feat(web): initialize Next.js project with Tailwind CSS and TypeScript setup

pkg/engine/emitter.go

@@ -0,0 +1,28 @@
+package engine
+
+import "context"
+
+type emitterKey struct{}
+
+// Emitter publishes execution events for a given execution ID.
+// Implemented by execevents.MemoryBus (default) and external backends (Postgres LISTEN/NOTIFY, Redis Streams).
+type Emitter interface {
+	Emit(ctx context.Context, execID string, e ExecutionEvent)
+}
+
+// WithEmitter returns a new context carrying the given Emitter.
+func WithEmitter(ctx context.Context, e Emitter) context.Context {
+	return context.WithValue(ctx, emitterKey{}, e)
+}
+
+// EmitterFromContext returns the Emitter stored in ctx, or a no-op emitter.
+func EmitterFromContext(ctx context.Context) Emitter {
+	if e, ok := ctx.Value(emitterKey{}).(Emitter); ok && e != nil {
+		return e
+	}
+	return noopEmitter{}
+}
+
+type noopEmitter struct{}
+
+func (noopEmitter) Emit(_ context.Context, _ string, _ ExecutionEvent) {}