Initial local project snapshot.

src/components/FuriganaLayer.tsx

@@ -0,0 +1,256 @@
+/**
+ * @license
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import React, { forwardRef, useEffect, useImperativeHandle, useRef, useState } from 'react';
+import { FuriganaItem } from '../types';
+
+export interface FuriganaLayerHandle {
+  focusFirstItem: () => void;
+  focusArea: () => void;
+}
+
+interface FuriganaLayerProps {
+  items: FuriganaItem[];
+  editable: boolean;
+  selectedItemId?: string | null;
+  fontSize: number;
+  fontFamily: string;
+  onChange?: (items: FuriganaItem[]) => void;
+  onItemSelect?: (itemId: string) => void;
+  onTextSelect?: (selectedText: string) => void;
+  onFocusMain?: () => void;
+  onFocusPreviousLine?: () => void;
+}
+
+const FURIGANA_ROW_Y = 12;
+
+export const FuriganaLayer = forwardRef<FuriganaLayerHandle, FuriganaLayerProps>(
+  (
+    {
+      items,
+      editable,
+      selectedItemId,
+      fontSize,
+      fontFamily,
+      onChange,
+      onItemSelect,
+      onTextSelect,
+      onFocusMain,
+      onFocusPreviousLine,
+    },
+    ref
+  ) => {
+    const areaRef = useRef<HTMLDivElement>(null);
+    const inputRefs = useRef<Record<string, HTMLInputElement | null>>({});
+    const itemsRef = useRef(items);
+
+    useEffect(() => {
+      itemsRef.current = items;
+    }, [items]);
+
+    useImperativeHandle(ref, () => ({
+      focusFirstItem: () => {
+        const firstItem = itemsRef.current[0];
+        if (firstItem) {
+          inputRefs.current[firstItem.id]?.focus({ preventScroll: true });
+        } else {
+          areaRef.current?.focus({ preventScroll: true });
+        }
+      },
+      focusArea: () => {
+        areaRef.current?.focus({ preventScroll: true });
+      },
+    }));
+
+    const getXPosition = (clientX: number) => {
+      const area = areaRef.current;
+      if (!area) return 0;
+
+      const rect = area.getBoundingClientRect();
+      return Math.max(0, (clientX - rect.left) / fontSize);
+    };
+
+    const commitItems = (nextItems: FuriganaItem[]) => {
+      onChange?.(nextItems);
+    };
+
+    const cleanEmptyItems = (itemsToClean = itemsRef.current) => {
+      const cleanedItems = itemsToClean.filter((item) => item.text.trim().length > 0);
+      if (cleanedItems.length !== itemsToClean.length) {
+        commitItems(cleanedItems);
+        itemsRef.current = cleanedItems;
+      }
+      return cleanedItems;
+    };
+
+    useEffect(() => {
+      if (!editable) return;
+
+      return () => {
+        cleanEmptyItems();
+      };
+    }, [editable]);
+
+    const createItem = (clientX: number) => {
+      if (!editable) return;
+
+      const cleanedItems = cleanEmptyItems();
+      const x = getXPosition(clientX);
+      const newItem: FuriganaItem = {
+        id: `furi-${Date.now()}-${Math.random().toString(36).slice(2, 6)}`,
+        text: '',
+        x,
+        y: FURIGANA_ROW_Y,
+      };
+
+      commitItems([...cleanedItems, newItem]);
+      onItemSelect?.(newItem.id);
+      window.setTimeout(() => {
+        inputRefs.current[newItem.id]?.focus({ preventScroll: true });
+      }, 0);
+    };
+
+    const updateItemText = (itemId: string, text: string) => {
+      commitItems(itemsRef.current.map((item) => (item.id === itemId ? { ...item, text } : item)));
+    };
+
+    const removeItem = (itemId: string) => {
+      commitItems(itemsRef.current.filter((item) => item.id !== itemId));
+    };
+
+    const removeItemIfEmpty = (itemId: string) => {
+      const item = itemsRef.current.find((candidate) => candidate.id === itemId);
+      if (item && item.text.trim() === '') {
+        removeItem(itemId);
+      }
+    };
+
+    const selectExistingItem = (itemId: string) => {
+      const nextItems = itemsRef.current.filter((item) => item.id === itemId || item.text.trim().length > 0);
+      if (nextItems.length !== itemsRef.current.length) {
+        commitItems(nextItems);
+        itemsRef.current = nextItems;
+      }
+      onItemSelect?.(itemId);
+    };
+
+    const renderedItems = items.map((item) => ({ ...item, y: FURIGANA_ROW_Y }));
+
+    return (
+      <div
+        ref={areaRef}
+        tabIndex={editable ? 0 : -1}
+        onPointerDown={(e) => {
+          if (editable && e.target === e.currentTarget) {
+            e.preventDefault();
+            e.stopPropagation();
+            createItem(e.clientX);
+          }
+        }}
+        onClick={(e) => {
+          if (editable) {
+            e.stopPropagation();
+          }
+        }}
+        onDoubleClick={(e) => {
+          if (editable) {
+            e.stopPropagation();
+          }
+        }}
+        onKeyDown={(e) => {
+          if (!editable) return;
+          if (e.key === 'ArrowDown') {
+            e.preventDefault();
+            onFocusMain?.();
+          } else if (e.key === 'ArrowUp') {
+            e.preventDefault();
+            onFocusPreviousLine?.();
+          }
+        }}
+        title={editable ? '点击空白处添加假名；点击已有假名可查看和修改' : undefined}
+        data-furigana-layer="true"
+        className={`relative w-full outline-none ${editable ? 'cursor-text' : 'select-none'}`}
+        style={{
+          fontSize: `${fontSize}px`,
+          fontFamily,
+          height: `${fontSize * 1.3}px`,
+          lineHeight: '1',
+        }}
+      >
+        {renderedItems.map((item) => (
+          <span
+            key={item.id}
+            className="absolute inline-flex items-center"
+            style={{
+              left: `${item.x}em`,
+              top: `${item.y}%`,
+            }}
+          >
+            {editable ? (
+              <input
+                ref={(el) => {
+                  inputRefs.current[item.id] = el;
+                }}
+                type="text"
+                value={item.text}
+                onFocus={() => selectExistingItem(item.id)}
+                onPointerDown={(e) => {
+                  e.stopPropagation();
+                  selectExistingItem(item.id);
+                }}
+                onChange={(e) => updateItemText(item.id, e.target.value)}
+                onBlur={() => removeItemIfEmpty(item.id)}
+                onKeyDown={(e) => {
+                  if (e.key === 'Enter') {
+                    e.preventDefault();
+                    onFocusMain?.();
+                  } else if (e.key === 'ArrowDown') {
+                    e.preventDefault();
+                    onFocusMain?.();
+                  } else if (e.key === 'ArrowUp') {
+                    e.preventDefault();
+                    onFocusPreviousLine?.();
+                  } else if (e.key === 'Backspace' && item.text === '') {
+                    e.preventDefault();
+                    removeItem(item.id);
+                  }
+                }}
+                onSelect={(e) => {
+                  const target = e.currentTarget;
+                  const start = target.selectionStart;
+                  const end = target.selectionEnd;
+                  if (start !== null && end !== null && start !== end) {
+                    const selectedText = target.value.substring(start, end).trim();
+                    if (selectedText) onTextSelect?.(selectedText);
+                  }
+                }}
+                className="bg-transparent border-none outline-none focus:outline-none focus:ring-0 m-0 p-0 text-[#8B7E74] tracking-wide font-mono"
+                style={{
+                  width: `${Math.max([...item.text].length, 1)}em`,
+                  fontSize: '0.6em',
+                  fontFamily,
+                  lineHeight: '1',
+                }}
+              />
+            ) : (
+              <span
+                className="inline-block text-[#8B7E74] tracking-wide"
+                style={{
+                  fontSize: '0.6em',
+                  fontFamily,
+                  lineHeight: '1',
+                }}
+              >
+                {item.text}
+              </span>
+            )}
+          </span>
+        ))}
+      </div>
+    );
+  }
+);
+
+FuriganaLayer.displayName = 'FuriganaLayer';

