branding: make product identity runtime-configurable

Adopt upstream owpengram/owpengram-server's branding.Config/Configure/
Current in place of the old package-level constants. This is the piece the
earlier merge attempt was blocked on (internal/branding failed to import
during that merge). The default identity is unchanged -- every existing
ProductName/ProductUsername/... default still reads "OwpenGram" -- so this
is a pure capability add: nothing currently calls Configure, and every call
site now reads the current snapshot via a function instead of a compile-time
constant.

Five string templates that concatenated branding.ProductName into a `const`
had to become `var`, since a func call is no longer a valid const operand.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

internal/app/account/lifecycle.go

@@ -80,7 +80,7 @@ func (s *Service) DeleteAccount(ctx context.Context, userID int64, authKeyID [8]
 	}
 	executeAt := now.Add(accountDeletionDelay)
 	message := fmt.Sprintf(
-		"A request was made to delete your "+branding.ProductName+" account. If this wasn't you, cancel the request: tg://confirmphone?phone=%s&hash=%s",
+		"A request was made to delete your "+branding.ProductName()+" account. If this wasn't you, cancel the request: tg://confirmphone?phone=%s&hash=%s",
 		url.QueryEscape(snapshot.User.Phone), url.QueryEscape(rawToken),
 	)
 	pending, _, err := s.lifecycle.ScheduleAccountDeletion(ctx, domain.ScheduleAccountDeletion{

internal/app/auth/service.go

@@ -1535,9 +1535,9 @@ func (s *Service) passwordNeeded(ctx context.Context, userID int64) (bool, error
 	return found && settings.HasPassword, nil
 }
 
-const loginMessageTpl = `Login code: %s. Do not give this code to anyone, even if they say they are from ` + branding.ProductName + `!
+var loginMessageTpl = `Login code: %s. Do not give this code to anyone, even if they say they are from ` + branding.ProductName() + `!
 
-This code can be used to log in to your ` + branding.ProductName + ` account. We never ask it for anything else.
+This code can be used to log in to your ` + branding.ProductName() + ` account. We never ask it for anything else.
 
 If you didn't request this code by trying to log in on another device, simply ignore this message.`
 

internal/app/bots/botfather.go

@@ -51,7 +51,7 @@ const (
 	maxTelegramLoginCommandsPerMessage = 32
 )
 
-const botFatherHelpText = `I can help you create and manage ` + branding.ProductName + ` bots.
+var botFatherHelpText = `I can help you create and manage ` + branding.ProductName() + ` bots.
 
 You can control me by sending these commands:
 

internal/app/bots/verifierbot.go

@@ -194,13 +194,13 @@ const (
 
 // verifierBotWhatText is the part of /start that is true whether or not an
 // operator has activated this bot, so it is said first and unconditionally.
-const verifierBotWhatText = `I hand out THIRD-PARTY verification.
+var verifierBotWhatText = `I hand out THIRD-PARTY verification.
 
 A third-party mark is a verifier's own icon, shown right before the name of a bot, a channel or an account, plus one line of description in its profile. It means "this verifier vouches for this peer" -- nothing more.
 
-It is NOT the official ` + branding.ProductName + ` checkmark. The platform badge is granted by the platform itself (@verifybot collects those applications); a third-party mark is granted by the company running a verifier bot. The two are stored, shown and taken away separately, and neither one implies the other.`
+It is NOT the official ` + branding.ProductName() + ` checkmark. The platform badge is granted by the platform itself (@verifybot collects those applications); a third-party mark is granted by the company running a verifier bot. The two are stored, shown and taken away separately, and neither one implies the other.`
 
-const verifierBotHelpText = `I am a verifier bot. I grant third-party marks: my icon before the name of your bot, channel or account, plus a description in its profile. This is not the official ` + branding.ProductName + ` checkmark.
+var verifierBotHelpText = `I am a verifier bot. I grant third-party marks: my icon before the name of your bot, channel or account, plus a description in its profile. This is not the official ` + branding.ProductName() + ` checkmark.
 
