feat(ui): P4 无障碍与打磨收尾

- P4-1 对比度：muted-soft 提到 WCAG AA 小字(≥4.5:1)于两主题各面
- P4-3 ConflictCard 原文/建议加 Minus/Plus 图标 + sr-only 标签（不靠颜色）
- P4-4 动效：3 处 chevron transition-transform 加 motion-safe 门控
- P4-5 命令面板 ⌘K 键帽提示 + 键盘操作读数 + 空态引导 + mono 快捷键
- P2-8 SegmentedControl 升级 radiogroup（role=radio/aria-checked + 方向键 roving）

apps/web/app/globals.css

@@ -16,7 +16,8 @@
   --color-body-strong: #3a342b;
   --color-body: #4a4234;
   --color-ink-soft: #6b6356;
-  --color-muted-soft: #8a8073;
+  /* muted-soft 达 WCAG AA 小字（≥4.5:1）于 bg/card/panel/soft 各面（P4-1）。 */
+  --color-muted-soft: #6f6556;
   /* 边框：主边框 + 同带内更弱分隔 */
   --color-line: #e5ddcd;
   --color-line-soft: #ece4d5;
@@ -54,7 +55,8 @@
   --color-body-strong: #ddd2c0;
   --color-body: #cdc0ab;
   --color-ink-soft: #b9ab96;
-  --color-muted-soft: #8f8474;
+  /* muted-soft 达 AA 小字（≥4.5:1）于夜读 bg/card/soft 各面（P4-1）。 */
+  --color-muted-soft: #9a8e7c;
   /* 边框 */
   --color-line: #3c352c;
   --color-line-soft: #2f2a23;

apps/web/components/command/CommandPalette.tsx

@@ -66,6 +66,15 @@ export function useCommandPaletteOpen(): boolean {
 const LIST_ID = "command-list";
 const optionId = (cmd: Command): string => `command-option-${cmd.id}`;
 
+// 统一的键帽（kbd）样式：暖纸感描边 + 等宽小字，与 NavDrawer 的 ⌘K 提示一致。
+function KeyCap({ children }: { children: React.ReactNode }) {
+  return (
+    <kbd className="rounded border border-line bg-panel px-1 font-mono text-2xs text-ink-soft">
+      {children}
+    </kbd>
+  );
+}
+
 // 从 pathname 抽取当前 projectId（/projects/<id>/...）。
 function projectIdFromPath(pathname: string): string | null {
   const m = pathname.match(/^\/projects\/([^/]+)/);
@@ -208,6 +217,7 @@ export function CommandPalette({ pathname }: CommandPaletteProps) {
           if (dialogRef.current) handleTabTrap(dialogRef.current, e);
         }}
       >
+        <div className="relative border-b border-line">
           <input
             ref={inputRef}
             value={query}
@@ -220,8 +230,13 @@ export function CommandPalette({ pathname }: CommandPaletteProps) {
             aria-controls={LIST_ID}
             aria-activedescendant={activeCmd ? optionId(activeCmd) : undefined}
             aria-autocomplete="list"
-          className={`w-full border-b border-line bg-bg px-4 py-3 text-sm text-ink ${focusRing}`}
+            className={`w-full bg-bg py-3 pl-4 pr-12 text-sm text-ink ${focusRing}`}
           />
+          {/* 触发快捷键读数：随面板常驻，强化 ⌘K 的可发现性（纯装饰，不入 Tab 序）。 */}
+          <span className="pointer-events-none absolute right-3 top-1/2 -translate-y-1/2">
+            <KeyCap>⌘K</KeyCap>
+          </span>
+        </div>
         <ul
           id={LIST_ID}
           role="listbox"
@@ -229,7 +244,14 @@ export function CommandPalette({ pathname }: CommandPaletteProps) {
           className="max-h-80 overflow-auto py-1 overscroll-contain"
         >
           {results.length === 0 ? (
-            <li className="px-4 py-3 text-sm text-ink-soft">无匹配命令</li>
+            <li className="px-4 py-6 text-center">
+              <p className="text-sm text-ink-soft">
+                没有匹配「{query.trim()}」的命令
+              </p>
+              <p className="mt-1 text-caption text-muted-soft">
+                试试「写本章」「审稿」「生成角色」「搜设定」
+              </p>
+            </li>
           ) : (
             results.map((cmd, i) => (
               <li
@@ -246,11 +268,30 @@ export function CommandPalette({ pathname }: CommandPaletteProps) {
                 }`}
               >
                 <span>{cmd.title}</span>
-                <span className="text-xs text-ink-soft">{cmd.group}</span>
+                <span className="text-caption text-ink-soft">{cmd.group}</span>
               </li>
             ))
           )}
         </ul>
+        {/* 键盘操作读数：↑↓ 选择 · ↵ 打开 · esc 关闭（常驻引导，纯装饰）。 */}
+        <div
+          aria-hidden="true"
+          className="flex flex-wrap items-center gap-x-4 gap-y-1 border-t border-line px-4 py-2 text-caption text-muted-soft"
+        >
+          <span className="flex items-center gap-1">
+            <KeyCap>↑</KeyCap>
+            <KeyCap>↓</KeyCap>
+            选择
+          </span>
+          <span className="flex items-center gap-1">
+            <KeyCap>↵</KeyCap>
+            打开
+          </span>
+          <span className="flex items-center gap-1">
+            <KeyCap>esc</KeyCap>
+            关闭
+          </span>
+        </div>
       </div>
     </div>
   );

apps/web/components/review/ConflictCard.tsx

@@ -1,6 +1,6 @@
 "use client";
 
