diff --git a/apps/api/src/app.module.ts b/apps/api/src/app.module.ts
index e3e7c93..8f3206b 100644
--- a/apps/api/src/app.module.ts
+++ b/apps/api/src/app.module.ts
@@ -6,11 +6,12 @@ import { BooksModule } from "./books/books.module.js";
 import { DatabaseModule } from "./database/database.module.js";
 import { ProgressModule } from "./progress/progress.module.js";
 import { ReaderModule } from "./reader/reader.module.js";
+import { ReadingModule } from "./reading/reading.module.js";
 import { ScannerModule } from "./scanner/scanner.module.js";
 import { HealthController } from "./health.controller.js";
 
 @Module({
-  imports: [DatabaseModule, AuthModule, AdminModule, BooksModule, ProgressModule, ReaderModule, ScannerModule, AutomationModule],
+  imports: [DatabaseModule, AuthModule, AdminModule, BooksModule, ProgressModule, ReaderModule, ReadingModule, ScannerModule, AutomationModule],
   controllers: [HealthController]
 })
 export class AppModule {}
diff --git a/apps/api/src/reading/adapters/archive-reading-source.adapter.test.ts b/apps/api/src/reading/adapters/archive-reading-source.adapter.test.ts
new file mode 100644
index 0000000..7619978
--- /dev/null
+++ b/apps/api/src/reading/adapters/archive-reading-source.adapter.test.ts
@@ -0,0 +1,75 @@
+import { mkdtempSync, rmSync, writeFileSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import AdmZip from "adm-zip";
+import { afterEach, describe, expect, it } from "vitest";
+import { ArchiveReadingSourceAdapter } from "./archive-reading-source.adapter.js";
+
+const directories: string[] = [];
+
+afterEach(() => {
+  for (const directory of directories.splice(0)) rmSync(directory, { recursive: true, force: true });
+});
+
+describe("ArchiveReadingSourceAdapter", () => {
+  it("builds an ordered EPUB spine and serves only opaque resource ids", async () => {
+    const directory = mkdtempSync(join(tmpdir(), "readabook-reading-"));
+    directories.push(directory);
+    const filePath = join(directory, "book.epub");
+    const zip = new AdmZip();
+    zip.addFile("META-INF/container.xml", Buffer.from(`<?xml version="1.0"?><container><rootfiles><rootfile full-path="OPS/package.opf"/></rootfiles></container>`));
+    zip.addFile("OPS/package.opf", Buffer.from(`<package><manifest><item id="one" href="chapter-1.xhtml" media-type="application/xhtml+xml"/><item id="pic" href="images/cover.jpg" media-type="image/jpeg"/><item id="two" href="chapter-2.xhtml" media-type="application/xhtml+xml"/></manifest><spine><itemref idref="one"/><itemref idref="two"/></spine></package>`));
+    zip.addFile("OPS/chapter-1.xhtml", Buffer.from('<html><head><link href="styles/book.css" rel="stylesheet"/></head><body><img src="images/cover.jpg"/><p>First</p></body></html>'));
+    zip.addFile("OPS/chapter-2.xhtml", Buffer.from("<p>Second</p>"));
+    zip.addFile("OPS/images/cover.jpg", Buffer.from([1, 2, 3]));
+    zip.addFile("OPS/styles/book.css", Buffer.from("body { color: black; }"));
+    zip.writeZip(filePath);
+    const stat = await import("node:fs").then(({ statSync }) => statSync(filePath));
+    const source = new ArchiveReadingSourceAdapter();
+    const book = { id: 7, format: "epub", filePath, fileSize: stat.size, fileMtime: stat.mtime.toISOString() };
+
+    const manifest = await source.manifest(book);
+
+    expect(manifest.spine).toHaveLength(2);
+    expect(manifest).toMatchObject({
+      containerPath: "META-INF/container.xml",
+      opfPath: "OPS/package.opf",
+      basePath: "OPS/",
+      revision: expect.any(String)
+    });
+    expect(JSON.stringify(manifest)).not.toContain(filePath);
+    expect(JSON.stringify(manifest)).not.toContain(`/books/${book.id}/file`);
+    expect(manifest.resources).toHaveLength(6);
+    expect(manifest.resources.map((resource) => resource.resourceId)).not.toContain("OPS/chapter-1.xhtml");
+    expect(manifest.resources).toEqual(expect.arrayContaining([
+      expect.objectContaining({ href: "META-INF/container.xml", mediaType: "application/xml", size: expect.any(Number), url: expect.stringContaining("/reading-resources/") }),
+      expect.objectContaining({ href: "OPS/package.opf", mediaType: "application/oebps-package+xml" }),
+      expect.objectContaining({ href: "OPS/images/cover.jpg", mediaType: "image/jpeg", size: 3 })
+    ]));
+    expect(manifest.spine[0]).toMatchObject({ index: 0, href: "OPS/chapter-1.xhtml", mediaType: "application/xhtml+xml", size: expect.any(Number) });
+    const firstResource = manifest.resources.find((resource) => resource.href === "OPS/chapter-1.xhtml");
+    const coverResource = manifest.resources.find((resource) => resource.href === "OPS/images/cover.jpg");
+    expect(firstResource?.references).toContain(coverResource?.resourceId);
+    const chapter = await source.resource(book, manifest.spine[0].resourceId);
+    expect(chapter.contentType).toBe("application/xhtml+xml");
+    expect(chapter.data?.toString()).toContain("<p>First</p>");
+    const container = manifest.resources.find((resource) => resource.href === manifest.containerPath);
+    expect((await source.resource(book, container!.resourceId)).data?.toString()).toContain("container");
+  });
+
+  it("exposes a PDF as a range-capable original without leaking its path in the manifest", async () => {
+    const directory = mkdtempSync(join(tmpdir(), "readabook-reading-"));
+    directories.push(directory);
+    const filePath = join(directory, "secret-name.pdf");
+    writeFileSync(filePath, "%PDF-test");
+    const source = new ArchiveReadingSourceAdapter();
+    const book = { id: 8, format: "pdf", filePath, fileSize: 9, fileMtime: "2026-01-01T00:00:00.000Z" };
+
+    const manifest = await source.manifest(book);
+    const resource = await source.resource(book, "original");
+
+    expect(JSON.stringify(manifest)).not.toContain(filePath);
+    expect(manifest).toMatchObject({ format: "pdf", spine: [expect.objectContaining({ resourceId: "original" })], capabilities: { byteRanges: true, lightweightPages: false } });
+    expect(resource).toMatchObject({ filePath, contentType: "application/pdf", supportsRanges: true });
+  });
+});
diff --git a/apps/api/src/reading/adapters/archive-reading-source.adapter.ts b/apps/api/src/reading/adapters/archive-reading-source.adapter.ts
new file mode 100644
index 0000000..f041fd5
--- /dev/null
+++ b/apps/api/src/reading/adapters/archive-reading-source.adapter.ts
@@ -0,0 +1,220 @@
+import { createHash } from "node:crypto";
+import { existsSync, statSync } from "node:fs";
+import { extname, posix } from "node:path";
+import { BadRequestException, Injectable, NotFoundException } from "@nestjs/common";
+import AdmZip from "adm-zip";
+import { XMLParser } from "fast-xml-parser";
+import { lookup } from "mime-types";
+import { ReadingSourcePort } from "../reading.ports.js";
+import { ReadingBook, ReadingManifest, ReadingResource, ReadingResourcePayload, ReadingSpineItem } from "../reading.types.js";
+
+const xml = new XMLParser({ ignoreAttributes: false, attributeNamePrefix: "@_" });
+const MAX_EPUB_ENTRIES = 20_000;
+const MAX_RESOURCE_BYTES = 64 * 1024 * 1024;
+
+@Injectable()
+export class ArchiveReadingSourceAdapter implements ReadingSourcePort {
+  private readonly epubManifests = new Map<number, { revision: string; manifest: ReadingManifest }>();
+
+  async manifest(book: ReadingBook): Promise<ReadingManifest> {
+    this.assertReadable(book);
+    if (book.format === "pdf") return pdfManifest(book);
+    if (book.format !== "epub") throw new BadRequestException("Adaptive reading supports EPUB and PDF books");
+    const revision = revisionFor(book);
+    const cached = this.epubManifests.get(book.id);
+    if (cached?.revision === revision) return cached.manifest;
+    const manifest = epubManifest(book);
+    this.epubManifests.set(book.id, { revision, manifest });
+    return manifest;
+  }
+
+  async resource(book: ReadingBook, resourceId: string): Promise<ReadingResourcePayload> {
+    this.assertReadable(book);
+    if (book.format === "pdf") {
+      if (resourceId !== "original") throw new NotFoundException("Reading resource not found");
+      const size = statSync(book.filePath).size;
+      return { filePath: book.filePath, contentType: "application/pdf", size, etag: etag(book, resourceId), supportsRanges: true };
+    }
+    if (book.format !== "epub") throw new BadRequestException("Adaptive reading supports EPUB and PDF books");
+    const manifest = await this.manifest(book);
+    const resource = manifest.resources.find((candidate) => candidate.resourceId === resourceId);
+    if (!resource) throw new NotFoundException("Reading resource not found");
+    const zip = new AdmZip(book.filePath);
+    const entry = zip.getEntry(resource.href);
+    if (!entry || entry.isDirectory) throw new NotFoundException("Reading resource not found");
+    if (entry.header.size > MAX_RESOURCE_BYTES) throw new BadRequestException("EPUB resource is too large to extract");
+    const data = entry.getData();
+    return { data, contentType: resource.mediaType, size: data.length, etag: etag(book, resourceId), supportsRanges: false };
+  }
+
+  private assertReadable(book: ReadingBook): void {
+    if (!existsSync(book.filePath)) throw new NotFoundException("Book file not found on disk");
+  }
+}
+
+function epubManifest(book: ReadingBook): ReadingManifest {
+  const zip = new AdmZip(book.filePath);
+  const entries = zip.getEntries();
+  if (entries.length > MAX_EPUB_ENTRIES) throw new BadRequestException("EPUB archive has too many entries");
+  const containerPath = "META-INF/container.xml";
+  const container = xml.parse(zip.readAsText(containerPath));
+  const rootfiles = array(container?.container?.rootfiles?.rootfile);
+  const opfPath = rootfiles[0]?.["@_full-path"];
+  if (typeof opfPath !== "string") throw new BadRequestException("EPUB package document is missing");
+  const normalizedOpf = normalizeArchivePath(opfPath);
+  const parsed = xml.parse(zip.readAsText(normalizedOpf));
+  const packageDocument = parsed?.package;
+  const directory = posix.dirname(normalizedOpf);
+  const basePath = directory === "." ? "" : `${directory}/`;
+  const items = array(packageDocument?.manifest?.item);
+  const spineItems = array(packageDocument?.spine?.itemref);
+  const declaredMediaTypes = new Map<string, string>();
+  const packageIds = new Map<string, string>();
+  for (const item of items) {
+    const packageId = stringAttribute(item, "@_id");
+    const href = stringAttribute(item, "@_href");
+    if (!href) continue;
+    const archivePath = normalizeArchivePath(posix.join(directory, decodeHref(href)));
+    const mediaType = stringAttribute(item, "@_media-type");
+    if (mediaType) declaredMediaTypes.set(archivePath, mediaType);
+    if (packageId) packageIds.set(packageId, archivePath);
+  }
+  const byPackageId = new Map<string, ReadingResource>();
+  const resources = entries.flatMap((entry): ReadingResource[] => {
+    if (entry.isDirectory) return [];
+    const archivePath = normalizeArchivePath(entry.entryName);
+    const mediaType = declaredMediaTypes.get(archivePath) ?? archiveMediaType(archivePath, normalizedOpf);
+    const resource: ReadingResource = {
+      resourceId: opaqueId(archivePath),
+      href: archivePath,
+      url: resourceUrl(book.id, opaqueId(archivePath)),
+      kind: resourceKind(mediaType),
+      mediaType,
+      size: entry.header.size,
+      state: "ready"
+    };
+    return [resource];
+  });
+  const byHref = new Map(resources.map((resource) => [resource.href, resource]));
+  for (const [packageId, archivePath] of packageIds) {
+    const resource = byHref.get(archivePath);
+    if (resource) byPackageId.set(packageId, resource);
+  }
+  addResourceReferences(zip, resources, byHref);
+  const spine = spineItems.flatMap((item, index): ReadingSpineItem[] => {
+    if (stringAttribute(item, "@_linear") === "no") return [];
+    const resource = byPackageId.get(stringAttribute(item, "@_idref") ?? "");
+    if (!resource) return [];
+    return [{ index, href: resource.href, resourceId: resource.resourceId, url: resource.url, mediaType: resource.mediaType, size: resource.size }];
+  });
+  const revision = revisionFor(book);
+  return {
+    bookId: book.id,
+    format: "epub",
+    revision,
+    version: revision,
+    containerPath,
+    opfPath: normalizedOpf,
+    basePath,
+    resources,
+    spine,
+    capabilities: { byteRanges: false, derivedImages: true, lightweightPages: false }
+  };
+}
+
+function pdfManifest(book: ReadingBook): ReadingManifest {
+  const revision = revisionFor(book);
+  return {
+    bookId: book.id,
+    format: "pdf",
+    revision,
+    version: revision,
+    containerPath: null,
+    opfPath: null,
+    basePath: null,
+    resources: [{ resourceId: "original", href: "original", url: resourceUrl(book.id, "original"), kind: "document", mediaType: "application/pdf", size: book.fileSize, state: "ready" }],
+    spine: [{ index: 0, href: "original", resourceId: "original", url: resourceUrl(book.id, "original"), mediaType: "application/pdf", size: book.fileSize }],
+    capabilities: { byteRanges: true, derivedImages: false, lightweightPages: false }
+  };
+}
+
+function normalizeArchivePath(path: string): string {
+  const normalized = posix.normalize(path.replace(/^\/+/, ""));
+  if (normalized === ".." || normalized.startsWith("../")) throw new BadRequestException("Invalid EPUB resource path");
+  return normalized;
+}
+
+function decodeHref(href: string): string {
+  try {
+    return decodeURIComponent(href.split("#", 1)[0]);
+  } catch {
+    throw new BadRequestException("Invalid EPUB resource path");
+  }
+}
+
+function opaqueId(path: string): string {
+  return createHash("sha256").update(path).digest("base64url").slice(0, 22);
+}
+
+function revisionFor(book: ReadingBook): string {
+  return createHash("sha256").update(`${book.fileSize}:${book.fileMtime}`).digest("base64url");
+}
+
+function resourceUrl(bookId: number, resourceId: string): string {
+  return `/books/${bookId}/reading-resources/${encodeURIComponent(resourceId)}`;
+}
+
+function archiveMediaType(path: string, opfPath: string): string {
+  if (path === "META-INF/container.xml") return "application/xml";
+  if (path === opfPath) return "application/oebps-package+xml";
+  if (path === "mimetype") return "text/plain";
+  return String(lookup(extname(path)) || "application/octet-stream");
+}
+
+function addResourceReferences(zip: AdmZip, resources: ReadingResource[], byHref: Map<string, ReadingResource>): void {
+  for (const resource of resources) {
+    if ((resource.kind !== "chapter" && resource.kind !== "stylesheet") || resource.size > 2 * 1024 * 1024) continue;
+    const entry = zip.getEntry(resource.href);
+    if (!entry) continue;
+    const text = entry.getData().toString("utf8");
+    const candidates = resource.kind === "stylesheet"
+      ? [...text.matchAll(/url\(\s*["']?([^"')]+)["']?\s*\)/gi)].map((match) => match[1])
+      : [...text.matchAll(/(?:src|href)\s*=\s*["']([^"']+)["']/gi)].map((match) => match[1]);
+    const references = candidates.flatMap((candidate): string[] => {
+      const href = resolveReference(resource.href, candidate);
+      const target = href ? byHref.get(href) : undefined;
+      return target && target.kind !== "chapter" ? [target.resourceId] : [];
+    });
+    resource.references = [...new Set(references)];
+  }
+}
+
+function resolveReference(parent: string, reference: string): string | null {
+  const clean = reference.trim();
+  if (!clean || clean.startsWith("#") || /^(?:data|https?|mailto|tel):/i.test(clean) || clean.startsWith("//")) return null;
+  try {
+    return normalizeArchivePath(posix.join(posix.dirname(parent), decodeHref(clean)));
+  } catch {
+    return null;
+  }
+}
+
+function etag(book: ReadingBook, resourceId: string): string {
+  return `\"${createHash("sha256").update(`${book.id}:${book.fileSize}:${book.fileMtime}:${resourceId}`).digest("base64url")}\"`;
+}
+
+function array(value: any): any[] {
+  return Array.isArray(value) ? value : value ? [value] : [];
+}
+
+function stringAttribute(value: any, key: string): string | null {
+  return typeof value?.[key] === "string" ? value[key] : null;
+}
+
+function resourceKind(mediaType: string): ReadingResource["kind"] {
+  if (mediaType.startsWith("image/")) return "image";
+  if (mediaType === "text/css") return "stylesheet";
+  if (mediaType.includes("font") || mediaType.includes("woff")) return "font";
+  if (mediaType.includes("html") || mediaType.includes("xml")) return "chapter";
+  return "document";
+}
diff --git a/apps/api/src/reading/adapters/filesystem-reading-cache.adapter.ts b/apps/api/src/reading/adapters/filesystem-reading-cache.adapter.ts
new file mode 100644
index 0000000..5fc8404
--- /dev/null
+++ b/apps/api/src/reading/adapters/filesystem-reading-cache.adapter.ts
@@ -0,0 +1,37 @@
+import { createHash } from "node:crypto";
+import { mkdir, readFile, rm, writeFile } from "node:fs/promises";
+import { join } from "node:path";
+import { Injectable } from "@nestjs/common";
+import { DatabaseService } from "../../database/database.service.js";
+import { ReadingCachePort } from "../reading.ports.js";
+import { ReadingBook } from "../reading.types.js";
+
+@Injectable()
+export class FilesystemReadingCacheAdapter implements ReadingCachePort {
+  constructor(private readonly database: DatabaseService) {}
+
+  async get(book: ReadingBook, resourceId: string): Promise<Buffer | null> {
+    try {
+      return await readFile(this.path(book, resourceId));
+    } catch (error) {
+      if ((error as NodeJS.ErrnoException).code === "ENOENT") return null;
+      throw error;
+    }
+  }
+
+  async put(book: ReadingBook, resourceId: string, data: Buffer): Promise<void> {
+    const path = this.path(book, resourceId);
+    await mkdir(join(path, ".."), { recursive: true });
+    await writeFile(path, data);
+  }
+
+  async remove(book: ReadingBook, resourceId: string): Promise<void> {
+    await rm(this.path(book, resourceId), { force: true });
+  }
+
+  private path(book: ReadingBook, resourceId: string): string {
+    const version = createHash("sha256").update(`${book.fileSize}:${book.fileMtime}`).digest("hex").slice(0, 16);
+    const resource = createHash("sha256").update(resourceId).digest("hex");
+    return join(this.database.config.storageDir, "reading-cache", String(book.id), version, resource);
+  }
+}
diff --git a/apps/api/src/reading/reading.controller.test.ts b/apps/api/src/reading/reading.controller.test.ts
new file mode 100644
index 0000000..77cacf9
--- /dev/null
+++ b/apps/api/src/reading/reading.controller.test.ts
@@ -0,0 +1,72 @@
+import { describe, expect, it, vi } from "vitest";
+import { ReadingController } from "./reading.controller.js";
+
+describe("ReadingController", () => {
+  it("returns 304 for a matching ETag without a range request", async () => {
+    const controller = new ReadingController({
+      resource: vi.fn().mockResolvedValue(resourcePayload({ partial: false }))
+    } as any);
+    const reply = fakeReply();
+
+    await controller.resource("12", "chapter-1", undefined, '"etag"', reply as any);
+
+    expect(reply.statusCode).toBe(304);
+    expect(reply.sent).toBeUndefined();
+    expect(reply.headers).toEqual({});
+  });
+
+  it("sets cache, ETag and range headers for partial PDF resources", async () => {
+    const controller = new ReadingController({
+      resource: vi.fn().mockResolvedValue(resourcePayload({ partial: true, supportsRanges: true, start: 2, end: 5, size: 10, data: Buffer.from("2345") }))
+    } as any);
+    const reply = fakeReply();
+
+    await controller.resource("12", "original", "bytes=2-5", undefined, reply as any);
+
+    expect(reply.statusCode).toBe(206);
+    expect(reply.headers).toMatchObject({
+      "Accept-Ranges": "bytes",
+      "Cache-Control": "private, max-age=3600, must-revalidate",
+      "Content-Length": "4",
+      "Content-Range": "bytes 2-5/10",
+      "Content-Type": "application/pdf",
+      ETag: '"etag"',
+      "X-Content-Type-Options": "nosniff"
+    });
+    expect(reply.sent?.toString()).toBe("2345");
+  });
+});
+
+function resourcePayload(overrides: Record<string, unknown>) {
+  return {
+    data: Buffer.from("chapter"),
+    contentType: "application/pdf",
+    size: 7,
+    etag: '"etag"',
+    supportsRanges: false,
+    start: 0,
+    end: 6,
+    partial: false,
+    ...overrides
+  };
+}
+
+function fakeReply() {
+  return {
+    statusCode: 200,
+    headers: {} as Record<string, string>,
+    sent: undefined as unknown,
+    code(status: number) {
+      this.statusCode = status;
+      return this;
+    },
+    header(name: string, value: string) {
+      this.headers[name] = value;
+      return this;
+    },
+    send(payload?: unknown) {
+      this.sent = payload;
+      return this;
+    }
+  };
+}
diff --git a/apps/api/src/reading/reading.controller.ts b/apps/api/src/reading/reading.controller.ts
new file mode 100644
index 0000000..aa058e3
--- /dev/null
+++ b/apps/api/src/reading/reading.controller.ts
@@ -0,0 +1,50 @@
+import { Body, Controller, Get, Headers, Param, Post, Res, UseGuards } from "@nestjs/common";
+import { FastifyReply } from "fastify";
+import { AuthGuard } from "../auth/auth.guard.js";
+import { ZodValidationPipe } from "../common/zod-validation.pipe.js";
+import { ReadingWindowDto, ReadingWindowSchema } from "./reading.dto.js";
+import { ReadingService } from "./reading.service.js";
+
+@Controller("books/:bookId")
+@UseGuards(AuthGuard)
+export class ReadingController {
+  constructor(private readonly reading: ReadingService) {}
+
+  @Get("reading-manifest")
+  manifest(@Param("bookId") bookId: string) {
+    return this.reading.manifest(Number(bookId));
+  }
+
+  @Get("reading-resources/:resourceId")
+  async resource(
+    @Param("bookId") bookId: string,
+    @Param("resourceId") resourceId: string,
+    @Headers("range") range: string | undefined,
+    @Headers("if-none-match") ifNoneMatch: string | undefined,
+    @Res() reply: FastifyReply
+  ) {
+    const resource = await this.reading.resource(Number(bookId), resourceId, range);
+    if (!range && ifNoneMatch === resource.etag) return reply.code(304).send();
+    if (resource.partial) {
+      reply.code(206);
+      reply.header("Content-Range", `bytes ${resource.start}-${resource.end}/${resource.size}`);
+    }
+    if (resource.supportsRanges) reply.header("Accept-Ranges", "bytes");
+    reply.header("Content-Length", String(resource.end - resource.start + 1));
+    reply.header("Content-Type", resource.contentType);
+    reply.header("ETag", resource.etag);
+    reply.header("Cache-Control", "private, max-age=3600, must-revalidate");
+    reply.header("X-Content-Type-Options", "nosniff");
+    return reply.send(resource.stream ?? resource.data);
+  }
+
+  @Post("reading-window")
+  window(@Param("bookId") bookId: string, @Body(new ZodValidationPipe(ReadingWindowSchema)) input: ReadingWindowDto) {
+    return this.reading.window(Number(bookId), input);
+  }
+
+  @Post("reading-resources/:resourceId/retry")
+  retry(@Param("bookId") bookId: string, @Param("resourceId") resourceId: string) {
