diff --git a/apps/api/src/app.ts b/apps/api/src/app.ts
index f60581c..21b68f0 100644
--- a/apps/api/src/app.ts
+++ b/apps/api/src/app.ts
@@ -34,6 +34,7 @@ import {
   type BrowserUnsupportedReason,
 } from "./browser-support.js";
 import { EventHub } from "./event-hub.js";
+import type { PublicAssetResolver } from "./local-data-root.js";
 import { isAllowedNetworkRequest, type NetworkBoundaryOptions } from "./network-boundary.js";
 
 const defaultBootstrap: BootstrapResponse = {
@@ -55,6 +56,7 @@ export interface CreateAppOptions {
   browserSupportSecret?: Buffer;
   eventHub?: EventHub;
   networkBoundary?: NetworkBoundaryOptions;
+  publicAssets?: PublicAssetResolver;
 }
 
 const supportGateDirectory = resolve("apps/web/support-gate");
@@ -211,6 +213,21 @@ export async function createApp(options: CreateAppOptions = {}) {
     status: "ready",
   }));
 
+  app.get(
+    "/api/v1/assets/public/:resourceVersion/:assetId",
+    { schema: { hide: true } },
+    async (request, reply) => {
+      const { assetId, resourceVersion } = request.params as { assetId?: string; resourceVersion?: string };
+      const resource = assetId && resourceVersion
+        ? options.publicAssets?.read(resourceVersion, assetId)
+        : undefined;
+      if (!resource) return reply.code(404).send();
+      reply.type(resource.mimeType);
+      reply.header("Content-Disposition", "inline");
+      return resource.bytes;
+    },
+  );
+
   app.post(
     "/api/v1/support/check",
     {
diff --git a/apps/api/src/local-data-root.ts b/apps/api/src/local-data-root.ts
new file mode 100644
index 0000000..0886f72
--- /dev/null
+++ b/apps/api/src/local-data-root.ts
@@ -0,0 +1,339 @@
+import { createHash, randomUUID } from "node:crypto";
+import {
+  accessSync,
+  constants,
+  existsSync,
+  lstatSync,
+  mkdirSync,
+  readFileSync,
+  readdirSync,
+  realpathSync,
+  renameSync,
+  rmSync,
+  statSync,
+  writeFileSync,
+} from "node:fs";
+import { createRequire } from "node:module";
+import { dirname, isAbsolute, join, parse, relative, resolve, sep } from "node:path";
+
+const require = createRequire(import.meta.url);
+const Database = require("better-sqlite3") as typeof import("better-sqlite3");
+
+const assetIdPattern = /^[0-9a-f]{8}-[0-9a-f]{4}-[1-8][0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/i;
+const fixedDirectories = [
+  "db",
+  "content/references",
+  "content/generated",
+  "content/exports",
+  "managed-assets",
+  "derived-assets",
+  "staging",
+  "logs/api",
+  "logs/worker",
+  "logs/supervisor",
+] as const;
+
+export const DATA_TRANSFER_POLICY = {
+  allowed_downloads: ["original_generation", "jpg", "png"],
+  application_backup: false,
+  business_import: false,
+  editable_project_archive: false,
+  p0b_migration: false,
+  recovery: false,
+} as const;
+
+export interface LocalDataRootBoundaries {
+  downloadsRoot: string;
+  programRoot: string;
+  projectRoots: string[];
+  readOnlyAssetRoots: string[];
+  repositoryRoot: string;
+}
+
+export type LocalDataRootRejectionReason =
+  | "repository_root"
+  | "program_root"
+  | "project_root"
+  | "downloads_root"
+  | "read_only_asset_root"
+  | "symbolic_link";
+
+export type LocalDataRootValidation =
+  | { ok: true; normalized_path: string }
+  | { ok: false; reason: LocalDataRootRejectionReason };
+
+interface InstanceConfiguration {
+  data_root: string;
+  initialized: true;
+  instance_id: string;
+  schema_version: 1;
+}
+
+export interface ValidatedReadOnlyAssetRoot {
+  absolute_root: string;
+  ok: true;
+  root_ref: string;
+}
+
+interface PublicAssetEntry {
+  assetId: string;
+  mimeType: string;
+  relativePath: string;
+  resourceVersion: string;
+  rootRef: string;
+  sha256: string;
+}
+
+export interface PublicAssetPayload {
+  assetId: string;
+  bytes: Buffer;
+  mimeType: string;
+  resourceVersion: string;
+}
+
+export interface PublicAssetResolver {
+  read(resourceVersion: string, assetId: string): PublicAssetPayload | undefined;
+}
+
+export function defaultLocalDataRoot(environment: NodeJS.ProcessEnv = process.env) {
+  const localAppData = environment.LOCALAPPDATA;
+  if (!localAppData || !isAbsolute(localAppData)) throw new Error("local_app_data_unavailable");
+  return join(localAppData, "Dada", "P0A", "data");
+}
+
+export function defaultInstanceConfigPath(environment: NodeJS.ProcessEnv = process.env) {
+  const localAppData = environment.LOCALAPPDATA;
+  if (!localAppData || !isAbsolute(localAppData)) throw new Error("local_app_data_unavailable");
+  return join(localAppData, "Dada", "P0A", "config", "instance.json");
+}
+
+function comparisonPath(path: string) {
+  const normalized = resolve(path).replace(/[\\/]+$/, "");
+  return process.platform === "win32" ? normalized.toLocaleLowerCase("en-US") : normalized;
+}
+
+function isSameOrWithin(candidate: string, root: string) {
+  const candidatePath = comparisonPath(candidate);
+  const rootPath = comparisonPath(root);
+  const child = relative(rootPath, candidatePath);
+  return child === "" || (!child.startsWith(`..${sep}`) && child !== ".." && !isAbsolute(child));
+}
+
+function pathsOverlap(left: string, right: string) {
+  return isSameOrWithin(left, right) || isSameOrWithin(right, left);
+}
+
+function containsSymbolicLink(path: string) {
+  const absolute = resolve(path);
+  const parsed = parse(absolute);
+  let current = parsed.root;
+  const segments = absolute.slice(parsed.root.length).split(sep).filter(Boolean);
+  for (const segment of segments) {
+    current = join(current, segment);
+    if (!existsSync(current)) break;
+    if (lstatSync(current).isSymbolicLink()) return true;
+  }
+  return false;
+}
+
+function canonicalExistingPath(path: string) {
+  const absolute = resolve(path);
+  let existing = absolute;
+  const missing: string[] = [];
+  while (!existsSync(existing)) {
+    const parent = dirname(existing);
+    if (parent === existing) break;
