feat(ui): 会话输入框发送键位可配置

0.3.2 把 Ctrl+Enter 发送改成了 Enter 发送，习惯旧键位的用户没有退路。
系统设置新增「会话输入框发送键位」，两种模式二选一：

- Enter 发送，Shift+Enter 换行（默认，即 0.3.2 现行为）
- Ctrl+Enter 发送，Enter 换行（0.3.2 之前的键位）

实现：

- 新增 lib/chat-send-mode.ts，复用已有的 local-storage.client 读写封装；
  纯前端偏好，不入库、不随账号同步
- 对话页与任务详情主 Agent 会话原本各自内联了一份相同判断，统一收敛到
  shouldSubmitOnKey()，加模式时不必两处各改一遍
- enter 模式保留原判断（只排除 Shift），没顺手把 Ctrl+Enter 也变成换行——
  原本它是会发送的，改掉会让没动设置的用户感到意外
- 中文输入法保护照旧：isComposing / keyCode 229 时放行，回车选词不误发送
- useSyncExternalStore + 自维护订阅集合：storage 事件只在其他标签页触发，
  本页改完需手动 emit 才能立即生效；getServerSnapshot 给默认值避免 SSR 不一致
- ctrl-enter 模式同时接受 Ctrl 与 Cmd（macOS）

按需求放在系统设置页，未采用 issue 中建议的输入框内控件。

Closes #39

Claude-Session: https://claude.ai/code/session_01Q8nhYZfS4H8fsSCBJXxbSy

web/src/app/(main)/chat/page.tsx

@@ -47,6 +47,7 @@ import { ScrollArea } from "@/components/ui/scroll-area";
 import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from "@/components/ui/select";
 import { Textarea } from "@/components/ui/textarea";
 import { api } from "@/lib/api";
+import { shouldSubmitOnKey, useChatSendMode } from "@/lib/chat-send-mode";
 import type { Activity, Agent, ChatAttachment, Conversation, LLMProfile } from "@/lib/types";
 import { cn } from "@/lib/utils";
 
@@ -128,9 +129,10 @@ function Composer({
 }) {
   const fileInputRef = React.useRef<HTMLInputElement>(null);
   const atts = attachments ?? [];
+  // 发送键位由系统设置决定（localStorage），默认 Enter 发送。
+  const sendMode = useChatSendMode();
   function onKeyDown(e: React.KeyboardEvent<HTMLTextAreaElement>) {
-    // Enter 发送；Shift+Enter 换行。isComposing 时是中文等输入法在选字,不拦截。
-    if (e.key !== "Enter" || e.shiftKey || e.nativeEvent.isComposing || e.nativeEvent.keyCode === 229) return;
+    if (!shouldSubmitOnKey(e, sendMode)) return;
     e.preventDefault();
     onSend();
   }

web/src/app/(main)/function/tasks/detail/_tabs/sessions-tab.tsx

@@ -44,6 +44,7 @@ import { InputGroup, InputGroupAddon, InputGroupButton, InputGroupTextarea } fro
 import { ScrollArea } from "@/components/ui/scroll-area";
 import { Tooltip, TooltipContent, TooltipProvider, TooltipTrigger } from "@/components/ui/tooltip";
 import { api, sseUrl } from "@/lib/api";
+import { shouldSubmitOnKey, useChatSendMode } from "@/lib/chat-send-mode";
 import { MOCK } from "@/lib/mock/enabled";
 import type {
   Activity,
@@ -1239,6 +1240,8 @@ export function SessionsTab({ taskId }: { taskId: string }) {
   }
 
   const mainLoaded = !!store.main?.loaded;
+  // 发送键位由系统设置决定（localStorage），默认 Enter 发送。
+  const sendMode = useChatSendMode();
   // What the transcript pane should show for the active session.
   const showLoader = !activeState || (activeState.loading && !activeState.loaded);
   const resolutionForSession = (session: Session): TaskLLMResolution | undefined => {
@@ -1511,8 +1514,7 @@ export function SessionsTab({ taskId }: { taskId: string }) {
                   value={input}
                   onChange={(e) => setInput(e.target.value)}
                   onKeyDown={(e) => {
-                    if (e.key !== "Enter" || e.shiftKey || e.nativeEvent.isComposing || e.nativeEvent.keyCode === 229)
-                      return;
+                    if (!shouldSubmitOnKey(e, sendMode)) return;
                     e.preventDefault();
                     if (!mainLive) send();
                   }}

web/src/app/(main)/system/settings/page.tsx

@@ -2,7 +2,7 @@
 
 import * as React from "react";
 