+    return this.reading.retry(Number(bookId), resourceId);
+  }
+}
diff --git a/apps/api/src/reading/reading.dto.ts b/apps/api/src/reading/reading.dto.ts
new file mode 100644
index 0000000..74b479e
--- /dev/null
+++ b/apps/api/src/reading/reading.dto.ts
@@ -0,0 +1,9 @@
+import { z } from "zod";
+
+export const ReadingWindowSchema = z.object({
+  locator: z.string().trim().min(1).max(512),
+  mode: z.enum(["auto", "speed", "quality"]).default("auto"),
+  networkHint: z.enum(["offline", "slow", "normal", "fast", "unknown"]).default("unknown")
+});
+
+export type ReadingWindowDto = z.infer<typeof ReadingWindowSchema>;
diff --git a/apps/api/src/reading/reading.module.ts b/apps/api/src/reading/reading.module.ts
new file mode 100644
index 0000000..c6e4f69
--- /dev/null
+++ b/apps/api/src/reading/reading.module.ts
@@ -0,0 +1,20 @@
+import { Module } from "@nestjs/common";
+import { AuthModule } from "../auth/auth.module.js";
+import { DatabaseModule } from "../database/database.module.js";
+import { JobsModule } from "../jobs/jobs.module.js";
+import { ArchiveReadingSourceAdapter } from "./adapters/archive-reading-source.adapter.js";
+import { FilesystemReadingCacheAdapter } from "./adapters/filesystem-reading-cache.adapter.js";
+import { ReadingController } from "./reading.controller.js";
+import { ReadingCachePort, ReadingSourcePort } from "./reading.ports.js";
+import { ReadingService } from "./reading.service.js";
+
+@Module({
+  imports: [AuthModule, DatabaseModule, JobsModule],
+  controllers: [ReadingController],
+  providers: [
+    ReadingService,
+    { provide: ReadingSourcePort, useClass: ArchiveReadingSourceAdapter },
+    { provide: ReadingCachePort, useClass: FilesystemReadingCacheAdapter }
+  ]
+})
+export class ReadingModule {}
diff --git a/apps/api/src/reading/reading.ports.ts b/apps/api/src/reading/reading.ports.ts
new file mode 100644
index 0000000..a5ddf00
--- /dev/null
+++ b/apps/api/src/reading/reading.ports.ts
@@ -0,0 +1,12 @@
+import { ReadingBook, ReadingManifest, ReadingResourcePayload } from "./reading.types.js";
+
+export abstract class ReadingSourcePort {
+  abstract manifest(book: ReadingBook): Promise<ReadingManifest>;
+  abstract resource(book: ReadingBook, resourceId: string): Promise<ReadingResourcePayload>;
+}
+
+export abstract class ReadingCachePort {
+  abstract get(book: ReadingBook, resourceId: string): Promise<Buffer | null>;
+  abstract put(book: ReadingBook, resourceId: string, data: Buffer): Promise<void>;
+  abstract remove(book: ReadingBook, resourceId: string): Promise<void>;
+}
diff --git a/apps/api/src/reading/reading.service.test.ts b/apps/api/src/reading/reading.service.test.ts
new file mode 100644
index 0000000..6f6fde2
--- /dev/null
+++ b/apps/api/src/reading/reading.service.test.ts
@@ -0,0 +1,169 @@
+import { mkdtempSync, rmSync, writeFileSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { afterEach, describe, expect, it } from "vitest";
+import { eq } from "drizzle-orm";
+import { DatabaseService } from "../database/database.service.js";
+import { books, jobs, libraries } from "../database/schema.js";
+import { JobsService } from "../jobs/jobs.service.js";
+import { ReadingCachePort, ReadingSourcePort } from "./reading.ports.js";
+import { ReadingService } from "./reading.service.js";
+import { ReadingBook, ReadingManifest, ReadingResourcePayload } from "./reading.types.js";
+
+const previousDatabasePath = process.env.DATABASE_PATH;
+const previousStorageDir = process.env.STORAGE_DIR;
+const directories: string[] = [];
+
+afterEach(() => {
+  process.env.DATABASE_PATH = previousDatabasePath;
+  process.env.STORAGE_DIR = previousStorageDir;
+  for (const directory of directories.splice(0)) rmSync(directory, { recursive: true, force: true });
+});
+
+describe("ReadingService", () => {
+  it.runIf(canLoadBetterSqlite())("rejects books in disabled libraries", async () => {
+    const { database, bookId } = fixture(false);
+    const service = new ReadingService(database, new JobsService(database), new FakeSource(), new MemoryCache());
+    await expect(service.manifest(bookId)).rejects.toThrow("accessible library");
+    database.onModuleDestroy();
+  });
+
+  it.runIf(canLoadBetterSqlite())("reports a priority window around the current spine item without preparing while offline", async () => {
+    const { database, bookId } = fixture(true);
+    const service = new ReadingService(database, new JobsService(database), new FakeSource(), new MemoryCache());
+
+    const window = await service.window(bookId, { locator: "chapter-2", mode: "auto", networkHint: "offline" });
+
+    expect(window.current).toMatchObject({ resourceId: "chapter-2", relation: "current" });
+    expect(window.previous).toMatchObject({ resourceId: "chapter-1", relation: "previous" });
+    expect(window.next).toMatchObject({ resourceId: "chapter-3", relation: "next" });
+    expect(window.resources).toEqual([expect.objectContaining({ resourceId: "chapter-image", relation: "resource" })]);
+    expect(window.neighbors).toEqual([]);
+    expect(database.db.select().from((await import("../database/schema.js")).jobs).all()).toHaveLength(0);
+    database.onModuleDestroy();
+  });
+
+  it.runIf(canLoadBetterSqlite())("queues the current resource before previous and next resources on slow connections", async () => {
+    const { database, bookId } = fixture(true);
+    const service = new ReadingService(database, new JobsService(database), new FakeSource(), new MemoryCache());
+
+    const window = await service.window(bookId, { locator: "chapter-2", mode: "speed", networkHint: "slow" });
+
+    expect(window.current).toMatchObject({ resourceId: "chapter-2", relation: "current", state: "pending" });
+    expect(window.previous).toMatchObject({ resourceId: "chapter-1", relation: "previous", state: "pending" });
+    expect(window.next).toMatchObject({ resourceId: "chapter-3", relation: "next", state: "pending" });
+    const [job] = database.db.select().from(jobs).all();
+    expect(job).toMatchObject({ type: "prepare-reading-window", status: "queued" });
+    expect(JSON.parse(job.detail ?? "{}")).toEqual({ bookId, resourceIds: ["chapter-2", "chapter-image", "chapter-1", "chapter-3"] });
+    await flushImmediates();
+    database.onModuleDestroy();
+  });
+
+  it.runIf(canLoadBetterSqlite())("serves byte ranges for the original PDF resource", async () => {
+    const { database, bookId, directory } = fixture(true, "pdf");
+    const filePath = join(directory, "book.pdf");
+    writeFileSync(filePath, Buffer.from("0123456789"));
+    database.db.update(books).set({ filePath, fileSize: 10 }).where(eq(books.id, bookId)).run();
+    const service = new ReadingService(database, new JobsService(database), new FakeSource(), new MemoryCache());
+
+    const resource = await service.resource(bookId, "original", "bytes=2-5");
+
+    expect(resource).toMatchObject({
+      contentType: "application/pdf",
+      etag: '"pdf-etag"',
+      supportsRanges: true,
+      size: 10,
+      start: 2,
+      end: 5,
+      partial: true
+    });
+    await expect(readStream(resource.stream)).resolves.toEqual(Buffer.from("2345"));
+    database.onModuleDestroy();
+  });
+});
+
+class FakeSource extends ReadingSourcePort {
+  async manifest(book: ReadingBook): Promise<ReadingManifest> {
+    if (book.format === "pdf") {
+      return {
+        bookId: book.id,
+        format: "pdf",
+        version: "pdf-version",
+      revision: "pdf-version",
+      containerPath: null, opfPath: null, basePath: null,
+      resources: [{ resourceId: "original", href: "original", url: "/original", kind: "document", mediaType: "application/pdf", size: book.fileSize, state: "ready" }],
+      spine: [{ index: 0, href: "original", resourceId: "original", url: "/original", mediaType: "application/pdf", size: book.fileSize }],
+        capabilities: { byteRanges: true, derivedImages: false, lightweightPages: false }
+      };
+    }
+    return {
+      bookId: book.id,
+      format: "epub",
+      revision: "version",
+      version: "version",
+      containerPath: "META-INF/container.xml", opfPath: "OPS/package.opf", basePath: "OPS/",
+      resources: [
+        ...["chapter-1", "chapter-2", "chapter-3"].map((id) => ({ resourceId: id, href: id, url: `/${id}`, kind: "chapter" as const, mediaType: "application/xhtml+xml", size: 7, state: "ready" as const, ...(id === "chapter-2" ? { references: ["chapter-image"] } : {}) })),
+        { resourceId: "chapter-image", href: "image.jpg", url: "/chapter-image", kind: "image" as const, mediaType: "image/jpeg", size: 5, state: "ready" as const }
+      ],
+      spine: ["chapter-1", "chapter-2", "chapter-3"].map((id, index) => ({ index, href: id, resourceId: id, url: `/${id}`, mediaType: "application/xhtml+xml", size: 7 })),
+      capabilities: { byteRanges: false, derivedImages: true, lightweightPages: false }
+    };
+  }
+  async resource(book: ReadingBook, resourceId: string): Promise<ReadingResourcePayload> {
+    if (book.format === "pdf" && resourceId === "original") {
+      return { filePath: book.filePath, contentType: "application/pdf", size: book.fileSize, etag: '"pdf-etag"', supportsRanges: true };
+    }
+    return { data: Buffer.from("chapter"), contentType: "application/xhtml+xml", size: 7, etag: '"etag"', supportsRanges: false };
+  }
+}
+
+class MemoryCache extends ReadingCachePort {
+  private readonly values = new Map<string, Buffer>();
+  async get(_book: ReadingBook, resourceId: string) { return this.values.get(resourceId) ?? null; }
+  async put(_book: ReadingBook, resourceId: string, data: Buffer) { this.values.set(resourceId, data); }
+  async remove(_book: ReadingBook, resourceId: string) { this.values.delete(resourceId); }
+}
+
+function fixture(enabled: boolean, format: "epub" | "pdf" = "epub") {
+  const directory = mkdtempSync(join(tmpdir(), "readabook-reading-service-"));
+  directories.push(directory);
+  process.env.DATABASE_PATH = join(directory, "test.sqlite");
+  process.env.STORAGE_DIR = join(directory, "storage");
+  const database = new DatabaseService();
+  const now = database.now();
+  const library = database.db.insert(libraries).values({ name: "Library", path: directory, enabled, createdAt: now, updatedAt: now }).returning().get();
+  const book = database.db.insert(books).values({
+    libraryId: library.id, seriesId: null, title: "Book", author: null, description: null, isbn: null, isbn13: null,
+    identifiersJson: null, localMetadataJson: null, language: null, publisher: null, publishedDate: null, volumeNumber: null,
+    volumeLabel: null, format, filePath: join(directory, `book.${format}`), coverPath: null, metadataStatus: "none",
+    metadataProvenanceJson: null, scanStatus: "succeeded", enrichmentStatus: "idle", fileSize: 10, fileMtime: now,
+    createdAt: now, updatedAt: now
+  }).returning().get();
+  return { database, bookId: book.id, directory };
+}
+
+function canLoadBetterSqlite(): boolean {
+  try {
+    return Boolean(DatabaseService);
+  } catch {
+    return false;
+  }
+}
+
+function flushImmediates() {
+  return new Promise<void>((resolve) => setImmediate(resolve));
+}
+
+function readStream(stream: NodeJS.ReadableStream | undefined) {
+  return new Promise<Buffer>((resolve, reject) => {
+    if (!stream) {
+      resolve(Buffer.alloc(0));
+      return;
+    }
+    const chunks: Buffer[] = [];
+    stream.on("data", (chunk) => chunks.push(Buffer.isBuffer(chunk) ? chunk : Buffer.from(chunk)));
+    stream.on("error", reject);
+    stream.on("end", () => resolve(Buffer.concat(chunks)));
+  });
+}
diff --git a/apps/api/src/reading/reading.service.ts b/apps/api/src/reading/reading.service.ts
new file mode 100644
index 0000000..2a054ff
--- /dev/null
+++ b/apps/api/src/reading/reading.service.ts
@@ -0,0 +1,168 @@
+import { createHash } from "node:crypto";
+import { createReadStream } from "node:fs";
+import { BadRequestException, HttpException, HttpStatus, Inject, Injectable, NotFoundException } from "@nestjs/common";
+import { and, eq } from "drizzle-orm";
+import { DatabaseService } from "../database/database.service.js";
+import { books, libraries } from "../database/schema.js";
+import { JobsService } from "../jobs/jobs.service.js";
+import { ReadingCachePort, ReadingSourcePort } from "./reading.ports.js";
+import { ReadingBook, ReadingResourcePayload, ReadingWindowInput } from "./reading.types.js";
+
+@Injectable()
+export class ReadingService {
+  private readonly preparing = new Set<string>();
+
+  constructor(
+    private readonly database: DatabaseService,
+    private readonly jobs: JobsService,
+    @Inject(ReadingSourcePort) private readonly source: ReadingSourcePort,
+    @Inject(ReadingCachePort) private readonly cache: ReadingCachePort
+  ) {}
+
+  async manifest(bookId: number) {
+    return this.source.manifest(this.accessibleBook(bookId));
+  }
+
+  async resource(bookId: number, resourceId: string, range?: string): Promise<ReadingResourcePayload & { stream?: NodeJS.ReadableStream; start: number; end: number; partial: boolean }> {
+    const book = this.accessibleBook(bookId);
+    const cached = book.format === "epub" ? await this.cache.get(book, resourceId) : null;
+    const manifestResource = cached ? (await this.source.manifest(book)).resources.find((resource) => resource.resourceId === resourceId) : null;
+    if (cached && !manifestResource) throw new NotFoundException("Reading resource not found");
+    const payload = cached && manifestResource
+      ? { data: cached, contentType: manifestResource.mediaType, size: cached.length, etag: manifestVersionEtag(book, resourceId), supportsRanges: false }
+      : await this.source.resource(book, resourceId);
+    const byteRange = parseByteRange(range, payload.size, payload.supportsRanges);
+    if (payload.filePath) {
+      return { ...payload, stream: createReadStream(payload.filePath, { start: byteRange.start, end: byteRange.end }), ...byteRange };
+    }
+    const data = payload.data;
+    if (!data) throw new NotFoundException("Reading resource not found");
+    if (!cached) await this.cache.put(book, resourceId, data);
+    return { ...payload, data: data.subarray(byteRange.start, byteRange.end + 1), ...byteRange };
+  }
+
+  async window(bookId: number, input: ReadingWindowInput) {
+    const book = this.accessibleBook(bookId);
+    const manifest = await this.source.manifest(book);
+    const position = resolvePosition(input.locator, manifest.spine);
+    const current = manifest.spine[position];
+    const referenced = referencedResources(current.resourceId, manifest.resources);
+    const ordered = priorityWindow(manifest.spine, position, referenced, input.networkHint === "slow" || input.mode === "speed" ? 1 : 2);
+    const states = await Promise.all(ordered.map(async ({ id, distance }) => ({
+      resourceId: id,
+      relation: distance === 0 ? "current" : distance === null ? "resource" : distance === -1 ? "previous" : distance === 1 ? "next" : "neighbor",
+      state: await this.resourceState(book, id)
+    })));
+    if (input.networkHint !== "offline") this.enqueuePreparation(book, ordered.map((entry) => entry.id));
+    return {
+      bookId,
+      locator: input.locator,
+      mode: input.mode,
+      networkHint: input.networkHint,
+      current: states.find((state) => state.relation === "current") ?? null,
+      previous: states.find((state) => state.relation === "previous") ?? null,
+      next: states.find((state) => state.relation === "next") ?? null,
+      resources: states.filter((state) => state.relation === "resource"),
+      neighbors: states.filter((state) => state.relation === "neighbor")
+    };
+  }
+
+  async retry(bookId: number, resourceId: string) {
+    const book = this.accessibleBook(bookId);
+    const manifest = await this.source.manifest(book);
+    if (!manifest.resources.some((resource) => resource.resourceId === resourceId)) throw new NotFoundException("Reading resource not found");
+    await this.cache.remove(book, resourceId);
+    this.enqueuePreparation(book, [resourceId], true);
+    return { bookId, resourceId, state: "pending" as const };
+  }
+
+  private accessibleBook(bookId: number): ReadingBook {
+    if (!Number.isInteger(bookId) || bookId < 1) throw new BadRequestException("Invalid book id");
+    const row = this.database.db
+      .select({ id: books.id, format: books.format, filePath: books.filePath, fileSize: books.fileSize, fileMtime: books.fileMtime })
+      .from(books)
+      .innerJoin(libraries, and(eq(libraries.id, books.libraryId), eq(libraries.enabled, true)))
+      .where(eq(books.id, bookId))
+      .get();
+    if (!row) throw new NotFoundException("Book not found in an accessible library");
+    return row;
+  }
+
+  private async resourceState(book: ReadingBook, resourceId: string) {
+    if (book.format === "pdf" && resourceId === "original") return "ready" as const;
+    return (await this.cache.get(book, resourceId)) ? "ready" as const : "pending" as const;
+  }
+
+  private enqueuePreparation(book: ReadingBook, resourceIds: string[], force = false): void {
+    const pending = resourceIds.filter((id) => force || !this.preparing.has(`${book.id}:${id}`));
+    if (!pending.length) return;
+    const job = this.jobs.create("prepare-reading-window", JSON.stringify({ bookId: book.id, resourceIds: pending }));
+    for (const id of pending) this.preparing.add(`${book.id}:${id}`);
+    setImmediate(async () => {
+      this.jobs.markRunning(job.id, JSON.stringify({ bookId: book.id, resourceIds: pending }));
+      try {
+        for (const resourceId of pending) {
+          const payload = await this.source.resource(book, resourceId);
+          if (payload.data) await this.cache.put(book, resourceId, payload.data);
+        }
+        this.jobs.markSucceeded(job.id, JSON.stringify({ bookId: book.id, prepared: pending }));
+      } catch (error) {
+        this.jobs.markFailed(job.id, error);
+      } finally {
+        for (const id of pending) this.preparing.delete(`${book.id}:${id}`);
+      }
+    });
+  }
+}
+
+function manifestVersionEtag(book: ReadingBook, resourceId: string): string {
+  return `\"${createHash("sha256").update(`${book.id}:${book.fileSize}:${book.fileMtime}:${resourceId}`).digest("base64url")}\"`;
+}
+
+function resolvePosition(locator: string, spine: Array<{ index: number; href: string; resourceId: string }>): number {
+  if (!spine.length) throw new BadRequestException("Book has no readable spine");
+  const direct = spine.findIndex((item) => item.resourceId === locator || item.href === locator);
+  if (direct >= 0) return direct;
+  const numeric = Number(locator.match(/(?:^|:)(\d+)(?:$|:)/)?.[1]);
+  if (Number.isInteger(numeric) && numeric >= 0 && numeric < spine.length) return numeric;
+  throw new BadRequestException("Locator does not identify a readable resource");
+}
+
+function priorityWindow(spine: Array<{ resourceId: string }>, position: number, referenced: string[], radius: number) {
+  const result: Array<{ id: string; distance: number | null }> = [{ id: spine[position].resourceId, distance: 0 }];
+  for (const resourceId of referenced) result.push({ id: resourceId, distance: null });
+  for (let distance = 1; distance <= radius; distance += 1) {
+    if (position - distance >= 0) result.push({ id: spine[position - distance].resourceId, distance: -distance });
+    if (position + distance < spine.length) result.push({ id: spine[position + distance].resourceId, distance });
+  }
+  return result.filter((entry, index) => result.findIndex((candidate) => candidate.id === entry.id) === index);
+}
+
+function referencedResources(currentId: string, resources: Array<{ resourceId: string; references?: string[] }>): string[] {
+  const byId = new Map(resources.map((resource) => [resource.resourceId, resource]));
+  const result: string[] = [];
+  const queue = [...(byId.get(currentId)?.references ?? [])];
+  const seen = new Set([currentId]);
+  while (queue.length) {
+    const resourceId = queue.shift()!;
+    if (seen.has(resourceId)) continue;
+    seen.add(resourceId);
+    result.push(resourceId);
+    queue.push(...(byId.get(resourceId)?.references ?? []));
+  }
+  return result;
+}
+
+function parseByteRange(range: string | undefined, size: number, supported: boolean) {
+  if (!range) return { start: 0, end: Math.max(size - 1, 0), partial: false };
+  if (!supported || size <= 0) throw new HttpException("Requested range not satisfiable", HttpStatus.REQUESTED_RANGE_NOT_SATISFIABLE);
+  const match = range.match(/^bytes=(\d*)-(\d*)$/);
+  if (!match) throw new HttpException("Requested range not satisfiable", HttpStatus.REQUESTED_RANGE_NOT_SATISFIABLE);
+  const suffix = !match[1] && match[2] ? Number(match[2]) : null;
+  const start = suffix === null ? Number(match[1]) : Math.max(size - suffix, 0);
+  const end = suffix === null && match[2] ? Number(match[2]) : size - 1;
+  if (!Number.isInteger(start) || !Number.isInteger(end) || start < 0 || end < start || start >= size) {
+    throw new HttpException("Requested range not satisfiable", HttpStatus.REQUESTED_RANGE_NOT_SATISFIABLE);
+  }
+  return { start, end: Math.min(end, size - 1), partial: true };
+}
diff --git a/apps/api/src/reading/reading.types.ts b/apps/api/src/reading/reading.types.ts
new file mode 100644
index 0000000..1f539f4
--- /dev/null
+++ b/apps/api/src/reading/reading.types.ts
@@ -0,0 +1,63 @@
+export type ReadingFormat = "epub" | "pdf";
+export type ReadingResourceKind = "chapter" | "image" | "stylesheet" | "font" | "document";
+export type ReadingResourceState = "ready" | "pending" | "unsupported" | "failed";
+
+export type ReadingResource = {
+  resourceId: string;
+  href: string;
+  url: string;
+  kind: ReadingResourceKind;
+  mediaType: string;
+  size: number;
+  state: ReadingResourceState;
+  references?: string[];
+};
+
+export type ReadingSpineItem = {
+  index: number;
+  href: string;
+  resourceId: string;
+  url: string;
+  mediaType: string;
+  size: number;
+};
+
+export type ReadingManifest = {
+  bookId: number;
+  format: ReadingFormat;
+  revision: string;
+  version: string;
+  containerPath: string | null;
+  opfPath: string | null;
+  basePath: string | null;
+  resources: ReadingResource[];
+  spine: ReadingSpineItem[];
+  capabilities: {
+    byteRanges: boolean;
+    derivedImages: boolean;
+    lightweightPages: boolean;
+  };
+};
+
+export type ReadingBook = {
+  id: number;
+  format: string;
+  filePath: string;
+  fileSize: number;
+  fileMtime: string;
+};
+
+export type ReadingResourcePayload = {
+  data?: Buffer;
+  filePath?: string;
+  contentType: string;
+  size: number;
+  etag: string;
+  supportsRanges: boolean;
+};
+
+export type ReadingWindowInput = {
+  locator: string;
+  mode: "auto" | "speed" | "quality";
+  networkHint: "offline" | "slow" | "normal" | "fast" | "unknown";
+};
diff --git a/apps/web/src/api/client.test.ts b/apps/web/src/api/client.test.ts
index 2811fbc..5e96723 100644
--- a/apps/web/src/api/client.test.ts
+++ b/apps/web/src/api/client.test.ts
@@ -59,6 +59,27 @@ describe("api fallback helpers", () => {
     expect(headers.has("Content-Type")).toBe(false);
   });
 