src/components/LineItem.tsx

@@ -0,0 +1,336 @@
+/**
+ * @license
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import React, { useRef, useEffect } from 'react';
+import { FuriganaItem, WritingLine, SidebarNote } from '../types';
+import { Trash2, Plus, ArrowUp, ArrowDown } from 'lucide-react';
+import { FuriganaLayer, FuriganaLayerHandle } from './FuriganaLayer';
+
+interface LineItemProps {
+  line: WritingLine;
+  lineNumber: number;
+  showLineNumber: boolean;
+  isActive: boolean;
+  fontStyle: 'sans' | 'serif';
+  fontSize: number;
+  lineSpacing: number;
+  readOnly?: boolean;
+  onUpdate: (lineId: string, newRawText: string, newFuriganaItems?: FuriganaItem[]) => void;
+  onDelete: (lineId: string) => void;
+  onActivate: (lineId: string) => void;
+  onDeactivate: () => void;
+  onDoubleClick?: (lineId: string) => void;
+  onInsertBelow: (lineId: string) => void;
+  onInsertAbove: (lineId: string) => void;
+  onTextSelect: (selectedText: string, lineId: string) => void;
+  selectedFuriganaItemId?: string | null;
+  onFuriganaSelect: (lineId: string, itemId: string) => void;
+  onNoteClick: (note: SidebarNote) => void;
+  moveFocusUp: (lineId: string, focusField: 'main' | 'furigana') => void;
+  moveFocusDown: (lineId: string, focusField: 'main' | 'furigana') => void;
+}
+
+export const LineItem: React.FC<LineItemProps> = ({
+  line,
+  lineNumber,
+  showLineNumber,
+  isActive,
+  fontStyle,
+  fontSize,
+  lineSpacing,
+  readOnly = false,
+  onUpdate,
+  onDelete,
+  onActivate,
+  onDeactivate,
+  onDoubleClick,
+  onInsertBelow,
+  onInsertAbove,
+  onTextSelect,
+  selectedFuriganaItemId,
+  onFuriganaSelect,
+  onNoteClick,
+  moveFocusUp,
+  moveFocusDown,
+}) => {
+  const furiganaLayerRef = useRef<FuriganaLayerHandle>(null);
+  const mainInputRef = useRef<HTMLInputElement>(null);
+  const displayRef = useRef<HTMLDivElement>(null);
+
+  const furiganaItems = line.furiganaItems;
+
+  // Expose focus methods dynamically
+  useEffect(() => {
+    const handleCustomFocus = (e: CustomEvent<{ field: 'main' | 'furigana' }>) => {
+      if (e.detail.field === 'furigana') {
+        furiganaLayerRef.current?.focusFirstItem();
+      } else {
+        mainInputRef.current?.focus({ preventScroll: true });
+      }
+    };
+
+    const el = document.getElementById(`line-${line.id}`);
+    if (el) {
+      el.addEventListener('focus-field' as any, handleCustomFocus as any);
+    }
+    return () => {
+      if (el) {
+        el.removeEventListener('focus-field' as any, handleCustomFocus as any);
+      }
+    };
+  }, [furiganaItems, line.id]);
+
+  const handleKeyDown = (e: React.KeyboardEvent<HTMLInputElement>, isFurigana: boolean) => {
+    if (e.key === 'Enter') {
+      e.preventDefault();
+      if (isFurigana) {
+        e.currentTarget.blur();
+      } else {
+        onInsertBelow(line.id);
+      }
+    } else if (e.key === 'Backspace') {
+      // If both inputs are completely empty, delete this line
+      if (!line.rawText && furiganaItems.length === 0) {
+        e.preventDefault();
+        onDelete(line.id);
+      }
+    } else if (e.key === 'ArrowUp') {
+      e.preventDefault();
+      if (isFurigana) {
+        // Go to previous line's main input
+        moveFocusUp(line.id, 'main');
+      } else {
+        // Go up to the furigana input of the same line
+        furiganaLayerRef.current?.focusFirstItem();
+      }
+    } else if (e.key === 'ArrowDown') {
+      e.preventDefault();
+      if (isFurigana) {
+        // Go down to the main input of the same line
+        mainInputRef.current?.focus({ preventScroll: true });
+      } else {
+        // Go to next line's furigana input
+        moveFocusDown(line.id, 'furigana');
+      }
+    }
+  };
+
+  const updateFuriganaItems = (nextItems: FuriganaItem[]) => {
+    onUpdate(line.id, line.rawText, nextItems);
+  };
+
+  // Capture selection in reading mode to add annotations
+  const handleSelection = () => {
+    const selection = window.getSelection();
+    if (!selection || selection.isCollapsed) return;
+
+    const selectedText = selection.toString().trim();
+    if (selectedText.length > 0) {
+      const lowerSelected = selectedText.toLowerCase();
+      const mainTextLower = (line.rawText || '').toLowerCase();
+      const furiTextLower = furiganaItems.map((item) => item.text).join(' ').toLowerCase();
+      
+      const isInside = displayRef.current && (
+        displayRef.current.contains(selection.anchorNode) || 
+        displayRef.current.contains(selection.focusNode)
+      );
+
+      if (isInside || mainTextLower.includes(lowerSelected) || furiTextLower.includes(lowerSelected)) {
+        onTextSelect(selectedText, line.id);
+      }
+    }
+  };
+
+  // Renders text highlighted with custom note overlays
+  const renderTextWithNotes = (text: string, notes: SidebarNote[]) => {
+    if (!text || notes.length === 0) return text;
+
+    const activeNotes = notes.filter((n) => text.includes(n.text));
+    if (activeNotes.length === 0) return text;
+
+    const splitText = (str: string, availableNotes: SidebarNote[]): React.ReactNode[] => {
+      if (!str) return [];
+      if (availableNotes.length === 0) return [str];
+
+      let earliestNote: SidebarNote | null = null;
+      let earliestIndex = Infinity;
+
+      for (const note of availableNotes) {
+        const idx = str.indexOf(note.text);
+        if (idx !== -1 && idx < earliestIndex) {
+          earliestIndex = idx;
+          earliestNote = note;
+        }
+      }
+
+      if (!earliestNote || earliestIndex === Infinity) {
+        return [str];
+      }
+
+      const matchText = earliestNote.text;
+      const before = str.slice(0, earliestIndex);
+      const after = str.slice(earliestIndex + matchText.length);
+
+      const parts: React.ReactNode[] = [];
+      if (before) {
+        parts.push(...splitText(before, availableNotes));
+      }
+
+      let colorClass = 'bg-[#FAF9F6] border-[#8B7E74] text-[#2D2926] hover:bg-[#E8E4DE]/50';
+      if (earliestNote.color === 'rose') {
+        colorClass = 'bg-rose-100/70 border-rose-300 text-rose-950 hover:bg-rose-200/80';
+      } else if (earliestNote.color === 'sky') {
+        colorClass = 'bg-sky-100/70 border-sky-300 text-sky-950 hover:bg-sky-200/80';
+      } else if (earliestNote.color === 'emerald') {
+        colorClass = 'bg-emerald-100/70 border-emerald-300 text-emerald-950 hover:bg-emerald-200/80';
+      } else if (earliestNote.color === 'violet') {
+        colorClass = 'bg-purple-100/70 border-purple-300 text-purple-950 hover:bg-purple-200/80';
+      }
+
+      parts.push(
+        <span
+          key={`highlight-${earliestNote.id}-${earliestIndex}`}
+          data-note-highlight="true"
+          onClick={(e) => {
+            e.stopPropagation();
+            onNoteClick(earliestNote!);
+          }}
+          className={`${colorClass} px-1 rounded border-b-2 font-medium cursor-pointer transition-all duration-200 inline-block active:scale-95`}
+          title={`点击查看注释: ${earliestNote.comment}`}
+        >
+          {matchText}
+        </span>
+      );
+
+      if (after) {
+        parts.push(...splitText(after, availableNotes));
+      }
+
+      return parts;
+    };
+
+    return splitText(text, activeNotes);
+  };
+
+  const calculatedLineHeight = fontSize * lineSpacing;
+  const isSerif = fontStyle === 'serif';
+
+  return (
+    <div
+      id={`line-${line.id}`}
+      className={`relative group flex gap-4 pr-3 transition-colors ${isActive ? 'bg-[#FAF9F6]/40' : ''} hover:bg-[#FAF9F6]/40 min-w-[800px] md:min-w-[1200px] xl:min-w-[1600px]`}
+      style={{ minHeight: `${calculatedLineHeight}px` }}
+    >
+      {/* 1. Left gutter with number */}
+      <div className="relative flex flex-col items-center justify-start py-1 select-none text-[#A69F92]/60 w-12 border-r border-[#E8E4DE]/50 font-mono">
+        {showLineNumber && (
+          <span className="text-[11px] font-bold select-none opacity-60">
+            {lineNumber.toString().padStart(2, '0')}
+          </span>
+        )}
+      </div>
+
+      {/* 2. Interactive sheet writing lines (Direct live editing) */}
+      <div className="flex-1 py-1 flex flex-col justify-center">
+        {!readOnly ? (
+          /* ================= EDIT MODE: FREE-POSITIONED FURIGANA + MAIN TEXT ================= */
+          <div className="flex flex-col w-full px-1 -mx-1 pr-1 font-mono">
+            {/* Top Row: Free-positioned Furigana / 假名 layer */}
+            <FuriganaLayer
+              ref={furiganaLayerRef}
+              items={furiganaItems}
+              editable
+              selectedItemId={selectedFuriganaItemId}
+              fontSize={fontSize}
+              fontFamily={isSerif ? 'var(--font-serif), monospace' : 'var(--font-sans), monospace'}
+              onChange={updateFuriganaItems}
+              onItemSelect={(itemId) => onFuriganaSelect(line.id, itemId)}
+              onTextSelect={(selectedText) => onTextSelect(selectedText, line.id)}
+              onFocusMain={() => mainInputRef.current?.focus({ preventScroll: true })}
+              onFocusPreviousLine={() => moveFocusUp(line.id, 'main')}
+            />
+
+            {/* Bottom Row: Main Kanji / 正文 input line */}
+            <input
+              ref={mainInputRef}
+              type="text"
+              value={line.rawText || ''}
+              onChange={(e) => onUpdate(line.id, e.target.value)}
+              onKeyDown={(e) => handleKeyDown(e, false)}
+              onSelect={(e) => {
+                const target = e.currentTarget;
+                const start = target.selectionStart;
+                const end = target.selectionEnd;
+                if (start !== null && end !== null && start !== end) {
+                  const selectedText = target.value.substring(start, end).trim();
+                  if (selectedText.length > 0) {
+                    onTextSelect(selectedText, line.id);
+                  }
+                }
+              }}
+              placeholder=""
+              className="w-full bg-transparent border-none outline-none focus:outline-none focus:ring-0 m-0 p-0 font-normal text-[#2D2926] placeholder-neutral-300 font-mono"
+              style={{
+                fontSize: `${fontSize}px`,
+                fontFamily: isSerif ? 'var(--font-serif), monospace' : 'var(--font-sans), monospace',
+                marginTop: '1px',
+                height: `${fontSize * 1.2}px`,
+                lineHeight: '1.2',
+              }}
+            />
+          </div>
+        ) : (
+          /* ================= READ MODE: ALIGNED STATIC TEXT DISPLAY ================= */
+          <div
+            ref={displayRef}
+            onMouseUp={handleSelection}
+            onClick={(e) => {
+              if ((e.target as HTMLElement).closest('[data-furigana-layer="true"]')) return;
+              const selection = window.getSelection();
+              if (selection && !selection.isCollapsed) return;
+              onActivate(line.id);
+            }}
+            onDoubleClick={(e) => {
+              if (onDoubleClick) {
+                onDoubleClick(line.id);
+              }
+            }}
+            className="flex flex-col w-full cursor-text select-text pr-1 font-mono hover:bg-[#FAF9F6]/80 rounded px-1 -mx-1"
+          >
+            {/* Furigana line */}
+            <FuriganaLayer
+              items={furiganaItems}
+              editable
+              selectedItemId={selectedFuriganaItemId}
+              fontSize={fontSize}
+              fontFamily={isSerif ? 'var(--font-serif), monospace' : 'var(--font-sans), monospace'}
+              onChange={updateFuriganaItems}
+              onItemSelect={(itemId) => onFuriganaSelect(line.id, itemId)}
+              onTextSelect={(selectedText) => onTextSelect(selectedText, line.id)}
+            />
+
+            {/* Main Kanji text line with word highlighter/comment select matches */}
+            <div
+              className="text-[#2D2926] m-0 p-0"
+              style={{
+                fontSize: `${fontSize}px`,
+                fontFamily: isSerif ? 'var(--font-serif), monospace' : 'var(--font-sans), monospace',
+                marginTop: '1px',
+                height: `${fontSize * 1.2}px`,
+                lineHeight: '1.2',
+              }}
+            >
+              {line.rawText ? (
+                renderTextWithNotes(line.rawText, line.notes)
+              ) : (
+                '\u00A0'
+              )}
+            </div>
+          </div>
+        )}
+      </div>
+    </div>
+  );
+};

