Lifecycle and hooks

Register builds a plan. It should decode configuration and declare contributions, without starting work that must later be undone.

Add lifecycle callbacks

Keep the registration small:

return reg.Lifecycle(wago.PluginLifecycle{
	Start: p.start,
	Stop:  p.stop,
})

Both callbacks receive a context.Context and return an error.

Start runs after Wago accepts the full plugin plan. Start listeners, files, and goroutines there.

Stop also runs after a partially failed Start. Check which resources exist, stop accepting work, wake blocked callbacks, and release each resource once.

See examples/09-plugin-config-lifecycle for a runnable lifecycle.

Choose a hook

Use RuntimeCloseObserver when runtime shutdown matters. Module work belongs in ModuleSourceTransformer, ModuleCompileObserver, or ModuleCloseObserver. Their Authorities are runtime.close.observe, module.source.transform, module.compile.observe, and module.close.observe.

For instances, an interceptor can reject work or attach state; an observer records the result. Use InstanceInstantiateInterceptor or InstanceInstantiateObserver while creating an instance, and InstanceInvokeInterceptor or InstanceInvokeObserver around calls. InstanceCloseObserver handles exact-instance close.

Request only the matching Authority: instance.instantiate.intercept, instance.instantiate.observe, instance.invoke.intercept, instance.invoke.observe, or instance.close.observe.

Observe a call

Get the observer during registration:

calls, err := reg.InstanceInvokeObserver()
if err != nil {
	return err
}

Attach the callback:

return calls.After(func(event wago.InvocationEvent) {
	log.Printf("%s: %v", event.Export, event.Err)
})

Observers record outcomes. Interceptors may return an error to stop an operation. Use opaque event identities to correlate state instead of retaining a Runtime, Module, or Instance.

Run examples/10-hooks to see the complete compile, instantiate, invoke, close, and runtime-close order.