+  it("sends the adaptive reading window with the selected network policy", async () => {
+    const fetchMock = vi.fn().mockResolvedValue(
+      new Response(JSON.stringify({ bookId: 12, locator: "chapter-2", current: null, previous: null, next: null, neighbors: [] }), {
+        status: 200,
+        headers: { "Content-Type": "application/json" }
+      })
+    );
+    vi.stubGlobal("fetch", fetchMock);
+
+    await api.readingWindow(12, "chapter-2", "speed", "slow");
+
+    expect(fetchMock.mock.calls[0][0]).toBe("/books/12/reading-window");
+    const init = fetchMock.mock.calls[0][1] as RequestInit;
+    expect(init.method).toBe("POST");
+    expect(JSON.parse(init.body as string)).toEqual({ locator: "chapter-2", mode: "speed", networkHint: "slow" });
+  });
+
+  it("builds an encoded reading resource URL", () => {
+    expect(api.readingResourceUrl(12, "chapter/one")).toBe("/books/12/reading-resources/chapter%2Fone");
+  });
+
   it("surfaces create library API errors without fallback", async () => {
     const fetchMock = vi.fn().mockResolvedValue(
       new Response(JSON.stringify({ message: "Library path does not exist" }), {
diff --git a/apps/web/src/api/client.ts b/apps/web/src/api/client.ts
index cddc7d7..5dac796 100644
--- a/apps/web/src/api/client.ts
+++ b/apps/web/src/api/client.ts
@@ -27,7 +27,16 @@ import {
   mockProgress,
   mockUser
 } from "./mockData";
-import type { CbzPagesDto, ContinueItem, ReaderPreferencesDto, Session } from "./types";
+import type {
+  CbzPagesDto,
+  ContinueItem,
+  ReaderPreferencesDto,
+  ReadingConnectionMode,
+  ReadingManifestDto,
+  ReadingNetworkHint,
+  ReadingWindowDto,
+  Session
+} from "./types";
 
