# Overview

## Overview

API v1 brings fully featured agent messaging to the Credal API. Your application can now interact with agents that use [actions](https://docs.credal.ai/user-guide/platform/governed-actions/overview) — the same rich agent experience available in the Credal UI, now accessible programmatically.

### What's new in v1

**Full agent messaging with [actions](https://docs.credal.ai/user-guide/platform/governed-actions/overview)** — v0 only supported simple text-in, text-out interactions. v1 supports the complete agent loop, including agents that use actions to search documents, query databases, create tickets, and more.

**Asynchronous messaging** — v0 was synchronous: you sent a message and blocked until the response came back. v1 uses a fire-and-poll pattern — `sendMessage` returns a `jobId`, and you poll `fetchAgentResponse` until the result is ready. This supports longer-running agent interactions involving actions. Note that responses are ephemeral and should be fetched promptly rather than relied on to be available indefinitely.

**Improved reliability** — v1 is built on Credal's new agent messaging system with greater investment in resilience and error handling, providing more robust delivery and clearer failure modes compared to v0.

**OAuth 2.0 authentication** — instead of a static API key scoped to a single agent, v1 uses OAuth. After a user completes the [OAuth flow](https://docs.credal.ai/api-reference/v-1/oauth-setup), your app can message any agent that user has access to.

### What changed from v0

|                     | v0                     | v1                                                                                                       |
| ------------------- | ---------------------- | -------------------------------------------------------------------------------------------------------- |
| **Agent messaging** | Synchronous, text-only | Async fire-and-poll with [actions](https://docs.credal.ai/user-guide/platform/governed-actions/overview) |
| **Auth method**     | Static API key         | OAuth 2.0                                                                                                |
| **Scope**           | Single agent           | All agents the user can access                                                                           |
| **Token lifetime**  | Long-lived             | Short-lived (refresh via OAuth)                                                                          |
| **User context**    | None                   | Requests run as the authenticated user                                                                   |

:::callout{intent="note" title="Active development"}
API v1 is in active development. New endpoints and capabilities will be added on an ongoing basis.
:::

### Getting started

1. **Register an OAuth client** — set up your application as an OAuth client in Credal. See [OAuth Setup](https://docs.credal.ai/api-reference/v-1/oauth-setup) for instructions.
2. **Implement the OAuth flow** — redirect users to Credal's authorization endpoint, then exchange the authorization code for an access token. Refer to the [OAuth Setup](https://docs.credal.ai/api-reference/v-1/oauth-setup) guide for details.
3. **Call the API** — use the access token as a Bearer token in API requests.

## Related pages

- [API v1 is currently under development](./apis-coming-soon.md)
- [Credal | Documentation](../index.md)
- [Actions](./concepts-actions.md)
- [Getting Started](./getting-started-index.md)
- [Introduction](./getting-started-introduction.md)
- [Overview](./overview-overview.md)
- [Agent Builder](./platform-agent-builder.md)
- [Oauth setup](./apis-oauth-setup.md)
- [Agents](./concepts-agents.md)
- [Quickstart](./getting-started-quickstart.md)

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