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# Function register_subscriber

> Register a global lifecycle event subscriber.

Generated from `cargo doc --no-deps -p nemo-relay -p nemo-relay-adaptive -p nemo-relay-ffi`.

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Register a global lifecycle event subscriber.

The subscriber is added to the process-wide registry and receives every emitted scope, tool, LLM, and mark event until it is deregistered.

## Parameters

* `name`: Unique subscriber name in the global registry.
* `callback`: Subscriber callback invoked for each emitted event.

## Returns

A [`Result`](/reference/api/rust-library-reference/nemo-relay/error/type-result) that is `Ok(())` when the subscriber was registered.

## Errors

Returns [`FlowError::AlreadyExists`](/reference/api/rust-library-reference/nemo-relay/error/enum-flowerror) when another global subscriber is already registered under the same name.

## Notes

Global subscribers remain active across scopes until explicitly removed. Native event-producing APIs enqueue subscriber work and return without waiting for callbacks.