diff --git a/tests/redis-replication.integration.test.ts b/tests/redis-replication.integration.test.ts
new file mode 100644
index 0000000..d4c5e49
--- /dev/null
+++ b/tests/redis-replication.integration.test.ts
@@ -0,0 +1,130 @@
+import { randomUUID } from "node:crypto";
+
+import Redis from "ioredis";
+import { afterAll, beforeAll, describe, expect, it } from "vitest";
+
+import { pageCacheTag } from "@/lib/cache/tags";
+import { parseInvalidationEvent } from "@/lib/events/invalidation";
+import {
+  createRedisOutboxTransport,
+  processOutboxEvent,
+} from "@/lib/outbox/processor";
+import {
+  redisCacheTagStateKey,
+  redisEventChannel,
+} from "@/lib/redis/client";
+
+const integrationUrl = process.env.REDIS_INTEGRATION_URL;
+const describeWithRedis = integrationUrl ? describe : describe.skip;
+
+function integrationClient(name: string): Redis {
+  const client = new Redis(integrationUrl!, {
+    connectionName: name,
+    enableOfflineQueue: false,
+    lazyConnect: true,
+    maxRetriesPerRequest: 1,
+  });
+  client.on("error", () => undefined);
+  return client;
+}
+
+async function closeClient(client: Redis | undefined): Promise<void> {
+  if (!client) return;
+  if (client.status === "wait" || client.status === "end") {
+    client.disconnect();
+    return;
+  }
+  await client.quit().catch(() => client.disconnect());
+}
+
+describeWithRedis("cross-replica Redis invalidation delivery", () => {
+  const runId = randomUUID();
+  const originalCachePrefix = process.env.REDIS_CACHE_PREFIX;
+  const originalEventPrefix = process.env.REDIS_EVENT_PREFIX;
+  const pageId = `integration-${runId}`;
+  const topic = `page:${pageId}`;
+  const cacheTag = pageCacheTag(pageId);
+  const invalidatedAt = 1_725_000_000_000;
+
+  let replicaA: Redis;
+  let replicaBEvents: Redis;
+  let replicaBCache: Redis;
+
+  beforeAll(async () => {
+    process.env.REDIS_CACHE_PREFIX = `buzz:test:${runId}:cache`;
+    process.env.REDIS_EVENT_PREFIX = `buzz:test:${runId}:events`;
+
+    replicaA = integrationClient(`buzz-sheet-test-a-${runId}`);
+    replicaBEvents = integrationClient(`buzz-sheet-test-b-events-${runId}`);
+    replicaBCache = integrationClient(`buzz-sheet-test-b-cache-${runId}`);
+    await Promise.all([
+      replicaA.connect(),
+      replicaBEvents.connect(),
+      replicaBCache.connect(),
+    ]);
+  });
+
+  afterAll(async () => {
+    if (replicaA?.status === "ready") {
+      await replicaA.del(redisCacheTagStateKey());
+    }
+    await Promise.all([
+      closeClient(replicaA),
+      closeClient(replicaBEvents),
+      closeClient(replicaBCache),
+    ]);
+
+    if (originalCachePrefix === undefined) delete process.env.REDIS_CACHE_PREFIX;
+    else process.env.REDIS_CACHE_PREFIX = originalCachePrefix;
+    if (originalEventPrefix === undefined) delete process.env.REDIS_EVENT_PREFIX;
+    else process.env.REDIS_EVENT_PREFIX = originalEventPrefix;
+  });
+
+  it("shares tag state and publishes only the typed event envelope", async () => {
+    const channel = redisEventChannel(topic);
+    await replicaBEvents.subscribe(channel);
+
+    const received = new Promise<string>((resolve, reject) => {
+      const timeout = setTimeout(
+        () => reject(new Error("Timed out waiting for the replica event.")),
+        5_000,
+      );
+      replicaBEvents.on("message", (receivedChannel, value) => {
+        if (receivedChannel !== channel) return;
+        clearTimeout(timeout);
+        resolve(value);
+      });
+    });
+
+    const processed = await processOutboxEvent(
+      {
+        aggregateId: pageId,
+        eventType: "page.updated",
+        payload: {
+          id: pageId,
+          version: 42,
+          privateContent: "must remain in PostgreSQL",
+        },
+        topic,
+      },
+      createRedisOutboxTransport(replicaA),
+      invalidatedAt,
+    );
+
+    const rawEvent = await received;
+    expect(parseInvalidationEvent(rawEvent)).toEqual(processed);
+    expect(JSON.parse(rawEvent)).toEqual({
+      type: "page.updated",
+      id: pageId,
+      version: 42,
+    });
+
+    const tagState = await replicaBCache.hget(
+      redisCacheTagStateKey(),
+      cacheTag,
+    );
+    expect(tagState && JSON.parse(tagState)).toEqual({
+      expired: invalidatedAt,
+    });
+  });
+});