diff --git a/tests/integration/README.md b/tests/integration/README.md
index 48ed058..5ef4218 100644
--- a/tests/integration/README.md
+++ b/tests/integration/README.md
@@ -1,5 +1,13 @@
 # tests/integration
 
-Full update lifecycle mocked transport + fault injection 9 stages, exp2 model.
+Full update lifecycle on fake-indexeddb with mocked transport + fault
+injection, mirroring `experiments/exp2-ab-update-sim.mjs` (SPIKE-02 §3)
+against the real pull → verify → stage → activate → boot state machine.
 
-Stage 1: directory exists with .gitkeep; no feature code yet per IMPLEMENTATION-CONTRACT.md Stage 1. See IMPLEMENTATION-CONTRACT.md §4 responsibilities and §6 B-1…B-7.
+- `ab-lifecycle.test.ts` — Stage 8 acceptance: S01–S14 + X1–X3 (16 SPIKE-02
+  scenarios as 18 tests; no-loop and retry-once covered separately).
+  Invariant: either the previous valid dataset stays active or the new one
+  becomes active; favorites are never lost. State-machine level only —
+  iOS jetsam proof is device test T10 (§36).
+
+See IMPLEMENTATION-CONTRACT.md §4 responsibilities and §6 B-1…B-7.
diff --git a/tests/integration/ab-lifecycle.test.ts b/tests/integration/ab-lifecycle.test.ts
new file mode 100644
index 0000000..ee8d7f4
--- /dev/null
+++ b/tests/integration/ab-lifecycle.test.ts
@@ -0,0 +1,609 @@
+/* eslint-disable @typescript-eslint/no-unsafe-call, @typescript-eslint/require-await, @typescript-eslint/no-non-null-assertion */
+/**
+ * Stage 8 — fault-injection integration suite mirroring SPIKE-02 §3
+ * (exp2-ab-update-sim.mjs S01–S14 + X1–X3) against the REAL
+ * pull→verify→stage→activate→boot state machine on fake-indexeddb.
+ *
+ * Invariant under test (SPIKE-02): "Either the previous valid dataset remains
+ * active or the new valid dataset becomes active. The app never knowingly
+ * exposes a partial dataset. Favorites are never lost."
+ *
+ * Acceptance is at state-machine level (IMPLEMENTATION-CONTRACT.md Stage 8);
+ * iOS jetsam proof remains device test T10 §36.
+ */
+import { describe, it, expect, beforeEach } from "vitest";
+// @ts-expect-error fake-indexeddb types via exports fallback
+import FDBFactory from "fake-indexeddb/lib/FDBFactory";
+// @ts-expect-error fake-indexeddb types via exports fallback
+import FDBKeyRange from "fake-indexeddb/lib/FDBKeyRange";
+
+const g = globalThis as unknown as Record<string, unknown>;
+g.indexedDB = new FDBFactory() as unknown;
+g.IDBKeyRange = FDBKeyRange as unknown;
+
+import { buildPackage } from "../../pipeline/package.js";
+import { generateTestKeyPair } from "../../pipeline/sign.js";
+import { makeValidInput } from "../../pipeline/fixtures.js";
+import { canonicalJson } from "../../pipeline/canonical-json.js";
+import type { KeyPair } from "../../pipeline/sign.js";
+import { publicKeyFromDerBase64 } from "../../src/sync/verifier/ed25519.js";
+import { verifyPackage } from "../../src/sync/verifier/package.js";
+import { pullCandidate } from "../../src/sync/pull.js";
+import type { Transport } from "../../src/sync/transport/types.js";
+import {
+  activateSlot,
+  openSystemDB,
+  readSystemMeta,
+  writeSystemMeta,
+} from "../../src/data/system-meta/store.js";
+import {
+  initializeStaging,
+  openSlotDB,
+  readStagingProgress,
+  writeSlotFileWithProgress,
+} from "../../src/data/slot/store.js";
+import { openUserDB, addFavorite, listFavorites } from "../../src/data/user/store.js";
+import { isQuarantined, quarantineSink } from "../../src/data/user/quarantine.js";
+import {
+  activateStagedPackage,
+  recoverPendingActivation,
+  restorePreviousSlot,
+  stageVerifiedPackage,
+} from "../../src/sync/activation.js";
+import type { StagedPackage } from "../../src/sync/activation.js";
+import type { VerifiedPackage } from "../../src/sync/verifier/types.js";