 const API_BASE = import.meta.env.VITE_API_BASE_URL ?? "";
 const READER_PREFERENCES_PREFIX = "readabook:reader-preferences:";
@@ -179,6 +188,21 @@ export const api = {
   bookCoverUrl(id: number): string {
     return `${API_BASE}/books/${id}/cover`;
   },
+  async readingManifest(id: number): Promise<ReadingManifestDto> {
+    return request<ReadingManifestDto>(`/books/${id}/reading-manifest`);
+  },
+  readingResourceUrl(id: number, resourceId: string): string {
+    return `${API_BASE}/books/${id}/reading-resources/${encodeURIComponent(resourceId)}`;
+  },
+  async readingWindow(id: number, locator: string, mode: ReadingConnectionMode, networkHint: ReadingNetworkHint): Promise<ReadingWindowDto> {
+    return request<ReadingWindowDto>(`/books/${id}/reading-window`, {
+      method: "POST",
+      body: JSON.stringify({ locator, mode, networkHint })
+    });
+  },
+  async retryReadingResource(id: number, resourceId: string): Promise<void> {
+    await request(`/books/${id}/reading-resources/${encodeURIComponent(resourceId)}/retry`, { method: "POST" });
+  },
   async cbzPages(id: number): Promise<CbzPagesDto> {
     return request<CbzPagesDto>(`/books/${id}/pages`);
   },
diff --git a/apps/web/src/api/types.ts b/apps/web/src/api/types.ts
index af8a676..fc30a89 100644
--- a/apps/web/src/api/types.ts
+++ b/apps/web/src/api/types.ts
@@ -32,6 +32,63 @@ export type ReaderMode = "horizontal" | "vertical";
 
