diff --git a/src/main/export.ts b/src/main/export.ts
index 85988f7..b4ebb96 100644
--- a/src/main/export.ts
+++ b/src/main/export.ts
@@ -1,5 +1,4 @@
 import { ZipArchive } from "archiver";
-import fs from "fs";
 import path from "path";
 import { loadBook } from "./project.js";
 import { listChaptersInOrder, loadChapterDoc } from "./chapters.js";
@@ -52,13 +51,17 @@ export async function buildZip(bookPath: string): Promise<Buffer> {
     archive.append(combineMarkdown(bookPath), { name: "book.md" });
 
     for (const ch of chapters) {
+      // Per-chapter entries are readable Markdown generated from the native
+      // document model (same source as book.md). Raw storage files are never
+      // leaked: a native chapter's .json would otherwise land in the bundle
+      // as opaque JSON next to readable .md files.
       let content = "";
       try {
-        content = fs.readFileSync(path.join(bookPath, ch.file), "utf-8");
+        content = nativeToMarkdown(loadChapterDoc(bookPath, ch.id));
       } catch {
         content = "";
       }
-      const entryName = path.posix.join("chapters", path.basename(ch.file));
+      const entryName = path.posix.join("chapters", `${ch.id}.md`);
       archive.append(content, { name: entryName });
     }
 
@@ -71,7 +74,7 @@ export async function buildZip(bookPath: string): Promise<Buffer> {
       chapters: chapters.map((c) => ({
         id: c.id,
         title: c.title,
-        file: path.basename(c.file),
+        file: `${c.id}.md`,
       })),
     };
     archive.append(JSON.stringify(manifest, null, 2), { name: "manifest.json" });
diff --git a/src/renderer/book/editor.ts b/src/renderer/book/editor.ts
index 3474d82..0459e31 100644
--- a/src/renderer/book/editor.ts
+++ b/src/renderer/book/editor.ts
@@ -1,10 +1,6 @@
 // The chapter editing surface: main Tiptap editor instance, dirty-tracking +
 // autosave engine, chapter selection (with stale-load guard), zoom, and the
 // writing-statistics modal.
-//
-// Storage note: state.dirty / state.loadedDocJson are the shared contract
-// fields; until Step 7 they are backed by the orchestrator's closure locals
-// through the accessor bridge, so writes here are visible to every module.
 
 import type { Editor } from "@tiptap/core";
 import type { BookCtx } from "./types.js";
diff --git a/src/renderer/book/exports.ts b/src/renderer/book/exports.ts
index 60e4c3f..993baa6 100644
--- a/src/renderer/book/exports.ts
+++ b/src/renderer/book/exports.ts
@@ -96,8 +96,7 @@ export function createExportsFeature(ctx: BookCtx): ExportsFeature {
 
   // Explicitly migrate the whole book to the native document format. The main
   // process performs a recovery backup and leaves the original .md files in
-  // place; after this, chapters are stored as native JSON but the (still
-  // Markdown-based) editor and exports keep working via the format bridge.
+  // place; after this, chapters are stored as native JSON.
   async function migrateBookNative(): Promise<void> {
     if (!state.currentBook) return;
     const confirmed = await confirmMessage(
diff --git a/src/renderer/book/index.ts b/src/renderer/book/index.ts
index c35df40..1cf79ed 100644
--- a/src/renderer/book/index.ts
+++ b/src/renderer/book/index.ts
@@ -1,6 +1,5 @@
-import type { BookMeta, ChapterComment } from "../../main/project.js";
-import { alertMessage, confirmMessage, promptInput } from "../dialog.js";
-import type { ChapterEntry, FolioAPI, Recent } from "./types.js";
+import type { FolioAPI } from "./types.js";
+import { alertMessage, confirmMessage } from "../dialog.js";
 import type { BookCtx, BookHooks, SharedState } from "./types.js";
 import { createEditorFeature } from "./editor.js";
 import { createToolbarFeature } from "./toolbar.js";
@@ -14,41 +13,21 @@ import { createSettingsFeature } from "./settings.js";
 import {
   $,
   basename,
-  closeEl,
-  hideUndoToast,
-  openEl,
-  selectedText,
-  showUndoToast,
   showToast,
 } from "./ui.js";
 
 export type { ChapterSnapshot, FolioAPI } from "./types.js";
 
 export function initBook(api: FolioAPI) {
-  let currentBook: { path: string; title: string } | null = null;
-  let meta: BookMeta | null = null;
-  let ordered: ChapterEntry[] = [];
-  let selectedId: string | null = null;
-  let dirty = false;
-  let loadedDocJson = "";
-
-  // ---- P7 decomposition bridge -------------------------------------------
-  // Temporary: exposes these closure locals through the SharedState contract so
-  // extracted feature modules share one source of truth. Removed in Step 7 when
-  // the last feature leaves and state becomes a plain object literal.
+  // Shared mutable session state. Plain object literal: every feature module
+  // receives the same reference via ctx, so mutations stay visible everywhere.
   const state: SharedState = {
-    get currentBook() { return currentBook; },
-    set currentBook(v) { currentBook = v; },
-    get meta() { return meta; },
-    set meta(v) { meta = v; },
-    get ordered() { return ordered; },
-    set ordered(v) { ordered = v; },
-    get selectedId() { return selectedId; },
-    set selectedId(v) { selectedId = v; },
-    get dirty() { return dirty; },
-    set dirty(v) { dirty = v; },
-    get loadedDocJson() { return loadedDocJson; },
-    set loadedDocJson(v) { loadedDocJson = v; },
+    currentBook: null,
+    meta: null,
+    ordered: [],
+    selectedId: null,
+    dirty: false,
+    loadedDocJson: "",
   };
   const hooks = {} as BookHooks;
   const ctx: BookCtx = { api, state, hooks };
@@ -110,35 +89,6 @@ export function initBook(api: FolioAPI) {
   // Wire comment facade from the extracted module.
   hooks.updateCommentsBadge = comments.updateCommentsBadge;
 
-  // ---- element consts (kept from the original file) ----
-  const editorPlaceholder = $("editorPlaceholder");
-  const chapterView = $("chapterView");
-  const chapterTitleEl = $("chapterTitle");
-  const saveStateEl = $("saveState");
-  const exportBtn = $("exportBtn") as HTMLButtonElement;
-  const exportZipBtn = $("exportZipBtn") as HTMLButtonElement;
-  const projectBar = $("projectBar");
-  const fullBookNav = $("fullBookNav");
-  const fullBookBtn = $("fullBookBtn") as HTMLButtonElement;
-  const exportMenuToggle = $("exportMenuToggle") as HTMLButtonElement;
-  const exportMenu = $("exportMenu");
-  const exportDropdown = $("exportDropdown");
-
-  const welcomeEl = $("welcome");
-  const recentList = $("recentList") as HTMLUListElement;
-
-  // ---- welcome / recents logic (moved from inline into createWelcomeFeature) ----
-  // The welcome module owns its own DOM chrome and wiring; here we only keep the
-  // top-level constructor call and the bridge assignments it already set above.
-
-  // ---- export workflow (whole book vs selected chapters) ----
-  // The exports module owns its own DOM chrome and wiring; here we only keep the
-  // top-level constructor call and the bridge assignments it already set above.
-
-  // ---- comments / annotations ----
-  // The comments module owns its own DOM chrome and wiring; here we only keep the
-  // top-level constructor call and the bridge assignments it already set above.
-
   // ---- update flow ----
   // "Check for Updates…" (File menu / welcome button): query the release
   // server, then offer a one-click install. The app downloads the tarball,