+import { withTx } from "../../src/platform/idb/wrapper.js";
+import { DB, SLOT_FILES } from "../../src/platform/idb/names.js";
+import type { SlotId } from "../../src/platform/idb/names.js";
+import { evaluateBootReadiness, defaultBootDeps } from "../../src/app/readiness.js";
+import type { BootReadinessDeps } from "../../src/app/readiness.js";
+
+const EDITION = "lumen-2026";
+
+// ——— harness ———
+
+function deleteDb(name: string): Promise<void> {
+  return new Promise((resolve, reject) => {
+    const req = (g.indexedDB as IDBFactory).deleteDatabase(name);
+    req.onsuccess = () => {
+      resolve();
+    };
+    req.onerror = () => {
+      reject(req.error ?? new Error("delete database failed"));
+    };
+    req.onblocked = () => {
+      resolve();
+    };
+  });
+}
+
+interface Built {
+  readonly keyPair: KeyPair;
+  /** file path → canonical bytes, keyed the way the manifest references them. */
+  readonly files: Map<string, Uint8Array>;
+  readonly manifestBytes: Uint8Array;
+  readonly signatureBytes: Uint8Array;
+  readonly pkg: VerifiedPackage | null; // direct-verify witness (used by activation paths)
+}
+
+async function built(version: number, keyPair = generateTestKeyPair()): Promise<Built> {
+  const pkg = buildPackage(makeValidInput({ packageVersion: version }), { signWith: keyPair });
+  if (!pkg.ok || !pkg.pkg.signature) throw new Error("fixture build failed");
+  const manifestBytes = new TextEncoder().encode(canonicalJson(pkg.pkg.manifest));
+  const files = new Map<string, Uint8Array>();
+  for (const [name, file] of pkg.pkg.files) files.set(name, file.canonicalBytes);
+  for (const asset of pkg.pkg.assets) files.set(asset.file, asset.bytesContent);
+  const result = await verifyPackage(
+    {
+      manifestBytes,
+      signature: pkg.pkg.signature,
+      files: { getFile: (name) => Promise.resolve(files.get(name)) },
+      emergencyFloor: pkg.pkg.emergencyFloor,
+    },
+    {
+      trustedKeys: new Map([
+        [keyPair.fingerprint, publicKeyFromDerBase64(keyPair.publicKeyDerBase64)],
+      ]),
+      appVersion: "1.0.0",
+      supportedSchemaRange: [1],
+    },
+  );
+  if (!result.ok) throw new Error(`fixture verify failed: ${result.reason}`);
+  return {
+    keyPair,
+    files,
+    manifestBytes,
+    signatureBytes: new TextEncoder().encode(JSON.stringify(pkg.pkg.signature)),
+    pkg: result,
+  };
+}
+
+/** Transport over an in-memory origin; records every URL it is asked for. */
+function originTransport(build: Built, fetches: string[], version: number): Transport {
+  const base = `/editions/${EDITION}/packages/${String(version)}/`;
+  return {
+    isAvailable: () => true,
+    fetchPointer: async () => {
+      fetches.push("latest.json");
+      return {
+        edition: EDITION,
+        packageVersion: version,
+        manifestUrl: `${base}manifest.json`,
+        generatedAt: "2026-08-30T12:00:00.000Z",
+      };
+    },
+    fetchBytes: async (url) => {
+      fetches.push(url);
+      if (url.endsWith("manifest.json")) return build.manifestBytes;
+      if (url.endsWith("signature.json")) return build.signatureBytes;
+      const name = url.split("/").pop() ?? "";
+      const sub = url.includes("/assets/") ? `assets/${name}` : name;
+      const content = build.files.get(sub);
+      if (content) return content;
+      throw new Error(`unexpected fetch ${url}`);
+    },
+  };
+}
+
+function bootDeps(): BootReadinessDeps {
+  return {
+    ...defaultBootDeps,
+    checkShell: async () => ({ ok: true, cacheName: "lumen-shell-test" }),
+    loadFloor: () => ({ ok: true, version: "embedded-1", bytes: 4096 }),
+    estimate: async () => null,
+    // Pipeline fixtures declare minAppVersion 1.0.0 / schema 1; the dev shell
+    // version in package.json is younger (same seam readiness.test uses).
