diff --git a/internal/app/app.go b/internal/app/app.go
index 80cac5ec..44579ece 100644
--- a/internal/app/app.go
+++ b/internal/app/app.go
@@ -271,6 +271,17 @@ func (a *App) ClearMessages() {
 	}
 }
 
+// ReloadMessagesFromTree clears the in-memory message store and reloads it
+// from the tree session's current branch. Unlike ClearMessages, this does NOT
+// reset the tree session's leaf pointer. Used after Branch() to sync the
+// store with the new branch position.
+func (a *App) ReloadMessagesFromTree() {
+	a.store.Clear()
+	if a.opts.TreeSession != nil {
+		a.store.Replace(a.opts.TreeSession.GetLLMMessages())
+	}
+}
+
 // GetTreeSession returns the tree session manager, or nil if not configured.
 func (a *App) GetTreeSession() *session.TreeManager {
 	return a.opts.TreeSession
diff --git a/internal/ui/model.go b/internal/ui/model.go
index d22c5796..6d4f00a7 100644
--- a/internal/ui/model.go
+++ b/internal/ui/model.go
@@ -74,6 +74,11 @@ type AppController interface {
 	ClearQueue()
 	// ClearMessages clears the conversation history.
 	ClearMessages()
+	// ReloadMessagesFromTree clears the in-memory message store and reloads
+	// it from the tree session's current branch. Unlike ClearMessages, this
+	// does NOT reset the tree session's leaf pointer. Used after Branch() to
+	// sync the store with the new branch position.
+	ReloadMessagesFromTree()
 	// CompactConversation summarises older messages to free context space.
 	// Runs asynchronously; results are delivered via CompactCompleteEvent or
 	// CompactErrorEvent sent through the registered tea.Program. Returns an
@@ -3047,8 +3052,12 @@ func (m *AppModel) performFork(targetID string, isUser bool, userText string) te
 		return nil
 	}
 
+	// Branch the tree session to the target entry. We must NOT call
+	// ClearMessages() here because it resets the leaf pointer back to "",
+	// undoing the branch we just set. Instead, branch first and then
+	// reload the in-memory store from the tree session's current branch.
 	_ = ts.Branch(targetID)
-	m.appCtrl.ClearMessages()
+	m.appCtrl.ReloadMessagesFromTree()
 
 	// If it was a user message, populate the input with the text.
 	if isUser && userText != "" {
diff --git a/internal/ui/model_test.go b/internal/ui/model_test.go
index ee0a69b8..62e0eb9e 100644
--- a/internal/ui/model_test.go
+++ b/internal/ui/model_test.go
@@ -46,6 +46,10 @@ func (s *stubAppController) ClearMessages() {
 	s.clearMsgCalled++
 }
 
+func (s *stubAppController) ReloadMessagesFromTree() {
+	// no-op in tests
+}
+
 func (s *stubAppController) CompactConversation(_ string) error {
 	return nil
 }