src/components/Sidebar.tsx

@@ -0,0 +1,509 @@
+/**
+ * @license
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import React, { useState } from 'react';
+import { SidebarNote, WritingLine } from '../types';
+import { BookOpen, Tag, Trash2, Search, FileText, ChevronRight, HelpCircle, X, Check } from 'lucide-react';
+
+interface SidebarProps {
+  lines: WritingLine[];
+  activeLineId: string | null;
+  currentSelection: { text: string; lineId: string } | null;
+  selectedFurigana: { lineId: string; itemId: string } | null;
+  focusedNoteId: string | null;
+  onFocusNote: (noteId: string | null) => void;
+  onAddNote: (lineId: string, noteText: string, comment: string, color: string, noteId?: string) => void;
+  onDeleteNote: (lineId: string, noteId: string) => void;
+  onDeleteFurigana: (lineId: string, itemId: string) => void;
+  onUpdateFurigana: (lineId: string, itemId: string, text: string) => void;
+  onUpdateFuriganaX: (lineId: string, itemId: string, x: number) => void;
+  onClearSelection: () => void;
+  onJumpToLine: (lineId: string) => void;
+}
+
+const HIGHLIGHT_COLORS = [
+  { value: 'yellow', label: '岩砂褐', bg: 'bg-[#E8E4DE]', border: 'border-[#8B7E74]', check: 'text-[#2D2926]' },
+  { value: 'rose', label: '绯樱红', bg: 'bg-rose-100', border: 'border-rose-400', check: 'text-rose-700' },
+  { value: 'sky', label: '琉璃蓝', bg: 'bg-sky-100', border: 'border-sky-400', check: 'text-sky-700' },
+  { value: 'emerald', label: '薄荷绿', bg: 'bg-emerald-100', border: 'border-emerald-400', check: 'text-emerald-700' },
+  { value: 'violet', label: '藤萝紫', bg: 'bg-purple-100', border: 'border-purple-400', check: 'text-purple-700' },
+];
+
+export const Sidebar: React.FC<SidebarProps> = ({
+  lines,
+  activeLineId,
+  currentSelection,
+  selectedFurigana,
+  focusedNoteId,
+  onFocusNote,
+  onAddNote,
+  onDeleteNote,
+  onDeleteFurigana,
+  onUpdateFurigana,
+  onUpdateFuriganaX,
+  onClearSelection,
+  onJumpToLine,
+}) => {
+  const [commentText, setCommentText] = useState('');
+  const [selectedColor, setSelectedColor] = useState('yellow');
+  const [searchQuery, setSearchQuery] = useState('');
+  const [filterMode, setFilterMode] = useState<'all' | 'active'>('all');
+
+  // Check if we are editing an existing note
+  const isEditing = !!(
+    focusedNoteId ||
+    (currentSelection &&
+      lines.find((l) => l.id === currentSelection.lineId)?.notes.some((n) => n.text === currentSelection.text))
+  );
+
+  let editingNoteId: string | undefined = focusedNoteId || undefined;
+  let editingLineId: string | undefined = currentSelection?.lineId || undefined;
+
+  if (!editingNoteId && currentSelection) {
+    const lineObj = lines.find((l) => l.id === currentSelection.lineId);
+    if (lineObj) {
+      const existing = lineObj.notes.find((n) => n.text === currentSelection.text);
+      if (existing) {
+        editingNoteId = existing.id;
+      }
+    }
+  }
+
+  const selectedFuriganaLineIndex = selectedFurigana
+    ? lines.findIndex((line) => line.id === selectedFurigana.lineId)
+    : -1;
+  const selectedFuriganaLine = selectedFuriganaLineIndex >= 0 ? lines[selectedFuriganaLineIndex] : undefined;
+  const selectedFuriganaItem = selectedFuriganaLine?.furiganaItems.find(
+    (item) => item.id === selectedFurigana?.itemId
+  );
+  const selectedFuriganaMaxX = selectedFuriganaLine
+    ? Math.max(4, [...selectedFuriganaLine.rawText].length + 4, (selectedFuriganaItem?.x || 0) + 2)
+    : 4;
+
+  // Automatically update the comment input field when the selected text/note changes
+  React.useEffect(() => {
+    let existingNote: SidebarNote | undefined;
+    if (focusedNoteId) {
+      for (const line of lines) {
+        const found = line.notes.find((n) => n.id === focusedNoteId);
+        if (found) {
+          existingNote = found;
+          break;
+        }
+      }
+    }
+    if (!existingNote && currentSelection) {
+      const lineObj = lines.find((l) => l.id === currentSelection.lineId);
+      existingNote = lineObj?.notes.find((n) => n.text === currentSelection.text);
+    }
+
+    if (existingNote) {
+      setCommentText(existingNote.comment);
+      setSelectedColor(existingNote.color);
+    } else if (currentSelection) {
+      setCommentText('');
+      setSelectedColor('yellow');
+    } else {
+      setCommentText('');
+    }
+  }, [currentSelection?.text, currentSelection?.lineId, focusedNoteId]);
+
+  const handleSaveNote = (e: React.FormEvent) => {
+    e.preventDefault();
+    if (!currentSelection || !commentText.trim()) return;
+
+    onAddNote(
+      currentSelection.lineId,
+      currentSelection.text,
+      commentText.trim(),
+      selectedColor,
+      editingNoteId
+    );
+    if (!editingNoteId) {
+      setCommentText('');
+      onClearSelection();
+    }
+  };
+
+  // Compile all notes across the writing pad
+  const allNotesWithLineContext = lines.flatMap((line, idx) => {
+    return line.notes.map((note) => ({
+      ...note,
+      lineId: line.id,
+      lineNumber: idx + 1,
+    }));
+  });
+
+  // Filter notes based on search query, current line focus, and focusedNoteId
+  const filteredNotes = allNotesWithLineContext.filter((note) => {
+    if (focusedNoteId) {
+      return note.id === focusedNoteId;
+    }
+
+    const matchesSearch =
+      note.text.toLowerCase().includes(searchQuery.toLowerCase()) ||
+      note.comment.toLowerCase().includes(searchQuery.toLowerCase());
+
+    if (filterMode === 'active') {
+      return matchesSearch && note.lineId === activeLineId;
+    }
+    return matchesSearch;
+  });
+
+  return (
+    <div className="flex flex-col h-full bg-[#FDFCFB] border-l border-[#E8E4DE]" id="annotations-sidebar">
+      {/* Header */}
+      <div className="p-4 border-b border-[#E8E4DE] bg-[#FAF9F6]/80 flex items-center justify-between">
+        <h2 className="font-serif font-bold text-[#2D2926] text-sm flex items-center gap-2">
+          <BookOpen className="w-4 h-4 text-[#8B7E74]" />
+          <span>释义与随堂笔录</span>
+          <span className="font-mono text-xs text-[#A69F92] font-normal">
+            ({allNotesWithLineContext.length})
+          </span>
+        </h2>
+      </div>
+
+      {/* Editor or Helper Section for Selection */}
+      <div className="p-4 border-b border-[#E8E4DE] bg-[#FAF9F6]/30">
+        {selectedFurigana && selectedFuriganaLine && selectedFuriganaItem ? (
+          <div className="space-y-3">
+            <div className="flex justify-between items-center">
+              <span className="text-xs font-semibold text-[#2D2926] bg-[#8B7E74]/10 border border-[#8B7E74]/20 px-2 py-0.5 rounded flex items-center gap-1 leading-none">
+                <Tag className="w-3 h-3" /> 假名操作区
+              </span>
+              <button
+                type="button"
+                onClick={onClearSelection}
+                className="text-[#A69F92] hover:text-[#2D2926] rounded-full hover:bg-[#FAF9F6] p-0.5 transition-colors"
+                title="关闭假名操作区"
+              >
+                <X className="w-4 h-4" />
+              </button>
+            </div>
+
+            <div className="bg-white border border-[#E8E4DE] rounded p-2.5 shadow-xs">
+              <div className="text-[10px] text-[#8B7E74] font-bold mb-1 uppercase font-mono tracking-wider">
+                当前假名:
+              </div>
+              <input