+    appVersion: "1.0.0",
+    supportedSchemaRange: [1],
+  };
+}
+
+/** Full sync run: pull (with quarantine wiring) → stage → activate. */
+async function syncRun(
+  build: Built,
+  version: number,
+  opts: { readonly trustedKeys?: Map<string, Uint8Array>; readonly fetches?: string[] } = {},
+): Promise<{ readonly ok: boolean; readonly reason?: string; readonly skipped?: string }> {
+  const user = await openUserDB();
+  const fetches = opts.fetches ?? [];
+  const outcome = await pullCandidate(
+    originTransport(build, fetches, version),
+    EDITION,
+    {
+      trustedKeys:
+        opts.trustedKeys ??
+        new Map([
+          [build.keyPair.fingerprint, publicKeyFromDerBase64(build.keyPair.publicKeyDerBase64)],
+        ]),
+      appVersion: "1.0.0",
+      supportedSchemaRange: [1],
+      quarantine: quarantineSink(user),
+    },
+    { isQuarantined: async (v) => isQuarantined(user, EDITION, v) },
+  );
+  user.close();
+  if (!outcome) return { ok: false, reason: "no pointer" };
+  if ("skipped" in outcome) return { ok: false, skipped: outcome.skipped };
+  if (!outcome.result.ok) return { ok: false, reason: outcome.result.reason };
+  const staged = await stageVerifiedPackage(outcome.result);
+  const activated = await activateStagedPackage(outcome.result, staged, "1.0.0");
+  return activated.reason === undefined
+    ? { ok: activated.ok }
+    : { ok: activated.ok, reason: activated.reason };
+}
+
+async function activateVersion(version: number): Promise<Built> {
+  const build = await built(version);
+  const staged = await stageVerifiedPackage(build.pkg!);
+  const activated = await activateStagedPackage(build.pkg!, staged, "1.0.0");
+  if (!activated.ok) throw new Error(`seed activation v${String(version)} failed`);
+  return build;
+}
+
+async function meta() {
+  const system = await openSystemDB();
+  const m = await readSystemMeta(system);
+  system.close();
+  return m;
+}
+
+async function bootState() {
+  return evaluateBootReadiness(bootDeps());
+}
+
+async function corruptFile(slot: SlotId, id: string): Promise<void> {
+  const db = await openSlotDB(slot);
+  await withTx(db, SLOT_FILES, "readwrite", (tx) => {
+    tx.objectStore(SLOT_FILES).delete(id);
+  });
+  db.close();
+}
+
+const SECTION_IDS = ["emergency", "schedule", "map", "info", "assets"] as const;
+
+beforeEach(async () => {
+  await Promise.all(Object.values(DB).map((name) => deleteDb(name)));
+});
+
+// ——— SPIKE-02 §3 walkthrough ———
+
+describe("Stage 8 integration — SPIKE-02 S01–S14 + X1–X3", () => {
+  it("S01: crash before any file lands → old (v1) still active, nothing staged", async () => {
+    await activateVersion(1);
+    const build = await built(2);
+    const fetches: string[] = [];
+    // "crash" = pull succeeds, staging never invoked (process died there).