+    missing.unshift(existing.slice(parent.length + 1));
+    existing = parent;
+  }
+  const canonical = existsSync(existing) ? realpathSync.native(existing) : existing;
+  return resolve(canonical, ...missing);
+}
+
+export function validateLocalDataRoot(
+  candidate: string,
+  boundaries: LocalDataRootBoundaries,
+): LocalDataRootValidation {
+  const absolute = resolve(candidate);
+  if (containsSymbolicLink(absolute)) return { ok: false, reason: "symbolic_link" };
+  const canonical = canonicalExistingPath(absolute);
+  const restricted: ReadonlyArray<readonly [LocalDataRootRejectionReason, string]> = [
+    ["repository_root", boundaries.repositoryRoot],
+    ["program_root", boundaries.programRoot],
+    ...boundaries.projectRoots.map((root) => ["project_root", root] as const),
+    ["downloads_root", boundaries.downloadsRoot],
+    ...boundaries.readOnlyAssetRoots.map((root) => ["read_only_asset_root", root] as const),
+  ];
+  for (const [reason, root] of restricted) {
+    if (pathsOverlap(canonical, canonicalExistingPath(root))) return { ok: false, reason };
+  }
+  return { normalized_path: absolute, ok: true };
+}
+
+export function resolvePathWithinRoot(root: string, objectKey: string) {
+  if (!objectKey || isAbsolute(objectKey) || objectKey.split(/[\\/]/).includes("..")) {
+    throw new Error("path_escape");
+  }
+  if (containsSymbolicLink(root)) throw new Error("symbolic_link");
+  const target = resolve(root, objectKey);
+  if (!isSameOrWithin(target, root) || containsSymbolicLink(target)) throw new Error("path_escape");
+  const canonicalRoot = canonicalExistingPath(root);
+  const canonicalTarget = canonicalExistingPath(target);
+  if (!isSameOrWithin(canonicalTarget, canonicalRoot)) throw new Error("path_escape");
+  return target;
+}
+
+function openInstanceDatabase(databasePath: string) {
+  const database = new Database(databasePath);
+  database.pragma("journal_mode = WAL");
+  database.exec(`
+    CREATE TABLE instance_metadata (
+      singleton INTEGER PRIMARY KEY CHECK (singleton = 1),
+      schema_version INTEGER NOT NULL CHECK (schema_version = 1)
+    );
+    INSERT INTO instance_metadata (singleton, schema_version) VALUES (1, 1);
+  `);
+  database.close();
+}
+
+export function initializeLocalDataRoot(input: {
+  boundaries: LocalDataRootBoundaries;
+  configFile: string;
+  dataRoot: string;
+}) {
+  const validation = validateLocalDataRoot(input.dataRoot, input.boundaries);
+  if (!validation.ok) throw new Error(validation.reason);
+  if (existsSync(input.configFile)) throw new Error("already_initialized");
+  if (existsSync(validation.normalized_path) && readdirSync(validation.normalized_path).length > 0) {
+    throw new Error("data_root_not_empty");
+  }
+
+  const createdRoot = !existsSync(validation.normalized_path);
+  try {
+    for (const directory of fixedDirectories) {
+      mkdirSync(join(validation.normalized_path, directory), { recursive: true });
+    }
+    openInstanceDatabase(join(validation.normalized_path, "db", "dada.sqlite3"));
+    const configuration: InstanceConfiguration = {
+      data_root: validation.normalized_path,
+      initialized: true,
+      instance_id: randomUUID(),
+      schema_version: 1,
+    };
+    mkdirSync(dirname(input.configFile), { recursive: true });
+    const temporaryConfig = `${input.configFile}.${randomUUID()}.tmp`;
+    writeFileSync(temporaryConfig, `${JSON.stringify(configuration, null, 2)}\n`, { flag: "wx" });
+    renameSync(temporaryConfig, input.configFile);
+    return {
+      database: "db/dada.sqlite3",
+      directories: [...fixedDirectories],
+      status: "ready" as const,
+    };
+  } catch (error) {
+    if (createdRoot && existsSync(validation.normalized_path)) {
+      rmSync(validation.normalized_path, { force: true, recursive: true });
+    }
+    throw error;
+  }
+}
+
+export function inspectInitializedLocalDataRoot(input: {
+  boundaries: LocalDataRootBoundaries;
+  configFile: string;
+}) {
+  const configuration = JSON.parse(readFileSync(input.configFile, "utf8")) as InstanceConfiguration;
+  const validation = validateLocalDataRoot(configuration.data_root, input.boundaries);
+  if (!validation.ok) throw new Error(validation.reason);
+  const rootExists = existsSync(validation.normalized_path) && statSync(validation.normalized_path).isDirectory();
+  const databasePath = join(validation.normalized_path, "db", "dada.sqlite3");
+  const databaseExists = rootExists && existsSync(databasePath) && statSync(databasePath).isFile();
+  if (!rootExists || !databaseExists) {
+    return {
+      database_exists: databaseExists,
+      root_exists: rootExists,
+      status: "data_missing" as const,
+    };
+  }
+  let writable = true;
+  try {
+    accessSync(validation.normalized_path, constants.R_OK | constants.W_OK);
+  } catch {
+    writable = false;
+  }
+  return {
+    database_exists: true,
+    root_exists: true,
+    status: "ready" as const,
+    writable,
+  };
+}
+
+export function validateReadOnlyAssetRoot(input: {
+  dataRoot: string;
+  expectedSha256: string;
+  manifestRelativePath: string;
+  root: string;
+  rootRef: string;
+}): ValidatedReadOnlyAssetRoot | { ok: false; reason: string } {
+  const absoluteRoot = resolve(input.root);
+  if (!existsSync(absoluteRoot) || !statSync(absoluteRoot).isDirectory()) {
+    return { ok: false, reason: "asset_root_missing" };
+  }
+  if (containsSymbolicLink(absoluteRoot)) return { ok: false, reason: "symbolic_link" };
+  if (pathsOverlap(absoluteRoot, input.dataRoot)) return { ok: false, reason: "data_root_overlap" };
+  let manifestPath: string;
+  try {
+    manifestPath = resolvePathWithinRoot(absoluteRoot, input.manifestRelativePath);
+  } catch {
+    return { ok: false, reason: "manifest_path_invalid" };
+  }
+  if (!existsSync(manifestPath) || !statSync(manifestPath).isFile()) {
+    return { ok: false, reason: "manifest_missing" };
+  }
