fix: match bot commands addressed with @botusername in groups

In group chats Telegram appends the bot addressee to the bot_command
entity (/sync@hs_dyzur_bot), and the library's MatchTypeCommand compares
the whole token verbatim, so commands never matched. Replace it with
custom MatchFuncs that read the bot_command entity span and strip any
@suffix before comparing the command name.

telegram.go

@@ -14,9 +14,8 @@ import (
 
 // Command names, the single source of truth shared by the handler registration
 // and the published command list. Underscore, not hyphen: Telegram command
-// names are [a-zA-Z0-9_] only, and MatchTypeCommand matches the parsed
-// bot_command entity, which would stop at a hyphen (/kto-sprzata -> entity
-// "/kto") and never match.
+// names are [a-zA-Z0-9_] only, and the bot_command entity we match against stops
+// at a hyphen (/kto-sprzata -> entity "/kto"), so a hyphen would never match.
 const (
 	cmdKtoSprzata = "kto_sprzata"
 	cmdSync       = "sync"
@@ -35,12 +34,48 @@ var botCommands = []models.BotCommand{
 // than silently 401-ing inside the poll loop. Long polling starts on Start(ctx).
 func NewBot(token string, svc *Service) (*bot.Bot, error) {
 	h := &botHandlers{svc: svc, now: time.Now}
-	opts := []bot.Option{
-		bot.WithDefaultHandler(h.unknown),
-		bot.WithMessageTextHandler(cmdKtoSprzata, bot.MatchTypeCommand, h.ktoSprzata),
-		bot.WithMessageTextHandler(cmdSync, bot.MatchTypeCommand, h.sync),
+	b, err := bot.New(token, bot.WithDefaultHandler(h.unknown))
+	if err != nil {
+		return nil, err
 	}
-	return bot.New(token, opts...)
+	// Custom match funcs instead of bot.MatchTypeCommand: in group chats Telegram
+	// appends the addressee (/sync@hs_dyzur_bot) inside the bot_command entity,
+	// and the library's MatchTypeCommand compares the whole token verbatim, so it
+	// never matches. matchCommandEntity strips the @suffix first.
+	b.RegisterHandlerMatchFunc(h.matchCommand(cmdKtoSprzata), h.ktoSprzata)
+	b.RegisterHandlerMatchFunc(h.matchCommand(cmdSync), h.sync)
+	return b, nil
+}
+
+// matchCommand builds a MatchFunc that fires when the message leads with the
+// given bot command, tolerant of the @botusername suffix Telegram adds in groups.
+func (h *botHandlers) matchCommand(cmd string) bot.MatchFunc {
+	return func(update *models.Update) bool {
+		return update.Message != nil &&
+			matchCommandEntity(update.Message.Text, update.Message.Entities, cmd)
+	}
+}
+
+// matchCommandEntity reports whether text carries a bot_command entity whose
+// name equals cmd. The name is taken from the entity span (dropping the leading
+// '/') with any @botusername suffix removed — Telegram includes that suffix in
+// the entity for group messages, but a bot still owns the bare command. Note: a
+// command explicitly addressed to another bot (/sync@otherbot) also matches;
+// acceptable for a single-bot group, the only place this bot runs.
+func matchCommandEntity(text string, entities []models.MessageEntity, cmd string) bool {
+	for _, e := range entities {
+		if e.Type != models.MessageEntityTypeBotCommand {
+			continue
+		}
+		name := text[e.Offset+1 : e.Offset+e.Length]
+		if at := strings.IndexByte(name, '@'); at >= 0 {
+			name = name[:at]
+		}
+		if name == cmd {
+			return true
+		}
+	}
+	return false
 }
 
 // BotSendFunc builds a SendFunc that posts to a fixed chat via the bot, so the

telegram_test.go

@@ -3,8 +3,49 @@ package dyzurbot
 import (
 	"testing"
 	"time"
+
+	"github.com/go-telegram/bot/models"
 )
 
+// cmdEntity builds the bot_command entity Telegram attaches to a leading
+// command, spanning the whole token (slash, name, and any @addressee).
+func cmdEntity(text string) []models.MessageEntity {
+	return []models.MessageEntity{{
+		Type:   models.MessageEntityTypeBotCommand,
+		Offset: 0,
+		Length: len(text),
+	}}
+}
+
+func TestMatchCommandEntity(t *testing.T) {
+	tests := []struct {
+		name string
+		text string
+		cmd  string
+		want bool
+	}{
+		{"bare command (private chat)", "/sync", cmdSync, true},
+		{"command with @botusername (group)", "/sync@hs_dyzur_bot", cmdSync, true},
+		{"kto_sprzata with @botusername", "/kto_sprzata@hs_dyzur_bot", cmdKtoSprzata, true},
+		{"underscore name survives @suffix", "/kto_sprzata@hs_dyzur_bot", cmdSync, false},
+		{"wrong command", "/sync", cmdKtoSprzata, false},
+	}
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			if got := matchCommandEntity(tc.text, cmdEntity(tc.text), tc.cmd); got != tc.want {
+				t.Errorf("matchCommandEntity(%q, %q) = %v, want %v", tc.text, tc.cmd, got, tc.want)
+			}
+		})
+	}
+}
+
+// A plain message carrying no bot_command entity must not match any command.
+func TestMatchCommandEntityNoEntity(t *testing.T) {
+	if matchCommandEntity("just chatting about /sync", nil, cmdSync) {
+		t.Error("text without a bot_command entity should not match")
+	}
+}
+
 // week is a small helper to build a DutyWeek from a YYYY-MM-DD start.
 func week(t *testing.T, start, p1, p2 string) DutyWeek {
 	t.Helper()