> ## Documentation Index
> Fetch the complete documentation index at: https://gofastmcp.com/llms.txt
> Use this file to discover all available pages before exploring further.

# lifespan

# `fastmcp.utilities.lifespan`

Lifespan utilities for combining async context manager lifespans.

## Functions

### `combine_lifespans` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/utilities/lifespan.py#L12" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
combine_lifespans(*lifespans: Callable[[AppT], AbstractAsyncContextManager[Mapping[str, Any] | None]]) -> Callable[[AppT], AbstractAsyncContextManager[dict[str, Any]]]
```

Combine multiple lifespans into a single lifespan.

Useful when mounting FastMCP into FastAPI and you need to run
both your app's lifespan and the MCP server's lifespan.

Works with both FastAPI-style lifespans (yield None) and FastMCP-style
lifespans (yield dict). Results are merged; later lifespans override
earlier ones on key conflicts.

Lifespans are entered in order and exited in reverse order (LIFO).

**Args:**

* `*lifespans`: Lifespan context manager factories to combine.

**Returns:**

* A combined lifespan context manager factory.