+  const actualSha256 = createHash("sha256").update(readFileSync(manifestPath)).digest("hex");
+  if (actualSha256.toLowerCase() !== input.expectedSha256.toLowerCase()) {
+    return { ok: false, reason: "manifest_hash_invalid" };
+  }
+  return { absolute_root: absoluteRoot, ok: true, root_ref: input.rootRef };
+}
+
+export function createPublicAssetResolver(input: {
+  entries: PublicAssetEntry[];
+  roots: ValidatedReadOnlyAssetRoot[];
+}): PublicAssetResolver {
+  const roots = new Map(input.roots.map((root) => [root.root_ref, root.absolute_root]));
+  const entries = new Map<string, PublicAssetEntry>();
+  for (const entry of input.entries) {
+    if (!assetIdPattern.test(entry.assetId) || entries.has(entry.assetId)) throw new Error("asset_id_invalid");
+    if (!roots.has(entry.rootRef)) throw new Error("asset_root_unvalidated");
+    if (!/^[a-z0-9][a-z0-9._-]{0,79}$/i.test(entry.resourceVersion)) throw new Error("resource_version_invalid");
+    if (!/^[a-z0-9][a-z0-9.+-]*\/[a-z0-9][a-z0-9.+-]*$/i.test(entry.mimeType)) throw new Error("mime_type_invalid");
+    entries.set(entry.assetId, { ...entry });
+  }
+
+  return {
+    read(resourceVersion, assetId) {
+      if (!assetIdPattern.test(assetId)) return undefined;
+      const entry = entries.get(assetId);
+      if (!entry || entry.resourceVersion !== resourceVersion) return undefined;
+      const root = roots.get(entry.rootRef);
+      if (!root) return undefined;
+      let path: string;
+      try {
+        path = resolvePathWithinRoot(root, entry.relativePath);
+      } catch {
+        return undefined;
+      }
+      if (!existsSync(path) || !statSync(path).isFile()) return undefined;
+      const bytes = readFileSync(path);
+      const sha256 = createHash("sha256").update(bytes).digest("hex");
+      if (sha256.toLowerCase() !== entry.sha256.toLowerCase()) return undefined;
+      return {
+        assetId: entry.assetId,
+        bytes,
+        mimeType: entry.mimeType,
+        resourceVersion: entry.resourceVersion,
+      };
+    },
+  };
+}
diff --git a/apps/web/src/local-data-boundary.css b/apps/web/src/local-data-boundary.css
new file mode 100644
index 0000000..36c766e
--- /dev/null
+++ b/apps/web/src/local-data-boundary.css
@@ -0,0 +1,132 @@
+:root {
+  color: #111111;
+  background: #ffffff;
+  font-family: "Segoe UI", Arial, sans-serif;
+  font-synthesis: none;
+  letter-spacing: 0;
+}
+
+* {
+  box-sizing: border-box;
+}
+
+body {
+  min-width: 320px;
+  min-height: 100vh;
+  margin: 0;
+  background: #ffffff;
+}
+
+.local-data-page {
+  min-height: 100vh;
+  display: grid;
+  grid-template-rows: 8px 1fr 44px;
+}
+
+.local-data-rule {
+  background: #eaff00;
+}
+
+.local-data-main {
+  width: min(920px, 100%);
+  margin: 0 auto;
+  padding: 64px 28px 48px;
+}
+
+.local-data-kicker {
+  margin: 0 0 14px;
+  font-family: Consolas, monospace;
+  font-size: 11px;
+  font-weight: 800;
+}
+
+.local-data-title {
+  margin: 0;
+  font-size: 34px;
+  line-height: 1.2;
+}
+
+.local-data-intro {
+  max-width: 680px;
+  margin: 14px 0 0;
+  color: #555555;
+  font-size: 15px;
+  line-height: 1.7;
+}
+
+.local-data-notice {
+  margin-top: 30px;
+  border-block: 2px solid #111111;
+  padding: 22px 0;
+}
+
+.local-data-notice strong {
+  display: block;
+  max-width: 760px;
+  font-size: 24px;
+  line-height: 1.45;
+}
+
+.local-data-facts {
+  display: grid;
+  grid-template-columns: repeat(2, minmax(0, 1fr));
+  gap: 0 36px;
+  margin: 30px 0 0;
+}
+
+.local-data-fact {
+  min-width: 0;
+  border-top: 1px solid #c7c7c7;
+  padding: 16px 0 18px;
+}
+
+.local-data-fact dt {
+  color: #666666;
+  font-size: 12px;
+}
+
+.local-data-fact dd {
+  margin: 7px 0 0;
+  overflow-wrap: anywhere;
+  font-size: 14px;
+  font-weight: 700;
+  line-height: 1.55;
+}
+
+.local-data-download {
+  margin: 26px 0 0;
+  padding: 14px 16px;
+  border-left: 6px solid #eaff00;
+  background: #f2f2f2;
+  font-size: 14px;
+  font-weight: 700;
+  line-height: 1.6;
+}
+
+.local-data-footer {
+  display: grid;
+  place-items: center;
+  color: #eaff00;
+  background: #111111;
+  font-family: Consolas, monospace;
+  font-size: 10px;
+  font-weight: 700;
+}
+
+@media (max-width: 640px) {
+  .local-data-main {
+    padding: 36px 18px 40px;
+  }
+
+  .local-data-title {
+    font-size: 30px;
+  }
+
+  .local-data-notice strong {
+    font-size: 20px;
+  }
+
+  .local-data-facts {
+    grid-template-columns: 1fr;
+  }
+}
diff --git a/apps/web/src/local-data-boundary.tsx b/apps/web/src/local-data-boundary.tsx
new file mode 100644
index 0000000..93ccb68
--- /dev/null
+++ b/apps/web/src/local-data-boundary.tsx
@@ -0,0 +1,55 @@
+import { StrictMode } from "react";
+import { createRoot } from "react-dom/client";
+
+import "./local-data-boundary.css";
+
+export const localDataRiskNotice = "测试数据仅保存在本机，不自动备份，也不会迁移到正式系统。";
+
+export function LocalDataBoundary() {
+  return (
+    <div className="local-data-page">
+      <div className="local-data-rule" aria-hidden="true" />
+      <main className="local-data-main">
+        <p className="local-data-kicker">SETTINGS / LOCAL DATA</p>
+        <h1 className="local-data-title">本机数据</h1>
+        <p className="local-data-intro">
+          Dada 的 P0-A 测试数据由本地后端管理。浏览器只通过资源 ID 访问文件，不会显示或直接读取本机目录路径。
+        </p>
+
+        <section className="local-data-notice" aria-labelledby="local-data-warning">
+          <strong id="local-data-warning">{localDataRiskNotice}</strong>
+        </section>
+
+        <dl className="local-data-facts">
+          <div className="local-data-fact">
+            <dt>逻辑位置</dt>
+            <dd>当前 Windows 用户的 Dada 本机数据目录</dd>
+          </div>
+          <div className="local-data-fact">
+            <dt>保护方式</dt>
+            <dd>依赖当前 Windows 用户登录和文件系统权限</dd>
+          </div>
+          <div className="local-data-fact">
+            <dt>备份与加密</dt>
+            <dd>不提供 Dada 应用层加密或云备份</dd>
+          </div>
+          <div className="local-data-fact">
+            <dt>恢复边界</dt>
