(new): rich message support

(fix): runtime reliability
(tests): regression coverage
(doc): v1.1 release notes

drafts.go

@@ -129,7 +129,19 @@ type Draft struct {
 //
 // The caller must set a chat with SetChat before Push or Flush.
 func (p *DraftProvider) NewDraft(parseMode tgapi.ParseMode) *Draft {
-	id := p.generator.Next()
+	p.mu.Lock()
+	defer p.mu.Unlock()
+
+	var id uint64
+	for {
+		id = p.generator.Next()
+		if id == 0 {
+			continue
+		}
+		if _, exists := p.drafts[id]; !exists {
+			break
+		}
+	}
 	draft := &Draft{
 		api:       p.api,
 		provider:  p,
@@ -137,9 +149,7 @@ func (p *DraftProvider) NewDraft(parseMode tgapi.ParseMode) *Draft {
 		ID:        id,
 		Message:   "",
 	}
-	p.mu.Lock()
 	p.drafts[id] = draft
-	p.mu.Unlock()
 	return draft
 }
 
@@ -154,10 +164,9 @@ func (d *Draft) SetChat(chatID int64, messageThreadID int) *Draft {
 
 // SetEntities replaces the draft's message entities.
 //
-// Entities are stored by reference. If you plan to mutate the slice later,
-// pass a copy: `SetEntities(append([]tgapi.MessageEntity{}, myEntities...))`.
+// The entities slice is copied.
 func (d *Draft) SetEntities(entities []tgapi.MessageEntity) *Draft {
-	d.entities = entities
+	d.entities = append([]tgapi.MessageEntity(nil), entities...)
 	return d
 }
 
@@ -220,6 +229,9 @@ func (d *Draft) Flush() error {
 	if err := validateMessageText(d.Message); err != nil {
 		return err
 	}
+	if d.api == nil {
+		return ErrAPIIsNil
+	}
 
 	params := tgapi.SendMessage{
 		ChatID:    d.chatID,
@@ -252,6 +264,9 @@ func (d *Draft) push(text string) error {
 		return err
 	}
 	d.Message = candidate
+	if d.api == nil {
+		return ErrAPIIsNil
+	}
 	params := tgapi.SendMessageDraft{
 		ChatID:    d.chatID,
 		DraftID:   d.ID,