fix keyboard fixed

src/components/AddPageMenu.tsx

@@ -16,6 +16,7 @@ export function AddPageMenu({ onAdd, onAddPart }: AddPageMenuProps) {
   const [open, setOpen] = useState(false);
   const [coords, setCoords] = useState({ top: 0, left: 0 });
   const btnRef = useRef<HTMLButtonElement>(null);
+  const popRef = useRef<HTMLDivElement>(null);
 
   const toggle = () => {
     if (!open && btnRef.current) {
@@ -38,6 +39,25 @@ export function AddPageMenu({ onAdd, onAddPart }: AddPageMenuProps) {
     };
   }, [open]);
 
+  useEffect(() => {
+    if (!open) return;
+    popRef.current?.querySelector<HTMLElement>(".add-page-item")?.focus();
+  }, [open]);
+
+  const onMenuKeyDown = (e: React.KeyboardEvent) => {
+    if (e.key === "Escape") {
+      e.preventDefault();
+      setOpen(false);
+      btnRef.current?.focus();
+    } else if (e.key === "ArrowDown" || e.key === "ArrowUp") {
+      e.preventDefault();
+      const items = Array.from(popRef.current?.querySelectorAll<HTMLElement>(".add-page-item") ?? []);
+      const idx = items.indexOf(document.activeElement as HTMLElement);
+      const nextIdx = e.key === "ArrowDown" ? (idx + 1) % items.length : (idx - 1 + items.length) % items.length;
+      items[nextIdx]?.focus();
+    }
+  };
+
   const pick = (group: "front" | "back", label: string) => {
     setOpen(false);
     onAdd(group, label);
@@ -56,9 +76,11 @@ export function AddPageMenu({ onAdd, onAddPart }: AddPageMenuProps) {
       </button>
       {open && (
         <div
+          ref={popRef}
           className="add-page-pop"
           style={{ top: coords.top, left: coords.left }}
           onMouseDown={(e) => e.stopPropagation()}
+          onKeyDown={onMenuKeyDown}
         >
           <div className="add-page-group">
             <div className="add-page-label">Body</div>

src/components/ConfirmDialog.tsx

@@ -1,4 +1,4 @@
-import type { ReactNode } from "react";
+import { useEffect, useRef, type ReactNode } from "react";
 import { Icon } from "./Icon";
 
 interface ConfirmDialogProps {
@@ -10,6 +10,21 @@ interface ConfirmDialogProps {
 }
 
 export function ConfirmDialog({ title, message, confirmLabel = "Delete", onConfirm, onClose }: ConfirmDialogProps) {
+  const confirmRef = useRef<HTMLButtonElement>(null);
+
+  useEffect(() => {
+    confirmRef.current?.focus();
+    const onKey = (e: KeyboardEvent) => {
+      if (e.key === "Escape") {
+        e.preventDefault();
+        onClose();
+      }
+    };
+    window.addEventListener("keydown", onKey);
+    return () => window.removeEventListener("keydown", onKey);
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, []);
+
   return (
     <div className="overlay" onClick={onClose}>
       <div className="panel panel-confirm" onClick={(e) => e.stopPropagation()}>
@@ -26,7 +41,7 @@ export function ConfirmDialog({ title, message, confirmLabel = "Delete", onConfi
           <button className="btn-ghost" onClick={onClose}>
             Cancel
           </button>
-          <button className="btn-danger" onClick={onConfirm}>
+          <button ref={confirmRef} className="btn-danger" onClick={onConfirm}>
             {confirmLabel}
           </button>
         </div>

src/components/EditorView.tsx

@@ -44,6 +44,9 @@ export function EditorView() {
 
   const isCompact = useCompact();
   const [editor, setEditor] = useState<TiptapEditor | null>(null);
+  const editorRef = useRef<TiptapEditor | null>(null);
+  editorRef.current = editor;
+  const lastChapterRef = useRef<string>("");
   const [sidebarOpen, setSidebarOpen] = useState(!isCompact);
   const [dock, setDock] = useState(!isCompact);
   const [settingsOpen, setSettingsOpen] = useState(false);
@@ -83,6 +86,18 @@ export function EditorView() {
     setFindOpen(true);
   }, []);
 