+    const user = await openUserDB();
+    const outcome = await pullCandidate(originTransport(build, fetches, 2), EDITION, {
+      trustedKeys: new Map([
+        [build.keyPair.fingerprint, publicKeyFromDerBase64(build.keyPair.publicKeyDerBase64)],
+      ]),
+      appVersion: "1.0.0",
+      supportedSchemaRange: [1],
+      quarantine: quarantineSink(user),
+    });
+    user.close();
+    expect(outcome && "result" in outcome && outcome.result.ok).toBe(true);
+    const m = await meta();
+    expect(m.activePackageVersion).toBe(1);
+    const report = await bootState();
+    expect(report.state).toBe("READY");
+    expect(report.packageVersion).toBe(1);
+  });
+
+  it("S02: partial staging (3/5 files) → old (v1) active; activation refuses incomplete slot", async () => {
+    await activateVersion(1);
+    const build = await built(2);
+    const slot = await openSlotDB("B");
+    let journal = await initializeStaging(slot, {
+      edition: EDITION,
+      packageVersion: 2,
+      manifestSha256: build.pkg!.manifestSha256,
+      startedAt: Date.now(),
+      lastProgressAt: Date.now(),
+    });
+    for (const id of SECTION_IDS.slice(0, 3)) {
+      const entry = build.pkg!.manifest.sections[id];
+      const bytes = build.pkg!.files.get(entry.file)!;
+      journal = await writeSlotFileWithProgress(
+        slot,
+        id,
+        {
+          bytes: entry.bytes,
+          sha256: entry.sha256,
+          json: JSON.parse(new TextDecoder().decode(bytes)) as unknown,
+        },
+        journal,
+      );
+    }
+    slot.close();
+    const fake: StagedPackage = { slot: "B", journal };
+    const result = await activateStagedPackage(build.pkg!, fake, "1.0.0");
+    expect(result).toMatchObject({ ok: false, rolledBack: false });
+    const m = await meta();
+    expect(m.activeSlot === "A" && m.activePackageVersion === 1).toBe(true);
+    const report = await bootState();
+    expect(report.state).toBe("READY");
+    expect(report.packageVersion).toBe(1);
+  });
+
+  it("S03: process terminated mid-staging → resume completes without redoing staged files", async () => {
+    await activateVersion(1);
+    const build = await built(2);
+    const slot = await openSlotDB("B");
+    let journal = await initializeStaging(slot, {
+      edition: EDITION,
+      packageVersion: 2,
+      manifestSha256: build.pkg!.manifestSha256,
+      startedAt: 1,
+      lastProgressAt: 1,
+    });
+    for (const id of SECTION_IDS.slice(0, 3)) {
+      const entry = build.pkg!.manifest.sections[id];
+      const bytes = build.pkg!.files.get(entry.file)!;
+      journal = await writeSlotFileWithProgress(
+        slot,
+        id,
+        {
+          bytes: entry.bytes,
+          sha256: entry.sha256,
+          json: JSON.parse(new TextDecoder().decode(bytes)) as unknown,
+        },
+        journal,
+      );
+    }
+    slot.close();
+    const resumed = await stageVerifiedPackage(build.pkg!);
+    expect(resumed.journal.complete).toBe(true);
+    expect(resumed.journal.startedAt).toBe(1); // resume, not restart
+    expect(resumed.journal.stagedFiles).toHaveLength(5);
+    const activated = await activateStagedPackage(build.pkg!, resumed, "1.0.0");
+    expect(activated.ok).toBe(true);
+    const report = await bootState();
+    expect(report.state).toBe("READY");
+    expect(report.packageVersion).toBe(2);
+  });
+
+  it("S04: reboot before activation (staged, never flipped) → old (v1) active, activationPending", async () => {
+    await activateVersion(1);
+    const build = await built(2);
+    await stageVerifiedPackage(build.pkg!); // fully staged; flip never happens
+    const m = await meta();
+    expect(m.activePackageVersion).toBe(1);
+    const report = await bootState();
+    // Active pointer still v1 → READY on old dataset (never exposes the unactivated slot).
+    expect(report.state).toBe("READY");
+    expect(report.packageVersion).toBe(1);
+  });
+
+  it("S05: dataset validation fails (generic reject) → old active, candidate quarantined", async () => {
+    await activateVersion(1);
+    const build = await built(2);
+    const fetches: string[] = [];
+    // Corrupt one staged file's bytes → post-download integrity/validation gate rejects.