-import { AlertTriangle, CheckCircle2, LocateFixed, Sparkles } from "lucide-react";
+import { AlertTriangle, CheckCircle2, LocateFixed, Minus, Plus, Sparkles } from "lucide-react";
 
 import { Badge } from "@/components/ui/Badge";
 import { TextInput } from "@/components/ui/TextInput";
@@ -80,10 +80,22 @@ export function ConflictCard({
       {conflict.original && conflict.replacement ? (
         <div className="mt-2 rounded border border-pass/30 bg-bg/40 px-3 py-1.5 text-xs leading-relaxed">
           <span className="mr-1 text-ink-soft">改法：</span>
+          {/* 非颜色线索：Minus/「原文」标签，色盲也可辨（不单靠红色 + 删除线） */}
+          <Minus
+            className="mr-0.5 inline-block h-3 w-3 align-[-1px] text-conflict"
+            aria-hidden="true"
+          />
+          <span className="sr-only">原文：</span>
           <span className="text-conflict line-through">{conflict.original}</span>
           <span className="mx-1 text-ink-soft" aria-hidden="true">
             →
           </span>
+          {/* 非颜色线索：Plus/「建议」标签，色盲也可辨（不单靠绿色） */}
+          <Plus
+            className="mr-0.5 inline-block h-3 w-3 align-[-1px] text-pass"
+            aria-hidden="true"
+          />
+          <span className="sr-only">建议：</span>
           <span className="text-pass">{conflict.replacement}</span>
           <span className="ml-2 text-ink-soft">（点「采纳改法」改入终稿）</span>
         </div>

apps/web/components/review/ReviewReport.tsx

@@ -604,7 +604,7 @@ export function ReviewReport({
                                 : "已处理"}
                             </span>
                             <ChevronDown
-                              className="h-4 w-4 text-ink-soft transition-transform group-open:rotate-180"
+                              className="h-4 w-4 text-ink-soft motion-safe:transition-transform group-open:rotate-180"
                               aria-hidden="true"
                             />
                           </span>

apps/web/components/review/ReviewSectionPanel.tsx

@@ -52,7 +52,7 @@ export function ReviewSectionPanel({
           <Badge variant={statusVariant}>{statusLabel}</Badge>
           <ChevronDown
             className={cn(
-              "h-4 w-4 text-ink-soft transition-transform",
+              "h-4 w-4 text-ink-soft motion-safe:transition-transform",
               "group-open:rotate-180",
             )}
             aria-hidden="true"

apps/web/components/ui/SegmentedControl.tsx

@@ -1,4 +1,5 @@
-import type { ReactNode } from "react";
+import type { KeyboardEvent, ReactNode } from "react";
+import { useRef } from "react";
 
 import { cn, focusRing, segmentedClass, transitionUi } from "@/lib/ui/variants";
 
@@ -22,16 +23,57 @@ export function SegmentedControl<T extends string>({
   ariaLabel,
   className,
 }: SegmentedControlProps<T>) {
+  const buttonsRef = useRef<Array<HTMLButtonElement | null>>([]);
+
+  const focusOption = (index: number) => {
+    const clamped = (index + options.length) % options.length;
+    const target = options[clamped];
+    if (!target) return;
+    onChange(target.value);
+    buttonsRef.current[clamped]?.focus();
+  };
+
+  const handleKeyDown = (event: KeyboardEvent<HTMLButtonElement>, index: number) => {
+    switch (event.key) {
+      case "ArrowRight":
+      case "ArrowDown":
+        event.preventDefault();
+        focusOption(index + 1);
+        break;
+      case "ArrowLeft":
+      case "ArrowUp":
+        event.preventDefault();
+        focusOption(index - 1);
+        break;
+      case "Home":
+        event.preventDefault();
+        focusOption(0);
+        break;
+      case "End":
+        event.preventDefault();
+        focusOption(options.length - 1);
+        break;
+      default:
+        break;
+    }
+  };
+
   return (
-    <div className={segmentedClass(className)} role="group" aria-label={ariaLabel}>
-      {options.map((option) => {
+    <div className={segmentedClass(className)} role="radiogroup" aria-label={ariaLabel}>
+      {options.map((option, index) => {
         const selected = option.value === value;
         return (
           <button
             key={option.value}
+            ref={(node) => {
+              buttonsRef.current[index] = node;
+            }}
             type="button"
-            aria-pressed={selected}
+            role="radio"
+            aria-checked={selected}
+            tabIndex={selected ? 0 : -1}
             onClick={() => onChange(option.value)}
+            onKeyDown={(event) => handleKeyDown(event, index)}
             className={cn(
               "rounded-md px-3 py-1.5 text-sm",
               transitionUi,

apps/web/components/workbench/AiToolbar.tsx

@@ -63,7 +63,7 @@ export function DirectivePanel({
             className={`group flex min-w-0 cursor-pointer items-center gap-2 rounded text-left font-serif text-title-md text-ink transition-colors duration-fast ease-standard hover:text-cinnabar ${focusRing}`}
           >
             <ChevronDown
-              className={`h-4 w-4 shrink-0 text-muted-soft transition-transform duration-fast ease-standard group-hover:text-cinnabar ${
+              className={`h-4 w-4 shrink-0 text-muted-soft motion-safe:transition-transform duration-fast ease-standard group-hover:text-cinnabar ${
                 open ? "rotate-180" : ""
               }`}
               aria-hidden="true"