+  const focusEditorSoon = useCallback(() => {
+    requestAnimationFrame(() => editorRef.current?.commands.focus(undefined, { scrollIntoView: false }));
+  }, []);
+
+  const switchChapter = useCallback(
+    (dir: 1 | -1) => {
+      useBook.getState().goToAdjacentChapter(dir);
+      focusEditorSoon();
+    },
+    [focusEditorSoon]
+  );
+
   const reproof = useCallback(() => {
     if (!editor) return;
     const state = useProofing.getState();
@@ -120,11 +135,36 @@ export function EditorView() {
       } else if ((e.metaKey || e.ctrlKey) && e.key.toLowerCase() === "f") {
         e.preventDefault();
         openFind(e.altKey);
+      } else if (e.metaKey && e.altKey && (e.key === "ArrowDown" || e.key === "ArrowRight")) {
+        e.preventDefault();
+        e.stopPropagation();
+        switchChapter(1);
+      } else if (e.metaKey && e.altKey && (e.key === "ArrowUp" || e.key === "ArrowLeft")) {
+        e.preventDefault();
+        e.stopPropagation();
+        switchChapter(-1);
+      } else if (e.ctrlKey && !e.metaKey && e.key === "Tab") {
+        e.preventDefault();
+        e.stopPropagation();
+        switchChapter(e.shiftKey ? -1 : 1);
+      }
+    };
+    window.addEventListener("keydown", onKey, true);
+    return () => window.removeEventListener("keydown", onKey, true);
+  }, [saveNow, openFind, switchChapter]);
+
+  useEffect(() => {
+    if (!widthOpen && !exportOpen && !moreOpen) return;
+    const onKey = (e: KeyboardEvent) => {
+      if (e.key === "Escape") {
+        setWidthOpen(false);
+        setExportOpen(false);
+        setMoreOpen(false);
       }
     };
     window.addEventListener("keydown", onKey);
     return () => window.removeEventListener("keydown", onKey);
-  }, [saveNow, openFind]);
+  }, [widthOpen, exportOpen, moreOpen]);
 
   useEffect(() => {
     if (!notice) return;
@@ -177,8 +217,11 @@ export function EditorView() {
   };
 
   if (!book) return null;
-  const idx = book.chapters.findIndex((c) => c.id === activeChapterId);
-  const chapter = book.chapters[idx] ?? book.chapters[0];
+  const activeIdx = book.chapters.findIndex((c) => c.id === activeChapterId);
+  const activeChapter = book.chapters[activeIdx];
+  if (activeChapter) lastChapterRef.current = activeChapter.id;
+  const editorIdx = activeChapter ? activeIdx : book.chapters.findIndex((c) => c.id === lastChapterRef.current);
+  const chapter = book.chapters[editorIdx] ?? book.chapters[0];
   const realIdx = book.chapters.findIndex((c) => c.id === chapter?.id);
   const kind = chapter ? chapterKind(chapter) : "body";
   const eyebrow =
@@ -342,50 +385,49 @@ export function EditorView() {
       />
 
