Diagnostics

Compiler diagnostics emitted by Observables source generators (IDs are stable per domain).

Events (OBS2001–OBS2004)

ID	Severity	When
OBS2001	Warning	Classic Events() — unsupported event delegate signature
OBS2002	Warning	EventHandlers() — not EventHandler / (object, T) shape
OBS2003	Warning	RoutedEvents() — unsupported routed event delegate
OBS2004	Warning	RoutedEventHandlers() — unsupported routed handler delegate

Category: Observables.Events.

RestAPI (OBS3001–OBS3005)

ID	Severity	When
OBS3001	Warning	Interface method missing HTTP verb attribute or non-literal path
OBS3002	Error	Observables.RestAPI runtime not referenced
OBS3003	Error	Unsupported return type on API method
OBS3004	Error	Path template does not match method parameters
OBS3005	Error	IObservable<T> return without Observables.RestAPI.Reactive package

Category: Observables.RestAPI.

SignalR (OBS4001–OBS4006)

ID	Severity	When
OBS4001	Warning	Hub member missing boundary attribute or non-literal hub method name
OBS4002	Error	Observables.SignalR runtime not referenced
OBS4003	Error	Unsupported return type (must be Observable<T> / IObservable<T>; Send needs Unit)
OBS4004	Error	Member shape mismatch (e.g. [HubOn] on a method)
OBS4005	Error	IObservable<T> without Observables.SignalR.Reactive package
OBS4006	Error	Unsupported client-to-server streaming parameter

Category: Observables.SignalR.

Mqtt (OBS5001–OBS5006)

ID	Severity	When
OBS5001	Warning	Mqtt member missing boundary attribute or non-literal topic template
OBS5002	Error	Observables.Mqtt runtime not referenced
OBS5003	Error	Unsupported return type on Mqtt member
OBS5004	Error	Member shape mismatch (e.g. [MqttSubscribe] on a method)
OBS5005	Error	IObservable<T> without Observables.Mqtt.Reactive package
OBS5006	Error	Unsupported topic template, extra parameters, or subscribe placeholder syntax

Category: Observables.Mqtt.