feat(broadcast): migrate to Subscribe(SelfTopic())+Publish

chat/main.go

@@ -37,8 +37,12 @@ type Message struct {
 	Timestamp string `json:"timestamp"`
 }
 
-// Mount is called once per session group. Sets up initial empty state.
+// Mount runs once per session group. Subscribes the self-topic so peer tabs
+// receive the UserJoined / NewMessage / UserLeft dispatches Publish'd below.
 func (c *ChatController) Mount(state ChatState, ctx *livetemplate.Context) (ChatState, error) {
+	if err := ctx.Subscribe(ctx.SelfTopic()); err != nil {
+		return state, err
+	}
 	c.mu.RLock()
 	defer c.mu.RUnlock()
 	state.Messages = c.copyMessages()
@@ -73,8 +77,14 @@ func (c *ChatController) Join(state ChatState, ctx *livetemplate.Context) (ChatS
 	state.OnlineCount = c.countOnline()
 	c.mu.Unlock()
 
-	// Tell other tabs someone joined
-	ctx.BroadcastAction("UserJoined", nil)
+	// Tell other tabs someone joined. We propagate Publish's error rather than
+	// log-and-swallow because the only errors it can return are programmer
+	// errors (empty SelfTopic from a misconfigured Authenticator, or the
+	// per-action publish cap exceeded). Surfacing them loudly is a feature.
+	// Same pattern applies to every Publish call site in this file.
+	if err := ctx.Publish(ctx.SelfTopic(), "UserJoined", nil); err != nil {
+		return state, err
+	}
 	return state, nil
 }
 
@@ -109,7 +119,9 @@ func (c *ChatController) Send(state ChatState, ctx *livetemplate.Context) (ChatS
 	c.mu.Unlock()
 
 	// Tell other tabs about the new message
-	ctx.BroadcastAction("NewMessage", nil)
+	if err := ctx.Publish(ctx.SelfTopic(), "NewMessage", nil); err != nil {
+		return state, err
+	}
 	return state, nil
 }
 
@@ -135,7 +147,9 @@ func (c *ChatController) Leave(state ChatState, ctx *livetemplate.Context) (Chat
 	state.OnlineCount = c.countOnline()
 	c.mu.Unlock()
 
-	ctx.BroadcastAction("UserLeft", nil)
+	if err := ctx.Publish(ctx.SelfTopic(), "UserLeft", nil); err != nil {
+		return state, err
+	}
 	return state, nil
 }
 

go.mod

@@ -7,7 +7,7 @@ require (
 	github.com/chromedp/chromedp v0.14.2
 	github.com/go-playground/validator/v10 v10.30.1
 	github.com/gorilla/websocket v1.5.3
-	github.com/livetemplate/livetemplate v0.9.0
+	github.com/livetemplate/livetemplate v0.9.2
 	github.com/livetemplate/lvt v0.1.6
 	github.com/livetemplate/lvt/components v0.1.2
 	modernc.org/sqlite v1.43.0

go.sum

@@ -92,8 +92,8 @@ github.com/ledongthuc/pdf v0.0.0-20220302134840-0c2507a12d80 h1:6Yzfa6GP0rIo/kUL
 github.com/ledongthuc/pdf v0.0.0-20220302134840-0c2507a12d80/go.mod h1:imJHygn/1yfhB7XSJJKlFZKl/J+dCPAknuiaGOshXAs=
 github.com/leodido/go-urn v1.4.0 h1:WT9HwE9SGECu3lg4d/dIA+jxlljEa1/ffXKmRjqdmIQ=
 github.com/leodido/go-urn v1.4.0/go.mod h1:bvxc+MVxLKB4z00jd1z+Dvzr47oO32F/QSNjSBOlFxI=
-github.com/livetemplate/livetemplate v0.9.0 h1:6vHNNpZLIY4gO08/Gth3vr1F3A3ANwSKTQvfuy1I8js=
-github.com/livetemplate/livetemplate v0.9.0/go.mod h1:GMvZKyPUq8LSGfgD3pftKOHa6v+I+RDYyff2mNjeAYs=
+github.com/livetemplate/livetemplate v0.9.2 h1:zF/mbhXxp5uLX3UBdgkdBk+Jmhfx3g5DAlUCisTXoZM=
+github.com/livetemplate/livetemplate v0.9.2/go.mod h1:GMvZKyPUq8LSGfgD3pftKOHa6v+I+RDYyff2mNjeAYs=
 github.com/livetemplate/lvt v0.1.6 h1:1rDU5hDo+EtZ0mT+868wYD9czF2EHEgdacS4kpIUPQ4=
 github.com/livetemplate/lvt v0.1.6/go.mod h1:OrTdx3zvh0WeuugVueQoRG3ILRNJe/dThErxKsos6Rw=
 github.com/livetemplate/lvt/components v0.1.2 h1:MM2M5IZnsUAu0py9ZbtcQCo0bvUrL4Z3Ly/yDkYNyag=

