---
url: >-
  https://adk.nht.io/api/@nhtio/adk/dispatch_runner/type-aliases/DispatchRunnerObservabilityHooks.md
description: 'Observability hook events on {@link @nhtio/adk!DispatchRunner}.'
---

# Type Alias: DispatchRunnerObservabilityHooks

```ts
type DispatchRunnerObservabilityHooks = {
  dispatchEnd: [[DispatchEndEvent], []];
  dispatchStart: [[DispatchStartEvent], []];
  error: [[BaseException], []];
  iterationEnd: [[IterationEndEvent], []];
  iterationStart: [[IterationStartEvent], []];
  log: [[LogEvent], []];
  toolExecutionEnd: [[ToolExecutionEndEvent], []];
  toolExecutionStart: [[ToolExecutionStartEvent], []];
};
```

Defined in: [lib/types/dispatch\_runner.ts:363](https://github.com/NHTIO/ADK/blob/v1.20260605.0/src/lib/types/dispatch_runner.ts#L363)

Observability hook events on [@nhtio/adk!DispatchRunner](../classes/DispatchRunner.md).

## Remarks

Instrumentation-only events. Register handlers via the `observers` field of the dispatch
input. Removing an observer does not affect dispatch correctness.

## Properties

| Property                                                      | Type                                                                                               | Description                                                                                                                                            | Defined in                                                                                                                |
| ------------------------------------------------------------- | -------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------ | ------------------------------------------------------------------------------------------------------------------------- |
|  `dispatchEnd`               | \[\[[`DispatchEndEvent`](../interfaces/DispatchEndEvent.md)], \[]]                              | Fired once when the dispatch ends (ack / nack / aborted).                                                                                              | [lib/types/dispatch\_runner.ts:375](https://github.com/NHTIO/ADK/blob/v1.20260605.0/src/lib/types/dispatch_runner.ts#L375) |
|  `dispatchStart`           | \[\[[`DispatchStartEvent`](../interfaces/DispatchStartEvent.md)], \[]]                          | Fired once when the dispatch begins.                                                                                                                   | [lib/types/dispatch\_runner.ts:373](https://github.com/NHTIO/ADK/blob/v1.20260605.0/src/lib/types/dispatch_runner.ts#L373) |
|  `error`                           | \[\[[`BaseException`](../../factories/classes/BaseException.md)], \[]]                          | Fired when a non-fatal pipeline or executor error occurs. The exception is also re-thrown.                                                             | [lib/types/dispatch\_runner.ts:377](https://github.com/NHTIO/ADK/blob/v1.20260605.0/src/lib/types/dispatch_runner.ts#L377) |
|  `iterationEnd`             | \[\[[`IterationEndEvent`](../interfaces/IterationEndEvent.md)], \[]]                            | Fired at the end of each iteration.                                                                                                                    | [lib/types/dispatch\_runner.ts:371](https://github.com/NHTIO/ADK/blob/v1.20260605.0/src/lib/types/dispatch_runner.ts#L371) |
|  `iterationStart`         | \[\[[`IterationStartEvent`](../interfaces/IterationStartEvent.md)], \[]]                        | Fired at the start of each iteration.                                                                                                                  | [lib/types/dispatch\_runner.ts:369](https://github.com/NHTIO/ADK/blob/v1.20260605.0/src/lib/types/dispatch_runner.ts#L369) |
|  `log`                               | \[\[[`LogEvent`](../interfaces/LogEvent.md)], \[]]                                              | Fired for every structured log event emitted by the executor via [DispatchExecutorHelpers.log](../interfaces/DispatchExecutorHelpers.md#property-log). | [lib/types/dispatch\_runner.ts:379](https://github.com/NHTIO/ADK/blob/v1.20260605.0/src/lib/types/dispatch_runner.ts#L379) |
|  `toolExecutionEnd`     | \[\[[`ToolExecutionEndEvent`](../../turn_runner/interfaces/ToolExecutionEndEvent.md)], \[]]     | Forwarded from the context after a tool handler returns or throws.                                                                                     | [lib/types/dispatch\_runner.ts:367](https://github.com/NHTIO/ADK/blob/v1.20260605.0/src/lib/types/dispatch_runner.ts#L367) |
|  `toolExecutionStart` | \[\[[`ToolExecutionStartEvent`](../../turn_runner/interfaces/ToolExecutionStartEvent.md)], \[]] | Forwarded from the context immediately before a tool handler is called.                                                                                | [lib/types/dispatch\_runner.ts:365](https://github.com/NHTIO/ADK/blob/v1.20260605.0/src/lib/types/dispatch_runner.ts#L365) |