+                type="text"
+                value={selectedFuriganaItem.text}
+                onChange={(e) =>
+                  onUpdateFurigana(selectedFurigana.lineId, selectedFurigana.itemId, e.target.value)
+                }
+                placeholder="在此修改假名"
+                className="w-full bg-[#FAF9F6] border border-[#E8E4DE] rounded px-2 py-1.5 text-[#2D2926] text-base font-serif focus:outline-none focus:ring-1 focus:ring-[#8B7E74] placeholder-[#A69F92]/60"
+              />
+              <div className="mt-1 text-[11px] text-[#A69F92] font-mono">
+                行 {(selectedFuriganaLineIndex + 1).toString().padStart(2, '0')}
+              </div>
+            </div>
+
+            <div className="bg-white border border-[#E8E4DE] rounded p-2.5 shadow-xs">
+              <div className="mb-2 flex items-center justify-between gap-2">
+                <span className="text-[10px] text-[#8B7E74] font-bold uppercase font-mono tracking-wider">
+                  X 坐标
+                </span>
+                <span className="text-[11px] text-[#2D2926] font-mono">
+                  {selectedFuriganaItem.x.toFixed(1)}
+                </span>
+              </div>
+              <input
+                type="range"
+                min={0}
+                max={selectedFuriganaMaxX}
+                step={0.1}
+                value={selectedFuriganaItem.x}
+                onChange={(e) =>
+                  onUpdateFuriganaX(
+                    selectedFurigana.lineId,
+                    selectedFurigana.itemId,
+                    Number(e.target.value)
+                  )
+                }
+                className="w-full accent-[#8B7E74] cursor-pointer"
+              />
+              <div className="mt-1 flex justify-between text-[10px] text-[#A69F92] font-mono">
+                <span>0</span>
+                <span>{selectedFuriganaMaxX.toFixed(1)}</span>
+              </div>
+            </div>
+
+            <div className="flex gap-2">
+              <button
+                type="button"
+                onClick={() => onJumpToLine(selectedFurigana.lineId)}
+                className="flex-1 border border-[#E8E4DE] bg-white hover:bg-[#FAF9F6] text-[#8B7E74] hover:text-[#2D2926] font-semibold text-xs py-2 rounded shadow-xs transition-all cursor-pointer"
+              >
+                定位该行
+              </button>
+              <button
+                type="button"
+                onClick={() => onDeleteFurigana(selectedFurigana.lineId, selectedFurigana.itemId)}
+                className="flex-1 border border-rose-200 hover:border-rose-400 bg-rose-50/55 hover:bg-rose-50 text-rose-700 hover:text-rose-800 font-semibold text-xs py-2 rounded shadow-xs transition-all flex items-center justify-center gap-1 cursor-pointer"
+              >
+                <Trash2 className="w-3.5 h-3.5" />
+                删除假名
+              </button>
+            </div>
+          </div>
+        ) : currentSelection ? (
+          /* ACTIVE NEW NOTE FORM */
+          <form onSubmit={handleSaveNote} className="space-y-3">
+            <div className="flex justify-between items-center">
+              <span className="text-xs font-semibold text-[#2D2926] bg-[#8B7E74]/10 border border-[#8B7E74]/20 px-2 py-0.5 rounded flex items-center gap-1 leading-none">
+                <Tag className="w-3 h-3" /> {isEditing ? '修改注释' : '新建注释'}
+              </span>
+              <button
+                type="button"
+                onClick={onClearSelection}
+                className="text-[#A69F92] hover:text-[#2D2926] rounded-full hover:bg-[#FAF9F6] p-0.5 transition-colors"
+                title="取消选择"
+              >
+                <X className="w-4 h-4" />
+              </button>
+            </div>
+
+            {/* Selected Text Showcase */}
+            <div className="bg-white border border-[#E8E4DE] rounded p-2.5 shadow-xs">
+              <div className="text-[10px] text-[#8B7E74] font-bold mb-1 uppercase font-mono tracking-wider">
+                选中的字符:
+              </div>
+              <div className="font-semibold text-[#2D2926] text-lg leading-relaxed tracking-wide font-serif break-all">
+                “{currentSelection.text}”
+              </div>
+            </div>
+
+            {/* Color preset picker */}
+            <div>
+              <label className="block text-xs font-semibold text-[#2D2926] mb-1.5">
+                高亮底色标签：
+              </label>
+              <div className="flex gap-2">
+                {HIGHLIGHT_COLORS.map((c) => (
+                  <button
+                    key={c.value}
+                    type="button"
+                    onClick={() => setSelectedColor(c.value)}
+                    title={c.label}
+                    className={`w-6 h-6 rounded-full border-2 transition-all flex items-center justify-center ${c.bg} ${
+                      selectedColor === c.value
+                        ? 'border-[#8B7E74] scale-110 shadow-xs'
+                        : 'border-transparent hover:scale-105'
+                    }`}
+                  >
+                    {selectedColor === c.value && (
+                      <Check className={`w-3.5 h-3.5 ${c.check} stroke-[3]`} />
+                    )}
+                  </button>
+                ))}
+              </div>
+            </div>
+
+            {/* Comment input textarea */}
+            <div>
+              <label htmlFor="comment-textarea" className="block text-xs font-semibold text-[#2D2926] mb-1.5">
+                写下你的释义或解析：
+              </label>
+              <textarea
+                id="comment-textarea"
+                rows={6}
+                value={commentText}
+                onChange={(e) => setCommentText(e.target.value)}
+                placeholder="在此录入释义、语法要点、生词短语等注释..."
+                className="w-full text-sm md:text-base bg-white border border-[#E8E4DE] rounded-lg p-3 focus:outline-none focus:ring-2 focus:ring-[#8B7E74]/40 focus:border-[#8B7E74] placeholder-neutral-400 text-[#2D2926] leading-relaxed shadow-inner"
+                required
+              />
+            </div>
+
+            <div className="flex gap-2">
+              {editingNoteId && editingLineId && (
+                <button
+                  type="button"
+                  onClick={() => {
+                    if (editingNoteId && editingLineId) {
+                      onDeleteNote(editingLineId, editingNoteId);
+                      onClearSelection();
+                    }
+                  }}
+                  className="flex-1 border border-rose-200 hover:border-rose-400 bg-rose-50/55 hover:bg-rose-50 text-rose-700 hover:text-rose-800 font-semibold text-xs py-2 rounded shadow-xs transition-all flex items-center justify-center gap-1 cursor-pointer"
+                  title="删除此条注释"
+                >
+                  <Trash2 className="w-3.5 h-3.5" />
+                  删除注释
+                </button>
+              )}
+              <button
+                type="submit"
+                className={`${editingNoteId ? 'flex-[2]' : 'w-full'} bg-[#8B7E74] text-white font-semibold text-xs py-2 rounded shadow-xs hover:bg-[#786C63] active:bg-[#665B53] transition-all font-sans cursor-pointer text-center`}
+              >
+                {isEditing ? '保存修改' : '保存此条注释'}
