runNode

The user-facing implementation of the node's execution logic.

Emits any of:

• A raw output value, which becomes this node's output and is normalized into an Event by the engine. It must be JSON-native (a map, list, string, number, boolean, null, or JsonElement) or a Content, the form a persistent session saves; any other value fails the node. For a typed value, call Context.setOutput, which writes its JSON form.

• A RequestInput, which the engine normalizes into an adk_request_input interrupt event that pauses the graph until the user answers.

• An Event, which passes through directly (useful for progress emissions or custom events); its output must have a JSON form too.

• null or Unit, both of which signify that no output was produced. Unit represents side-effecting Kotlin lambdas/functions that return no value, while null represents the explicit absence of an output.