+    const original = build.files.get("schedule.json")!;
+    build.files.set("schedule.json", new TextEncoder().encode("NOT JSON"));
+    const run = await syncRun(build, 2, { fetches });
+    expect(run.ok).toBe(false);
+    const m = await meta();
+    expect(m.activePackageVersion).toBe(1);
+    const user = await openUserDB();
+    expect(await isQuarantined(user, EDITION, 2)).toBe(true);
+    user.close();
+    // restore for a clean boot check
+    build.files.set("schedule.json", original);
+    const report = await bootState();
+    expect(report.state).toBe("READY");
+  });
+
+  it("S06: integrity hash fails (corrupt file) → old active, candidate rejected + quarantined", async () => {
+    await activateVersion(1);
+    const build = await built(2);
+    build.files.set("map.json", new Uint8Array([1, 2, 3, 4])); // wrong bytes, manifest hash still original
+    const run = await syncRun(build, 2);
+    expect(run.ok).toBe(false);
+    const m = await meta();
+    expect(m.activePackageVersion).toBe(1);
+    const user = await openUserDB();
+    expect(await isQuarantined(user, EDITION, 2)).toBe(true);
+    user.close();
+  });
+
+  it("S07: signature validation fails → rejected BEFORE any section/file fetch; quarantined under pointer identity", async () => {
+    await activateVersion(1);
+    const build = await built(2);
+    const fetches: string[] = [];
+    // Trust a DIFFERENT key: the package's fingerprint is unknown → signature gate fails.
+    const wrongTrusted = generateTestKeyPair();
+    const run = await syncRun(build, 2, {
+      trustedKeys: new Map([
+        [wrongTrusted.fingerprint, publicKeyFromDerBase64(wrongTrusted.publicKeyDerBase64)],
+      ]),
+      fetches,
+    });
+    expect(run.ok).toBe(false);
+    // Only pointer + manifest + signature fetched — zero section/asset bytes downloaded.
+    const fileFetches = fetches.filter(
+      (f) =>
+        !f.endsWith("latest.json") && !f.endsWith("manifest.json") && !f.endsWith("signature.json"),
+    );
+    expect(fileFetches).toEqual([]);
+    const m = await meta();
+    expect(m.activePackageVersion).toBe(1);
+    const user = await openUserDB();
+    expect(await isQuarantined(user, EDITION, 2)).toBe(true); // hint-keyed despite pre-manifest rejection
+    user.close();
+  });
+
+  it("S08: schema validation fails → old active, candidate rejected", async () => {
+    await activateVersion(1);
+    const build = await built(2);
+    const user = await openUserDB();
+    const fetches: string[] = [];
+    const outcome = await pullCandidate(originTransport(build, fetches, 2), EDITION, {
+      trustedKeys: new Map([
+        [build.keyPair.fingerprint, publicKeyFromDerBase64(build.keyPair.publicKeyDerBase64)],
+      ]),
+      appVersion: "1.0.0",
+      supportedSchemaRange: [2], // shell does not support schema 1 of the package
+      quarantine: quarantineSink(user),
+    });
+    user.close();
+    expect(outcome && "result" in outcome && outcome.result.ok).toBe(false);
+    const m = await meta();
+    expect(m.activePackageVersion).toBe(1);
+  });
+
+  it("S09: compatibility validation fails (app too old) → rejected before files; nothing downloaded", async () => {
+    await activateVersion(1);
+    const build = await built(2);
+    const user = await openUserDB();
+    const fetches: string[] = [];
+    const outcome = await pullCandidate(originTransport(build, fetches, 2), EDITION, {
+      trustedKeys: new Map([
+        [build.keyPair.fingerprint, publicKeyFromDerBase64(build.keyPair.publicKeyDerBase64)],
+      ]),
+      appVersion: "0.5.0", // below manifest minAppVersion 1.0.0
+      supportedSchemaRange: [1],
+      quarantine: quarantineSink(user),
+    });
+    user.close();
+    expect(outcome && "result" in outcome && outcome.result.ok).toBe(false);
