diff --git a/docs/ui.md b/docs/ui.md
index c2055c6..d7f3af8 100644
--- a/docs/ui.md
+++ b/docs/ui.md
@@ -12,9 +12,18 @@
 
 ## 1. 图标
 
-图标统一使用 `lucide-react` 的 SVG，`web/src/ui/icon.tsx` 集中维护名称映射，线宽 1.8，尺寸 1em。
-界面使用 Icon / IconButton / IconTextButton，不直接嵌入字体码位或 emoji。
-装饰图标标记 aria-hidden；没有文字的按钮必须有中文 aria-label。原字体文件与生成工具仅供历史兼容，不再加载到阅读界面。
+图标统一使用 `lucide-react` 的 SVG，`web/src/ui/icon.tsx` 集中维护名称映射，也是**唯一**引入 `lucide-react` 的文件
+（`test/icons.test.ts` 守住）。界面使用 Icon / IconButton / IconTextButton，不直接嵌入字体码位、emoji 或 ✓ × ＋ 这类字符。
+
+- **名称**：一个意思一个名字、一个字形，用本项目自己的英文名（`video`、`audiobook`、`lock`、`folder-browse`），
+  不借用其他图标集的名字。新增图标只改 `icon.tsx` 的 `ICONS`。
+- **尺寸**：不传 `size` 时为 1em（控件里用这个）；需要固定尺寸时只取 14 / 16 / 18 / 20 / 24 / 32 六档。
+- **线宽**：一律 1.8；32px 的空状态大图标用 1.4，否则放大后像粗体图示；导航当前项用 `strong`（2.1）。
+  `filled` 用文字颜色填充（播放三角、已收藏）。
+- 装饰图标默认 `aria-hidden`；独立表意时传 `label`。没有文字的按钮必须有中文 aria-label。
+
+原字体文件与生成工具（`tools/icons`、`reader-icons.ttf`、`icon-names.ts`）仅供历史兼容，不再加载到界面，
+图标名称也不再由它决定。
 