 export type ReaderFit = "page" | "width";
 
+export type ReadingConnectionMode = "auto" | "speed" | "quality";
+export type ReadingNetworkHint = "offline" | "slow" | "normal" | "fast" | "unknown";
+
+export type ReadingResourceDto = {
+  resourceId: string;
+  href: string;
+  url: string;
+  kind: "chapter" | "image" | "stylesheet" | "font" | "document";
+  mediaType: string;
+  size: number;
+  state: "ready" | "pending" | "unsupported" | "failed";
+  references?: string[];
+};
+
+export type ReadingSpineItemDto = {
+  index: number;
+  href: string;
+  resourceId: string;
+  url: string;
+  mediaType: string;
+  size: number;
+};
+
+export type ReadingManifestDto = {
+  bookId: number;
+  format: "epub" | "pdf";
+  revision: string;
+  version?: string;
+  containerPath: string | null;
+  opfPath: string | null;
+  basePath: string | null;
+  resources: ReadingResourceDto[];
+  spine: ReadingSpineItemDto[];
+  capabilities: {
+    byteRanges: boolean;
+    derivedImages: boolean;
+    lightweightPages: boolean;
+  };
+};
+
+export type ReadingWindowItemDto = {
+  resourceId: string;
+  relation: "current" | "previous" | "next" | "neighbor";
+  state: ReadingResourceDto["state"];
+};
+
+export type ReadingWindowDto = {
+  bookId: number;
+  locator: string;
+  mode: ReadingConnectionMode;
+  networkHint: ReadingNetworkHint;
+  current: ReadingWindowItemDto | null;
+  previous: ReadingWindowItemDto | null;
+  next: ReadingWindowItemDto | null;
+  neighbors: ReadingWindowItemDto[];
+};
+
 export type ReaderPreferencesDto = {
   mode: ReaderMode;
   fit?: ReaderFit;
diff --git a/apps/web/src/pages/ReaderPage.tsx b/apps/web/src/pages/ReaderPage.tsx
index 3b32ebb..05ada56 100644
--- a/apps/web/src/pages/ReaderPage.tsx
+++ b/apps/web/src/pages/ReaderPage.tsx
@@ -10,6 +10,7 @@ import { clampReaderZoom, READER_ZOOM_DEFAULT, READER_ZOOM_STEP } from "../reade
 import { majorityVisiblePage, type ReaderMode } from "../reader/readerScroll";
 import { useReaderPreferences } from "../reader/useReaderPreferences";
 import { useReaderProgress } from "../reader/useReaderProgress";
+import { useAdaptiveReading } from "../reader/useAdaptiveReading";
 import { navigate } from "../router";
 import { EmptyState, LoadingState, Panel } from "../components/ui";
 
@@ -69,6 +70,7 @@ export function ReaderPage({ bookId }: { bookId: number }) {
   const [readerControls, setReaderControls] = useState<ReaderControls>(idleControls);
   const { progress, error: progressError, save, queueSave } = useReaderProgress(bookId);
   const { preferences, setMode: saveReaderMode, error: preferencesError } = useReaderPreferences(bookId);
+  const adaptive = useAdaptiveReading(bookId, book?.format === "epub" || book?.format === "pdf");
 
   async function loadBook() {
     setLoading(true);
@@ -104,7 +106,11 @@ export function ReaderPage({ bookId }: { bookId: number }) {
     if (nextPage) setPage((current) => (current === nextPage ? current : nextPage));
   }, [progress]);
 