+              </button>
+            </div>
+          </form>
+        ) : (
+          /* EMPTY SELECTION WELCOME STATE */
+          <div className="text-xs text-[#A69F92] leading-relaxed py-2 flex flex-col items-center text-center gap-1.5">
+            <HelpCircle className="w-5 h-5 text-[#8B7E74]/40" />
+            <p>
+              想要添加右侧注释吗？
+              <br />
+              在写字板里<span className="font-bold text-[#2D2926]">用鼠标拖拽选中任意字词</span>，即可在此快速记录属于你自己的日语注释！
+            </p>
+          </div>
+        )}
+      </div>
+
+      {/* FILTER & SEARCH OVERVIEW */}
+      <div className="p-3 bg-[#FAF9F6] border-b border-[#E8E4DE] flex flex-col gap-2">
+        {/* Toggle line vs document */}
+        <div className="flex bg-[#E8E4DE]/60 rounded p-0.5 text-xs font-sans">
+          <button
+            onClick={() => setFilterMode('all')}
+            className={`flex-1 py-1 rounded text-center transition-all cursor-pointer ${
+              filterMode === 'all'
+                ? 'bg-white text-[#2D2926] font-semibold border border-[#E8E4DE]/40 shadow-xs'
+                : 'text-[#A69F92] hover:bg-white/30'
+            }`}
+          >
+            全篇注释
+          </button>
+          <button
+            onClick={() => setFilterMode('active')}
+            className={`flex-1 py-1 rounded text-center transition-all cursor-pointer ${
+              filterMode === 'active'
+                ? 'bg-white text-[#2D2926] font-semibold border border-[#E8E4DE]/40 shadow-xs'
+                : 'text-[#A69F92] hover:bg-white/30 font-medium'
+            }`}
+            disabled={!activeLineId}
+            title={!activeLineId ? '请先在写作板中双击或选中一行' : ''}
+          >
+            仅看当前行
+          </button>
+        </div>
+
+        {/* Search bar */}
+        <div className="relative font-sans">
+          <Search className="w-3.5 h-3.5 absolute left-2.5 top-1/2 -translate-y-1/2 text-[#A69F92]" />
+          <input
+            type="text"
+            placeholder="搜索已有注释..."
+            value={searchQuery}
+            onChange={(e) => setSearchQuery(e.target.value)}
+            className="w-full text-xs bg-[#FAF9F6] border border-[#E8E4DE] text-[#2D2926] pl-8 pr-3 py-1.5 rounded focus:outline-none focus:bg-white focus:ring-1 focus:ring-[#8B7E74]"
+          />
+        </div>
+      </div>
+
+      {focusedNoteId && (
+        <div className="mx-3 mt-3 px-3 py-2 bg-[#8B7E74]/10 rounded-md border border-[#8B7E74]/20 flex items-center justify-between text-xs text-[#2D2926] font-medium font-sans animate-fadeIn">
+          <span className="flex items-center gap-1.5">
+            <span className="w-1.5 h-1.5 bg-[#8B7E74] rounded-full animate-pulse"></span>
+            已聚焦单条注释
+          </span>
+          <button
+            onClick={() => onFocusNote(null)}
+            className="text-[#8B7E74] hover:text-[#2D2926] font-semibold hover:underline flex items-center gap-0.5 cursor-pointer"
+          >
+            显示全部注释
+            <X className="w-3.5 h-3.5" />
+          </button>
+        </div>
+      )}
+
+      {/* LIST OF PREVIOUS NOTES */}
+      <div className="flex-1 overflow-y-auto p-3 space-y-3.5 select-none bg-[#FAF9F6]/20">
+        {filteredNotes.length > 0 ? (
+          filteredNotes.map((note) => {
+            let badgeColorClass = 'bg-[#FAF9F6] border-[#E8E4DE] text-[#2D2926]';
+            let dotColor = 'bg-[#8B7E74]';
+            if (note.color === 'rose') {
+              badgeColorClass = 'bg-rose-50 border-rose-200 text-rose-950';
+              dotColor = 'bg-rose-500';
+            } else if (note.color === 'sky') {
+              badgeColorClass = 'bg-sky-50 border-sky-200 text-sky-950';
+              dotColor = 'bg-sky-500';
+            } else if (note.color === 'emerald') {
+              badgeColorClass = 'bg-emerald-50 border-emerald-200 text-emerald-950';
+              dotColor = 'bg-emerald-500';
+            } else if (note.color === 'violet') {
+              badgeColorClass = 'bg-purple-50 border-purple-200 text-purple-950';
+              dotColor = 'bg-purple-500';
+            }
+
+            const isFocused = focusedNoteId === note.id;
+
+            return (
+              <div
+                key={note.id}
+                onClick={() => {
+                  if (isFocused) {
+                    onFocusNote(null);
+                  } else {
+                    onFocusNote(note.id);
+                  }
+                }}
+                className={`group border rounded-lg p-3 bg-white hover:shadow-xs transition-all flex flex-col gap-2 relative cursor-pointer ${
+                  isFocused ? 'border-[#8B7E74] ring-1 ring-[#8B7E74]/30' : 'border-[#E8E4DE]/60 hover:border-[#8B7E74]/60'
+                }`}
+              >
+                {/* Note metadata */}
+                <div className="flex items-center justify-between">
+                  {/* Highlight text indicator */}
+                  <span
+                    className={`text-xs font-semibold px-2 py-0.5 rounded border ${badgeColorClass} font-serif max-w-[70%] truncate`}
+                    title={note.text}
+                  >
+                    {note.text}
+                  </span>
+
+                  {/* Jump-to Line indicator */}
+                  <button
+                    onClick={(e) => {
+                      e.stopPropagation();
+                      onJumpToLine(note.lineId);
+                    }}
+                    className="text-[#A69F92] hover:text-[#2D2926] border border-transparent hover:border-[#E8E4DE] hover:bg-[#FAF9F6] px-1.5 py-0.5 rounded font-mono text-[10px] flex items-center gap-0.5 transition-all cursor-pointer"
+                    title="点击跳转并定位此行"
+                  >
+                    行 {note.lineNumber.toString().padStart(2, '0')}
+                    <ChevronRight className="w-2.5 h-2.5" />
+                  </button>
+                </div>
+
+                {/* Comment contents */}
+                <div className="text-[#2D2926] text-xs leading-relaxed break-words pr-2 font-sans select-text">
+                  {note.comment}
+                </div>
+
+                {/* Delete button (displays on card hover) */}
+                <button
+                  onClick={(e) => {
+                    e.stopPropagation();
+                    onDeleteNote(note.lineId, note.id);
+                  }}
+                  title="删除此注释"
+                  className="absolute bottom-2.5 right-2.5 p-1 bg-[#FAF9F6] hover:bg-rose-50 border border-[#E8E4DE]/60 hover:border-rose-200 text-[#A69F92] hover:text-rose-700 rounded transition-all md:opacity-0 md:group-hover:opacity-100 cursor-pointer"
+                >
+                  <Trash2 className="w-3 h-3" />
+                </button>
+              </div>
+            );
+          })
+        ) : (
+          <div className="flex flex-col items-center justify-center text-center py-12 text-neutral-400 gap-2">
+            <FileText className="w-8 h-8 text-neutral-200" />
+            <div className="text-xs font-medium">无匹配的注释记录</div>
+            {searchQuery && (
+              <div className="text-[10px] text-neutral-400 px-4">
+                尝试缩减包含 “{searchQuery}” 的检索词
+              </div>
+            )}
+          </div>
+        )}
+      </div>
+    </div>
+  );
+};