       <div className="body">
-        <Sidebar onNavigate={() => isCompact && setSidebarOpen(false)} />
+        <Sidebar
+          onNavigate={() => {
+            if (isCompact) setSidebarOpen(false);
+            focusEditorSoon();
+          }}
+        />
         {sidebarOpen && !isCompact && <ResizeHandle pane="sidebar" />}
         <main className="editor-pane">
-          {coverActive ? (
-            <CoverView />
-          ) : (
-            <>
-              <article className="sheet">
-                <header className="chapter-opener">
-                  <div className="chapter-num">{eyebrow}</div>
-                  <ChapterTitleInput
-                    value={chapter.title}
-                    placeholder={
-                      chapter.noTitle ? "No title" : kind === "body" ? "Chapter title" : kind === "part" ? "Part title (optional)" : "Page title"
-                    }
-                    disabled={!!chapter.noTitle}
-                    onChange={(value) => setChapterTitle(chapter.id, value)}
+          {coverActive && <CoverView />}
+          <article className="sheet" hidden={coverActive}>
+            <header className="chapter-opener">
+              <div className="chapter-num">{eyebrow}</div>
+              <ChapterTitleInput
+                value={chapter.title}
+                placeholder={
+                  chapter.noTitle ? "No title" : kind === "body" ? "Chapter title" : kind === "part" ? "Part title (optional)" : "Page title"
+                }
+                disabled={!!chapter.noTitle}
+                onChange={(value) => setChapterTitle(chapter.id, value)}
+              />
+              {(chapter.noTitle || !chapter.title.trim()) && (
+                <label className="no-title-check">
+                  <input
+                    type="checkbox"
+                    checked={!!chapter.noTitle}
+                    onChange={(e) => setChapterNoTitle(chapter.id, e.target.checked)}
                   />
-                  {(chapter.noTitle || !chapter.title.trim()) && (
-                    <label className="no-title-check">
-                      <input
-                        type="checkbox"
-                        checked={!!chapter.noTitle}
-                        onChange={(e) => setChapterNoTitle(chapter.id, e.target.checked)}
-                      />
-                      No title
-                    </label>
-                  )}
-                </header>
-                <Editor
-                  key={chapter.id}
-                  bookId={book.id}
-                  chapterId={chapter.id}
-                  content={chapter.content}
-                  onChange={(content) => setChapterContent(chapter.id, content)}
-                  onReady={setEditor}
-                  onContentError={() =>
-                    setNotice("This chapter contains content Margin couldn't fully read; editing may drop the unrecognized parts.")
-                  }
-                />
-              </article>
-              <FloatingToolbar editor={editor} />
-            </>
-          )}
+                  No title
+                </label>
+              )}
+            </header>
+            <Editor
+              bookId={book.id}
+              chapterId={chapter.id}
+              content={chapter.content}
+              onChange={(content) => setChapterContent(chapter.id, content)}
+              onReady={setEditor}
+              onContentError={() =>
+                setNotice("This chapter contains content Margin couldn't fully read; editing may drop the unrecognized parts.")
+              }
+            />
+          </article>
+          {!coverActive && <FloatingToolbar editor={editor} />}
         </main>
         {dock && !isCompact && <ResizeHandle pane="dock" />}
         {dock && <Dock />}

src/components/FindBar.tsx

@@ -58,7 +58,7 @@ export function FindBar({ editor, open, initialExpanded, onClose }: FindBarProps
     return () => {
       editor.off("transaction", update);
     };
-  }, [editor]);
+  }, [editor, activeChapterId]);
 
   useEffect(() => {
     if (!editor) return;
@@ -67,7 +67,7 @@ export function FindBar({ editor, open, initialExpanded, onClose }: FindBarProps
     } else {
       editor.commands.clearSearch();
     }
-  }, [editor, open, query, caseSensitive, wholeWord]);
+  }, [editor, open, query, caseSensitive, wholeWord, activeChapterId]);
 
   useEffect(() => {
     if (open) {

src/components/Library.tsx

@@ -51,6 +51,11 @@ export function Library({ onOpen }: { onOpen: (book: Book) => void }) {
     onOpen(copy);
   };
 
+  const openById = (id: string) =>
+    loadBook(id)
+      .then(onOpen)
+      .catch((e) => setNotice(`Could not open book: ${e}`));
+
   const removeBook = async () => {
     if (!pendingDelete) return;
     await deleteBook(pendingDelete.id);
@@ -108,7 +113,15 @@ export function Library({ onOpen }: { onOpen: (book: Book) => void }) {
             <div
               key={b.id}
               className="card card-book"
-              onClick={() => loadBook(b.id).then(onOpen).catch((e) => setNotice(`Could not open book: ${e}`))}
+              role="button"
+              tabIndex={0}
+              onClick={() => openById(b.id)}
+              onKeyDown={(e) => {
+                if (e.key === "Enter" || e.key === " ") {
+                  e.preventDefault();
+                  openById(b.id);
+                }
+              }}
             >
               <span className="card-title">{b.title || "Untitled"}</span>
               {b.author && <span className="card-author">{b.author}</span>}

src/components/RowMenu.tsx

@@ -33,6 +33,25 @@ export function RowMenu({ label, onDuplicate, onDelete, onToggleTitle, titleHidd
     setOpen((v) => !v);
   };
 
