diff --git a/.env.example b/.env.example
index a589881..ae5499b 100644
--- a/.env.example
+++ b/.env.example
@@ -70,3 +70,12 @@ CLASSIFIER_MIN_AGGRESSOR_RATIO=0.55
 CLASSIFIER_0DTE_MAX_ATM_PCT=0.01
 CLASSIFIER_0DTE_MIN_PREMIUM=20000
 CLASSIFIER_0DTE_MIN_SIZE=400
+
+# Replay service
+REPLAY_ENABLED=false
+REPLAY_STREAMS=options,nbbo,equities,equity-quotes
+REPLAY_START_TS=0
+REPLAY_END_TS=0
+REPLAY_SPEED=1
+REPLAY_BATCH_SIZE=200
+REPLAY_LOG_EVERY=1000
diff --git a/README.md b/README.md
index 56597bc..3468c9c 100644
--- a/README.md
+++ b/README.md
@@ -200,6 +200,16 @@ Provider links: [Interactive Brokers](https://www.interactivebrokers.com/), [IBK
 - `CLASSIFIER_0DTE_MIN_PREMIUM` (default `20000`) — 0DTE gamma punch premium floor.  
 - `CLASSIFIER_0DTE_MIN_SIZE` (default `400`) — 0DTE gamma punch size floor.  
 
+### Replay service
+
+- `REPLAY_ENABLED` (default `false`) — start the replay streamer when running `bun run dev`.  
+- `REPLAY_STREAMS` (default `options,nbbo,equities,equity-quotes`) — comma list of streams to re-publish.  
+- `REPLAY_START_TS` (default `0`) — start timestamp in ms since epoch (0 means beginning).  
+- `REPLAY_END_TS` (default `0`) — end timestamp in ms since epoch (0 means no end).  
+- `REPLAY_SPEED` (default `1`) — playback speed (1 = real-time, 2 = 2x, 0 = as fast as possible).  
+- `REPLAY_BATCH_SIZE` (default `200`) — batch size per ClickHouse fetch.  
+- `REPLAY_LOG_EVERY` (default `1000`) — log progress every N events.  
+
 ### Testing + throttling
 
 - `TESTING_MODE` (default `false`) — enable ingest throttling for local dev.  
diff --git a/scripts/dev.ts b/scripts/dev.ts
index 97651cf..b8bd265 100644
--- a/scripts/dev.ts
+++ b/scripts/dev.ts
@@ -18,6 +18,14 @@ const sleep = (delayMs: number): Promise<void> => {
   return new Promise((resolve) => setTimeout(resolve, delayMs));
 };
 
+const parseBool = (value: string | undefined): boolean => {
+  if (!value) {
+    return false;
+  }
+  const normalized = value.trim().toLowerCase();
+  return ["1", "true", "yes", "on"].includes(normalized);
+};
+
 const parseUrlHostPort = (
   value: string,
   fallbackHost: string,
@@ -154,6 +162,10 @@ const serviceTasks: ChildSpec[] = [
   { name: "api", cmd: ["bun", "run", "dev"], cwd: "services/api" }
 ];
 
+if (parseBool(process.env.REPLAY_ENABLED)) {
+  serviceTasks.push({ name: "replay", cmd: ["bun", "run", "dev"], cwd: "services/replay" });
+}
+
 spawnChild(infraTask);
 await waitForInfra();
 
diff --git a/services/replay/package.json b/services/replay/package.json
new file mode 100644
index 0000000..23bcfe3
--- /dev/null
+++ b/services/replay/package.json
@@ -0,0 +1,16 @@
+{
+  "name": "@islandflow/replay",