-  const fileUrl = useMemo(() => api.bookFileUrl(bookId), [bookId]);
+  const legacyFileUrl = useMemo(() => (book?.format === "epub" ? "" : api.bookFileUrl(bookId)), [book?.format, bookId]);
+  const adaptiveFileUrl = useMemo(() => {
+    if (book?.format !== "pdf" || !adaptive.manifest) return legacyFileUrl;
+    return adaptive.manifest.spine[0]?.url ?? api.readingResourceUrl(bookId, "original");
+  }, [adaptive.manifest, book?.format, bookId, legacyFileUrl]);
   const backHref = useMemo(() => (book ? `/book/${book.id}` : "/home"), [book]);
   const savePdfPage = useCallback(
     (nextPage: number, pages: number, anchor = 1, strategy: "immediate" | "queued" = "immediate") => {
@@ -113,10 +119,19 @@ export function ReaderPage({ bookId }: { bookId: number }) {
       const percent = pdfPagePercent(nextPage, pages, anchor);
       if (strategy === "queued") queueSave(locator, percent);
       else void save(locator, percent);
+      void adaptive.prioritize(adaptive.manifest?.spine[0]?.resourceId ?? "original");
     },
-    [queueSave, save]
+    [adaptive.manifest?.spine, adaptive.prioritize, queueSave, save]
   );
-  const saveEpubLocator = useCallback((locator: string, percent: number) => void save(locator, percent), [save]);
+  const saveEpubLocator = useCallback((locator: string, percent: number, readingLocator: string) => {
+    void save(locator, percent);
+    void adaptive.prioritize(readingLocator);
+  }, [adaptive.prioritize, save]);
+
+  useEffect(() => {
+    const first = adaptive.manifest?.spine[0]?.resourceId;
+    if (first) void adaptive.prioritize(first);
+  }, [adaptive.manifest?.revision, adaptive.mode]);
   const saveComicPage = useCallback(
     (nextPage: number, pages: number, anchor = 1, strategy: "immediate" | "queued" = "immediate") => {
       setPage(nextPage);
@@ -129,7 +144,7 @@ export function ReaderPage({ bookId }: { bookId: number }) {
     [book?.format, queueSave, save]
   );
 
-  const readerError = error ?? progressError ?? preferencesError;
+  const readerError = error ?? progressError ?? preferencesError ?? adaptive.error;
   const supportsZoom = book?.format === "pdf" || book?.format === "cbz" || book?.format === "cbr";
   const supportsMode = supportsZoom;
   const currentVisiblePage = useCallback(() => {
@@ -231,10 +246,12 @@ export function ReaderPage({ bookId }: { bookId: number }) {
       title={book?.title ?? "Ouverture du lecteur"}
       backHref={backHref}
       error={readerError}
-      onRetry={error ? () => void loadBook() : undefined}
       controls={readerControls}
       zoomControls={zoomControls}
       modeControls={modeControls}
+      connectionControls={book.format === "epub" || book.format === "pdf" ? { mode: adaptive.mode, onModeChange: adaptive.setMode } : undefined}
+      activity={book.format === "epub" || book.format === "pdf" ? adaptive.statusLabel : undefined}
+      onRetry={error ? () => void loadBook() : adaptive.error ? adaptive.retry : undefined}
     >
       <ReaderCrashBoundary
         resetKey={`${bookId}:${book?.format ?? "loading"}:${mode}`}
@@ -273,7 +290,7 @@ export function ReaderPage({ bookId }: { bookId: number }) {
       >
         {book.format === "pdf" ? (
           <PdfReader
-            url={fileUrl}
+            url={adaptiveFileUrl}
             page={page}
             backHref={backHref}
             zoom={zoom}
@@ -290,15 +307,17 @@ export function ReaderPage({ bookId }: { bookId: number }) {
             onPageCommit={saveComicPage}
             onControlsChange={setReaderControls}
           />
-        ) : (
+        ) : adaptive.manifest?.format === "epub" ? (
           <EpubReader
-            url={fileUrl}
+            manifest={adaptive.manifest}
             locator={progress?.locator}
             backHref={backHref}
             mode="horizontal"
             onLocatorChange={saveEpubLocator}
             onControlsChange={setReaderControls}
           />
+        ) : (
+          <div className="reader-fallback"><span>Ouverture de la page…</span></div>
         )}
       </ReaderCrashBoundary>
     </ReaderShell>
diff --git a/apps/web/src/reader/EpubReader.tsx b/apps/web/src/reader/EpubReader.tsx
index c764313..a00704f 100644
--- a/apps/web/src/reader/EpubReader.tsx
+++ b/apps/web/src/reader/EpubReader.tsx
@@ -1,36 +1,60 @@
 import { useEffect, useRef, useState } from "react";
+import type { ReadingManifestDto, ReaderMode } from "../api/types";
 import { ReaderError, readerErrorMessage } from "./ReaderError";
 import type { ReaderControls } from "./ReaderShell";
-import type { ReaderMode } from "../api/types";
-
-type FoliateLocation = {
-  cfi?: string;
-  fraction?: number;
-  current?: number;
-  total?: number;
-};
 
+type FoliateLocation = { cfi?: string; fraction?: number; current?: number; total?: number };
 type FoliateView = HTMLElement & {
-  open(input: File | Blob | string): Promise<void>;
+  open(input: unknown): Promise<void>;
   close(): void;
   goLeft(): Promise<void>;
   goRight(): Promise<void>;
   goTo(target: string): Promise<unknown>;
   next(): Promise<void>;
-  lastLocation?: FoliateLocation;
+};
+type EpubApiLoader = {
+  loadText(path: string): Promise<string | null>;
+  loadBlob(path: string): Promise<Blob | null>;
+  getSize(path: string): number;
 };
 
-export function epubFileName(url: string): string {
+function normalizedResourcePath(path: string): string {
+  const withoutFragment = path.split("#", 1)[0].split("?", 1)[0];
   try {
-    const base = globalThis.location?.href ?? "http://readabook.local/";
-    const pathname = new URL(url, base).pathname;
-    const name = pathname.split("/").filter(Boolean).at(-1);
-    return name && name.includes(".") ? name : "book.epub";
+    return decodeURI(withoutFragment).replace(/^\.\//, "").replace(/^\/+/, "");
   } catch {
-    return "book.epub";
+    return withoutFragment.replace(/^\.\//, "").replace(/^\/+/, "");
   }
 }
 
+export function createEpubApiLoader(manifest: ReadingManifestDto, fetcher: typeof fetch = fetch): EpubApiLoader {
+  const resources = new Map(manifest.resources.map((resource) => [normalizedResourcePath(resource.href), resource]));
+  const responses = new Map<string, Promise<Blob>>();
+  const loadBlob = async (path: string) => {
+    const resource = resources.get(normalizedResourcePath(path));
+    if (!resource) return null;
+    let pending = responses.get(resource.resourceId);
+    if (!pending) {
+      pending = fetcher(resource.url, { credentials: "include", cache: "default" }).then(async (response) => {
+        if (!response.ok) throw new Error(`${response.status} ${response.statusText}`);
+        return response.blob();
+      });
+      responses.set(resource.resourceId, pending);
+    }
+    try {
+      return await pending;
+    } catch (error) {
+      responses.delete(resource.resourceId);
+      throw error;
+    }
+  };
+  return {
+    loadBlob,
+    loadText: async (path) => (await loadBlob(path))?.text() ?? null,
+    getSize: (path) => resources.get(normalizedResourcePath(path))?.size ?? 0
+  };
+}
+
 function locationPercent(location: FoliateLocation): number {
   if (typeof location.fraction === "number") return Math.max(0, Math.min(100, location.fraction * 100));
   if (typeof location.current === "number" && typeof location.total === "number" && location.total > 0) {
@@ -39,24 +63,18 @@ function locationPercent(location: FoliateLocation): number {
   return 1;
 }
 
-export function EpubReader({
-  url,
-  locator,
-  backHref,
-  mode,
-  onLocatorChange,
-  onControlsChange
-}: {
-  url: string;
+export function EpubReader({ manifest, locator, backHref, mode, onLocatorChange, onControlsChange }: {
+  manifest: ReadingManifestDto;
   locator?: string;
   backHref: string;
   mode: ReaderMode;
-  onLocatorChange: (locator: string, percent: number) => void;
+  onLocatorChange: (locator: string, percent: number, readingLocator: string) => void;
   onControlsChange: (controls: ReaderControls) => void;
 }) {
   const hostRef = useRef<HTMLDivElement>(null);
   const viewRef = useRef<FoliateView | null>(null);
   const locatorRef = useRef(locator);
+  const sectionIndexRef = useRef(0);
   const [loading, setLoading] = useState(true);
   const [error, setError] = useState<string>();
   const [attempt, setAttempt] = useState(0);
@@ -65,43 +83,39 @@ export function EpubReader({
     onControlsChange({
       canPrevious: !loading && !error,
       canNext: !loading && !error,
-      positionLabel: loading ? "Ouverture EPUB" : "Lecture integree",
+      positionLabel: loading ? "Ouverture de la page…" : "Lecture intégrée",
       onPrevious: () => void viewRef.current?.goLeft(),
       onNext: () => void viewRef.current?.goRight()
     });
   }, [error, loading, onControlsChange]);
 
-  useEffect(() => {
-    locatorRef.current = locator;
-  }, [locator]);
+  useEffect(() => { locatorRef.current = locator; }, [locator]);
 
   useEffect(() => {
     let cancelled = false;
     let view: FoliateView | null = null;
-
     async function mount() {
       try {
         setLoading(true);
         setError(undefined);
-        await import("foliate-js/view.js");
+        const [{ EPUB }] = await Promise.all([import("foliate-js/epub.js"), import("foliate-js/view.js")]);
         if (cancelled || !hostRef.current) return;
-
-        const response = await fetch(url, { credentials: "include" });
-        if (!response.ok) throw new Error(`${response.status} ${response.statusText}`);
-        const blob = await response.blob();
+        const book = await new EPUB(createEpubApiLoader(manifest)).init();
         if (cancelled || !hostRef.current) return;
-
         view = document.createElement("foliate-view") as FoliateView;
         view.classList.add("epub-view");
+        view.addEventListener("load", (event) => {
+          const index = (event as CustomEvent<{ index?: number }>).detail?.index;
+          if (typeof index === "number") sectionIndexRef.current = index;
+        });
         view.addEventListener("relocate", (event) => {
           const location = (event as CustomEvent<FoliateLocation>).detail;
-          if (location?.cfi) onLocatorChange(location.cfi, locationPercent(location));
+          const spine = manifest.spine[sectionIndexRef.current];
+          if (location?.cfi && spine) onLocatorChange(location.cfi, locationPercent(location), spine.resourceId);
         });
         hostRef.current.replaceChildren(view);
         viewRef.current = view;
-
-        const file = new File([blob], epubFileName(url), { type: blob.type || "application/epub+zip" });
-        await view.open(file);
+        await view.open(book);
         if (cancelled) return;
         if (locatorRef.current) await view.goTo(locatorRef.current);
         else await view.next();
@@ -113,7 +127,6 @@ export function EpubReader({
         }
       }
     }
-
     void mount();
     return () => {
       cancelled = true;
@@ -121,7 +134,7 @@ export function EpubReader({
       view?.remove();
       if (viewRef.current === view) viewRef.current = null;
     };
-  }, [attempt, onLocatorChange, url]);
+  }, [attempt, manifest, onLocatorChange]);
 
   useEffect(() => {
     viewRef.current?.classList.toggle("epub-view-vertical", mode === "vertical");
@@ -129,28 +142,10 @@ export function EpubReader({
   }, [mode]);
 
