---
title: observabilityRevivers
description: Standard reviver functions for deserializing workflow data types in observability tools.
type: reference
summary: Pass observabilityRevivers to hydrateResourceIO or hydrateData to deserialize standard workflow data types.
related:
  - /docs/api-reference/workflow-observability/hydrate-resource-io
  - /docs/api-reference/workflow-observability/hydrate-data
---

A set of reviver functions that handle the workflow serialization format's workflow-specific types — streams, step/workflow function references, class instances, `AbortController`/`AbortSignal`, and `DOMException` — reviving them as display-friendly marker objects or strings. Built-in JavaScript types (`Date`, `Map`, `Set`, `RegExp`, etc.) are handled by the devalue format itself and need no revivers.

Pass it as the `revivers` argument to [`hydrateResourceIO()`](/docs/api-reference/workflow-observability/hydrate-resource-io) or [`hydrateData()`](/docs/api-reference/workflow-observability/hydrate-data).

```typescript lineNumbers
import { hydrateResourceIO, observabilityRevivers } from "workflow/observability"; // [!code highlight]
import type { Step } from "@workflow/world";
declare const step: Step; // @setup

const hydrated = hydrateResourceIO(step, observabilityRevivers); // [!code highlight]
```

## API Signature

```typescript
import type { Revivers } from "workflow/observability";

declare const observabilityRevivers: Revivers;
```

Where `Revivers` is:

```typescript
type Revivers = Record<string, (value: any) => any>;
```

Each key is a serialized type tag, and each function revives a serialized value of that type. You can spread `observabilityRevivers` into a custom reviver map to override how specific types are displayed:

```typescript lineNumbers
import { hydrateData, observabilityRevivers } from "workflow/observability";
declare const value: unknown; // @setup

const customRevivers = {
  ...observabilityRevivers,
  // Render stream references as plain strings instead of marker objects
  ReadableStream: () => "<stream>",
};

const hydrated = hydrateData(value, customRevivers);
```