+  "private": true,
+  "type": "module",
+  "scripts": {
+    "dev": "bun run src/index.ts"
+  },
+  "dependencies": {
+    "@islandflow/bus": "workspace:*",
+    "@islandflow/config": "workspace:*",
+    "@islandflow/observability": "workspace:*",
+    "@islandflow/storage": "workspace:*",
+    "@islandflow/types": "workspace:*",
+    "zod": "^3.23.8"
+  }
+}
diff --git a/services/replay/src/index.ts b/services/replay/src/index.ts
new file mode 100644
index 0000000..9de942b
--- /dev/null
+++ b/services/replay/src/index.ts
@@ -0,0 +1,458 @@
+import { readEnv } from "@islandflow/config";
+import { createLogger, createMetrics } from "@islandflow/observability";
+import {
+  SUBJECT_EQUITY_PRINTS,
+  SUBJECT_EQUITY_QUOTES,
+  SUBJECT_OPTION_NBBO,
+  SUBJECT_OPTION_PRINTS,
+  STREAM_EQUITY_PRINTS,
+  STREAM_EQUITY_QUOTES,
+  STREAM_OPTION_NBBO,
+  STREAM_OPTION_PRINTS,
+  connectJetStreamWithRetry,
+  ensureStream,
+  publishJson
+} from "@islandflow/bus";
+import {
+  createClickHouseClient,
+  fetchEquityPrintsAfter,
+  fetchEquityQuotesAfter,
+  fetchOptionNBBOAfter,
+  fetchOptionPrintsAfter
+} from "@islandflow/storage";
+import type { EquityPrint, EquityQuote, OptionNBBO, OptionPrint } from "@islandflow/types";
+import { z } from "zod";
+
+const service = "replay";
+const logger = createLogger({ service });
+const metrics = createMetrics({ service });
+
+const envSchema = z.object({
+  NATS_URL: z.string().default("nats://127.0.0.1:4222"),
+  CLICKHOUSE_URL: z.string().default("http://127.0.0.1:8123"),
+  CLICKHOUSE_DATABASE: z.string().default("default"),
+  REPLAY_STREAMS: z.string().default("options,nbbo,equities,equity-quotes"),
+  REPLAY_START_TS: z.coerce.number().int().nonnegative().default(0),
+  REPLAY_END_TS: z.coerce.number().int().nonnegative().default(0),
+  REPLAY_SPEED: z.coerce.number().nonnegative().default(1),
+  REPLAY_BATCH_SIZE: z.coerce.number().int().positive().default(200),
+  REPLAY_LOG_EVERY: z.coerce.number().int().positive().default(1000)
+});
+
+const env = readEnv(envSchema);
+
+type ReplayCursor = {
+  ts: number;
+  seq: number;
+};
+
+type ReplayStreamKind = "options" | "nbbo" | "equities" | "equity-quotes";
+
+type ReplayEvent = OptionPrint | OptionNBBO | EquityPrint | EquityQuote;
+
+type FetchAfter = (
+  afterTs: number,
+  afterSeq: number,
+  limit: number
+) => Promise<ReplayEvent[]>;
+
+type ReplayStream = {
+  kind: ReplayStreamKind;
+  subject: string;
+  streamName: string;
+  fetchAfter: FetchAfter;
+  buffer: ReplayEvent[];
+  cursor: ReplayCursor;
+  done: boolean;
+  emitted: number;
+  rank: number;
+};
+
+// Tie-breaker order favors quotes before prints when timestamps match.
