diff --git a/memento-note/components/contextual-ai-chat.tsx b/memento-note/components/contextual-ai-chat.tsx
index 63a3bc2..695033f 100644
--- a/memento-note/components/contextual-ai-chat.tsx
+++ b/memento-note/components/contextual-ai-chat.tsx
@@ -515,11 +515,21 @@ export function ContextualAIChat({
 
 
   return (
-    <aside className={cn(
-      'border-l border-border/40 bg-background flex flex-col h-full flex-shrink-0 z-10 transition-all duration-300',
-      expanded ? 'w-[560px]' : 'w-[360px]',
-      className,
-    )}>
+    <>
+      {/* Backdrop when expanded */}
+      {expanded && (
+        <div
+          className="fixed inset-0 z-[199] bg-black/10 dark:bg-black/20 backdrop-blur-[1px]"
+          onClick={() => setExpanded(false)}
+        />
+      )}
+      <aside className={cn(
+        'border-l border-border/40 bg-background flex flex-col flex-shrink-0 z-10 transition-all duration-300',
+        expanded
+          ? 'fixed right-0 top-0 h-screen w-[640px] z-[200] shadow-2xl border-l'
+          : 'h-full w-[360px]',
+        !expanded && className,
+      )}>
 
       {/* ── Header ─────────────────────────────────────────── */}
       <div className="px-5 pt-5 pb-4 border-b border-border/40 shrink-0">
@@ -1386,6 +1396,7 @@ export function ContextualAIChat({
         </div>
       )}
     </aside>
+    </>
   )
 }
 
diff --git a/memento-note/components/note-editor.tsx b/memento-note/components/note-editor.tsx
index a4be045..2456866 100644
--- a/memento-note/components/note-editor.tsx
+++ b/memento-note/components/note-editor.tsx
@@ -783,18 +783,23 @@ export function NoteEditor({ note, readOnly = false, onClose, fullPage = false }
                   </span>
                 </div>
 
-                {/* Title — editable input styled as h1 */}
+                {/* Title — auto-resizing textarea to prevent overflow */}
                 <div className="group relative">
-                  <input
+                  <textarea
                     dir="auto"
-                    type="text"
+                    rows={1}
                     placeholder={t('notes.titlePlaceholder') || 'Untitled…'}
                     value={title}
                     onChange={(e) => { setTitle(e.target.value); setIsDirty(true); setDismissedTitleSuggestions(true) }}
+                    onInput={(e) => {
+                      const el = e.currentTarget
+                      el.style.height = 'auto'
+                      el.style.height = el.scrollHeight + 'px'
+                    }}
                     disabled={readOnly}
                     className={cn(
                       'w-full text-4xl md:text-5xl font-memento-serif font-bold border-0 outline-none px-0 bg-transparent text-foreground leading-tight',
-                      'placeholder:text-foreground/20',
+                      'placeholder:text-foreground/20 resize-none overflow-hidden',
                       !readOnly && 'pr-12'
                     )}
                   />
@@ -804,7 +809,11 @@ export function NoteEditor({ note, readOnly = false, onClose, fullPage = false }
                       type="button"
                       onClick={async () => {
                         const plain = content.replace(/<[^>]+>/g, ' ').trim()
-                        if (plain.split(/\s+/).filter(Boolean).length < 3) return
+                        const wordCount = plain.split(/\s+/).filter(Boolean).length
+                        if (wordCount < 10) {
+                          toast.error('Ajoutez au moins 10 mots avant de générer un titre.')
+                          return
+                        }
                         setIsProcessingAI(true)
                         try {
                           const res = await fetch('/api/ai/title-suggestions', {
@@ -814,13 +823,21 @@ export function NoteEditor({ note, readOnly = false, onClose, fullPage = false }
                           })
                           if (res.ok) {
                             const data = await res.json()
-                            const s = data.title || data.suggestedTitle || (data.suggestions?.[0]?.title ?? '')
-                            if (s) { setTitle(s); setIsDirty(true) }
+                            const s = data.suggestions?.[0]?.title ?? ''
+                            if (s) {
+                              setTitle(s)
+                              setIsDirty(true)
+                              toast.success('Titre généré !')
+                            } else {
+                              toast.error('Impossible de générer un titre.')
+                            }
+                          } else {
+                            toast.error('Erreur lors de la génération du titre.')
                           }
-                        } catch {} finally { setIsProcessingAI(false) }
+                        } catch { toast.error('Erreur réseau.') } finally { setIsProcessingAI(false) }
                       }}
                       disabled={isProcessingAI}
-                      className="absolute right-0 top-1/2 -translate-y-1/2 opacity-0 group-hover:opacity-60 hover:!opacity-100 transition-opacity rounded-lg p-2 text-foreground/50 hover:bg-black/5"
+                      className="absolute right-0 top-2 opacity-0 group-hover:opacity-60 hover:!opacity-100 transition-opacity rounded-lg p-2 text-foreground/50 hover:bg-black/5"
                       title="Générer un titre automatique avec l'IA"
                     >
                       {isProcessingAI ? <Loader2 className="h-5 w-5 animate-spin" /> : <Sparkles className="h-5 w-5" />}
@@ -918,7 +935,11 @@ export function NoteEditor({ note, readOnly = false, onClose, fullPage = false }
                 diagramInsertFormat={noteType === 'richtext' ? 'html' : 'markdown'}
                 onGenerateTitle={async () => {
                   const plain = content.replace(/<[^>]+>/g, ' ').trim()
-                  if (plain.split(/\s+/).filter(Boolean).length < 3) return
+                  const wordCount = plain.split(/\s+/).filter(Boolean).length
+                  if (wordCount < 10) {
+                    toast.error('Ajoutez au moins 10 mots avant de générer un titre.')
+                    return
+                  }
                   setIsProcessingAI(true)
                   try {
                     const res = await fetch('/api/ai/title-suggestions', {
@@ -928,10 +949,18 @@ export function NoteEditor({ note, readOnly = false, onClose, fullPage = false }
                     })
                     if (res.ok) {
                       const data = await res.json()
-                      const s = data.title || data.suggestedTitle || (data.suggestions?.[0]?.title ?? '')
-                      if (s) { setTitle(s); setIsDirty(true) }
+                      const s = data.suggestions?.[0]?.title ?? ''
+                      if (s) {
+                        setTitle(s)
+                        setIsDirty(true)
+                        toast.success('Titre généré !')
+                      } else {
+                        toast.error('Impossible de générer un titre.')
+                      }
+                    } else {
+                      toast.error('Erreur lors de la génération du titre.')
                     }
-                  } catch {} finally { setIsProcessingAI(false) }
+                  } catch { toast.error('Erreur réseau.') } finally { setIsProcessingAI(false) }
                 }}
               />
             </div>