+            <dd>机器损坏、重装或删除本机数据目录后不可恢复</dd>
+          </div>
+        </dl>
+
+        <p className="local-data-download">请主动下载需要保留的原始生成图或 JPG/PNG 成品。</p>
+      </main>
+      <footer className="local-data-footer">P0-A · LOCAL FILESYSTEM · NO BACKUP</footer>
+    </div>
+  );
+}
+
+export function mountLocalDataBoundary(element: Element) {
+  createRoot(element).render(
+    <StrictMode>
+      <LocalDataBoundary />
+    </StrictMode>,
+  );
+}
diff --git a/package.json b/package.json
index 7432c95..9c2684b 100644
--- a/package.json
+++ b/package.json
@@ -14,7 +14,7 @@
     "test:integration": "vitest run tests/integration",
     "test:api": "pnpm check:openapi && vitest run tests/api",
     "test:worker": "pnpm --filter @dada/worker build && node scripts/worker-smoke.mjs",
-    "test:e2e": "pnpm check:openapi && playwright test tests/e2e/event-sync.spec.ts tests/e2e/support-gate.spec.ts --config playwright.config.ts",
+    "test:e2e": "pnpm check:openapi && playwright test tests/e2e/event-sync.spec.ts tests/e2e/support-gate.spec.ts tests/e2e/local-data-boundary.spec.ts --config playwright.config.ts",
     "test:visual": "node scripts/validate-layer-scope.mjs VISUAL",
     "test:performance": "node scripts/validate-layer-scope.mjs PERFORMANCE",
     "test:security": "node scripts/verify-frozen-dependencies.mjs && node scripts/redaction-scan.mjs",
@@ -26,7 +26,9 @@
     "test:all": "pnpm test:unit && pnpm test:integration && pnpm test:api && pnpm test:worker && pnpm test:e2e && pnpm test:visual && pnpm test:performance && pnpm test:security && pnpm test:package && pnpm validate:tdd-trace",
     "test:wp0-01": "node scripts/run-wp0-01-validation.mjs",
     "test:wp0-02": "node scripts/run-wp0-02-validation.mjs",
-    "test:wp0-03": "node scripts/run-wp0-03-validation.mjs"
+    "test:wp0-03": "node scripts/run-wp0-03-validation.mjs",
+    "test:wp0-04": "node scripts/run-wp0-04-validation.mjs",
+    "test:wp0-04:red": "node scripts/run-wp0-04-validation.mjs --phase red"
   },
   "devDependencies": {
     "@playwright/test": "1.62.0",
diff --git a/scripts/run-wp0-04-validation.mjs b/scripts/run-wp0-04-validation.mjs
new file mode 100644
index 0000000..d27182e
--- /dev/null
+++ b/scripts/run-wp0-04-validation.mjs
@@ -0,0 +1,181 @@
+import { createHash } from "node:crypto";
+import { spawnSync } from "node:child_process";
+import { copyFileSync, existsSync, mkdirSync, readFileSync, readdirSync, statSync, writeFileSync } from "node:fs";
+import { resolve } from "node:path";
+
+const phaseArgument = process.argv.indexOf("--phase");
+const phase = phaseArgument >= 0 ? process.argv[phaseArgument + 1] : "green";
+if (phase !== "red" && phase !== "green") throw new Error(`Unsupported phase: ${phase}`);
+
+const runId = process.env.DADA_TDD_RUN_ID ?? `wp0-04-${phase}-${new Date().toISOString().replace(/[^0-9]/g, "")}`;
+const runDirectory = resolve("artifacts", "tdd", runId);
+const rootCaseId = "TDD-WP0-DATA-001-root-validation";
+const transferCaseId = "TDD-WP0-DATA-002-no-backup-migration";
+const rootDirectory = resolve(runDirectory, "cases", rootCaseId);
+const transferDirectory = resolve(runDirectory, "cases", transferCaseId);
+const playwrightDirectory = resolve(runDirectory, "playwright");
+
+if (existsSync(runDirectory)) throw new Error(`Evidence run already exists: ${runId}`);
+for (const directory of [rootDirectory, transferDirectory]) mkdirSync(directory, { recursive: true });
+
+const redCommands = [
+  { command: "pnpm exec vitest run tests/integration/wp0-04-local-data-root.test.ts", args: ["exec", "vitest", "run", "tests/integration/wp0-04-local-data-root.test.ts"] },
+  { command: "pnpm exec vitest run tests/api/wp0-04-resource-boundary.test.ts", args: ["exec", "vitest", "run", "tests/api/wp0-04-resource-boundary.test.ts"] },
+  { command: "pnpm exec playwright test tests/e2e/local-data-boundary.spec.ts --config playwright.config.ts", args: ["exec", "playwright", "test", "tests/e2e/local-data-boundary.spec.ts", "--config", "playwright.config.ts"] },
+];
+const greenCommands = [
+  { command: "pnpm test:integration", args: ["test:integration"] },
+  { command: "pnpm test:api", args: ["test:api"] },
+  { command: "pnpm test:security", args: ["test:security"] },
+  { command: "pnpm test:package", args: ["test:package"] },
+  { command: "pnpm test:e2e", args: ["test:e2e"] },
+  { command: "pnpm validate:tdd-trace", args: ["validate:tdd-trace"] },
+];
+const startedAt = new Date().toISOString();
+const commands = [];
+
+for (const definition of phase === "red" ? redCommands : greenCommands) {
+  const commandStartedAt = new Date().toISOString();
+  const executable = process.platform === "win32" ? (process.env.ComSpec ?? "cmd.exe") : "pnpm";
+  const args = process.platform === "win32"
+    ? ["/d", "/s", "/c", `pnpm ${definition.args.join(" ")}`]
+    : definition.args;
+  const execution = spawnSync(executable, args, {
+    encoding: "utf8",
+    env: {
+      ...process.env,
+      DADA_EVIDENCE_DIR_DATA_ROOT: rootDirectory,
+      DADA_EVIDENCE_DIR_NO_TRANSFER: transferDirectory,
+      DADA_PLAYWRIGHT_OUTPUT_DIR: playwrightDirectory,
+    },
+  });
+  if (execution.stdout) process.stdout.write(execution.stdout);
+  if (execution.stderr) process.stderr.write(execution.stderr);
+  commands.push({
+    command: definition.command,
+    exit_code: execution.status ?? 1,
+    finished_at: new Date().toISOString(),
+    started_at: commandStartedAt,
+  });
+}
+
+const commandEvidence = { commands, phase, run_id: runId, schema_version: "1.0" };
+for (const directory of [rootDirectory, transferDirectory]) {
+  writeFileSync(resolve(directory, "commands.json"), `${JSON.stringify(commandEvidence, null, 2)}\n`);
+}
+
+const manifest = {
+  path: "tasks.manifest.json",
+  sha256: createHash("sha256").update(readFileSync("tasks.manifest.json")).digest("hex").toUpperCase(),
+};
+const commit = spawnSync("git", ["rev-parse", "--short", "HEAD"], { encoding: "utf8" }).stdout.trim();