src/components/Toolbar.tsx

@@ -0,0 +1,109 @@
+/**
+ * @license
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import React from 'react';
+import {
+  BookOpen,
+  FolderOpen,
+  Plus,
+  Save,
+  Upload,
+} from 'lucide-react';
+
+interface ToolbarProps {
+  onNewDocument: () => void;
+  onViewSavedDocuments: () => void;
+  onSaveDocument: () => void;
+  onToggleBulkImport: () => void;
+  fileStatus: string;
+  showImportArea: boolean;
+  showSavedArea: boolean;
+  savedDocumentCount: number;
+}
+
+export const Toolbar: React.FC<ToolbarProps> = ({
+  onNewDocument,
+  onViewSavedDocuments,
+  onSaveDocument,
+  onToggleBulkImport,
+  fileStatus,
+  showImportArea,
+  showSavedArea,
+  savedDocumentCount,
+}) => {
+  return (
+    <div id="main-toolbar" className="bg-[#FDFCFB] border-b border-[#E8E4DE] p-4 flex flex-col xl:flex-row xl:items-center justify-between gap-4 select-none">
+      {/* Brand / Logo */}
+      <div className="flex items-center gap-3">
+        <div className="bg-[#8B7E74] text-white rounded-lg p-2.5 shadow-sm">
+          <BookOpen className="w-5 h-5" />
+        </div>
+        <div>
+          <h1 className="font-serif font-bold text-[#2D2926] text-lg leading-none tracking-widest flex items-center gap-2">
+            言の葉 <span className="text-[#8B7E74]">Kotonoha</span> 写字板
+            <span className="text-[10px] bg-[#8B7E74]/10 text-[#8B7E74] border border-[#8B7E74]/20 px-2 py-0.5 rounded-full font-sans tracking-normal font-bold">
+              無AI纯净版
+            </span>
+          </h1>
+          <p className="text-[11px] text-[#A69F92] font-sans mt-1.5 tracking-tight">
+            在阅览模式下划词记录释义 · {fileStatus}
+          </p>
+        </div>
+      </div>
+
+      {/* Document actions */}
+      <div className="flex flex-wrap items-center gap-2 text-xs select-none font-sans">
+        <button
+          onClick={onSaveDocument}
+          className="flex items-center gap-1 px-3 py-1.5 bg-[#8B7E74] hover:bg-[#786C63] text-white font-medium rounded-lg border border-[#8B7E74] shadow-2xs transition-all cursor-pointer"
+          title="按当前文档标题保存到项目 saves 目录"
+        >
+          <Save className="w-3.5 h-3.5 text-white" />
+          <span>保存</span>
+        </button>
+
+        <button
+          onClick={onToggleBulkImport}
+          className={`flex items-center gap-1 px-3 py-1.5 font-medium rounded-lg border shadow-2xs transition-all cursor-pointer ${
+            showImportArea
+              ? 'bg-[#8B7E74] text-white border-[#8B7E74]'
+              : 'bg-white hover:bg-[#FAF9F6] text-[#2D2926] border-[#E8E4DE]'
+          }`}
+          title="粘贴整段文本并按行导入"
+        >
+          <Upload className={`w-3.5 h-3.5 ${showImportArea ? 'text-white' : 'text-[#8B7E74]'}`} />
+          <span>整段导入</span>
+        </button>
+
+        <button
+          onClick={onNewDocument}
+          className="flex items-center gap-1 px-3 py-1.5 bg-white hover:bg-[#FAF9F6] text-[#2D2926] font-medium rounded-lg border border-[#E8E4DE] shadow-2xs transition-all cursor-pointer"
+          title="新建空白文档"
+        >
+          <Plus className="w-3.5 h-3.5 text-[#8B7E74]" />
+          <span>新建</span>
+        </button>
+
+        <button
+          onClick={onViewSavedDocuments}
+          className={`flex items-center gap-1 px-3 py-1.5 font-medium rounded-lg border shadow-2xs transition-all cursor-pointer ${
+            showSavedArea
+              ? 'bg-[#8B7E74] text-white border-[#8B7E74]'
+              : 'bg-white hover:bg-[#FAF9F6] text-[#2D2926] border-[#E8E4DE]'
+          }`}
+          title="查看项目 saves 目录里的保存文件"
+        >
+          <FolderOpen className={`w-3.5 h-3.5 ${showSavedArea ? 'text-white' : 'text-[#8B7E74]'}`} />
+          <span>查看</span>
+          {savedDocumentCount > 0 && (
+            <span className={`font-mono text-[10px] ${showSavedArea ? 'text-white/80' : 'text-[#A69F92]'}`}>
+              {savedDocumentCount}
+            </span>
+          )}
+        </button>
+      </div>
+    </div>
+  );
+};