+  useEffect(() => {
+    if (!open) return;
+    popRef.current?.querySelector<HTMLElement>(".row-menu-item")?.focus();
+  }, [open]);
+
+  const onMenuKeyDown = (e: React.KeyboardEvent) => {
+    if (e.key === "Escape") {
+      e.preventDefault();
+      setOpen(false);
+      btnRef.current?.focus();
+    } else if (e.key === "ArrowDown" || e.key === "ArrowUp") {
+      e.preventDefault();
+      const items = Array.from(popRef.current?.querySelectorAll<HTMLElement>(".row-menu-item") ?? []);
+      const idx = items.indexOf(document.activeElement as HTMLElement);
+      const nextIdx = e.key === "ArrowDown" ? (idx + 1) % items.length : (idx - 1 + items.length) % items.length;
+      items[nextIdx]?.focus();
+    }
+  };
+
   useEffect(() => {
     if (!open) return;
     const onDown = (e: MouseEvent) => {
@@ -88,7 +107,7 @@ export function RowMenu({ label, onDuplicate, onDelete, onToggleTitle, titleHidd
       </button>
       {open &&
         createPortal(
-          <div ref={popRef} className="row-menu-pop" style={{ top: coords.top, right: coords.right }}>
+          <div ref={popRef} className="row-menu-pop" style={{ top: coords.top, right: coords.right }} onKeyDown={onMenuKeyDown}>
             {onToggleTitle && (
               <button className="row-menu-item" onClick={toggleTitle}>
                 {titleHidden ? (

src/components/Settings.tsx

@@ -94,6 +94,17 @@ export function Settings({ onClose, onSave }: { onClose: () => void; onSave: ()
     });
   }, []);
 
+  useEffect(() => {
+    const onKey = (e: KeyboardEvent) => {
+      if (e.key === "Escape") {
+        e.preventDefault();
+        onClose();
+      }
+    };
+    window.addEventListener("keydown", onKey);
+    return () => window.removeEventListener("keydown", onKey);
+  }, [onClose]);
+
   if (!book) return null;
 
   const set = (patch: Partial<Draft>) => setDraft((d) => ({ ...d, ...patch }));
@@ -121,7 +132,7 @@ export function Settings({ onClose, onSave }: { onClose: () => void; onSave: ()
         </div>
         <div className="panel-body">
           <Field label="Title">
-            <input value={draft.title} placeholder="Untitled" onChange={(e) => set({ title: e.target.value })} />
+            <input autoFocus value={draft.title} placeholder="Untitled" onChange={(e) => set({ title: e.target.value })} />
           </Field>
           <Field label="Subtitle">
             <input value={draft.subtitle} onChange={(e) => set({ subtitle: e.target.value })} />

src/components/Sidebar.tsx

@@ -155,6 +155,33 @@ export function Sidebar({ onNavigate }: { onNavigate?: () => void }) {
     onNavigate?.();
   };
 
+  const focusRow = (id: string) =>
+    requestAnimationFrame(() => {
+      document.querySelector<HTMLElement>(`.chapter[data-id="${CSS.escape(id)}"]`)?.focus();
+    });
+
+  const onRowKeyDown = (e: React.KeyboardEvent, index: number, id: string) => {
+    if (e.key === "Enter" || e.key === " ") {
+      e.preventDefault();
+      setActiveChapter(id);
+      onNavigate?.();
+    } else if (e.key === "ArrowDown" || e.key === "ArrowUp" || e.key === "Home" || e.key === "End") {
+      e.preventDefault();
+      const target =
+        e.key === "Home"
+          ? chapters[0]
+          : e.key === "End"
+            ? chapters[chapters.length - 1]
+            : chapters[index + (e.key === "ArrowDown" ? 1 : -1)];
+      if (target) {
+        setActiveChapter(target.id);
+        focusRow(target.id);
+      }
+    }
+  };
+
+  const tabStopId = chapters.some((c) => c.id === activeChapterId) ? activeChapterId : chapters[0]?.id;
+
   return (
     <aside className="sidebar">
       <button className="brand" onClick={closeBook} title="All books">
@@ -193,6 +220,7 @@ export function Sidebar({ onNavigate }: { onNavigate?: () => void }) {
                     key={row.chapter.id}
                     className="chapter"
                     data-idx={row.index}
+                    data-id={row.chapter.id}
                     data-kind={group.kind}
                     data-part={isPart}
                     data-indent={row.indent}
@@ -200,7 +228,11 @@ export function Sidebar({ onNavigate }: { onNavigate?: () => void }) {
                     data-dragging={dragIndex === row.index}
                     data-drop-before={dropTarget?.kind === group.kind && dropTarget.index === row.index}
                     data-drop-after={dropTarget?.kind === group.kind && i === group.rows.length - 1 && dropTarget.index === row.index + 1}
+                    role="button"
+                    tabIndex={row.chapter.id === tabStopId ? 0 : -1}
+                    aria-current={row.chapter.id === activeChapterId}
                     onClick={() => onRowClick(row.chapter.id)}
+                    onKeyDown={(e) => onRowKeyDown(e, row.index, row.chapter.id)}
                     onPointerDown={(e) => onRowPointerDown(e, row.index)}
                   >
                     <span className="grip" title="Drag to reorder">