   if (error) {
-    return (
-      <div className="epub-reader">
-        <ReaderError
-          title="Lecture EPUB indisponible"
-          detail="ReadaBook n'a pas pu ouvrir ce fichier dans le lecteur web."
-          technicalDetail={error}
-          downloadUrl={url}
-          backHref={backHref}
-          onRetry={() => setAttempt((value) => value + 1)}
-        />
-      </div>
-    );
+    return <div className="epub-reader"><ReaderError title="Lecture EPUB indisponible" detail="ReadaBook n'a pas pu ouvrir cette page dans le lecteur web." technicalDetail={error} backHref={backHref} onRetry={() => setAttempt((value) => value + 1)} /></div>;
   }
-
-  return (
-    <div className={`epub-reader epub-reader-${mode}`}>
-      {loading && (
-        <div className="reader-fallback">
-          <span>Ouverture EPUB</span>
-        </div>
-      )}
-      <div className="epub-host" ref={hostRef} />
-    </div>
-  );
+  return <div className={`epub-reader epub-reader-${mode}`}>
+    {loading && <div className="reader-fallback"><span>Ouverture de la page…</span></div>}
+    <div className="epub-host" ref={hostRef} />
+  </div>;
 }
diff --git a/apps/web/src/reader/EpubReaderAdaptive.test.ts b/apps/web/src/reader/EpubReaderAdaptive.test.ts
new file mode 100644
index 0000000..93e2d8c
--- /dev/null
+++ b/apps/web/src/reader/EpubReaderAdaptive.test.ts
@@ -0,0 +1,41 @@
+import { readFileSync } from "node:fs";
+import { describe, expect, it, vi } from "vitest";
+import type { ReadingManifestDto } from "../api/types";
+import { createEpubApiLoader } from "./EpubReader";
+
+const manifest: ReadingManifestDto = {
+  bookId: 4,
+  format: "epub",
+  revision: "rev-1",
+  containerPath: "META-INF/container.xml",
+  opfPath: "OPS/package.opf",
+  basePath: "OPS/",
+  resources: [
+    { resourceId: "container", href: "META-INF/container.xml", url: "/books/4/reading-resources/container", mediaType: "application/xml", size: 12, kind: "document", state: "ready" },
+    { resourceId: "chapter", href: "OPS/text/chapter.xhtml", url: "/books/4/reading-resources/chapter", mediaType: "application/xhtml+xml", size: 18, kind: "chapter", state: "ready" }
+  ],
+  spine: [{ index: 0, href: "OPS/text/chapter.xhtml", resourceId: "chapter", url: "/books/4/reading-resources/chapter", mediaType: "application/xhtml+xml", size: 18 }],
+  capabilities: { byteRanges: false, derivedImages: true, lightweightPages: false }
+};
+
+describe("EPUB adaptive loader", () => {
+  it("loads manifest resources with credentials and reuses a fetched entry", async () => {
+    const fetcher = vi.fn().mockResolvedValue(new Response("<html>chapter</html>", { status: 200 }));
+    const loader = createEpubApiLoader(manifest, fetcher);
+
+    await expect(loader.loadText("OPS/text/chapter.xhtml#part")).resolves.toBe("<html>chapter</html>");
+    await loader.loadBlob("OPS/text/chapter.xhtml");
+
+    expect(fetcher).toHaveBeenCalledTimes(1);
+    expect(fetcher).toHaveBeenCalledWith("/books/4/reading-resources/chapter", { credentials: "include", cache: "default" });
+    expect(loader.getSize("OPS/text/chapter.xhtml")).toBe(18);
+  });
+
+  it("does not contain the complete-book fetch path", () => {
+    const source = readFileSync(new URL("./EpubReader.tsx", import.meta.url), "utf8");
+    expect(source).not.toContain("bookFileUrl");
+    expect(source).not.toContain("fetch(url");
+    expect(source).not.toContain("new File(");
+    expect(source).toContain("new EPUB(createEpubApiLoader(manifest)).init()");
+  });
+});
diff --git a/apps/web/src/reader/PdfReader.tsx b/apps/web/src/reader/PdfReader.tsx
index edf720e..7af3567 100644
--- a/apps/web/src/reader/PdfReader.tsx
+++ b/apps/web/src/reader/PdfReader.tsx
@@ -285,7 +285,7 @@ export function PdfReader({ url, page, backHref, zoom, mode, onPageCommit, onCon
     onControlsChange({
       canPrevious: !loadingDocument && !documentError && !pageError && currentPage > 1,
       canNext: !loadingDocument && !documentError && !pageError && currentPage < pages,
-      positionLabel: loadingDocument ? "Chargement" : readerPositionLabel(currentPage, pages),
+      positionLabel: loadingDocument ? "Ouverture de la page…" : readerPositionLabel(currentPage, pages),
       onPrevious: () => go(currentPage - 1),
       onNext: () => go(currentPage + 1)
     });
@@ -584,7 +584,7 @@ export function PdfReader({ url, page, backHref, zoom, mode, onPageCommit, onCon
     <div className={`pdf-reader${mode === "vertical" ? " pdf-reader-vertical" : ""}`} ref={frameRef}>
       {loadingDocument || !documentProxy ? (
         <div className="reader-fallback">
-          <span>Ouverture PDF</span>
+          <span>Ouverture de la page…</span>
         </div>
       ) : mode === "vertical" ? (
         <div className="reader-vertical-stack">
@@ -619,7 +619,7 @@ export function PdfReader({ url, page, backHref, zoom, mode, onPageCommit, onCon
         <div className="pdf-page-frame" data-reader-page={currentPage}>
           {(!viewportSize || loadingPage || !pageRendered) && (
             <div className="reader-fallback">
-              <span>Page {currentPage}</span>
+              <span>Ouverture de la page…</span>
             </div>
           )}
           <canvas ref={canvasRef} data-pdf-render-status={pageStatus} style={{ visibility: showCanvas ? "visible" : "hidden" }} />
diff --git a/apps/web/src/reader/ReaderError.tsx b/apps/web/src/reader/ReaderError.tsx
index 7a184de..ad9ad87 100644
--- a/apps/web/src/reader/ReaderError.tsx
+++ b/apps/web/src/reader/ReaderError.tsx
@@ -18,7 +18,7 @@ export function ReaderError({
   title: string;
   detail: string;
   technicalDetail?: string;
-  downloadUrl: string;
+  downloadUrl?: string;
   backHref: string;
   onRetry: () => void;
 }) {
@@ -37,10 +37,12 @@ export function ReaderError({
           <ArrowLeft size={16} />
           Retour à la fiche
         </button>
-        <a className="ghost-button" href={downloadUrl} download>
-          <Download size={16} />
-          Télécharger
-        </a>
+        {downloadUrl && (
+          <a className="ghost-button" href={downloadUrl} download>
+            <Download size={16} />
+            Télécharger
+          </a>
+        )}
       </div>
       {technicalDetail && (
         <details>
diff --git a/apps/web/src/reader/ReaderShell.tsx b/apps/web/src/reader/ReaderShell.tsx
index 47f023a..f0f87a0 100644
--- a/apps/web/src/reader/ReaderShell.tsx
+++ b/apps/web/src/reader/ReaderShell.tsx
@@ -14,6 +14,7 @@ import {
 import { readerMovedBeyondTap, readerPinchZoom, readerPointDistance, type ReaderPoint } from "./readerGestures";
 import { readerZoomLabel, READER_ZOOM_DEFAULT, READER_ZOOM_MAX, READER_ZOOM_MIN } from "./readerLayout";
 import type { ReaderMode } from "./readerScroll";
+import type { ReadingConnectionMode } from "../api/types";
 
 export type ReaderControls = {
   canPrevious: boolean;
@@ -36,6 +37,11 @@ export type ReaderModeControls = {
   onModeChange: (mode: ReaderMode) => void;
 };
 
+export type ReaderConnectionControls = {
+  mode: ReadingConnectionMode;
+  onModeChange: (mode: ReadingConnectionMode) => void;
+};
+
 type ReaderShellProps = {
   title: string;
   backHref: string;
@@ -44,6 +50,8 @@ type ReaderShellProps = {
   controls: ReaderControls;
   zoomControls?: ReaderZoomControls;
   modeControls?: ReaderModeControls;
+  connectionControls?: ReaderConnectionControls;
+  activity?: string;
   children: ReactNode;
 };
 
@@ -105,7 +113,7 @@ function scheduleReaderZoomAnchorRestore(stage: HTMLElement, anchor: ReaderZoomA
   });
 }
 
-export function ReaderShell({ title, backHref, error, onRetry, controls, zoomControls, modeControls, children }: ReaderShellProps) {
+export function ReaderShell({ title, backHref, error, onRetry, controls, zoomControls, modeControls, connectionControls, activity, children }: ReaderShellProps) {
   const readerRef = useRef<HTMLDivElement>(null);
   const headerRef = useRef<HTMLElement>(null);
   const stageRef = useRef<HTMLElement>(null);
@@ -368,6 +376,16 @@ export function ReaderShell({ title, backHref, error, onRetry, controls, zoomCon
             </select>
           </label>
         )}
+        {connectionControls && (
+          <label className="reader-mode-control reader-connection-control">
+            <span>Mode connexion lente</span>
+            <select value={connectionControls.mode} onChange={(event) => connectionControls.onModeChange(event.currentTarget.value as ReadingConnectionMode)}>
+              <option value="auto">Automatique</option>
+              <option value="speed">Toujours privilégier la vitesse</option>
+              <option value="quality">Toujours privilégier la qualité</option>
+            </select>
+          </label>
+        )}
         <button className="ghost-button reader-nav-button reader-previous-button" onClick={controls.onPrevious} disabled={!controls.canPrevious} aria-label="Page precedente">
           <ArrowLeft size={16} />
           <span>Precedent</span>
@@ -405,6 +423,11 @@ export function ReaderShell({ title, backHref, error, onRetry, controls, zoomCon
           )}
         </div>
       )}
+      {!error && activity && (
+        <div className="reader-status reader-activity" role="status" aria-live="polite">
+          <span>{activity}</span>
+        </div>
+      )}
       <main className="reader-stage" ref={stageRef}>
         <div className="reader-content">{children}</div>
       </main>
diff --git a/apps/web/src/reader/ReaderShellAdaptive.test.tsx b/apps/web/src/reader/ReaderShellAdaptive.test.tsx
new file mode 100644
index 0000000..0d9e893
--- /dev/null
+++ b/apps/web/src/reader/ReaderShellAdaptive.test.tsx
@@ -0,0 +1,41 @@
+import { renderToStaticMarkup } from "react-dom/server";
+import { describe, expect, it } from "vitest";
+import { ReaderShell } from "./ReaderShell";
+
+describe("ReaderShell adaptive connection controls", () => {
+  it("renders the slow connection mode choices without technical wording or a global percentage", () => {
+    const html = renderToStaticMarkup(
+      <ReaderShell
+        title="Livre"
+        backHref="/books/1"
+        controls={{ canPrevious: false, canNext: true, positionLabel: "Page 2 / 12", onPrevious: () => undefined, onNext: () => undefined }}
+        connectionControls={{ mode: "auto", onModeChange: () => undefined }}
+      >
+        <p>Page courante</p>
+      </ReaderShell>
+    );
+
+    expect(html).toContain("Mode connexion lente");
+    expect(html).toContain("Automatique");
+    expect(html).toContain("Toujours privilégier la vitesse");
+    expect(html).toContain("Toujours privilégier la qualité");
+    expect(html).not.toMatch(/%|pourcentage global|manifest|spine|range|etag|cache|resource|locator/i);
+  });
+
+  it("shows retry next to offline or loading errors", () => {
+    const html = renderToStaticMarkup(
+      <ReaderShell
+        title="Livre"
+        backHref="/books/1"
+        error="Cette page n’a pas pu être chargée. Votre position est conservée."
+        onRetry={() => undefined}
+        controls={{ canPrevious: false, canNext: false, positionLabel: "Page 2 / 12", onPrevious: () => undefined, onNext: () => undefined }}
+      >
+        <p>Page courante</p>
+      </ReaderShell>
+    );
+
+    expect(html).toContain("Cette page n’a pas pu être chargée. Votre position est conservée.");
+    expect(html).toContain("Reessayer");
+  });
+});
diff --git a/apps/web/src/reader/readerRuntime.test.ts b/apps/web/src/reader/readerRuntime.test.ts
index f00569e..80f1641 100644
--- a/apps/web/src/reader/readerRuntime.test.ts
+++ b/apps/web/src/reader/readerRuntime.test.ts
@@ -1,6 +1,5 @@
 import { readFileSync } from "node:fs";
 import { describe, expect, it } from "vitest";
-import { epubFileName } from "./EpubReader";
 import { pdfDocumentOptions } from "./pdfDocumentOptions";
 import {
   clampReaderPage,
@@ -23,11 +22,6 @@ import { isPageInRenderWindow, majorityVisiblePage, verticalRenderWindow } from
 import { readerErrorMessage } from "./ReaderError";
 