+const STREAM_ORDER: ReplayStreamKind[] = ["nbbo", "options", "equity-quotes", "equities"];
+
+const STREAM_DEFS: Record<
+  ReplayStreamKind,
+  {
+    subject: string;
+    streamName: string;
+    rank: number;
+    fetchAfter: (client: ReturnType<typeof createClickHouseClient>, afterTs: number, afterSeq: number, limit: number) => Promise<ReplayEvent[]>;
+  }
+> = {
+  options: {
+    subject: SUBJECT_OPTION_PRINTS,
+    streamName: STREAM_OPTION_PRINTS,
+    rank: STREAM_ORDER.indexOf("options"),
+    fetchAfter: (client, afterTs, afterSeq, limit) =>
+      fetchOptionPrintsAfter(client, afterTs, afterSeq, limit)
+  },
+  nbbo: {
+    subject: SUBJECT_OPTION_NBBO,
+    streamName: STREAM_OPTION_NBBO,
+    rank: STREAM_ORDER.indexOf("nbbo"),
+    fetchAfter: (client, afterTs, afterSeq, limit) =>
+      fetchOptionNBBOAfter(client, afterTs, afterSeq, limit)
+  },
+  equities: {
+    subject: SUBJECT_EQUITY_PRINTS,
+    streamName: STREAM_EQUITY_PRINTS,
+    rank: STREAM_ORDER.indexOf("equities"),
+    fetchAfter: (client, afterTs, afterSeq, limit) =>
+      fetchEquityPrintsAfter(client, afterTs, afterSeq, limit)
+  },
+  "equity-quotes": {
+    subject: SUBJECT_EQUITY_QUOTES,
+    streamName: STREAM_EQUITY_QUOTES,
+    rank: STREAM_ORDER.indexOf("equity-quotes"),
+    fetchAfter: (client, afterTs, afterSeq, limit) =>
+      fetchEquityQuotesAfter(client, afterTs, afterSeq, limit)
+  }
+};
+
+const sleep = (delayMs: number): Promise<void> =>
+  new Promise((resolve) => setTimeout(resolve, delayMs));
+
+const normalizeStreamName = (value: string): ReplayStreamKind | null => {
+  switch (value.trim().toLowerCase()) {
+    case "options":
+    case "option-prints":
+    case "option_prints":
+    case "options-prints":
+      return "options";
+    case "nbbo":
+    case "option-nbbo":
+    case "option_nbbo":
+    case "options-nbbo":
+      return "nbbo";
+    case "equities":
+    case "equity":
+    case "equity-prints":
+    case "equity_prints":
+      return "equities";
+    case "equity-quotes":
+    case "equity_quotes":
+    case "quotes":
+      return "equity-quotes";
+    case "all":
+      return null;
+    default:
+      return null;
+  }
+};
+
+const parseStreamList = (value: string): ReplayStreamKind[] => {
+  const tokens = value
+    .split(",")
+    .map((entry) => entry.trim())
+    .filter(Boolean);
+
+  if (tokens.some((entry) => entry.toLowerCase() === "all")) {
+    return [...STREAM_ORDER];
+  }
+
+  const seen = new Set<ReplayStreamKind>();
+  const result: ReplayStreamKind[] = [];
+  const invalid: string[] = [];
+
+  for (const token of tokens) {
+    const kind = normalizeStreamName(token);
+    if (!kind) {
+      invalid.push(token);
+      continue;
+    }
+    if (!seen.has(kind)) {
+      seen.add(kind);
+      result.push(kind);
+    }
+  }
+
+  if (invalid.length > 0) {
+    throw new Error(`Unknown replay stream(s): ${invalid.join(", ")}`);
+  }
+
+  if (result.length === 0) {
+    throw new Error("No replay streams selected.");
+  }
+
+  return result;
+};
+
+const buildStreamConfig = (name: string, subject: string) => ({
+  name,
+  subjects: [subject],
+  retention: "limits",
+  storage: "file",
+  discard: "old",
+  max_msgs_per_subject: -1,
+  max_msgs: -1,
+  max_bytes: -1,
+  max_age: 0,
+  num_replicas: 1
+});
+
+const buildStartCursor = (startTs: number): ReplayCursor => {
+  if (startTs <= 0) {
+    return { ts: 0, seq: 0 };
+  }
+
+  const adjusted = Math.max(0, startTs - 1);
+  return { ts: adjusted, seq: 0 };
+};
+