 /start - what a third-party mark is and who grants it
 /verify - apply for the mark
@@ -1121,7 +1121,7 @@ func verifierSummaryText(state domain.BotChatState, settings domain.BotVerifierS
 	b.WriteString("\n\nWhy:\n")
 	b.WriteString(state.Draft[verifierDraftReason])
 	b.WriteString("\n\nThis is a third-party mark, not the official ")
-	b.WriteString(branding.ProductName)
+	b.WriteString(branding.ProductName())
 	b.WriteString(" checkmark, and I do not decide: an operator reads the application and either grants the mark or refuses it. I will message you here either way.")
 	return b.String()
 }
@@ -1170,7 +1170,7 @@ func verifierDecisionText(req domain.CustomVerificationRequest) (string, bool) {
 	switch req.Status {
 	case domain.CustomVerificationApproved:
 		return fmt.Sprintf("Application #%d is approved: %s now carries my mark -- my icon before the name and my description in the profile.\n\nThis is a third-party mark, not the official %s checkmark. Send /revoke if you ever want it removed.",
-			req.ID, label, branding.ProductName), true
+			req.ID, label, branding.ProductName()), true
 	case domain.CustomVerificationRejected:
 		text := fmt.Sprintf("Application #%d for %s was not approved, so no mark was granted.", req.ID, label)
 		if reason := strings.TrimSpace(req.DecisionReason); reason != "" {

internal/app/bots/verifybot.go

@@ -114,7 +114,7 @@ const (
 	verifyChoiceBlockedPrefix  = "no:"
 )
 
-const verifyBotStartText = `I collect applications for official ` + branding.ProductName + ` verification: the badge shown next to the name of a channel, supergroup or bot whose identity has been confirmed.
+var verifyBotStartText = `I collect applications for official ` + branding.ProductName() + ` verification: the badge shown next to the name of a channel, supergroup or bot whose identity has been confirmed.
 
 Before you apply, check that the subject of the application:
 - is a channel, supergroup or bot with a public @username;
@@ -126,7 +126,7 @@ This badge is never sold and never granted automatically. A person reads every a
 
 Tap the button below, or send /new, to start. Send /help for the full list of commands.`
 
-const verifyBotHelpText = `I collect official ` + branding.ProductName + ` verification applications.
+var verifyBotHelpText = `I collect official ` + branding.ProductName() + ` verification applications.
 
 /new - file a verification application
 /status - list your applications and their status

internal/app/botverification/seed.go

@@ -42,7 +42,7 @@ func (s *Service) SeedDefaultVerifier(ctx context.Context) (bool, error) {
 	if _, err := s.GrantVerifier(ctx, domain.BotVerifierSettings{
 		BotID:                      domain.VerifierBotUserID,
 		IconDocumentID:             icon.DocumentID,
-		CompanyName:                branding.ProductName,
+		CompanyName:                branding.ProductName(),
 		DefaultDescription:         "Bundled reference verifier -- auto-granted on first boot.",
 		CanModifyCustomDescription: false,
 		Enabled:                    true,

internal/app/langpack/service.go

@@ -54,7 +54,7 @@ func newServiceWithCacheLimits(packs store.LangPackStore, maxBytes int64, maxEnt
 		packs:         packs,
 		packCache:     newLangPackCache(maxBytes, maxEntries),
 		languageCache: newLanguageListCache(languageEntries),
-		publicBaseURL: branding.DefaultPublicURL,
+		publicBaseURL: branding.PublicBaseURL(),
 	}
 }
 

internal/app/passkey/service.go

@@ -71,7 +71,7 @@ func NewService(creds store.PasskeyStore, challenges store.PasskeyChallengeStore
 		creds:        creds,
 		challenges:   challenges,
 		rpID:         rpID,
-		rpName:       branding.ProductName,
+		rpName:       branding.ProductName(),
 		dcID:         dcID,
 		challengeTTL: defaultChallengeTTL,
 		now:          time.Now,

internal/branding/branding.go

@@ -6,44 +6,133 @@
 package branding
 
 import (
+	"fmt"
 	"net/url"
 	"regexp"
 	"strings"
+	"sync/atomic"
+	"unicode"
+
+	"telesrv/internal/links"
 )
 