+    const fileFetches = fetches.filter(
+      (f) =>
+        !f.endsWith("latest.json") && !f.endsWith("manifest.json") && !f.endsWith("signature.json"),
+    );
+    expect(fileFetches).toEqual([]);
+    const m = await meta();
+    expect(m.activePackageVersion).toBe(1);
+  });
+
+  it("S10+S11: activation succeeds — pointer, version, edition, verification record flip together to v2", async () => {
+    const v1 = await activateVersion(1);
+    const build = await built(2);
+    const run = await syncRun(build, 2);
+    expect(run.ok).toBe(true);
+    const m = await meta();
+    expect(m.activeSlot).toBe("B");
+    expect(m.activePackageVersion).toBe(2);
+    expect(m.activeEdition).toBe(EDITION);
+    expect(m.verification?.manifestSha256).toBe(build.pkg!.manifestSha256);
+    expect(m.verification?.publicKeyFingerprint).toBe(build.keyPair.fingerprint);
+    expect(m.verification?.packageVersion).toBe(2);
+    expect(m.readbackPending).toBe(false); // cleared post-readback
+    // v1 remains intact in slot A (rollback depth 1)
+    const slotA = await openSlotDB("A");
+    const journalA = await readStagingProgress(slotA);
+    slotA.close();
+    expect(journalA?.packageVersion).toBe(1);
+    expect(v1.pkg !== null).toBe(true);
+  });
+
+  it("S12: process terminated immediately after flip → next-boot recovery confirms new (v2), pending cleared", async () => {
+    await activateVersion(1);
+    await activateVersion(2);
+    // Simulate the kill window (F-3): flip committed, readbackPending still set.
+    const m0 = await meta();
+    const system = await openSystemDB();
+    await writeSystemMeta(system, { ...m0, readbackPending: true });
+    system.close();
+    expect(await recoverPendingActivation()).toBe(true);
+    const m = await meta();
+    expect(m.activePackageVersion).toBe(2);
+    expect(m.readbackPending).toBe(false);
+    const report = await bootState();
+    expect(report.state).toBe("READY");
+    expect(report.packageVersion).toBe(2);
+  });
+
+  it("S13: crash during flip (transaction never commits) → old pointer stands", async () => {
+    await activateVersion(1);
+    const build = await built(2);
+    const staged = await stageVerifiedPackage(build.pkg!);
+    const result = await activateStagedPackage(build.pkg!, staged, "1.0.0", Date.now, {
+      // Model the uncommitted flip: both attempts die without committing.
+      activate: async () => {
+        throw new Error("transaction aborted mid-flip");
+      },
+    });
+    expect(result).toMatchObject({ ok: false, rolledBack: false });
+    const m = await meta();
+    expect(m.activeSlot === "A" && m.activePackageVersion === 1).toBe(true);
+    expect(m.readbackPending).toBe(false);
+    const report = await bootState();
+    expect(report.state).toBe("READY");
+    expect(report.packageVersion).toBe(1);
+  });
+
+  it("S14: corruption found by post-activation readback → automatic rollback to last complete slot", async () => {
+    await activateVersion(1);
+    const build = await built(2);
+    const staged = await stageVerifiedPackage(build.pkg!);
+    const result = await activateStagedPackage(build.pkg!, staged, "1.0.0", Date.now, {
+      afterFlip: async (slot) => corruptFile(slot, "map"),
+    });
+    expect(result).toMatchObject({ ok: false, rolledBack: true });
+    const m = await meta();
+    expect(m.activeSlot === "A" && m.activePackageVersion === 1).toBe(true);
+    const report = await bootState();
+    expect(report.state).toBe("READY");
+    expect(report.packageVersion).toBe(1);
+  });
+
+  it("X1: active slot corrupted at boot (readback pending) → fallback slot served", async () => {
+    await activateVersion(1);
+    await activateVersion(2); // A=v1, B=v2 active
+    // Post-activation bitrot hits the active slot B before next boot confirms it.
