feat(misc): add /trongtruonghop disclaimer command

Vietnamese disclaimer one-liner. Interpolates a target name (default "VNG")
and the sender — @username when set, else tg://user?id link with the display
name. User-supplied text HTML-escaped; reply routed through ReplyHTML to keep
forum-topic threading.

internal/modules/misc/handlers_test.go

@@ -6,6 +6,8 @@ import (
 	"testing"
 	"time"
 
+	"github.com/go-telegram/bot/models"
+
 	"github.com/tiennm99/miti99bot/internal/modules"
 	"github.com/tiennm99/miti99bot/internal/storage"
 	"github.com/tiennm99/miti99bot/internal/testutil"
@@ -86,6 +88,83 @@ func TestMstats_DeniedToNonAdmin(t *testing.T) {
 	}
 }
 
+// trongTruongHopUpdate is the inline counterpart of testutil.NewPrivateMessage
+// for cases that need control over From (username, names). The dispatcher
+// requires a bot_command entity, so we lift that from the helper API by reusing
+// NewPrivateMessage and overwriting From.
+func trongTruongHopUpdate(t *testing.T, text string, from *models.User) *models.Update {
+	t.Helper()
+	u := testutil.NewPrivateMessage(from.ID, text)
+	u.Message.From = from
+	return u
+}
+
+func TestTrongTruongHop_DefaultArgUsesVNG(t *testing.T) {
+	rb, _ := installMisc(t, 999)
+	rb.Bot.ProcessUpdate(context.Background(), trongTruongHopUpdate(t, "/trongtruonghop",
+		&models.User{ID: 7, Username: "boss", FirstName: "Boss"}))
+
+	got := rb.LastSent().Text()
+	if !strings.Contains(got, "VNG") {
+		t.Errorf("reply missing default target VNG: %q", got)
+	}
+	if n := strings.Count(got, "@boss"); n != 2 {
+		t.Errorf("reply mentions @boss %d times, want 2: %q", n, got)
+	}
+}
+
+func TestTrongTruongHop_CustomArg(t *testing.T) {
+	rb, _ := installMisc(t, 999)
+	rb.Bot.ProcessUpdate(context.Background(), trongTruongHopUpdate(t, "/trongtruonghop Acme Corp",
+		&models.User{ID: 7, Username: "boss", FirstName: "Boss"}))
+
+	got := rb.LastSent().Text()
+	if !strings.Contains(got, "Acme Corp") {
+		t.Errorf("reply missing custom arg Acme Corp: %q", got)
+	}
+	if strings.Contains(got, "VNG") {
+		t.Errorf("reply unexpectedly contains default VNG: %q", got)
+	}
+}
+
+func TestTrongTruongHop_HTMLEscapesArg(t *testing.T) {
+	rb, _ := installMisc(t, 999)
+	rb.Bot.ProcessUpdate(context.Background(), trongTruongHopUpdate(t, "/trongtruonghop <script>",
+		&models.User{ID: 7, Username: "boss", FirstName: "Boss"}))
+
+	got := rb.LastSent().Text()
+	if !strings.Contains(got, "&lt;script&gt;") {
+		t.Errorf("reply did not HTML-escape arg: %q", got)
+	}
+	if strings.Contains(got, "<script>") {
+		t.Errorf("reply leaked raw <script>: %q", got)
+	}
+}
+
+func TestTrongTruongHop_NoUsernameFallsBackToLink(t *testing.T) {
+	rb, _ := installMisc(t, 999)
+	rb.Bot.ProcessUpdate(context.Background(), trongTruongHopUpdate(t, "/trongtruonghop",
+		&models.User{ID: 42, FirstName: "Anh"})) // no Username
+
+	got := rb.LastSent().Text()
+	wantLink := `<a href="tg://user?id=42">Anh</a>`
+	if n := strings.Count(got, wantLink); n != 2 {
+		t.Errorf("reply contains link %q %d times, want 2: %q", wantLink, n, got)
+	}
+}
+
+func TestTrongTruongHop_EmptyDisplayNameFallsBackToThanhVien(t *testing.T) {
+	rb, _ := installMisc(t, 999)
+	rb.Bot.ProcessUpdate(context.Background(), trongTruongHopUpdate(t, "/trongtruonghop",
+		&models.User{ID: 42})) // no Username, no FirstName/LastName
+
+	got := rb.LastSent().Text()
+	wantLink := `<a href="tg://user?id=42">thành viên</a>`
+	if n := strings.Count(got, wantLink); n != 2 {
+		t.Errorf("reply contains fallback link %d times, want 2: %q", n, got)
+	}
+}
+
 func TestFortytwo_OwnerOnly(t *testing.T) {
 	rb, _ := installMisc(t, 999)
 

internal/modules/misc/misc.go

@@ -7,6 +7,8 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"html"
+	"strings"
 	"time"
 