-const (
+// Config is the deployment-wide, user-visible product identity. It is loaded
-	ProductName      = "OwpenGram"
+// once during process startup; protocol identifiers and client detection
-	ProductUsername  = "owpengram"
+// tokens deliberately remain outside this structure.
-	DesktopAppName   = "OwpenGram Desktop"
+type Config struct {
-	AndroidAppName   = "OwpenGram Android"
+	ProductName     string
-	IOSAppName       = "OwpenGram iOS"
+	ProductUsername string
-	MacOSAppName     = "OwpenGram macOS"
+	DesktopAppName  string
-	WebAAppName      = "OwpenGram Web A"
+	AndroidAppName  string
-	WebKAppName      = "OwpenGram Web K"
+	IOSAppName      string
-	PremiumName      = "OwpenGram Premium"
+	MacOSAppName    string
-	StarsName        = "OwpenGram Stars"
+	WebAAppName     string
-	DefaultPublicURL = "https://owpengram.org"
+	WebKAppName     string
+	PremiumName     string
+	StarsName       string
+	PublicBaseURL   string
+}
+
+var (
+	defaultConfig = Config{
+		ProductName:     "OwpenGram",
+		ProductUsername: "owpengram",
+		DesktopAppName:  "OwpenGram Desktop",
+		AndroidAppName:  "OwpenGram Android",
+		IOSAppName:      "OwpenGram iOS",
+		MacOSAppName:    "OwpenGram macOS",
+		WebAAppName:     "OwpenGram Web A",
+		WebKAppName:     "OwpenGram Web K",
+		PremiumName:     "OwpenGram Premium",
+		StarsName:       "OwpenGram Stars",
+		PublicBaseURL:   links.DefaultDownloadURL,
+	}
+	configured atomic.Pointer[Config]
 )
 
+// DefaultConfig returns a copy of the default product identity.
+func DefaultConfig() Config { return defaultConfig }
+
+// Validate normalizes and validates a product identity without installing it.
+func Validate(cfg Config) (Config, error) {
+	for _, field := range []struct {
+		name  string
+		value *string
+	}{
+		{name: "product name", value: &cfg.ProductName},
+		{name: "desktop app name", value: &cfg.DesktopAppName},
+		{name: "Android app name", value: &cfg.AndroidAppName},
+		{name: "iOS app name", value: &cfg.IOSAppName},
+		{name: "macOS app name", value: &cfg.MacOSAppName},
+		{name: "Web A app name", value: &cfg.WebAAppName},
+		{name: "Web K app name", value: &cfg.WebKAppName},
+		{name: "Premium name", value: &cfg.PremiumName},
+		{name: "Stars name", value: &cfg.StarsName},
+	} {
+		normalized, err := validateDisplayName(*field.value)
+		if err != nil {
+			return Config{}, fmt.Errorf("%s: %w", field.name, err)
+		}
+		*field.value = normalized
+	}
+	cfg.ProductUsername = strings.TrimPrefix(strings.TrimSpace(cfg.ProductUsername), "@")
+	if !validProductUsername(cfg.ProductUsername) {
+		return Config{}, fmt.Errorf("product username must be 5-32 ASCII username characters and start with a letter")
+	}
+	cfg.ProductUsername = strings.ToLower(cfg.ProductUsername)
+	var err error
+	cfg.PublicBaseURL, err = links.ValidateBaseURL(cfg.PublicBaseURL)
+	if err != nil {
+		return Config{}, fmt.Errorf("public base URL: %w", err)
+	}
+	return cfg, nil
+}
+
+// Configure installs the validated process-wide identity before services are
+// constructed. Readers only ever observe complete immutable snapshots.
+func Configure(cfg Config) error {
+	normalized, err := Validate(cfg)
+	if err != nil {
+		return err
+	}
+	configured.Store(&normalized)
+	return nil
+}
+
+// Current returns a copy of the installed product identity.
+func Current() Config {
+	if cfg := configured.Load(); cfg != nil {
+		return *cfg
+	}
+	return defaultConfig
+}
+
+func ProductName() string     { return Current().ProductName }
+func ProductUsername() string { return Current().ProductUsername }
+func PremiumName() string     { return Current().PremiumName }
+func StarsName() string       { return Current().StarsName }
+func PublicBaseURL() string   { return Current().PublicBaseURL }
+
 // ClientAppName returns the branded display name for a stored client platform.
 // Stored detection tokens remain unchanged; this is only used at presentation
 // boundaries such as account.getAuthorizations.
 func ClientAppName(platform string) string {
+	cfg := Current()
 	switch strings.ToLower(strings.TrimSpace(platform)) {
 	case "android":
-		return AndroidAppName
+		return cfg.AndroidAppName
 	case "ios":
-		return IOSAppName
+		return cfg.IOSAppName
 	case "macos":
-		return MacOSAppName
+		return cfg.MacOSAppName
 	case "telegram-tt", "weba":
-		return WebAAppName
+		return cfg.WebAAppName
 	case "tweb", "webk":
-		return WebKAppName
+		return cfg.WebKAppName
 	case "tdesktop", "desktop", "windows":
-		return DesktopAppName
+		return cfg.DesktopAppName
 	default:
-		return ProductName
+		return cfg.ProductName
 	}
 }
 