+const getEventTs = (event: ReplayEvent): number => (Number.isFinite(event.ts) ? event.ts : 0);
+
+const getEventIngestTs = (event: ReplayEvent): number =>
+  Number.isFinite(event.ingest_ts) ? event.ingest_ts : 0;
+
+const getEventSeq = (event: ReplayEvent): number => (Number.isFinite(event.seq) ? event.seq : 0);
+
+const pickNextEvent = (streams: ReplayStream[]): { stream: ReplayStream; event: ReplayEvent } | null => {
+  let choice: { stream: ReplayStream; event: ReplayEvent } | null = null;
+
+  for (const stream of streams) {
+    const event = stream.buffer[0];
+    if (!event) {
+      continue;
+    }
+
+    if (!choice) {
+      choice = { stream, event };
+      continue;
+    }
+
+    const candidateTs = getEventTs(event);
+    const currentTs = getEventTs(choice.event);
+    if (candidateTs !== currentTs) {
+      if (candidateTs < currentTs) {
+        choice = { stream, event };
+      }
+      continue;
+    }
+
+    const candidateIngest = getEventIngestTs(event);
+    const currentIngest = getEventIngestTs(choice.event);
+    if (candidateIngest !== currentIngest) {
+      if (candidateIngest < currentIngest) {
+        choice = { stream, event };
+      }
+      continue;
+    }
+
+    const candidateSeq = getEventSeq(event);
+    const currentSeq = getEventSeq(choice.event);
+    if (candidateSeq !== currentSeq) {
+      if (candidateSeq < currentSeq) {
+        choice = { stream, event };
+      }
+      continue;
+    }
+
+    if (stream.rank < choice.stream.rank) {
+      choice = { stream, event };
+    }
+  }
+
+  return choice;
+};
+
+const retry = async <T>(
+  label: string,
+  attempts: number,
+  delayMs: number,
+  task: () => Promise<T>
+): Promise<T> => {
+  let lastError: unknown;
+
+  for (let attempt = 1; attempt <= attempts; attempt += 1) {
+    try {
+      return await task();
+    } catch (error) {
+      lastError = error;
+      logger.warn(`${label} attempt failed`, {
+        attempt,
+        error: error instanceof Error ? error.message : String(error)
+      });
+
+      if (attempt < attempts) {
+        await sleep(delayMs);
+      }
+    }
+  }
+
+  throw lastError ?? new Error(`${label} failed after retries`);
+};
+
+const run = async () => {
+  logger.info("service starting");
+
+  if (env.REPLAY_END_TS > 0 && env.REPLAY_END_TS < env.REPLAY_START_TS) {
+    throw new Error("REPLAY_END_TS must be >= REPLAY_START_TS when set.");
+  }
+
+  const streamKinds = parseStreamList(env.REPLAY_STREAMS);
+
+  const { nc, js, jsm } = await connectJetStreamWithRetry(
+    {
+      servers: env.NATS_URL,
+      name: service
+    },
+    { attempts: 120, delayMs: 500 }
+  );
+
+  for (const kind of streamKinds) {
+    const def = STREAM_DEFS[kind];
+    await ensureStream(jsm, buildStreamConfig(def.streamName, def.subject));
+  }
+
+  const clickhouse = createClickHouseClient({
+    url: env.CLICKHOUSE_URL,
+    database: env.CLICKHOUSE_DATABASE
+  });
+
+  await retry("clickhouse ready", 20, 500, async () => {
+    await clickhouse.query({ query: "SELECT 1", format: "JSONEachRow" });
+  });
+
+  const startCursor = buildStartCursor(env.REPLAY_START_TS);
+  const streams: ReplayStream[] = streamKinds.map((kind) => {
+    const def = STREAM_DEFS[kind];
+    return {
+      kind,
+      subject: def.subject,
+      streamName: def.streamName,
+      fetchAfter: (afterTs, afterSeq, limit) => def.fetchAfter(clickhouse, afterTs, afterSeq, limit),
+      buffer: [],
+      cursor: { ...startCursor },
+      done: false,
+      emitted: 0,
+      rank: def.rank
+    };
+  });
+
+  logger.info("replay configured", {