+    const system = await openSystemDB();
+    const m0 = await readSystemMeta(system);
+    await writeSystemMeta(system, { ...m0, readbackPending: true });
+    system.close();
+    await corruptFile("B", "schedule");
+    expect(await recoverPendingActivation()).toBe(true);
+    const m = await meta();
+    expect(m.activeSlot === "A" && m.activePackageVersion === 1).toBe(true);
+    const report = await bootState();
+    expect(report.state).toBe("READY");
+    expect(report.packageVersion).toBe(1);
+  });
+
+  it("X2: both slots lost → RECOVERY with emergency floor; favorites intact", async () => {
+    await activateVersion(1);
+    const user = await openUserDB();
+    await addFavorite(user, { eventId: "evt-x2", addedAt: 1 });
+    user.close();
+    await deleteDb(DB.SLOT_A);
+    await deleteDb(DB.SLOT_B);
+    const report = await bootState();
+    expect(report.state).toBe("RECOVERY");
+    expect(report.reason).toBe("missing");
+    expect(report.floorVersion).toBeTruthy(); // embedded emergency baseline present
+    const user2 = await openUserDB();
+    const favs = await listFavorites(user2);
+    user2.close();
+    expect(favs.map((f) => f.eventId)).toEqual(["evt-x2"]);
+  });
+
+  it("X3: favorites survive a full update lifecycle (v1 → v2 → rollback)", async () => {
+    const user = await openUserDB();
+    await addFavorite(user, { eventId: "evt-keep", addedAt: 7 });
+    user.close();
+    await activateVersion(1);
+    const build = await built(2);
+    expect((await syncRun(build, 2)).ok).toBe(true);
+    expect(await restorePreviousSlot()).toBe(true);
+    const user2 = await openUserDB();
+    const favs = await listFavorites(user2);
+    user2.close();
+    expect(favs.map((f) => f.eventId)).toEqual(["evt-keep"]);
+    const report = await bootState();
+    expect(report.state).toBe("READY");
+    expect(report.packageVersion).toBe(1);
+  });
+
+  it("no-loop: quarantined v2 is never re-fetched until latest.json advances past it", async () => {
+    await activateVersion(1);
+    const build = await built(2);
+    build.files.set("map.json", new Uint8Array([9, 9, 9])); // poison v2 → quarantine
+    expect((await syncRun(build, 2)).ok).toBe(false);
+    const fetches: string[] = [];
+    const user = await openUserDB();
+    const outcome = await pullCandidate(
+      originTransport(build, fetches, 2),
+      EDITION,
+      {
+        trustedKeys: new Map([
+          [build.keyPair.fingerprint, publicKeyFromDerBase64(build.keyPair.publicKeyDerBase64)],
+        ]),
+        appVersion: "1.0.0",
+        supportedSchemaRange: [1],
+        quarantine: quarantineSink(user),
+      },
+      { isQuarantined: async (v) => isQuarantined(user, EDITION, v) },
+    );
+    user.close();
+    expect(outcome).toMatchObject({ skipped: "quarantined" });
+    expect(fetches).toEqual(["latest.json"]);
+    const m = await meta();
+    expect(m.activePackageVersion).toBe(1);
+  });
+
+  it("activation seam honors single-txn contract: retry-once recovers a transient flip failure", async () => {
+    await activateVersion(1);
+    const build = await built(2);
+    const staged = await stageVerifiedPackage(build.pkg!);
+    let attempts = 0;
+    const result = await activateStagedPackage(build.pkg!, staged, "1.0.0", Date.now, {
+      activate: async (db, next) => {
+        attempts += 1;
+        if (attempts === 1) throw new Error("transient IDB failure");
+        return activateSlot(db, next);
+      },
+    });
+    expect(result.ok).toBe(true);
+    expect(attempts).toBe(2);
+    const report = await bootState();
+    expect(report.state).toBe("READY");
+    expect(report.packageVersion).toBe(2);
+  });
+});