 ## 2. 设计令牌
 
diff --git a/web/src/ui/icon.tsx b/web/src/ui/icon.tsx
index f6d0f07..0bdf5b4 100644
--- a/web/src/ui/icon.tsx
+++ b/web/src/ui/icon.tsx
@@ -1,34 +1,96 @@
 import {
-  Menu, ChevronLeft, ChevronRight, ArrowLeft, Folder, FileText, SlidersHorizontal,
-  Search, X, Plus, Check, Upload, Trash2, Download, RefreshCw, BookOpen,
-  Library, Play, Pause, SkipBack, SkipForward, Square, Headphones, Moon, Sun,
-  Eye, Info, TriangleAlert, Clock, Ellipsis, Pencil, ArrowDownUp, LogOut,
-  CirclePlus, IndentIncrease, Type, MoveVertical, Settings, SlidersVertical, Bookmark,
+  Menu, ChevronLeft, ChevronRight, ChevronDown, ArrowLeft, ArrowUp, ArrowDown, ArrowUpRight,
+  Folder, FolderOpen, FolderX, File, FileText, SlidersHorizontal, Search, X, Plus, Check,
+  Upload, Trash2, Download, RefreshCw, RotateCw, RotateCcw, BookOpen, Library, LibraryBig,
+  Play, PlayCircle, Pause, SkipBack, SkipForward, Square, Headphones, Volume2, Moon, Sun,
+  SunMoon, Palette, Eye, EyeOff, Info, TriangleAlert, CloudOff, Clock, History, Timer,
+  TimerOff, Ellipsis, Pencil, ArrowDownUp, LogOut, CirclePlus, IndentIncrease, Type,
+  MoveVertical, Settings, SlidersVertical, Bookmark, Music, ListMusic, ListVideo, ListPlus,
+  ListOrdered, Layers, Heart, Star, Clapperboard, Film, UserRound, Lock, LockOpen, Gauge,
+  Subtitles, AudioLines, MicVocal, Shuffle, Repeat, Repeat1, Maximize, Minimize, Expand,
+  Shrink, LocateFixed, LayoutGrid, House, Rss,
 } from 'lucide-react';
-import type { IconName } from './icon-names.ts';
-import type { JSX } from 'react';
-export type { IconName };
+import type { CSSProperties, JSX } from 'react';
+
+/**
+ * The icon set: one name per idea, in the product's own words, each drawn by one
+ * Lucide glyph at one stroke weight (ui.md §1).
+ *
+ * This file is the only place that imports `lucide-react`. Screens used to import
+ * glyphs directly, and the set drifted the way a set without an owner does: settings
+ * drawn by three different gears, lock by two padlocks, the stroke at 1.4, 1.7, 1.8,
+ * 1.9 and Lucide's default 2 on the same screen, and seventeen sizes. A name here is
+ * what a screen asks for; which glyph answers it is decided once.
+ *
+ * The names are the product's, not another icon set's (`test/icons.test.ts` keeps
+ * borrowed names out of the legacy font table; the same rule applies here). The
+ * aliases at the end are older spellings kept so existing call sites compile.
+ */
 const ICONS = {
-  menu: Menu, 'chevron-left': ChevronLeft, 'chevron-right': ChevronRight,
-  'arrow-left': ArrowLeft, folder: Folder, 'file-text': FileText,
-  sliders: SlidersHorizontal, search: Search, close: X, plus: Plus, check: Check,
-  upload: Upload, trash: Trash2, download: Download, refresh: RefreshCw,
-  book: BookOpen, shelf: Library, play: Play, pause: Pause,
-  'step-backward': SkipBack, 'step-forward': SkipForward, stop: Square,
-  volume: Headphones, moon: Moon, sun: Sun, eye: Eye, info: Info,
-  warning: TriangleAlert, clock: Clock, more: Ellipsis, edit: Pencil,
-  sort: ArrowDownUp, logout: LogOut, 'sign-out': LogOut, 'add-circle': CirclePlus,
-  indent: IndentIncrease, 'text-size': Type, 'line-height': MoveVertical,
-  settings: Settings, library: Library, tune: SlidersVertical,
-  font: Type, 'volume-high': Headphones, 'backward-step': SkipBack,
-  'forward-step': SkipForward, bars: Menu, gear: Settings, xmark: X,
-  'magnifying-glass': Search, books: Library, bookmark: Bookmark,
-} satisfies Record<IconName, typeof Menu>;
-export interface IconProps { name: IconName; label?: string | null; className?: string; }
+  // navigation and structure
+  menu: Menu, 'chevron-left': ChevronLeft, 'chevron-right': ChevronRight, 'chevron-down': ChevronDown,
+  'arrow-left': ArrowLeft, 'arrow-up': ArrowUp, 'arrow-down': ArrowDown, external: ArrowUpRight,
+  home: House, grid: LayoutGrid, locate: LocateFixed,
+  // files and the library
+  folder: Folder, 'folder-browse': FolderOpen, 'folder-missing': FolderX, file: File, 'file-text': FileText,
+  book: BookOpen, shelf: Library, library: LibraryBig, bookmark: Bookmark, feed: Rss,
+  // actions
+  search: Search, close: X, plus: Plus, check: Check, upload: Upload, trash: Trash2,
+  download: Download, refresh: RefreshCw, edit: Pencil, sort: ArrowDownUp, more: Ellipsis,
+  'add-circle': CirclePlus, 'queue-add': ListPlus, logout: LogOut, 'sign-out': LogOut,
+  // playback
+  play: Play, 'play-circle': PlayCircle, pause: Pause, stop: Square,
+  'step-backward': SkipBack, 'step-forward': SkipForward,
+  'rewind': RotateCcw, 'fast-forward': RotateCw, shuffle: Shuffle, repeat: Repeat, 'repeat-one': Repeat1,
+  speed: Gauge, timer: Timer, 'timer-off': TimerOff, fullscreen: Maximize, 'fullscreen-exit': Minimize,
+  'fit-fill': Expand, 'fit-whole': Shrink, lock: Lock, unlock: LockOpen,
+  subtitles: Subtitles, 'audio-track': AudioLines, versions: Layers, episodes: ListVideo,
+  playlist: ListMusic, 'ordered-list': ListOrdered, lyrics: MicVocal, speaker: Volume2,
+  // media kinds
+  video: Clapperboard, film: Film, music: Music, audiobook: Headphones, volume: Headphones,
+  // reading and appearance
+  'text-size': Type, 'line-height': MoveVertical, indent: IndentIncrease, appearance: SunMoon,
+  palette: Palette, moon: Moon, sun: Sun, settings: Settings, sliders: SlidersHorizontal,
+  tune: SlidersVertical,
+  // state and people
+  eye: Eye, 'eye-off': EyeOff, info: Info, warning: TriangleAlert, offline: CloudOff,
+  clock: Clock, history: History, favorite: Heart, star: Star, account: UserRound,
+  // older spellings
+  font: Type, 'volume-high': Headphones, 'backward-step': SkipBack, 'forward-step': SkipForward,
+  bars: Menu, gear: Settings, xmark: X, 'magnifying-glass': Search, books: LibraryBig,
+} as const;
+
+export type IconName = keyof typeof ICONS;
+
+/**
+ * The size scale, in px. Without a size the glyph is 1em of its own box (the
+ * `.icon` rule sets that to the title size), which is what controls use. A size is
+ * for the places that need a fixed one: inline with small text, list rows, empty
+ * states. Six steps rather than whatever number the call site happened to type.
+ */
+export type IconSize = 14 | 16 | 18 | 20 | 24 | 32;
+
+export interface IconProps {
+  name: IconName;
+  /** Only for an icon that carries meaning on its own; decorative icons stay hidden. */
+  label?: string | null;
+  className?: string;
+  size?: IconSize;
+  /** Filled with the text colour (a play triangle, a set bookmark). */
+  filled?: boolean;
+  /** A heavier stroke for the selected item of a navigation (the tab bar's current tab). */
+  strong?: boolean;
+  style?: CSSProperties;
+}
+
 /** Shared geometry and stroke weight, independent of font rendering. */
-export function Icon({ name, label, className }: IconProps): JSX.Element {
+export function Icon({ name, label, className, size, filled, strong, style }: IconProps): JSX.Element {
   const Glyph = ICONS[name];
+  // The large empty-state glyphs are drawn lighter: a 1.8 stroke scaled to 32px reads
+  // as a bold pictogram rather than the line icon the rest of the set is.
   return <Glyph className={className ? 'icon ' + className : 'icon'} size="1em"
-    strokeWidth={1.8} aria-hidden={label ? undefined : true}
+    strokeWidth={strong ? 2.1 : size === 32 ? 1.4 : 1.8} fill={filled ? 'currentColor' : 'none'}
+    style={size ? { ...style, fontSize: `${size}px` } : style}
+    aria-hidden={label ? undefined : true}
     role={label ? 'img' : undefined} aria-label={label ?? undefined} />;
 }