landing-demo/landing_demo_test.go

@@ -213,27 +213,27 @@ func TestLandingDemoE2E(t *testing.T) {
 		}
 	})
 
-	t.Run("BroadcastAction_Propagates_To_Peer_Tab", func(t *testing.T) {
+	t.Run("Publish_Propagates_To_Peer_Tab", func(t *testing.T) {
 		// SKIP rationale: this scenario IS what the README and landing
 		// page describe — "open this page in another tab and watch them
-		// sync." The controller calls BroadcastAction after counter
-		// mutations to dispatch peer-tab updates. But
-		// reliably exercising that across two chromedp browser contexts
-		// turns out to need more work than fits this PR:
+		// sync." The controller Publishes to SelfTopic() after counter
+		// mutations to dispatch peer-tab updates. But reliably exercising
+		// that across two chromedp browser contexts turns out to need more
+		// work than fits this PR:
 		//   - chromedp.NewContext(parent) shares the browser allocator
 		//     but each new target gets its own request context, so the
 		//     session cookie may not propagate the way two real-world
 		//     tabs in the same browser would.
 		//   - Even when both tabs DO land in the same session group,
-		//     the peer-side broadcast round-trip wasn't observed within 10s
+		//     the peer-side publish round-trip wasn't observed within 10s
 		//     in this harness, suggesting either a session-group
 		//     mismatch or an artifact of how the docker-chrome target
 		//     attaches.
 		// Manual verification: load https://lt-landing-demo.fly.dev/ in
 		// two tabs of the same browser and click +1 in either; both
 		// counters move. The cross-tab claim on the landing page holds.
 		// Tracking proper e2e coverage as a follow-up.
-		t.Skip("cross-tab BroadcastAction e2e: tracked at livetemplate/examples#94 — pending session-group propagation work in chromedp peer context; manual verification documented in test comment")
+		t.Skip("cross-tab Publish e2e: tracked at livetemplate/examples#94 — pending session-group propagation work in chromedp peer context; manual verification documented in test comment")
 	})
 
 	t.Run("HTTP_POST_Fallback_Without_JS", func(t *testing.T) {

landing-demo/main.go

@@ -1,7 +1,7 @@
 // Minimal LiveTemplate counter, sized for a landing-page demo. The whole
 // app fits in this file; the template is a single counter.tmpl. Per-session
-// state means each visitor has their own counter; explicit BroadcastAction
-// calls keep their WebSocket-connected tabs in step.
+// state means each visitor has their own counter; explicit Publish-to-
+// SelfTopic calls keep their WebSocket-connected tabs in step.
 package main
 
 import (
@@ -19,9 +19,20 @@ type CounterState struct {
 	Count int `json:"count" lvt:"persist"`
 }
 
+// Mount subscribes the self-topic so peer tabs receive the Increment /
+// Decrement / Reset dispatches Publish'd from the actions below.
+func (c *CounterController) Mount(s CounterState, ctx *livetemplate.Context) (CounterState, error) {
+	if err := ctx.Subscribe(ctx.SelfTopic()); err != nil {
+		return s, err
+	}
+	return s, nil
+}
+
 func (c *CounterController) Increment(s CounterState, ctx *livetemplate.Context) (CounterState, error) {
 	s.Count++
-	ctx.BroadcastAction("Increment", nil)
+	if err := ctx.Publish(ctx.SelfTopic(), "Increment", nil); err != nil {
+		return s, err
+	}
 	return s, nil
 }
 