src/index.css

@@ -0,0 +1,85 @@
+@import "tailwindcss";
+
+@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700&family=Noto+Sans+JP:wght@400;500;700&family=Noto+Serif+JP:wght@400;500;700&family=JetBrains+Mono:wght@400;500&display=swap');
+
+@theme {
+  --font-sans: "Inter", "Noto Sans JP", ui-sans-serif, system-ui, sans-serif;
+  --font-serif: "Noto Serif JP", Georgia, Cambria, serif;
+  --font-mono: "JetBrains Mono", ui-monospace, SFMono-Regular, monospace;
+  --color-artistic-primary: #8B7E74;
+  --color-artistic-dark: #2D2926;
+  --color-artistic-muted: #A69F92;
+  --color-artistic-bg: #FAF9F6;
+  --color-artistic-border: #E8E4DE;
+  --color-artistic-paper: #FDFCFB;
+}
+
+/* Base resets & scrollbar styles */
+body {
+  background-color: #FAF9F6; /* Artistic light cream */
+  color: #2D2926; /* Deep artistic charcoal */
+  font-feature-settings: "palt"; /* Proportional Japanese spacing */
+  font-family: var(--font-serif);
+}
+
+/* Customized ledger and grid paper backgrounds */
+.paper-lined {
+  background-image: linear-gradient(#E8E4DE 1px, transparent 1px);
+  background-size: 100% 4.5rem; /* Matches line-height height scaling */
+}
+
+.paper-grid {
+  background-image: 
+    linear-gradient(to right, rgba(232, 228, 222, 0.7) 1px, transparent 1px),
+    linear-gradient(to bottom, rgba(232, 228, 222, 0.7) 1px, transparent 1px);
+  background-size: 1.5rem 1.5rem;
+}
+
+/* Custom shadow effects for premium depth */
+.premium-shadow {
+  box-shadow: 0 12px 40px -10px rgba(139, 126, 116, 0.12), 0 4px 16px -4px rgba(139, 126, 116, 0.05);
+}
+
+/* Smooth custom selection styles - beautiful warm brown tint matching paper character */
+::selection {
+  background-color: rgba(139, 126, 116, 0.25);
+  color: #2D2926;
+}
+
+/* Ruby spacing and formatting adjustments */
+ruby {
+  ruby-position: over;
+  ruby-align: center;
+  white-space: nowrap;
+}
+
+rt {
+  font-size: 0.55em;
+  font-weight: 500;
+  color: #A69F92; /* Artistic Muted */
+  user-select: none; /* Make furigana non-selectable so copy-pasting is easy */
+  padding-bottom: 0.15em;
+  letter-spacing: 0.1em;
+  transition: color 0.2s;
+}
+
+/* Interactive focus transitions */
+.writing-line:hover rt {
+  color: #8B7E74;
+}
+
+/* Smooth custom scrollbars for subtle design */
+::-webkit-scrollbar {
+  width: 6px;
+  height: 6px;
+}
+::-webkit-scrollbar-track {
+  background: #FAF9F6;
+}
+::-webkit-scrollbar-thumb {
+  background: #E8E4DE;
+  border-radius: 3px;
+}
+::-webkit-scrollbar-thumb:hover {
+  background: #8B7E74;
+}

src/main.tsx

@@ -0,0 +1,10 @@
+import {StrictMode} from 'react';
+import {createRoot} from 'react-dom/client';
+import App from './App.tsx';
+import './index.css';
+
+createRoot(document.getElementById('root')!).render(
+  <StrictMode>
+    <App />
+  </StrictMode>,
+);

src/types.ts

@@ -0,0 +1,45 @@
+/**
+ * @license
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+export interface LineSegment {
+  type: 'text' | 'ruby';
+  text: string;
+  rt?: string; // Furigana reading
+}
+
+export interface SidebarNote {
+  id: string;
+  text: string;     // The highlighted Japanese characters
+  comment: string;  // The user's annotation
+  color: string;    // Highlight color class or name
+  createdAt: number;
+}
+
+export interface FuriganaItem {
+  id: string;
+  text: string;
+  x: number; // Horizontal position in main-text em units from the line start
+  y: number; // Vertical position within the furigana area, as a percentage
+}
+
+export interface WritingLine {
+  id: string;
+  rawText: string;  // Main Japanese text
+  /** @deprecated Runtime furigana is stored in furiganaItems. Kept for legacy import/export compatibility. */
+  furiganaText: string;
+  furiganaItems: FuriganaItem[]; // Freely positioned furigana notes above the main text
+  /** @deprecated Parsed segments are transient import data, not runtime state. */
+  segments: LineSegment[];
+  notes: SidebarNote[];
+}
+
+export interface WritingPadState {
+  lines: WritingLine[];
+  paperStyle: 'lined' | 'grid' | 'blank';
+  fontSize: number; // in pixels, e.g., 20
+  lineSpacing: number; // multiplier, e.g., 2.5
+  themeColor: string; // theme color preset
+  showLineNumbers: boolean;
+}

