feat: configurable send shortcut (Enter vs Ctrl+Enter)

Add toggle in chat input to switch between Enter-to-send (default)
and Ctrl+Enter-to-send modes. Preference persists in localStorage.
Keyboard shortcuts modal reflects the current setting.

src/components/ChatInput.tsx

@@ -1,6 +1,7 @@
 import { useState, useRef, useEffect, useCallback, lazy, Suspense } from 'react';
 import { Send, Square, Paperclip, X, FileText, Eye, EyeOff } from 'lucide-react';
 import { useT } from '../hooks/useLocale';
+import { useSendShortcut } from '../hooks/useSendShortcut';
 
 const ReactMarkdown = lazy(() => import('react-markdown'));
 const remarkGfm = import('remark-gfm').then(m => m.default);
@@ -87,6 +88,7 @@ function formatSize(bytes: number): string {
 
 export function ChatInput({ onSend, onAbort, isGenerating, disabled, sessionKey }: Props) {
   const t = useT();
+  const { sendOnEnter, toggle: toggleSendShortcut } = useSendShortcut();
   const [text, setText] = useState('');
   const [files, setFiles] = useState<FileAttachment[]>([]);
   const [isDragOver, setIsDragOver] = useState(false);
@@ -179,9 +181,20 @@ export function ChatInput({ onSend, onAbort, isGenerating, disabled, sessionKey
   };
 
   const handleKeyDown = (e: React.KeyboardEvent) => {
-    if (e.key === 'Enter' && !e.shiftKey) {
-      e.preventDefault();
-      handleSubmit();
+    if (e.key === 'Enter') {
+      if (sendOnEnter) {
+        // Enter sends, Shift+Enter for newline
+        if (!e.shiftKey && !e.ctrlKey && !e.metaKey) {
+          e.preventDefault();
+          handleSubmit();
+        }
+      } else {
+        // Ctrl+Enter (or Cmd+Enter on Mac) sends, Enter for newline
+        if (e.ctrlKey || e.metaKey) {
+          e.preventDefault();
+          handleSubmit();
+        }
+      }
     }
   };
 
@@ -305,6 +318,14 @@ export function ChatInput({ onSend, onAbort, isGenerating, disabled, sessionKey
               rows={1}
               className="flex-1 bg-transparent resize-none rounded-2xl border border-pc-border bg-pc-input/35 px-4 py-3 text-sm text-pc-text placeholder:text-pc-text-muted outline-none transition-all max-h-[200px]"
             />
+            {/* Send shortcut toggle */}
+            <button
+              onClick={toggleSendShortcut}
+              className="hidden sm:flex shrink-0 h-7 rounded-xl border border-pc-border bg-pc-elevated/30 px-2 items-center gap-1 text-[10px] text-pc-text-muted hover:text-pc-text-secondary hover:bg-[var(--pc-hover)] transition-colors"
+              title={`${t('settings.sendShortcut')}: ${sendOnEnter ? t('settings.sendEnter') : t('settings.sendCtrlEnter')}`}
+            >
+              <span>{sendOnEnter ? '↵' : (navigator.userAgent.includes('Mac') ? '⌘↵' : 'Ctrl↵')}</span>
+            </button>
             {isGenerating ? (
               <button
                 onClick={onAbort}

src/components/KeyboardShortcuts.tsx

@@ -1,6 +1,7 @@
 import { useEffect } from 'react';
 import { X, Keyboard } from 'lucide-react';
 import { useT } from '../hooks/useLocale';
+import { useSendShortcut } from '../hooks/useSendShortcut';
 
 interface Props {
   open: boolean;
@@ -37,6 +38,7 @@ const mod = isMac ? '⌘' : 'Ctrl';
 
 export function KeyboardShortcuts({ open, onClose }: Props) {
   const t = useT();
+  const { sendOnEnter } = useSendShortcut();
 
   useEffect(() => {
     if (!open) return;
@@ -79,11 +81,11 @@ export function KeyboardShortcuts({ open, onClose }: Props) {
           <div className="pb-3">
             <SectionTitle>{t('shortcuts.chatSection')}</SectionTitle>
             <ShortcutRow
-              keys={<Kbd>Enter</Kbd>}
+              keys={sendOnEnter ? <Kbd>Enter</Kbd> : <><Kbd>{mod}</Kbd><span className="text-pc-text-faint">+</span><Kbd>Enter</Kbd></>}
               label={t('shortcuts.send')}
             />
             <ShortcutRow
-              keys={<><Kbd>Shift</Kbd><span className="text-pc-text-faint">+</span><Kbd>Enter</Kbd></>}
+              keys={sendOnEnter ? <><Kbd>Shift</Kbd><span className="text-pc-text-faint">+</span><Kbd>Enter</Kbd></> : <Kbd>Enter</Kbd>}
               label={t('shortcuts.newline')}
             />
             <ShortcutRow

src/hooks/useSendShortcut.ts

@@ -0,0 +1,21 @@
+import { useState, useCallback } from 'react';
+
+const STORAGE_KEY = 'pinchchat-send-on-enter';
+
+/** Hook to manage the send shortcut preference (Enter vs Ctrl+Enter). */
+export function useSendShortcut() {
+  const [sendOnEnter, setSendOnEnter] = useState(() => {
+    const stored = localStorage.getItem(STORAGE_KEY);
+    return stored === null ? true : stored === 'true';
+  });
+
+  const toggle = useCallback(() => {
+    setSendOnEnter(prev => {
+      const next = !prev;
+      localStorage.setItem(STORAGE_KEY, String(next));
+      return next;
+    });
+  }, []);
+
+  return { sendOnEnter, toggle };
+}

src/lib/i18n.ts

@@ -137,6 +137,11 @@ const en = {
   'search.prev': 'Previous match',
   'search.next': 'Next match',
   'shortcuts.searchMessages': 'Search messages',
+
+  // Send shortcut setting
+  'settings.sendShortcut': 'Send with',
+  'settings.sendEnter': 'Enter',
+  'settings.sendCtrlEnter': 'Ctrl+Enter',
 } as const;
 
 const fr: Record<keyof typeof en, string> = {
@@ -255,6 +260,10 @@ const fr: Record<keyof typeof en, string> = {
   'search.prev': 'Résultat précédent',
   'search.next': 'Résultat suivant',
   'shortcuts.searchMessages': 'Rechercher dans les messages',
+
+  'settings.sendShortcut': 'Envoyer avec',
+  'settings.sendEnter': 'Entrée',
+  'settings.sendCtrlEnter': 'Ctrl+Entrée',
 };
 
 export type TranslationKey = keyof typeof en;