CHANGELOG.md

@@ -14,6 +14,7 @@
 - Added `MsgContext.UpsertKeyboard(...)` and `MsgContext.UpsertKeyboardMarkdown(...)` helpers that edit callback messages, replace photo callback messages with a fresh chat message, and send a new chat message outside callback flow.
 - Added `CommandGroup`, `NewCommandGroup(...)`, `Plugin.CommandGroup(...)`, and `Plugin.AddCommandGroup(...)` helpers for registering prefixed command groups with shared middleware.
 - Added the `tgfmt` package with typed MarkdownV2, HTML, legacy Markdown formatting helpers, and a message entity builder.
+- Added `InlineKeyboardButtonBuilder.SetPayloadType(...)`, `InlineKeyboardButtonBuilder.SetCallbackData(...)`, and `MsgContext.NewInlineKeyboardButton(...)` helpers for payload-aware button building.
 
 ### Changed
 - Version metadata now reports the stable `v1.0.0` release instead of `v1.0.0-rc.16`.
@@ -31,6 +32,7 @@
 - Added regression coverage for inline callback keyboard upserts and callback target detection.
 - Added regression coverage for command group prefixing, middleware order, clone behavior, and plugin registration.
 - Added formatting coverage for escaping, composition, link destinations, HTML attributes, and legacy Markdown code blocks.
+- Added regression coverage for context-aware inline keyboard button payload encoding.
 
 ## v1.0.0-rc.16
 

keyboard.go

@@ -27,11 +27,14 @@ const (
 // Call build() to produce the final tgapi.InlineKeyboardButton.
 // Builder methods are immutable — each returns a copy.
 type InlineKeyboardButtonBuilder struct {
-	text              string
-	iconCustomEmojiID string
-	style             tgapi.KeyboardButtonStyle
-	url               string
-	callbackData      string
+	text    string
+	emojiID string
+	style   tgapi.KeyboardButtonStyle
+
+	url  string
+	data string
+
+	payloadType BotPayloadType
 }
 
 // NewInlineKeyboardButton creates a new button builder with the given display text.
@@ -43,7 +46,7 @@ func NewInlineKeyboardButton(text string) InlineKeyboardButtonBuilder {
 // SetIconCustomEmojiID sets a custom emoji ID to display as the button's icon.
 // This is a Telegram Bot API feature for custom emoji icons.
 func (b InlineKeyboardButtonBuilder) SetIconCustomEmojiID(id string) InlineKeyboardButtonBuilder {
-	b.iconCustomEmojiID = id
+	b.emojiID = id
 	return b
 }
 
@@ -62,6 +65,12 @@ func (b InlineKeyboardButtonBuilder) SetURL(url string) InlineKeyboardButtonBuil
 	return b
 }
 
+// SetPayloadType sets the encoding used by SetCallbackData.
+func (b InlineKeyboardButtonBuilder) SetPayloadType(t BotPayloadType) InlineKeyboardButtonBuilder {
+	b.payloadType = t
+	return b
+}
+
 // SetCallbackDataJSON sets a structured callback payload that will be sent to the bot
 // when the button is pressed. The command and arguments are serialized as JSON.
 //
@@ -70,7 +79,7 @@ func (b InlineKeyboardButtonBuilder) SetURL(url string) InlineKeyboardButtonBuil
 //
 // Example: SetCallbackDataJSON("delete_user", 123, "confirm") → {"cmd":"delete_user","args":["123","confirm"]}.
 func (b InlineKeyboardButtonBuilder) SetCallbackDataJSON(cmd string, args ...any) InlineKeyboardButtonBuilder {
-	b.callbackData = NewCallbackData(cmd, args...).ToJSON()
+	b.data = NewCallbackData(cmd, args...).ToJSON()
 	return b
 }
 
@@ -78,7 +87,18 @@ func (b InlineKeyboardButtonBuilder) SetCallbackDataJSON(cmd string, args ...any
 // This can be useful when the JSON payload exceeds Telegram's callback data length limit.
 // Args are converted to strings using fmt.Sprint.
 func (b InlineKeyboardButtonBuilder) SetCallbackDataBase64(cmd string, args ...any) InlineKeyboardButtonBuilder {
-	b.callbackData = NewCallbackData(cmd, args...).ToBase64()
+	b.data = NewCallbackData(cmd, args...).ToBase64()
+	return b
+}
+
+// SetCallbackData sets a structured callback payload using the configured payload type.
+// The default payload type is JSON.
+func (b InlineKeyboardButtonBuilder) SetCallbackData(cmd string, args ...any) InlineKeyboardButtonBuilder {
+	if b.payloadType == BotPayloadBase64 {
+		b.data = NewCallbackData(cmd, args...).ToBase64()
+	} else {
+		b.data = NewCallbackData(cmd, args...).ToJSON()
+	}
 	return b
 }
 