src/utils.ts

@@ -0,0 +1,312 @@
+/**
+ * @license
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { FuriganaItem, LineSegment, SidebarNote, WritingLine } from './types';
+
+// Regex to check if a character is Kanji, including common iteration marks like 々, 〆, ヶ
+export const KANJI_REGEX = /[\u4E00-\u9FFF\u3400-\u4DBF\uF900-\uFAFF々〆ヶ]/;
+
+/**
+ * Parses raw text containing custom ruby bindings into LineSegments.
+ * Supported syntaxes:
+ * 1. Bracket explicit syntax: [漢字]{かんじ} or [日本語]{にほんご}
+ * 2. Auto-Kanji binding sync: 漢字{かんじ} (automatically binds to consecutive kanji characters preceding the brace)
+ * 3. Fallback binding: 文字{もじ} (for non-kanji, binds to the sequence preceding `{`)
+ */
+export function parseRawTextToSegments(rawText: string): LineSegment[] {
+  const segments: LineSegment[] = [];
+  if (!rawText) return segments;
+
+  const appendPlainText = (text: string) => {
+    if (!text) return;
+    const lastSegment = segments[segments.length - 1];
+    if (lastSegment?.type === 'text') {
+      lastSegment.text += text;
+    } else {
+      segments.push({ type: 'text', text });
+    }
+  };
+
+  let i = 0;
+  const len = rawText.length;
+
+  while (i < len) {
+    // 1. Explicit bracket syntax: [base]{rt}
+    if (rawText[i] === '[') {
+      const closeBracketIndex = rawText.indexOf(']', i);
+      if (closeBracketIndex !== -1 && rawText[closeBracketIndex + 1] === '{') {
+        const closeBraceIndex = rawText.indexOf('}', closeBracketIndex + 1);
+        if (closeBraceIndex !== -1) {
+          const baseText = rawText.slice(i + 1, closeBracketIndex);
+          const rtText = rawText.slice(closeBracketIndex + 2, closeBraceIndex);
+          
+          segments.push({ type: 'ruby', text: baseText, rt: rtText });
+          i = closeBraceIndex + 1;
+          continue;
+        }
+      }
+
+      appendPlainText(rawText[i]);
+      i++;
+      continue;
+    }
+
+    // 2. Simple brace syntax: TEXT{rt}
+    if (rawText[i] === '{') {
+      const closeBraceIndex = rawText.indexOf('}', i);
+      const baseStartProbe = i - 1;
+
+      if (closeBraceIndex !== -1 && baseStartProbe >= 0) {
+        const rtText = rawText.slice(i + 1, closeBraceIndex);
+
+        let baseStart = baseStartProbe;
+        const lastChar = rawText[baseStart];
+        if (KANJI_REGEX.test(lastChar)) {
+          while (baseStart > 0 && KANJI_REGEX.test(rawText[baseStart - 1])) {
+            baseStart--;
+          }
+        } else {
+          const stopChars = /[\s{}·・，。、！￥…\-[\]]/;
+          while (baseStart > 0 && !stopChars.test(rawText[baseStart - 1])) {
+            baseStart--;
+          }
+        }
+
+        const baseText = rawText.slice(baseStart, i);
+        if (baseText) {
+          let lengthToRemove = baseText.length;
+          while (lengthToRemove > 0 && segments.length > 0) {
+            const lastSegment = segments[segments.length - 1];
+            if (lastSegment.type !== 'text') {
+              break;
+            }
+
+            if (lastSegment.text.length <= lengthToRemove) {
+              lengthToRemove -= lastSegment.text.length;
+              segments.pop();
+            } else {
+              lastSegment.text = lastSegment.text.slice(0, -lengthToRemove);
+              lengthToRemove = 0;
+            }
+          }
+
+          segments.push({ type: 'ruby', text: baseText, rt: rtText });
+          i = closeBraceIndex + 1;
+          continue;
+        }
+      }
+
+      appendPlainText(rawText[i]);
+      i++;
+      continue;
+    }
+
+    let plainText = '';
+    while (i < len && rawText[i] !== '[' && rawText[i] !== '{') {
+      plainText += rawText[i];
+      i++;
+    }
+
+    appendPlainText(plainText);
+  }
+
+  return segments;
+}
+
+/**
+ * Converts line segments back into raw mark-up string.
+ */
+export function segmentsToRawText(segments: LineSegment[]): string {
+  return segments
+    .map((s) => {
+      if (s.type === 'ruby') {
+        // Use simpler auto-binding syntax if base is pure Kanji, otherwise use bracket syntax [base]{rt}
+        const isPureKanji = [...s.text].every((char) => KANJI_REGEX.test(char));
+        if (isPureKanji) {
+          return `${s.text}{${s.rt || ''}}`;
+        } else {
+          return `[${s.text}]{${s.rt || ''}}`;
+        }
+      }
+      return s.text;
+    })
+    .join('');
+}
+
+/**
+ * Helper to check if a string contains any Kanji.
+ */
+export function containsKanji(text: string): boolean {
+  return [...text].some((char) => KANJI_REGEX.test(char));
+}
+
+/**
+ * Parses legacy text with curly braces (e.g. 日本語{にほんご}或者吾輩{わがはい}は猫{ねこ}である)
+ * into clean main text plus freely positioned furigana items.
+ */
+export function convertLegacyText(rawText: string): { main: string; furigana: string; furiganaItems: FuriganaItem[] } {
+  const segments = parseRawTextToSegments(rawText);
+  let mainText = '';
+  const furiganaItems: FuriganaItem[] = [];
+
+  for (const seg of segments) {
+    if (seg.type === 'ruby') {
+      const baseText = seg.text;
+      const rtText = seg.rt || '';
+      const startIndex = mainText.length;
+
+      mainText += baseText;
+
+      if (rtText) {
+        furiganaItems.push({
+          id: `ruby-${furiganaItems.length}-${startIndex}`,
+          text: rtText,
+          x: startIndex,
+          y: 12,
+        });
+      }
+    } else {
+      mainText += seg.text;
+    }
+  }
+
+  return { main: mainText, furigana: '', furiganaItems };
+}
+
+const clamp = (value: number, min: number, max: number) => Math.min(Math.max(value, min), max);
+
+export function migrateLegacyFuriganaTextToItems(rawText: string, furiganaText: string): FuriganaItem[] {
+  const items: FuriganaItem[] = [];
+  const pattern = /[^\s　]+/g;
+  let match: RegExpExecArray | null;
+
+  while ((match = pattern.exec(furiganaText)) !== null) {
+    const text = match[0].trim();
+    if (!text) continue;
+
+    const startIndex = Math.min(match.index, Math.max(rawText.length, 1));
+    items.push({
+      id: `legacy-${items.length}-${startIndex}`,
+      text,
+      x: startIndex,
+      y: 12,
+    });
+  }
+
+  return items;
+}
+
+export function sanitizeFuriganaItems(value: unknown): FuriganaItem[] {
+  if (!Array.isArray(value)) return [];
+
+  return value
+    .map((item, index) => {
+      if (!item || typeof item !== 'object') return null;
+      const candidate = item as Partial<FuriganaItem>;
+      const text = typeof candidate.text === 'string' ? candidate.text : '';
+
+      return {
+        id: typeof candidate.id === 'string' && candidate.id ? candidate.id : `furi-${index}`,
+        text,
+        x: typeof candidate.x === 'number' && Number.isFinite(candidate.x) ? Math.max(0, candidate.x) : 0,
+        y: typeof candidate.y === 'number' && Number.isFinite(candidate.y) ? clamp(candidate.y, 0, 80) : 12,
+      };
+    })
+    .filter((item): item is FuriganaItem => !!item && item.text.trim().length > 0);
+}
+
+const sanitizeNotes = (value: unknown): SidebarNote[] => {
+  if (!Array.isArray(value)) return [];
+
+  return value
+    .map((note, index) => {
+      if (!note || typeof note !== 'object') return null;
+      const candidate = note as Partial<SidebarNote>;
+
+      return {
+        id: typeof candidate.id === 'string' && candidate.id ? candidate.id : `note-${Date.now()}-${index}`,
+        text: typeof candidate.text === 'string' ? candidate.text : '',
+        comment: typeof candidate.comment === 'string' ? candidate.comment : '',
+        color: typeof candidate.color === 'string' ? candidate.color : 'yellow',
+        createdAt: typeof candidate.createdAt === 'number' ? candidate.createdAt : Date.now(),
+      };
+    })
+    .filter((note): note is SidebarNote => !!note && note.text.trim().length > 0);
+};
+
+export function normalizeLine(value: Partial<WritingLine> & { rawText?: unknown }, fallbackId: string): WritingLine {
+  const rawTextInput = typeof value.rawText === 'string' ? value.rawText : '';
+  const legacyFuriganaText = typeof value.furiganaText === 'string' ? value.furiganaText : '';
+  const parsed = convertLegacyText(rawTextInput);
+  const hasMarkup = parsed.furiganaItems.length > 0 || parsed.main !== rawTextInput;
+  const rawText = hasMarkup ? parsed.main : rawTextInput;
+  const providedItems = sanitizeFuriganaItems(value.furiganaItems);
+  const furiganaItems = hasMarkup
+    ? providedItems.length > 0
+      ? providedItems
+      : parsed.furiganaItems
+    : providedItems.length > 0
+      ? providedItems
+      : migrateLegacyFuriganaTextToItems(rawText, legacyFuriganaText);
+
+  return {
+    id: typeof value.id === 'string' && value.id ? value.id : fallbackId,
+    rawText,
+    furiganaText: '',
+    furiganaItems,
+    segments: [],
+    notes: sanitizeNotes(value.notes),
+  };
+}
+
+export function normalizeLines(value: unknown, idPrefix = 'line'): WritingLine[] {
+  if (!Array.isArray(value)) return [];
+
+  return value.map((line, index) =>
+    normalizeLine((line && typeof line === 'object' ? line : {}) as Partial<WritingLine>, `${idPrefix}-${Date.now()}-${index}`)
+  );
+}
+
+export function adjustFuriganaItemsForTextChange(
+  previousText: string,
+  nextText: string,
+  items: FuriganaItem[]
+): FuriganaItem[] {
+  if (previousText === nextText || items.length === 0) return items;
+
+  let prefixLength = 0;
+  while (
+    prefixLength < previousText.length &&
+    prefixLength < nextText.length &&
+    previousText[prefixLength] === nextText[prefixLength]
+  ) {
+    prefixLength++;
+  }
+
+  let previousSuffix = previousText.length - 1;
+  let nextSuffix = nextText.length - 1;
+  while (
+    previousSuffix >= prefixLength &&
+    nextSuffix >= prefixLength &&
+    previousText[previousSuffix] === nextText[nextSuffix]
+  ) {
+    previousSuffix--;
+    nextSuffix--;
+  }
+
+  const removedLength = Math.max(0, previousSuffix - prefixLength + 1);
+  const insertedLength = Math.max(0, nextSuffix - prefixLength + 1);
+  const delta = insertedLength - removedLength;
+  if (delta === 0) return items;
+
+  return items.map((item) => {
+    if (item.x < prefixLength) return item;
+    return {
+      ...item,
+      x: Math.max(0, item.x + delta),
+    };
+  });
+}
+