src/editor/Editor.tsx

@@ -1,8 +1,10 @@
-import { useEffect, useRef } from "react";
+import { useEffect, useLayoutEffect, useRef } from "react";
 import { EditorContent, useEditor, type Editor as TiptapEditor } from "@tiptap/react";
+import { EditorState } from "@tiptap/pm/state";
 import type { JSONContent } from "@tiptap/core";
 import { editorExtensions } from "./extensions";
 import { loadPosition, savePosition, type ChapterPosition } from "./positions";
+import { useBook } from "../store/useBook";
 
 interface EditorProps {
   bookId: string;
@@ -13,13 +15,34 @@ interface EditorProps {
   onContentError: (error: Error) => void;
 }
 
+interface Cached {
+  state: EditorState;
+  content: JSONContent;
+  scroll: number;
+}
+
+function buildState(editor: TiptapEditor, content: JSONContent, onError: (error: Error) => void): EditorState {
+  const base = editor.view.state;
+  try {
+    const doc = editor.schema.nodeFromJSON(content);
+    doc.check();
+    return EditorState.create({ doc, plugins: base.plugins });
+  } catch (error) {
+    onError(error as Error);
+    return EditorState.create({ schema: base.schema, plugins: base.plugins });
+  }
+}
+
 export function Editor({ bookId, chapterId, content, onChange, onReady, onContentError }: EditorProps) {
   const onChangeRef = useRef(onChange);
   onChangeRef.current = onChange;
   const onContentErrorRef = useRef(onContentError);
   onContentErrorRef.current = onContentError;
 
+  const cache = useRef(new Map<string, Cached>());
+  const activeId = useRef(chapterId);
   const latest = useRef<ChapterPosition | null>(null);
+  const restoreToken = useRef(0);
 
   const editor = useEditor({
     extensions: editorExtensions,
@@ -31,49 +54,84 @@ export function Editor({ bookId, chapterId, content, onChange, onReady, onConten
     onUpdate: ({ editor }) => onChangeRef.current(editor.getJSON()),
   });
 
-  useEffect(() => {
-    onReady(editor);
-    return () => onReady(null);
-  }, [editor, onReady]);
+  const scrollerOf = (ed: TiptapEditor) => ed.view.dom.closest(".editor-pane") as HTMLElement | null;
+
+  const restorePosition = (ed: TiptapEditor, id: string, focus: boolean) => {
+    const scroller = scrollerOf(ed);
+    const saved = loadPosition(bookId, id);
+    const size = ed.state.doc.content.size;
+    const selection = saved ? { from: Math.min(saved.from, size), to: Math.min(saved.to, size) } : 0;
+    const chain = ed.chain().setTextSelection(selection);
+    if (focus) chain.focus(undefined, { scrollIntoView: false });
+    chain.run();
+    if (scroller) {
+      const token = ++restoreToken.current;
+      const top = saved?.scroll ?? 0;
+      const apply = () => {
+        if (restoreToken.current === token) scroller.scrollTop = top;
+      };
+      apply();
+      requestAnimationFrame(apply);
+      document.fonts?.ready.then(apply).catch(() => {});
+    }
+  };
+
+  const stash = (ed: TiptapEditor, id: string) => {
+    const scroller = scrollerOf(ed);
+    const { from, to } = ed.state.selection;
+    const scroll = scroller?.scrollTop ?? 0;
+    const stored = useBook.getState().book?.chapters.find((c) => c.id === id)?.content ?? cache.current.get(id)?.content ?? ed.getJSON();
+    cache.current.set(id, { state: ed.view.state, content: stored, scroll });
+    savePosition(bookId, id, { from, to, scroll });
+  };
 
   useEffect(() => {
     if (!editor) return;
-    let active = true;
-    const scroller = editor.view.dom.closest(".editor-pane") as HTMLElement | null;
-
-    const saved = loadPosition(bookId, chapterId);
-    const size = editor.state.doc.content.size;
-    const selection = saved ? { from: Math.min(saved.from, size), to: Math.min(saved.to, size) } : 0;
-    editor.chain().setTextSelection(selection).focus(undefined, { scrollIntoView: false }).run();
-
-    if (scroller) {
-      const top = saved?.scroll ?? 0;
-      const restore = () => {
-        if (active) scroller.scrollTop = top;
-      };
-      restore();
-      requestAnimationFrame(restore);
-      document.fonts?.ready.then(restore).catch(() => {});
-    }
-
-    return () => {
-      active = false;
-    };
+    cache.current.set(chapterId, { state: editor.view.state, content, scroll: 0 });
+    activeId.current = chapterId;
+    restorePosition(editor, chapterId, true);
+    onReady(editor);
+    return () => onReady(null);
     // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [editor]);
 