+    streams: streams.map((stream) => stream.kind),
+    start_ts: env.REPLAY_START_TS,
+    end_ts: env.REPLAY_END_TS > 0 ? env.REPLAY_END_TS : null,
+    speed: env.REPLAY_SPEED,
+    batch_size: env.REPLAY_BATCH_SIZE
+  });
+
+  let stopping = false;
+  let baseEventTs: number | null = null;
+  let startWallMs = 0;
+  let totalEmitted = 0;
+
+  const shutdown = async (signal: string) => {
+    if (stopping) {
+      return;
+    }
+    stopping = true;
+    logger.info("service stopping", { signal });
+    await nc.drain();
+    await clickhouse.close();
+    process.exit(0);
+  };
+
+  process.on("SIGINT", () => void shutdown("SIGINT"));
+  process.on("SIGTERM", () => void shutdown("SIGTERM"));
+
+  const speed = env.REPLAY_SPEED;
+  const endTs = env.REPLAY_END_TS > 0 ? env.REPLAY_END_TS : null;
+
+  while (!stopping) {
+    for (const stream of streams) {
+      if (stream.done || stream.buffer.length > 0) {
+        continue;
+      }
+
+      const data = await stream.fetchAfter(
+        stream.cursor.ts,
+        stream.cursor.seq,
+        env.REPLAY_BATCH_SIZE
+      );
+
+      if (data.length === 0) {
+        stream.done = true;
+        logger.info("replay stream exhausted", { stream: stream.kind });
+        continue;
+      }
+
+      stream.buffer = data;
+      metrics.gauge("replay.buffer_depth", data.length, { stream: stream.kind });
+    }
+
+    const next = pickNextEvent(streams);
+    if (!next) {
+      break;
+    }
+
+    const { stream, event } = next;
+    const eventTs = getEventTs(event);
+    const eventSeq = getEventSeq(event);
+
+    if (endTs !== null && eventTs > endTs) {
+      logger.info("replay reached end timestamp", { end_ts: endTs, last_ts: eventTs });
+      break;
+    }
+
+    if (baseEventTs === null) {
+      baseEventTs = eventTs;
+      startWallMs = Date.now();
+    }
+
+    if (speed > 0 && baseEventTs !== null) {
+      const targetMs = startWallMs + (eventTs - baseEventTs) / speed;
+      const delayMs = Math.max(0, targetMs - Date.now());
+      if (delayMs > 0) {
+        await sleep(delayMs);
+      }
+    }
+
+    try {
+      await publishJson(js, stream.subject, event);
+    } catch (error) {
+      logger.error("failed to publish replay event", {
+        error: error instanceof Error ? error.message : String(error),
+        stream: stream.kind,
+        ts: eventTs,
+        seq: eventSeq
+      });
+      throw error;
+    }
+
+    stream.buffer.shift();
+    stream.cursor = { ts: eventTs, seq: eventSeq };
+    stream.emitted += 1;
+    totalEmitted += 1;
+    metrics.count("replay.emitted", 1, { stream: stream.kind });
+
+    if (totalEmitted % env.REPLAY_LOG_EVERY === 0) {
+      logger.info("replay progress", {
+        emitted: totalEmitted,
+        last_ts: eventTs
+      });
+    }
+  }
+
+  logger.info("replay complete", {
+    emitted: totalEmitted,
+    streams: streams.map((stream) => ({
+      stream: stream.kind,
+      emitted: stream.emitted
+    }))
+  });
+
+  await nc.drain();
+  await clickhouse.close();
+  process.exit(0);
+};
+
+try {
+  await run();
+} catch (error) {
+  logger.error("replay service failed", {
+    error: error instanceof Error ? error.message : String(error)
+  });
+  process.exit(1);
+}
diff --git a/services/replay/tsconfig.json b/services/replay/tsconfig.json
new file mode 100644
index 0000000..d8c6443
--- /dev/null
+++ b/services/replay/tsconfig.json
@@ -0,0 +1,7 @@
+{
+  "extends": "../../tsconfig.base.json",
+  "compilerOptions": {
+    "types": []
+  },
+  "include": ["src/**/*.ts"]
+}