-import { CpuIcon, RadioTowerIcon, SearchIcon } from "lucide-react";
+import { CpuIcon, KeyboardIcon, RadioTowerIcon, SearchIcon } from "lucide-react";
 import { toast } from "sonner";
 
 import { Button } from "@/components/ui/button";
@@ -12,6 +12,12 @@ import { Label } from "@/components/ui/label";
 import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from "@/components/ui/select";
 import { Switch } from "@/components/ui/switch";
 import { api } from "@/lib/api";
+import {
+  CHAT_SEND_MODE_OPTIONS,
+  type ChatSendMode,
+  setChatSendMode,
+  useChatSendMode,
+} from "@/lib/chat-send-mode";
 import type { Settings } from "@/lib/types";
 
 export default function SystemSettingsPage() {
@@ -32,6 +38,8 @@ export default function SystemSettingsPage() {
   const [pyInterp, setPyInterp] = React.useState("");
   const [workers, setWorkers] = React.useState("3");
   const [savingWorkers, setSavingWorkers] = React.useState(false);
+  // 纯前端偏好：不走 /api/settings，直接读写 localStorage。
+  const sendMode = useChatSendMode();
 
   const apply = React.useCallback((s: Settings) => {
     setTrafficCapture(!!s.traffic_capture);
@@ -424,6 +432,37 @@ export default function SystemSettingsPage() {
           </div>
         </CardContent>
       </Card>
+
+      <Card className="max-w-2xl">
+        <CardHeader>
+          <CardTitle className="flex items-center gap-2 text-base">
+            <KeyboardIcon className="size-4" />
+            会话输入框发送键位
+          </CardTitle>
+          <CardDescription>
+            对话页与任务详情的主 Agent 会话输入框共用此设置，选择后立即生效、无需保存。
+            <br />
+            该偏好<b>只存在本浏览器</b>，不随账号同步，换浏览器或清理站点数据后需重新设置。
+          </CardDescription>
+        </CardHeader>
+        <CardContent className="flex items-center justify-between gap-4">
+          <Label htmlFor="chat-send-mode" className="text-sm font-normal text-muted-foreground">
+            发送方式
+          </Label>
+          <Select value={sendMode} onValueChange={(v) => setChatSendMode(v as ChatSendMode)}>
+            <SelectTrigger id="chat-send-mode" className="w-72">
+              <SelectValue />
+            </SelectTrigger>
+            <SelectContent>
+              {CHAT_SEND_MODE_OPTIONS.map((option) => (
+                <SelectItem key={option.value} value={option.value}>
+                  {option.label}
+                </SelectItem>
+              ))}
+            </SelectContent>
+          </Select>
+        </CardContent>
+      </Card>
     </div>
   );
 }

web/src/lib/chat-send-mode.ts

@@ -0,0 +1,65 @@
+"use client";
+
+import * as React from "react";
+
+import { getLocalStorageValue, setLocalStorageValue } from "@/lib/local-storage.client";
+
+// 会话输入框的发送/换行键位。纯前端偏好：只落 localStorage，不入库、不随账号同步，
+// 因此换浏览器需要重设。见 issue #39——0.3.2 把 Ctrl+Enter 发送改成了 Enter 发送，
+// 这里把旧键位还回来作为可选项。
+export type ChatSendMode = "enter" | "ctrl-enter";
+
+export const CHAT_SEND_MODE_KEY = "artex_chat_send_mode";
+export const DEFAULT_CHAT_SEND_MODE: ChatSendMode = "enter";
+
+export const CHAT_SEND_MODE_OPTIONS: { value: ChatSendMode; label: string }[] = [
+  { value: "enter", label: "Enter 发送，Shift+Enter 换行" },
+  { value: "ctrl-enter", label: "Ctrl+Enter 发送，Enter 换行" },
+];
+
+function parseMode(raw: string | null): ChatSendMode {
+  return raw === "ctrl-enter" || raw === "enter" ? raw : DEFAULT_CHAT_SEND_MODE;
+}
+
+// 同一标签页内的订阅者集合。localStorage 的 storage 事件只在「其他」标签页触发，
+// 本页在设置里改完后要靠 emit 通知同页的输入框，否则得刷新才生效。
+const listeners = new Set<() => void>();
+
+function subscribe(listener: () => void) {
+  listeners.add(listener);
+  window.addEventListener("storage", listener);
+  return () => {
+    listeners.delete(listener);
+    window.removeEventListener("storage", listener);
+  };
+}
+
+// 返回的是字符串字面量，Object.is 按值比较，不会让 useSyncExternalStore 陷入循环。
+function getSnapshot(): ChatSendMode {
+  return parseMode(getLocalStorageValue(CHAT_SEND_MODE_KEY));
+}
+
+// 服务端没有 localStorage，先渲染默认值，hydrate 后 getSnapshot 再纠正。
+function getServerSnapshot(): ChatSendMode {
+  return DEFAULT_CHAT_SEND_MODE;
+}
+
+export function useChatSendMode(): ChatSendMode {
+  return React.useSyncExternalStore(subscribe, getSnapshot, getServerSnapshot);
+}
+
+export function setChatSendMode(mode: ChatSendMode) {
+  setLocalStorageValue(CHAT_SEND_MODE_KEY, mode);
+  for (const listener of listeners) listener();
+}
+
+// shouldSubmitOnKey 判断一次按键是否应当发送。
+// isComposing / keyCode 229 是中文等输入法正在选字，必须放行，否则回车选词会误发送。
+// enter 模式只排除 Shift，与 0.3.2 的行为逐字保持一致——不改设置的用户手感不变。
+// ctrl-enter 模式同时接受 Ctrl 与 Cmd（macOS）。
+export function shouldSubmitOnKey(e: React.KeyboardEvent, mode: ChatSendMode): boolean {
+  if (e.key !== "Enter") return false;
+  if (e.nativeEvent.isComposing || e.nativeEvent.keyCode === 229) return false;
+  if (mode === "ctrl-enter") return e.ctrlKey || e.metaKey;
+  return !e.shiftKey;
+}