feat(01-02): dispatch typed events with request context

- App-owned festival bus with Fire, Collect and UntilHandled
- Recover listener panics with owner plugin IDs; isolate buses per app
- towel context accessors and hello command demo of all three modes

examples/hello/plugins/greeter/plugin.go

@@ -5,10 +5,15 @@ import (
 
 	"git.golem15.com/golem15/summercms/backpack"
 	"git.golem15.com/golem15/summercms/bonfire"
+	"git.golem15.com/golem15/summercms/festival"
 	"git.golem15.com/golem15/summercms/pact"
 	"git.golem15.com/golem15/summercms/party"
+	"git.golem15.com/golem15/summercms/towel"
 )
 
+var _ festival.Collectable = (*HelloEvent)(nil)
+var _ festival.Handleable = (*HelloEvent)(nil)
+
 // Plugin is the golem15.greeter plugin. It requires golem15.hello.
 type Plugin struct {
 	app   *backpack.App
@@ -28,6 +33,19 @@ func (p *Plugin) Boot(app *backpack.App) error {
 			p.extra = msg.Message()
 		}
 	}
+	if app != nil && app.Events != nil {
+		app.Events.Listen[*HelloEvent]("golem15.greeter", func(ctx context.Context, e *HelloEvent) error {
+			if e.data == nil {
+				e.data = map[string]any{}
+			}
+			e.data["source"] = "greeter"
+			if actor, ok := towel.Actor(ctx); ok {
+				e.data["actor"] = actor
+			}
+			e.handled = true
+			return nil
+		})
+	}
 	return nil
 }
 
@@ -44,12 +62,50 @@ func (p *Plugin) Commands() []bonfire.Command {
 				posts = p.app.Config.Int("golem15.hello.posts_per_page")
 				debug = p.app.Config.Bool("app.debug")
 			}
-			out.Printf("name=%s posts_per_page=%d debug=%t extra=%s\n", name, posts, debug, p.extra)
+			events := "ok"
+			collected := ""
+			handled := false
+			if p.app != nil && p.app.Events != nil {
+				if err := p.app.Events.Fire(ctx, &HelloEvent{}); err != nil {
+					events = "err"
+				}
+				payload, err := p.app.Events.Collect(ctx, &HelloEvent{})
+				if err != nil {
+					events = "err"
+				}
+				if src, ok := payload["source"].(string); ok {
+					collected = src
+				}
+				ok, err := p.app.Events.UntilHandled(ctx, &HelloEvent{})
+				if err != nil {
+					events = "err"
+				}
+				handled = ok
+			}
+			out.Printf("name=%s posts_per_page=%d debug=%t extra=%s events=%s collected=%s handled=%t\n", name, posts, debug, p.extra, events, collected, handled)
 			return nil
 		},
 	}}
 }
 
+// HelloEvent is a typed greeter event used to demonstrate Fire, Collect
+// and UntilHandled on the app bus.
+type HelloEvent struct {
+	data    map[string]any
+	handled bool
+}
+
+func (e *HelloEvent) Collected() map[string]any {
+	if e == nil {
+		return nil
+	}
+	return e.data
+}
+
+func (e *HelloEvent) IsHandled() bool {
+	return e != nil && e.handled
+}
+
 var _ pact.HasCommands = (*Plugin)(nil)
 
 func init() {