+const worktreeDirty = spawnSync("git", ["status", "--porcelain"], { encoding: "utf8" }).stdout.trim().length > 0;
+const environment = { arch: process.arch, node: process.version.slice(1), os: process.platform };
+
+function findFiles(root, target) {
+  if (!existsSync(root)) return [];
+  const files = [];
+  for (const name of readdirSync(root)) {
+    const child = resolve(root, name);
+    if (statSync(child).isDirectory()) files.push(...findFiles(child, target));
+    else if (name === target) files.push(child);
+  }
+  return files;
+}
+
+if (phase === "green") {
+  for (const trace of findFiles(playwrightDirectory, "trace.zip")) {
+    if (trace.replaceAll("\\", "/").includes("local-data-boundary")) {
+      copyFileSync(trace, resolve(transferDirectory, "trace.zip"));
+    }
+  }
+}
+
+function writeResult(directory, result) {
+  writeFileSync(resolve(directory, "result.json"), `${JSON.stringify(result, null, 2)}\n`);
+  return result;
+}
+
+const common = {
+  commit,
+  environment,
+  finished_at: new Date().toISOString(),
+  manifest,
+  phase,
+  release_gate: ["work_package:WP-0", "release:P0-A"],
+  run_id: runId,
+  schema_version: "1.0",
+  started_at: startedAt,
+  task_id: "TASK-WP0-04",
+  work_package: "WP-0",
+  worktree_under_test: worktreeDirty ? "uncommitted implementation" : "clean committed implementation",
+};
+
+let rootResult;
+let transferResult;
+if (phase === "red") {
+  const redConfirmed = commands.every(({ exit_code }) => exit_code !== 0);
+  rootResult = writeResult(rootDirectory, {
+    ...common,
+    acceptance_criteria: ["AC-41", "AC-55", "AC-56"],
+    expected_failure: "LocalDataRoot validation, data_missing and stable resource isolation are not implemented.",
+    layer: ["DB", "API", "PKG-SEC"],
+    parent_family: "TDD-WP0-DATA-001",
+    requirements: ["NFR-09", "17.19"],
+    status: redConfirmed ? "red_confirmed" : "failed",
+    test_id: rootCaseId,
+  });
+  transferResult = writeResult(transferDirectory, {
+    ...common,
+    acceptance_criteria: ["AC-24", "AC-56"],
+    expected_failure: "No-backup/no-migration policy and fixed settings copy are not implemented.",
+    layer: ["API", "E2E", "MANUAL"],
+    parent_family: "TDD-WP0-DATA-002",
+    requirements: ["AUTH-06", "NFR-09"],
+    status: redConfirmed ? "red_confirmed" : "failed",
+    test_id: transferCaseId,
+  });
+} else {
+  const commandsPassed = commands.every(({ exit_code }) => exit_code === 0);
+  const rootEvidence = ["config-result.json", "fs-before.json", "fs-after.json", "response.json"];
+  const transferEvidence = ["route-inventory.json", "package-scan.json", "trace.zip", "screenshots/fixed-copy.png"];
+  const rootMissing = rootEvidence.filter((file) => !existsSync(resolve(rootDirectory, file)));
+  const transferMissing = transferEvidence.filter((file) => !existsSync(resolve(transferDirectory, file)));
+  rootResult = writeResult(rootDirectory, {
+    ...common,
+    acceptance_criteria: ["AC-41", "AC-55", "AC-56"],
+    automation: ["automated"],
+    evidence_refs: rootEvidence,
+    layer: ["DB", "API", "PKG-SEC"],
+    missing_evidence: rootMissing,
+    parent_family: "TDD-WP0-DATA-001",
+    requirements: ["NFR-09", "17.19"],
+    status: commandsPassed && rootMissing.length === 0 ? "passed" : "failed",
+    test_id: rootCaseId,
+  });
+  transferResult = writeResult(transferDirectory, {
+    ...common,
+    acceptance_criteria: ["AC-24", "AC-56"],
+    automation: ["automated", "manual_review"],
+    evidence_refs: transferEvidence,
+    layer: ["API", "E2E", "MANUAL"],
+    missing_evidence: transferMissing,
+    parent_family: "TDD-WP0-DATA-002",
+    requirements: ["AUTH-06", "NFR-09"],
+    status: commandsPassed && transferMissing.length === 0 ? "passed" : "failed",
+    test_id: transferCaseId,
+  });
+}
+
+const passed = phase === "red"
+  ? rootResult.status === "red_confirmed" && transferResult.status === "red_confirmed"
+  : rootResult.status === "passed" && transferResult.status === "passed";
+const summary = {
+  cases: [rootResult, transferResult].map(({ status, test_id }) => ({ status, test_id })),
+  phase,
+  run_id: runId,
+  status: passed ? (phase === "red" ? "red_confirmed" : "passed") : "failed",
+};
+writeFileSync(resolve(runDirectory, "evidence.json"), `${JSON.stringify(summary, null, 2)}\n`);
+console.log(JSON.stringify(summary, null, 2));
+if (!passed) process.exit(1);
diff --git a/tests/api/wp0-04-resource-boundary.test.ts b/tests/api/wp0-04-resource-boundary.test.ts
new file mode 100644
index 0000000..285183c
--- /dev/null
+++ b/tests/api/wp0-04-resource-boundary.test.ts
@@ -0,0 +1,133 @@
+import { createHash, randomUUID } from "node:crypto";
+import { mkdirSync, mkdtempSync, readFileSync, rmSync, writeFileSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join, resolve } from "node:path";
+
+import { afterEach, describe, expect, it } from "vitest";
+
+import { createApp } from "../../apps/api/src/app.js";
+import {
+  createPublicAssetResolver,
+  validateReadOnlyAssetRoot,
+} from "../../apps/api/src/local-data-root.js";
+
+const temporaryDirectories: string[] = [];
+
+afterEach(() => {
+  for (const directory of temporaryDirectories.splice(0)) {
+    if (resolve(directory).startsWith(resolve(tmpdir()))) rmSync(directory, { force: true, recursive: true });
+  }
+});
+
+describe("TDD-WP0-DATA-001-root-validation resource boundary", () => {
+  it("serves a manifest resource by stable ID without exposing the absolute root or object key", async () => {
+    const base = mkdtempSync(join(tmpdir(), "dada-wp0-04-api-"));
+    temporaryDirectories.push(base);
+    const assetRoot = join(base, "read-only-assets");
+    const relativePath = "images/source.png";
+    const bytes = Buffer.from("synthetic png fixture");
+    const assetId = randomUUID();
+    mkdirSync(join(assetRoot, "images"), { recursive: true });
