       }
-      if (prevIds === incomingIds) {
-        return prev.map((p) => {
-          const fresh = notes.find((n) => n.id === p.id)
-          if (!fresh) return p
-          return merge(fresh, p)
-        })
-      }
-      return notes.map((fresh) => {
-        const local = prev.find((p) => p.id === fresh.id)
-        if (!local) return fresh
-        return merge(fresh, local)
+    }
+    
+    let newItems: Note[]
+    if (prevIds === incomingIds) {
+      newItems = items.map((local) => {
+        const fresh = notes.find((n) => n.id === local.id)
+        if (!fresh) return local
+        const oldFresh = prevNotesRef.current.find((n) => n.id === local.id)
+        return merge(fresh, local, oldFresh)
       })
-    })
-  }, [notes])
+    } else {
+      newItems = notes.map((fresh) => {
+        const local = items.find((p) => p.id === fresh.id)
+        if (!local) return fresh
+        const oldFresh = prevNotesRef.current.find((n) => n.id === fresh.id)
+        return merge(fresh, local, oldFresh)
+      })
+    }
+    
+    setItems(newItems)
+    prevNotesRef.current = notes
+  }
 
   useEffect(() => {
     if (items.length === 0) {
@@ -932,7 +946,7 @@ export function NotesTabsView({
             )}
           >
             <NoteInlineEditor
-              key={selected.id}
+              key={`${selected.id}-${String(selected.updatedAt)}`}
               note={selected}
               noteHistoryMode={noteHistoryMode}
               onOpenHistory={onOpenHistory}