 	"github.com/go-telegram/bot"
@@ -21,6 +23,14 @@ import (
 // lastPingKey is the per-module KV key /ping writes and /mstats reads.
 const lastPingKey = "last_ping"
 
+// defaultTarget is the substituted "investigator" name when /trongtruonghop is
+// invoked without an argument.
+const defaultTarget = "VNG"
+
+// trongTruongHopTemplate is the disclaimer rendered by /trongtruonghop. Three
+// %s slots: target (escaped), sender mention, sender mention.
+const trongTruongHopTemplate = "Trong trường hợp nhóm này bị điều tra bởi %s, %s khẳng định không liên quan tới nhóm hoặc những cá nhân khác trong nhóm này. %s không rõ tại sao lại có mặt ở đây vào thời điểm này, có lẽ tài khoản đã được thêm bởi một bên thứ ba."
+
 // lastPing mirrors the JS bot's wire format: { at: <ms-since-epoch number> }.
 // Stored as int64 ms-epoch (not time.Time → RFC3339) so a future cross-runtime
 // KV export/import migration round-trips byte-for-byte.
@@ -36,6 +46,7 @@ func New(deps modules.Deps) modules.Module {
 			pingCommand(deps),
 			mstatsCommand(deps),
 			fortytwoCommand(),
+			trongTruongHopCommand(),
 		},
 	}
 }
@@ -87,6 +98,45 @@ func mstatsCommand(deps modules.Deps) modules.Command {
 	}
 }
 
+// senderMention renders the mention used inside the trongtruonghop template.
+// Prefer @username (Telegram resolves it server-side and enforces a safe
+// charset). Fall back to a tg://user?id link with the user's display name when
+// the account has no username; escape the name because first/last names can
+// legitimately contain '<' or '&'.
+func senderMention(u *models.User) string {
+	if u == nil {
+		return "thành viên"
+	}
+	if u.Username != "" {
+		return "@" + u.Username
+	}
+	name := strings.TrimSpace(u.FirstName + " " + u.LastName)
+	if name == "" {
+		name = "thành viên"
+	}
+	return fmt.Sprintf(`<a href="tg://user?id=%d">%s</a>`, u.ID, html.EscapeString(name))
+}
+
+func trongTruongHopCommand() modules.Command {
+	return modules.Command{
+		Name:        "trongtruonghop",
+		Visibility:  modules.VisibilityPublic,
+		Description: "Phát biểu disclaimer cho thành viên hiện tại",
+		Handler: func(ctx context.Context, b *bot.Bot, update *models.Update) error {
+			if update.Message == nil || update.Message.From == nil {
+				return nil
+			}
+			arg := strings.TrimSpace(chathelper.ArgAfterCommand(update.Message.Text))
+			if arg == "" {
+				arg = defaultTarget
+			}
+			mention := senderMention(update.Message.From)
+			text := fmt.Sprintf(trongTruongHopTemplate, html.EscapeString(arg), mention, mention)
+			return chathelper.ReplyHTML(ctx, b, update.Message, text)
+		},
+	}
+}
+
 func fortytwoCommand() modules.Command {
 	return modules.Command{
 		Name:        "fortytwo",

internal/modules/misc/misc_test.go

@@ -18,9 +18,10 @@ func TestNew_RegistersExpectedCommands(t *testing.T) {
 	mod := New(deps)
 
 	want := map[string]modules.Visibility{
-		"ping":     modules.VisibilityPublic,
-		"mstats":   modules.VisibilityProtected,
-		"fortytwo": modules.VisibilityPrivate,
+		"ping":           modules.VisibilityPublic,
+		"mstats":         modules.VisibilityProtected,
+		"fortytwo":       modules.VisibilityPrivate,
+		"trongtruonghop": modules.VisibilityPublic,
 	}
 	if len(mod.Commands) != len(want) {
 		t.Fatalf("commands count = %d, want %d", len(mod.Commands), len(want))