+    writeFileSync(join(assetRoot, relativePath), bytes);
+    const manifest = JSON.stringify({ assets: [{ asset_id: assetId, relative_path: relativePath }] });
+    writeFileSync(join(assetRoot, "catalog.json"), manifest);
+    const validatedRoot = validateReadOnlyAssetRoot({
+      dataRoot: join(base, "data"),
+      expectedSha256: createHash("sha256").update(manifest).digest("hex"),
+      manifestRelativePath: "catalog.json",
+      root: assetRoot,
+      rootRef: "fixture_assets",
+    });
+    if (!validatedRoot.ok) throw new Error(validatedRoot.reason);
+    const publicAssets = createPublicAssetResolver({
+      entries: [{
+        assetId,
+        mimeType: "image/png",
+        relativePath,
+        resourceVersion: "fixture-v1",
+        rootRef: "fixture_assets",
+        sha256: createHash("sha256").update(bytes).digest("hex"),
+      }],
+      roots: [validatedRoot],
+    });
+    const app = await createApp({ browserGate: false, publicAssets });
+
+    try {
+      const resourceUrl = `/api/v1/assets/public/fixture-v1/${assetId}`;
+      const response = await app.inject({
+        headers: { host: "127.0.0.1:43121" },
+        method: "GET",
+        url: resourceUrl,
+      });
+      expect(response.statusCode).toBe(200);
+      expect(response.headers["content-type"]).toContain("image/png");
+      expect(response.rawPayload).toEqual(bytes);
+      const wrongVersion = await app.inject({
+        headers: { host: "127.0.0.1:43121" },
+        method: "GET",
+        url: `/api/v1/assets/public/other-version/${assetId}`,
+      });
+      expect(wrongVersion.statusCode).toBe(404);
+      const browserVisible = JSON.stringify({
+        headers: response.headers,
+        resource_id: assetId,
+        url: resourceUrl,
+      });
+      expect(browserVisible).not.toContain(assetRoot);
+      expect(browserVisible).not.toContain(relativePath);
+      expect(browserVisible).not.toMatch(/[A-Za-z]:\\/);
+
+      const evidenceDirectory = process.env.DADA_EVIDENCE_DIR_DATA_ROOT;
+      if (evidenceDirectory) {
+        mkdirSync(evidenceDirectory, { recursive: true });
+        writeFileSync(join(evidenceDirectory, "response.json"), `${JSON.stringify({
+          content_type: response.headers["content-type"],
+          path_exposed: false,
+          resource_id: assetId,
+          status: "passed",
+        }, null, 2)}\n`);
+      }
+    } finally {
+      await app.close();
+    }
+  });
+
+  it("does not resolve unknown IDs or path-like route parameters", async () => {
+    const app = await createApp({ browserGate: false, publicAssets: createPublicAssetResolver({ entries: [], roots: [] }) });
+    try {
+      for (const target of [randomUUID(), "..%2F..%2Fsecret", "C:%5CUsers%5Csecret"]) {
+        const response = await app.inject({
+          headers: { host: "127.0.0.1:43121" },
+          method: "GET",
+          url: `/api/v1/assets/public/fixture-v1/${target}`,
+        });
+        expect(response.statusCode).toBe(404);
+        expect(response.body).not.toMatch(/[A-Za-z]:\\/);
+      }
+    } finally {
+      await app.close();
+    }
+  });
+});
+
+describe("TDD-WP0-DATA-002-no-backup-migration route inventory", () => {
+  it("contains no product backup, archive, business import, migration or recovery route", async () => {
+    const app = await createApp({ browserGate: false });
+    try {
+      const routes = app.printRoutes();
+      for (const forbidden of ["backup", "archive", "project-package", "business-import", "migration", "restore", "recovery"]) {
+        expect(routes.toLowerCase()).not.toContain(forbidden);
+      }
+      const evidenceDirectory = process.env.DADA_EVIDENCE_DIR_NO_TRANSFER;
+      if (evidenceDirectory) {
+        mkdirSync(evidenceDirectory, { recursive: true });
+        writeFileSync(join(evidenceDirectory, "route-inventory.json"), `${JSON.stringify({
+          forbidden_routes: [],
+          status: "passed",
+        }, null, 2)}\n`);
+      }
+    } finally {
+      await app.close();
+    }
+  });
+});
diff --git a/tests/e2e/fixtures/local-data-boundary.html b/tests/e2e/fixtures/local-data-boundary.html
new file mode 100644
index 0000000..fb9a023
--- /dev/null
+++ b/tests/e2e/fixtures/local-data-boundary.html
@@ -0,0 +1,12 @@
+<!doctype html>
+<html lang="zh-CN">
+  <head>
+    <meta charset="UTF-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1" />
+    <title>Dada 本机数据</title>
+  </head>
+  <body>
+    <div id="root"></div>
+    <script type="module" src="/tests/e2e/fixtures/local-data-boundary.tsx"></script>
+  </body>
+</html>
diff --git a/tests/e2e/fixtures/local-data-boundary.tsx b/tests/e2e/fixtures/local-data-boundary.tsx
new file mode 100644
index 0000000..7430f6d
--- /dev/null
+++ b/tests/e2e/fixtures/local-data-boundary.tsx
@@ -0,0 +1,6 @@
+import { mountLocalDataBoundary } from "../../../apps/web/src/local-data-boundary.js";
+
+const root = document.querySelector("#root");
+if (!root) throw new Error("Fixture root is missing.");
+
+mountLocalDataBoundary(root);
diff --git a/tests/e2e/local-data-boundary.spec.ts b/tests/e2e/local-data-boundary.spec.ts
new file mode 100644
index 0000000..3ba9c60
--- /dev/null
+++ b/tests/e2e/local-data-boundary.spec.ts
@@ -0,0 +1,62 @@
+import { mkdirSync, writeFileSync } from "node:fs";
+import { resolve } from "node:path";
+
+import { expect, test } from "@playwright/test";
+import { createServer, type ViteDevServer } from "vite";
+
+let vite: ViteDevServer;
+let webUrl: string;
+
+test.beforeAll(async () => {
+  vite = await createServer({
+    configFile: false,
+    root: process.cwd(),
+    server: { host: "127.0.0.1", port: 0 },
+  });
+  await vite.listen();
+  const address = vite.httpServer?.address();
+  if (!address || typeof address === "string") throw new Error("Vite did not expose a test port.");
+  webUrl = `http://127.0.0.1:${address.port}`;
+});
+
+test.afterAll(async () => {
+  await vite.close();
+});
+
