## Compatibility
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44description: Get notified when major events happen without polling.
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7## Compatibility
8- Status: Beta
9- [Beta header](https://platform.claude.com/docs/en/api/beta-headers): `managed-agents-2026-04-01`
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711Sessions are long-running interactions. While most real-time interactions happen through the [SSE event stream](https://platform.claude.com/docs/en/managed-agents/events-and-streaming), webhooks notify you of major state changes.
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913Webhook events return the event `type` and `id`, not the full object. When you receive a webhook event, you need to fetch the object directly with a `GET` call. This avoids delivering stale data on retries and keeps every delivery small.