@agentrewind/test

Test helpers for asserting that a harness still replays from a recorded AgentRewind session.

Install

npm install @agentrewind/sdk

One-Shot Assertion

Use assertReplay() when the test only needs to prove that the current harness still matches a stored recording:

import { defineHarness, openaiChatCodec } from "@agentrewind/sdk";
import { assertReplay } from "@agentrewind/sdk/testing";

const harness = defineHarness(async (ctx) => {
  await ctx.model.create(
    {
      model: "gpt-5.5",
      messages: [{ role: "user", content: `Request ${ctx.uuid()}` }]
    },
    { site: "decision" }
  );
});

await assertReplay("latest", { store: ".rewind", codec: openaiChatCodec() }, harness);

The session argument can be a full path, a session id with { store }, latest with { store }, or a store directory that contains exactly one session.

Inspect Then Assert

Use fromSession() when the test needs to inspect recorded events before running the replay assertion:

import { defineHarness, openaiChatCodec } from "@agentrewind/sdk";
import { fromSession } from "@agentrewind/sdk/testing";

const session = await fromSession("demo", {
  store: ".rewind",
  codec: openaiChatCodec()
});

const harness = defineHarness(async (ctx) => {
  await ctx.model.create(
    {
      model: "gpt-5.5",
      messages: [{ role: "user", content: `Request ${ctx.uuid()}` }]
    },
    { site: "decision" }
  );
});

expect(session.path).toBe(".rewind/demo");
expect(session.replay.events().some((event) => event.kind === "model_call")).toBe(true);
await session.assertReplay(harness);

fromSession() also exposes assertSemanticTrajectory() as a compatibility alias for older tests. Prefer assertReplay() in new tests because the name matches the behavior.

If replay drift occurs, the helpers convert the AgentRewind DriftError into a Node AssertionError. The assertion message includes a human-readable explanation with expected vs actual boundary details and useful CLI commands. The structured drift data is attached as actual.