@@ -88,8 +108,8 @@ func (b InlineKeyboardButtonBuilder) build() tgapi.InlineKeyboardButton {
 		Text:              b.text,
 		URL:               b.url,
 		Style:             b.style,
-		IconCustomEmojiID: b.iconCustomEmojiID,
-		CallbackData:      b.callbackData,
+		IconCustomEmojiID: b.emojiID,
+		CallbackData:      b.data,
 	}
 }
 
@@ -177,7 +197,7 @@ func (in *InlineKeyboard) AddURLButtonStyle(text string, style tgapi.KeyboardBut
 
 // AddCallbackButton adds a button that sends a structured callback payload to the bot.
 // The command and args are serialized according to the current payloadType.
-func (in *InlineKeyboard) AddCallbackButton(text string, cmd string, args ...any) *InlineKeyboard {
+func (in *InlineKeyboard) AddCallbackButton(text, cmd string, args ...any) *InlineKeyboard {
 	return in.append(tgapi.InlineKeyboardButton{
 		Text:         text,
 		CallbackData: NewCallbackData(cmd, args...).Encode(in.payloadType),

keyboard_test.go

@@ -45,6 +45,34 @@ func TestInlineKeyboardBuilderPreservesConfiguredButtonFields(t *testing.T) {
 	}
 }
 
+func TestInlineKeyboardButtonBuilderSetCallbackDataDefaultsToJSON(t *testing.T) {
+	kb := NewInlineKeyboardBase64(1).
+		AddButton(NewInlineKeyboardButton("A").SetCallbackData("cmd", 1, "two"))
+
+	button := kb.Get().InlineKeyboard[0][0]
+	if !strings.Contains(button.CallbackData, `"cmd":"cmd"`) {
+		t.Fatalf("expected JSON callback payload, got %q", button.CallbackData)
+	}
+}
+
+func TestInlineKeyboardButtonBuilderSetCallbackDataUsesConfiguredPayloadType(t *testing.T) {
+	kb := NewInlineKeyboardJSON(1).
+		AddButton(NewInlineKeyboardButton("A").
+			SetPayloadType(BotPayloadBase64).
+			SetCallbackData("cmd", 1, "two"),
+		)
+
+	got, _, err := decodePayload(BotPayloadJSON, kb.Get().InlineKeyboard[0][0].CallbackData, false)
+	if err != nil {
+		t.Fatalf("decodePayload returned error: %v", err)
+	}
+
+	want := CallbackData{Command: "cmd", Args: []string{"1", "two"}}
+	if !reflect.DeepEqual(got, want) {
+		t.Fatalf("unexpected payload: got %#v want %#v", got, want)
+	}
+}
+
 func TestInlineKeyboardGetPayloadTypeReturnsLocalOverride(t *testing.T) {
 	kb := NewInlineKeyboardJSON(2)
 	if got := kb.GetPayloadType(); got != BotPayloadJSON {

msg_context.go

@@ -594,6 +594,11 @@ func (ctx *MsgContext) NewInlineKeyboard(maxRow int) *InlineKeyboard {
 	return NewInlineKeyboard(ctx.payloadType, maxRow)
 }
 
+// NewInlineKeyboardButton creates a button builder using the context payload encoding.
+func (ctx *MsgContext) NewInlineKeyboardButton(text string) InlineKeyboardButtonBuilder {
+	return NewInlineKeyboardButton(text).SetPayloadType(ctx.payloadType)
+}
+
 func bindPositional(args []string, dst any) error {
 	v := reflect.ValueOf(dst)
 	if v.Kind() != reflect.Pointer || v.IsNil() {

msg_context_test.go

@@ -91,6 +91,23 @@ func TestBindArgsBindsScalarFields(t *testing.T) {
 	}
 }
 
+func TestNewInlineKeyboardButtonUsesContextPayloadType(t *testing.T) {
+	ctx := &MsgContext{payloadType: BotPayloadBase64}
+
+	kb := NewInlineKeyboardJSON(1).
+		AddButton(ctx.NewInlineKeyboardButton("A").SetCallbackData("cmd", 1, "two"))
+
+	got, _, err := decodePayload(BotPayloadJSON, kb.Get().InlineKeyboard[0][0].CallbackData, false)
+	if err != nil {
+		t.Fatalf("decodePayload returned error: %v", err)
+	}
+
+	want := CallbackData{Command: "cmd", Args: []string{"1", "two"}}
+	if !reflect.DeepEqual(got, want) {
+		t.Fatalf("unexpected payload: got %#v want %#v", got, want)
+	}
+}
+
 func TestBindArgsLeavesTrailingFieldsZeroWhenArgsRunOut(t *testing.T) {
 	type input struct {
 		ID     int