+test("TDD-WP0-DATA-002 keeps the fixed local-data warning visible without transfer entry points", async ({ page }) => {
+  await page.goto(`${webUrl}/tests/e2e/fixtures/local-data-boundary.html`);
+  const fixedCopy = "测试数据仅保存在本机，不自动备份，也不会迁移到正式系统。";
+  await expect(page.getByRole("heading", { name: "本机数据" })).toBeVisible();
+  await expect(page.getByText(fixedCopy, { exact: true })).toBeVisible();
+  await expect(page.getByText("当前 Windows 用户的 Dada 本机数据目录", { exact: true })).toBeVisible();
+  await expect(page.getByText(/不提供 Dada 应用层加密或云备份/)).toBeVisible();
+  await expect(page.getByText(/机器损坏、重装或删除本机数据目录后不可恢复/)).toBeVisible();
+  await expect(page.getByText(/主动下载需要保留的原始生成图或 JPG\/PNG 成品/)).toBeVisible();
+  await expect(page.getByRole("button")).toHaveCount(0);
+  await expect(page.getByRole("link")).toHaveCount(0);
+  const text = await page.locator("body").innerText();
+  expect(text).not.toMatch(/[A-Za-z]:\\/);
+
+  await page.reload();
+  await expect(page.getByText(fixedCopy, { exact: true })).toBeVisible();
+  expect(await page.evaluate(() => document.documentElement.scrollWidth <= window.innerWidth)).toBe(true);
+
+  const evidenceDirectory = process.env.DADA_EVIDENCE_DIR_NO_TRANSFER;
+  if (evidenceDirectory) {
+    mkdirSync(resolve(evidenceDirectory, "screenshots"), { recursive: true });
+    await page.screenshot({ path: resolve(evidenceDirectory, "screenshots", "fixed-copy.png") });
+    writeFileSync(resolve(evidenceDirectory, "package-scan.json"), `${JSON.stringify({
+      absolute_path_exposed: false,
+      automatic_backup_entry: false,
+      business_import_entry: false,
+      editable_project_archive_entry: false,
+      migration_entry: false,
+      recovery_entry: false,
+      status: "passed",
+    }, null, 2)}\n`);
+  }
+
+  await page.setViewportSize({ height: 844, width: 390 });
+  await expect(page.getByText(fixedCopy, { exact: true })).toBeVisible();
+  expect(await page.evaluate(() => document.documentElement.scrollWidth <= window.innerWidth)).toBe(true);
+});
diff --git a/tests/integration/wp0-04-local-data-root.test.ts b/tests/integration/wp0-04-local-data-root.test.ts
new file mode 100644
index 0000000..147e931
--- /dev/null
+++ b/tests/integration/wp0-04-local-data-root.test.ts
@@ -0,0 +1,237 @@
+import { createHash } from "node:crypto";
+import {
+  existsSync,
+  lstatSync,
+  mkdirSync,
+  mkdtempSync,
+  readFileSync,
+  readdirSync,
+  rmSync,
+  symlinkSync,
+  writeFileSync,
+} from "node:fs";
+import { tmpdir } from "node:os";
+import { dirname, join, resolve } from "node:path";
+import { createRequire } from "node:module";
+
+import { afterEach, describe, expect, it } from "vitest";
+
+import {
+  DATA_TRANSFER_POLICY,
+  defaultInstanceConfigPath,
+  defaultLocalDataRoot,
+  initializeLocalDataRoot,
+  inspectInitializedLocalDataRoot,
+  resolvePathWithinRoot,
+  validateLocalDataRoot,
+  validateReadOnlyAssetRoot,
+  type LocalDataRootBoundaries,
+} from "../../apps/api/src/local-data-root.js";
+
+const requireFromApi = createRequire(new URL("../../apps/api/package.json", import.meta.url));
+const Database = requireFromApi("better-sqlite3");
+const temporaryDirectories: string[] = [];
+
+function temporaryDirectory() {
+  const directory = mkdtempSync(join(tmpdir(), "dada-wp0-04-"));
+  temporaryDirectories.push(directory);
+  return directory;
+}
+
+function fixture() {
+  const base = temporaryDirectory();
+  const projectRoot = join(base, "project");
+  const downloadsRoot = join(base, "Downloads");
+  const assetRoot = join(base, "read-only-assets");
+  for (const directory of [projectRoot, downloadsRoot, assetRoot]) mkdirSync(directory);
+  const boundaries: LocalDataRootBoundaries = {
+    downloadsRoot,
+    programRoot: process.cwd(),
+    projectRoots: [projectRoot],
+    readOnlyAssetRoots: [assetRoot],
+    repositoryRoot: process.cwd(),
+  };
+  return { assetRoot, base, boundaries, downloadsRoot, projectRoot };
+}
+
+function snapshot(directory: string): string[] {
+  if (!existsSync(directory)) return [];
+  return readdirSync(directory, { recursive: true }).map(String).sort();
+}
+
+afterEach(() => {
+  for (const directory of temporaryDirectories.splice(0)) {
+    if (resolve(directory).startsWith(resolve(tmpdir()))) rmSync(directory, { force: true, recursive: true });
+  }
+});
+
+describe("TDD-WP0-DATA-001-root-validation", () => {
+  it("derives default data and configuration paths from LOCALAPPDATA without a hardcoded user", () => {
+    const localAppData = join(temporaryDirectory(), "LocalAppData");
+    expect(defaultLocalDataRoot({ LOCALAPPDATA: localAppData })).toBe(join(localAppData, "Dada", "P0A", "data"));
+    expect(defaultInstanceConfigPath({ LOCALAPPDATA: localAppData })).toBe(
+      join(localAppData, "Dada", "P0A", "config", "instance.json"),
+    );
+    expect(() => defaultLocalDataRoot({})).toThrow("local_app_data_unavailable");
+  });
+
+  it("rejects repository, project, Downloads, read-only asset, junction and escaped paths without writes", () => {
+    const { assetRoot, base, boundaries, downloadsRoot, projectRoot } = fixture();
+    const outside = join(base, "junction-target");
+    const junction = join(base, "junction-root");
+    mkdirSync(outside);
+    symlinkSync(outside, junction, "junction");
+    expect(lstatSync(junction).isSymbolicLink()).toBe(true);
+
+    const cases = [
+      { path: join(process.cwd(), ".dada-local", "forbidden"), reason: "repository_root" },
+      { path: join(projectRoot, "data"), reason: "project_root" },
+      { path: join(downloadsRoot, "data"), reason: "downloads_root" },
+      { path: join(assetRoot, "data"), reason: "read_only_asset_root" },
+      { path: join(junction, "data"), reason: "symbolic_link" },
+    ] as const;
+    const before = snapshot(base);
+    for (const [index, candidate] of cases.entries()) {
+      expect(validateLocalDataRoot(candidate.path, boundaries)).toEqual({
+        ok: false,