@@ -31,13 +42,17 @@ func (c *CounterController) Decrement(s CounterState, ctx *livetemplate.Context)
 	if s.Count > 0 {
 		s.Count--
 	}
-	ctx.BroadcastAction("Decrement", nil)
+	if err := ctx.Publish(ctx.SelfTopic(), "Decrement", nil); err != nil {
+		return s, err
+	}
 	return s, nil
 }
 
 func (c *CounterController) Reset(s CounterState, ctx *livetemplate.Context) (CounterState, error) {
 	s.Count = 0
-	ctx.BroadcastAction("Reset", nil)
+	if err := ctx.Publish(ctx.SelfTopic(), "Reset", nil); err != nil {
+		return s, err
+	}
 	return s, nil
 }
 

shared-notepad/main.go

@@ -25,6 +25,11 @@ type NotepadState struct {
 }
 
 func (c *NotepadController) Mount(state NotepadState, ctx *livetemplate.Context) (NotepadState, error) {
+	// Subscribe the self-topic so peer tabs of the same user receive the
+	// Refresh dispatch from Save's Publish below — multi-device sync.
+	if err := ctx.Subscribe(ctx.SelfTopic()); err != nil {
+		return state, err
+	}
 	state.Username = ctx.UserID()
 	c.mu.RLock()
 	if saved, ok := c.notes[ctx.UserID()]; ok {
@@ -45,7 +50,9 @@ func (c *NotepadController) Save(state NotepadState, ctx *livetemplate.Context)
 	c.notes[ctx.UserID()] = state
 	c.mu.Unlock()
 
-	ctx.BroadcastAction("Refresh", nil)
+	if err := ctx.Publish(ctx.SelfTopic(), "Refresh", nil); err != nil {
+		return state, err
+	}
 	return state, nil
 }
 

todos/controller.go

@@ -17,6 +17,11 @@ type TodoController struct {
 }
 
 func (c *TodoController) Mount(state TodoState, ctx *livetemplate.Context) (TodoState, error) {
+	// Subscribe self-topic so peer tabs of the same user receive the
+	// RefreshTodos dispatch from Publish calls in actions below.
+	if err := ctx.Subscribe(ctx.SelfTopic()); err != nil {
+		return state, err
+	}
 	state.Username = ctx.UserID()
 	state = initComponents(state)
 	return c.loadTodos(context.Background(), state, ctx.UserID())
@@ -60,7 +65,9 @@ func (c *TodoController) Add(state TodoState, ctx *livetemplate.Context) (TodoSt
 	if err != nil {
 		return state, err
 	}
-	ctx.BroadcastAction("RefreshTodos", nil)
+	if err := ctx.Publish(ctx.SelfTopic(), "RefreshTodos", nil); err != nil {
+		return state, err
+	}
 	return state, nil
 }
 
@@ -99,7 +106,9 @@ func (c *TodoController) Toggle(state TodoState, ctx *livetemplate.Context) (Tod
 	if err != nil {
 		return state, err
 	}
-	ctx.BroadcastAction("RefreshTodos", nil)
+	if err := ctx.Publish(ctx.SelfTopic(), "RefreshTodos", nil); err != nil {
+		return state, err
+	}
 	return state, nil
 }
 
@@ -134,7 +143,9 @@ func (c *TodoController) ConfirmDeleteConfirm(state TodoState, ctx *livetemplate
 	if err != nil {
 		return state, err
 	}
-	ctx.BroadcastAction("RefreshTodos", nil)
+	if err := ctx.Publish(ctx.SelfTopic(), "RefreshTodos", nil); err != nil {
+		return state, err
+	}
 	return state, nil
 }
 
@@ -225,7 +236,9 @@ func (c *TodoController) ClearCompleted(state TodoState, ctx *livetemplate.Conte
 	if err != nil {
 		return state, err
 	}
-	ctx.BroadcastAction("RefreshTodos", nil)
+	if err := ctx.Publish(ctx.SelfTopic(), "RefreshTodos", nil); err != nil {
+		return state, err
+	}
 	return state, nil
 }