+  useLayoutEffect(() => {
+    if (!editor) return;
+    const prev = activeId.current;
+    if (prev === chapterId) return;
+
+    stash(editor, prev);
+    const entry = cache.current.get(chapterId);
+    if (entry && entry.content === content) {
+      editor.view.updateState(entry.state);
+      const scroller = scrollerOf(editor);
+      if (scroller) scroller.scrollTop = entry.scroll;
+      ++restoreToken.current;
+    } else {
+      editor.view.updateState(buildState(editor, content, onContentErrorRef.current));
+      cache.current.set(chapterId, { state: editor.view.state, content, scroll: 0 });
+      restorePosition(editor, chapterId, false);
+    }
+    activeId.current = chapterId;
+    latest.current = null;
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [chapterId, content, editor]);
+
   useEffect(() => {
     if (!editor) return;
-    const scroller = editor.view.dom.closest(".editor-pane") as HTMLElement | null;
+    const scroller = scrollerOf(editor);
     let timer: ReturnType<typeof setTimeout>;
     const capture = () => {
       const { from, to } = editor.state.selection;
-      latest.current = { from, to, scroll: scroller?.scrollTop ?? 0 };
+      const scroll = scroller?.scrollTop ?? 0;
+      latest.current = { from, to, scroll };
+      const entry = cache.current.get(activeId.current);
+      if (entry) entry.scroll = scroll;
     };
     const persist = () => {
       capture();
       clearTimeout(timer);
-      timer = setTimeout(() => savePosition(bookId, chapterId, latest.current!), 400);
+      timer = setTimeout(() => savePosition(bookId, activeId.current, latest.current!), 400);
     };
     editor.on("selectionUpdate", persist);
     scroller?.addEventListener("scroll", persist, { passive: true });
@@ -81,9 +139,9 @@ export function Editor({ bookId, chapterId, content, onChange, onReady, onConten
       clearTimeout(timer);
       editor.off("selectionUpdate", persist);
       scroller?.removeEventListener("scroll", persist);
-      if (latest.current) savePosition(bookId, chapterId, latest.current);
+      if (latest.current) savePosition(bookId, activeId.current, latest.current);
     };
-  }, [editor, bookId, chapterId]);
+  }, [editor, bookId]);
 
   return <EditorContent editor={editor} className="editor-host" />;
 }

src/store/useBook.ts

@@ -30,6 +30,7 @@ interface BookState {
   openBook: (book: Book) => void;
   closeBook: () => void;
   setActiveChapter: (id: string) => void;
+  goToAdjacentChapter: (dir: 1 | -1) => void;
   setChapterContent: (id: string, content: JSONContent) => void;
   setChapterTitle: (id: string, title: string) => void;
   setChapterNoTitle: (id: string, noTitle: boolean) => void;
@@ -73,6 +74,15 @@ export const useBook = create<BookState>((set, get) => ({
     set({ book: null, activeChapterId: "", dirty: false });
   },
   setActiveChapter: (id) => set({ activeChapterId: id }),
+  goToAdjacentChapter: (dir) => {
+    const { book, activeChapterId } = get();
+    if (!book) return;
+    const ids = [COVER_ID, ...book.chapters.map((c) => c.id)];
+    const i = ids.indexOf(activeChapterId);
+    if (i === -1) return;
+    const next = ids[(i + dir + ids.length) % ids.length];
+    if (next !== activeChapterId) set({ activeChapterId: next });
+  },
   setChapterContent: (id, content) =>
     set((s) =>
       s.book

src/styles/app.css

@@ -40,6 +40,22 @@ button {
   padding: 0;
 }
 
+:focus-visible {
+  outline: 2px solid var(--accent);
+  outline-offset: 2px;
+}
+
+.chapter:focus-visible,
+.card:focus-visible {
+  outline-offset: -2px;
+}
+
+.prose:focus,
+.prose:focus-visible,
+.editor-host:focus-visible {
+  outline: none;
+}
+
 .app {
   display: flex;
   flex-direction: column;