+        reason: candidate.reason,
+      });
+      expect(() => initializeLocalDataRoot({
+        boundaries,
+        configFile: join(base, `invalid-config-${index}`, "instance.json"),
+        dataRoot: candidate.path,
+      })).toThrow(candidate.reason);
+    }
+    expect(() => resolvePathWithinRoot(join(base, "safe"), "../escaped/file.png")).toThrow("path_escape");
+    const after = snapshot(base);
+    expect(after).toEqual(before);
+    const evidenceDirectory = process.env.DADA_EVIDENCE_DIR_DATA_ROOT;
+    if (evidenceDirectory) {
+      mkdirSync(evidenceDirectory, { recursive: true });
+      writeFileSync(join(evidenceDirectory, "fs-before.json"), `${JSON.stringify({ entries: before }, null, 2)}\n`);
+    }
+  });
+
+  it("creates the fixed layout and SQLite only during explicit initialization", () => {
+    const { base, boundaries } = fixture();
+    const dataRoot = join(base, "compliant-data");
+    const configFile = join(base, "config", "instance.json");
+    const initialized = initializeLocalDataRoot({ boundaries, configFile, dataRoot });
+
+    expect(initialized.status).toBe("ready");
+    for (const relativePath of [
+      "db/dada.sqlite3",
+      "content/references",
+      "content/generated",
+      "content/exports",
+      "managed-assets",
+      "derived-assets",
+      "staging",
+      "logs/api",
+      "logs/worker",
+      "logs/supervisor",
+    ]) {
+      expect(existsSync(join(dataRoot, relativePath))).toBe(true);
+    }
+
+    const database = new Database(join(dataRoot, "db", "dada.sqlite3"), { readonly: true });
+    expect(database.prepare("select schema_version from instance_metadata").get()).toEqual({ schema_version: 1 });
+    database.close();
+    expect(JSON.parse(readFileSync(configFile, "utf8"))).toMatchObject({ initialized: true, schema_version: 1 });
+    const evidenceDirectory = process.env.DADA_EVIDENCE_DIR_DATA_ROOT;
+    if (evidenceDirectory) {
+      mkdirSync(evidenceDirectory, { recursive: true });
+      writeFileSync(join(evidenceDirectory, "config-result.json"), `${JSON.stringify({
+        database: "db/dada.sqlite3",
+        fixed_layout: true,
+        path_exposed: false,
+        status: initialized.status,
+      }, null, 2)}\n`);
+    }
+  });
+
+  it("reports data_missing without recreating a deleted initialized root or database", () => {
+    const { base, boundaries } = fixture();
+    const dataRoot = join(base, "initialized-data");
+    const configFile = join(base, "config", "instance.json");
+    initializeLocalDataRoot({ boundaries, configFile, dataRoot });
+    rmSync(join(dataRoot, "db", "dada.sqlite3"));
+
+    expect(inspectInitializedLocalDataRoot({ boundaries, configFile })).toMatchObject({
+      database_exists: false,
+      root_exists: true,
+      status: "data_missing",
+    });
+    expect(existsSync(join(dataRoot, "db", "dada.sqlite3"))).toBe(false);
+
+    rmSync(dataRoot, { recursive: true });
+    expect(inspectInitializedLocalDataRoot({ boundaries, configFile })).toMatchObject({
+      database_exists: false,
+      root_exists: false,
+      status: "data_missing",
+    });
+    expect(existsSync(dataRoot)).toBe(false);
+    const evidenceDirectory = process.env.DADA_EVIDENCE_DIR_DATA_ROOT;
+    if (evidenceDirectory) {
+      mkdirSync(evidenceDirectory, { recursive: true });
+      writeFileSync(join(evidenceDirectory, "fs-after.json"), `${JSON.stringify({
+        database_recreated: false,
+        root_recreated: false,
+        status: "data_missing",
+      }, null, 2)}\n`);
+    }
+  });
+
+  it("validates a read-only manifest by hash without copying or writing its source root", () => {
+    const { assetRoot, base } = fixture();
+    const manifest = join(assetRoot, "catalog.json");
+    writeFileSync(manifest, "{\"assets\":[]}\n");
+    const expectedSha256 = createHash("sha256").update(readFileSync(manifest)).digest("hex");
+    const before = snapshot(assetRoot);
+
+    expect(validateReadOnlyAssetRoot({
+      dataRoot: join(base, "data"),
+      expectedSha256,
+      manifestRelativePath: "catalog.json",
+      root: assetRoot,
+      rootRef: "fixture_assets",
+    })).toMatchObject({ ok: true, root_ref: "fixture_assets" });
+    expect(snapshot(assetRoot)).toEqual(before);
+  });
+});
+
+describe("TDD-WP0-DATA-002-no-backup-migration", () => {
+  it("does not recover deleted data or treat retained downloads as migration input", () => {
+    const { base, boundaries } = fixture();
+    const dataRoot = join(base, "instance-a");
+    const configFile = join(base, "config-a", "instance.json");
+    initializeLocalDataRoot({ boundaries, configFile, dataRoot });
+    const businessMarker = join(dataRoot, "content", "generated", "private-record.json");
+    mkdirSync(dirname(businessMarker), { recursive: true });
+    writeFileSync(businessMarker, "private business data");
+    const retainedDownload = join(base, "user-downloads", "finished.png");
+    mkdirSync(dirname(retainedDownload));
+    writeFileSync(retainedDownload, "downloaded image");
+
+    rmSync(dataRoot, { recursive: true });
+    expect(inspectInitializedLocalDataRoot({ boundaries, configFile }).status).toBe("data_missing");
+    expect(existsSync(dataRoot)).toBe(false);
+    expect(readFileSync(retainedDownload, "utf8")).toBe("downloaded image");
+
+    const replacementRoot = join(base, "instance-b");
+    initializeLocalDataRoot({
+      boundaries,
+      configFile: join(base, "config-b", "instance.json"),
+      dataRoot: replacementRoot,
+    });
+    expect(existsSync(join(replacementRoot, "content", "generated", "private-record.json"))).toBe(false);
+    expect(DATA_TRANSFER_POLICY).toEqual({
+      allowed_downloads: ["original_generation", "jpg", "png"],
+      application_backup: false,
+      business_import: false,
+      editable_project_archive: false,
+      p0b_migration: false,
+      recovery: false,
+    });
+  });
+});