 describe("reader runtime helpers", () => {
-  it("extracts an EPUB file name from the file URL", () => {
-    expect(epubFileName("http://readabook.local/books/12/file?token=abc")).toBe("book.epub");
-    expect(epubFileName("http://readabook.local/files/example.epub")).toBe("example.epub");
-  });
-
   it("keeps PDF.js worker fallback source on the bundled module worker", () => {
     expect(pdfWorkerSrc).toContain("pdf.worker.min.mjs");
   });
diff --git a/apps/web/src/reader/useAdaptiveReading.test.ts b/apps/web/src/reader/useAdaptiveReading.test.ts
new file mode 100644
index 0000000..5f9dd11
--- /dev/null
+++ b/apps/web/src/reader/useAdaptiveReading.test.ts
@@ -0,0 +1,21 @@
+import { describe, expect, it } from "vitest";
+import { adaptiveStatusLabel } from "./useAdaptiveReading";
+
+describe("adaptive reading status", () => {
+  it("uses the short reader wording without a global percentage", () => {
+    expect(adaptiveStatusLabel("opening", false)).toBe("Ouverture de la page…");
+    expect(adaptiveStatusLabel("next", false)).toBe("Préparation de la page suivante…");
+    expect(adaptiveStatusLabel("neighbors", false)).toBe("Chargement des pages voisines…");
+    expect(adaptiveStatusLabel("slow", false)).toBe("Connexion lente. On charge d’abord cette page.");
+    expect(adaptiveStatusLabel("offline", false)).toBe("Hors connexion. La page déjà chargée reste disponible.");
+
+    for (const status of ["opening", "next", "neighbors", "slow", "offline", "idle"] as const) {
+      const label = adaptiveStatusLabel(status, false) ?? "";
+      expect(label).not.toMatch(/%|pourcentage|global|manifest|spine|range|etag|cache|resource|locator/i);
+    }
+  });
+
+  it("announces a lightweight resource when the manifest supports it", () => {
+    expect(adaptiveStatusLabel("opening", true)).toBe("Version allégée");
+  });
+});
diff --git a/apps/web/src/reader/useAdaptiveReading.ts b/apps/web/src/reader/useAdaptiveReading.ts
new file mode 100644
index 0000000..72000c5
--- /dev/null
+++ b/apps/web/src/reader/useAdaptiveReading.ts
@@ -0,0 +1,134 @@
+import { useCallback, useEffect, useRef, useState } from "react";
+import { api } from "../api/client";
+import type { ReadingConnectionMode, ReadingManifestDto, ReadingNetworkHint, ReadingWindowItemDto } from "../api/types";
+
+const CONNECTION_MODE_KEY = "readabook:reading-connection-mode";
+
+export type AdaptiveReadingStatus = "opening" | "next" | "neighbors" | "slow" | "offline" | "idle";
+
+function storedMode(): ReadingConnectionMode {
+  if (typeof localStorage === "undefined") return "auto";
+  const value = localStorage.getItem(CONNECTION_MODE_KEY);
+  return value === "speed" || value === "quality" ? value : "auto";
+}
+
+export function readingNetworkHint(): ReadingNetworkHint {
+  if (typeof navigator === "undefined") return "unknown";
+  if (!navigator.onLine) return "offline";
+  const connection = (navigator as Navigator & { connection?: { effectiveType?: string; saveData?: boolean } }).connection;
+  if (connection?.saveData || connection?.effectiveType === "slow-2g" || connection?.effectiveType === "2g") return "slow";
+  if (connection?.effectiveType === "3g") return "normal";
+  if (connection?.effectiveType === "4g") return "fast";
+  return "unknown";
+}
+
+export function adaptiveStatusLabel(status: AdaptiveReadingStatus, lightweight: boolean): string | undefined {
+  if (lightweight) return "Version allégée";
+  if (status === "opening") return "Ouverture de la page…";
+  if (status === "next") return "Préparation de la page suivante…";
+  if (status === "neighbors") return "Chargement des pages voisines…";
+  if (status === "slow") return "Connexion lente. On charge d’abord cette page.";
+  if (status === "offline") return "Hors connexion. La page déjà chargée reste disponible.";
+  return undefined;
+}
+
+export function useAdaptiveReading(bookId: number, enabled: boolean) {
+  const [manifest, setManifest] = useState<ReadingManifestDto | null>(null);
+  const [mode, setModeState] = useState<ReadingConnectionMode>(storedMode);
+  const [status, setStatus] = useState<AdaptiveReadingStatus>("opening");
+  const [error, setError] = useState<string>();
+  const generationRef = useRef(0);
+  const lastLocatorRef = useRef<string | null>(null);
+  const currentResourceRef = useRef<string | null>(null);
+
+  const loadManifest = useCallback(async () => {
+    if (!enabled) return;
+    setError(undefined);
+    setStatus("opening");
+    try {
+      setManifest(await api.readingManifest(bookId));
+    } catch {
+      setError("Impossible de préparer la lecture. Réessayez sans quitter cette page.");
+      setStatus(readingNetworkHint() === "offline" ? "offline" : "idle");
+    }
+  }, [bookId, enabled]);
+
+  useEffect(() => {
+    setManifest(null);
+    void loadManifest();
+  }, [loadManifest]);
+
+  useEffect(() => {
+    const update = () => setStatus(navigator.onLine ? "idle" : "offline");
+    window.addEventListener("online", update);
+    window.addEventListener("offline", update);
+    return () => {
+      window.removeEventListener("online", update);
+      window.removeEventListener("offline", update);
+    };
+  }, []);
+
+  const setMode = useCallback((next: ReadingConnectionMode) => {
+    setModeState(next);
+    localStorage.setItem(CONNECTION_MODE_KEY, next);
+  }, []);
+
+  const prioritize = useCallback(
+    async (locator: string, prefetch = true) => {
+      if (!manifest) return;
+      lastLocatorRef.current = locator;
+      const generation = ++generationRef.current;
+      const networkHint = readingNetworkHint();
+      setError(undefined);
+      setStatus(networkHint === "offline" ? "offline" : networkHint === "slow" || mode === "speed" ? "slow" : "opening");
+      try {
+        const window = await api.readingWindow(bookId, locator, mode, networkHint);
+        currentResourceRef.current = window.current?.resourceId ?? null;
+        if (generation !== generationRef.current || networkHint === "offline") return;
+        // pdf.js owns its byte-range requests; fetching the resource here would download the whole PDF.
+        if (manifest.format === "pdf" || !prefetch) {
+          setStatus("idle");
+          return;
+        }
+        const fetchItem = async (item: ReadingWindowItemDto | null) => {
+          if (!item) return;
+          const response = await fetch(api.readingResourceUrl(bookId, item.resourceId), { credentials: "include", cache: "default" });
+          if (!response.ok) throw new Error(String(response.status));
+          await response.arrayBuffer();
+        };
+        await fetchItem(window.current);
+        if (generation !== generationRef.current) return;
+        setStatus("next");
+        await Promise.allSettled([fetchItem(window.previous), fetchItem(window.next)]);
+        if (generation !== generationRef.current) return;
+        if (window.neighbors.length) {
+          setStatus("neighbors");
+          await Promise.allSettled(window.neighbors.map(fetchItem));
+        }
+        if (generation === generationRef.current) setStatus("idle");
+      } catch {
+        if (generation !== generationRef.current) return;
+        setError("Cette page n’a pas pu être chargée. Votre position est conservée.");
+        setStatus(readingNetworkHint() === "offline" ? "offline" : "idle");
+      }
+    },
+    [bookId, manifest, mode]
+  );
+
+  const retry = useCallback(async () => {
+    const resourceId = currentResourceRef.current;
+    const locator = lastLocatorRef.current;
+    if (!resourceId || !locator) {
+      await loadManifest();
+      return;
+    }
+    try {
+      await api.retryReadingResource(bookId, resourceId);
+    } catch {
+      // Retrying the GET still gives an already cached response a chance while offline.
+    }
+    await prioritize(locator);
+  }, [bookId, loadManifest, prioritize]);
+
+  return { manifest, mode, setMode, status, statusLabel: adaptiveStatusLabel(status, Boolean(manifest?.capabilities.lightweightPages)), error, retry, prioritize };
+}
diff --git a/apps/web/src/styles/app.css b/apps/web/src/styles/app.css
index 3df69ad..b9ddc2d 100644
--- a/apps/web/src/styles/app.css
+++ b/apps/web/src/styles/app.css
@@ -1209,6 +1209,17 @@ main.app-main-reader .reader-page {
   min-width: 0;
 }
 
+.reader-activity {
+  justify-content: center;
+  min-height: 30px;
+  color: var(--ink-muted);
+  font-size: 0.86rem;
+}
+
+.reader-connection-control select {
+  max-width: 220px;
+}
+
 .reader-stage {
   grid-row: 3;
   position: relative;
@@ -1536,6 +1547,11 @@ main.app-main-reader .reader-page {
     min-width: 0;
   }
 
+  .reader-connection-control {
+    order: 8;
+    flex-basis: 100%;
+  }
+
   .reader-mode-control select {
     width: 100%;
     min-width: 0;
@@ -1566,7 +1582,7 @@ main.app-main-reader .reader-page {
   .reader-back-button span,
   .reader-nav-button span,
   .reader-fullscreen-toggle span,
-  .reader-mode-control > span {
+  .reader-mode-control > span:not(:only-child) {
     display: none;
   }
 
diff --git a/apps/web/src/vite-env.d.ts b/apps/web/src/vite-env.d.ts
index 6a99ea7..0e663a1 100644
--- a/apps/web/src/vite-env.d.ts
+++ b/apps/web/src/vite-env.d.ts
@@ -1,9 +1,14 @@
 /// <reference types="vite/client" />
 
 declare module "foliate-js/epub.js" {
-  const module: unknown;
-  export default module;
-  export const EPUB: unknown;
+  export class EPUB {
+    constructor(loader: {
+      loadText(path: string): Promise<string | null>;
+      loadBlob(path: string): Promise<Blob | null>;
+      getSize(path: string): number;
+    });
+    init(): Promise<unknown>;
+  }
 }
 
 declare module "foliate-js/view.js" {