@@ -78,18 +167,49 @@ func UserVisibleText(value, publicBaseURL string) string {
 	if technicalIDRE.MatchString(value) {
 		return value
 	}
-	return officialBrandRE.ReplaceAllString(value, ProductName)
+	return officialBrandRE.ReplaceAllString(value, ProductName())
 }
 
 func publicDestination(raw string) (string, string) {
 	raw = strings.TrimRight(strings.TrimSpace(raw), "/")
 	if raw == "" {
-		raw = DefaultPublicURL
+		raw = PublicBaseURL()
 	}
 	parsed, err := url.Parse(raw)
 	if err != nil || parsed.Scheme == "" || parsed.Hostname() == "" {
-		raw = DefaultPublicURL
+		raw = PublicBaseURL()
 		parsed, _ = url.Parse(raw)
 	}
 	return raw, parsed.Host
 }
+
+func validateDisplayName(raw string) (string, error) {
+	name := strings.TrimSpace(raw)
+	if name == "" {
+		return "", fmt.Errorf("must not be empty")
+	}
+	if len([]rune(name)) > 64 {
+		return "", fmt.Errorf("must not exceed 64 characters")
+	}
+	for _, r := range name {
+		if unicode.IsControl(r) {
+			return "", fmt.Errorf("must not contain control characters")
+		}
+	}
+	return name, nil
+}
+
+func validProductUsername(username string) bool {
+	if len(username) < 5 || len(username) > 32 {
+		return false
+	}
+	for i, r := range username {
+		switch {
+		case r >= 'a' && r <= 'z', r >= 'A' && r <= 'Z':
+		case i > 0 && (r >= '0' && r <= '9' || r == '_'):
+		default:
+			return false
+		}
+	}
+	return true
+}

internal/branding/branding_test.go

@@ -46,13 +46,14 @@ func TestUserVisibleTextRebrandsLocalizedProductNames(t *testing.T) {
 }
 
 func TestClientPresentationNames(t *testing.T) {
+	cfg := Current()
 	for platform, want := range map[string]string{
-		"tdesktop":    DesktopAppName,
+		"tdesktop":    cfg.DesktopAppName,
-		"android":     AndroidAppName,
+		"android":     cfg.AndroidAppName,
-		"ios":         IOSAppName,
+		"ios":         cfg.IOSAppName,
-		"macos":       MacOSAppName,
+		"macos":       cfg.MacOSAppName,
-		"telegram-tt": WebAAppName,
+		"telegram-tt": cfg.WebAAppName,
-		"tweb":        WebKAppName,
+		"tweb":        cfg.WebKAppName,
 	} {
 		if got := ClientAppName(platform); got != want {
 			t.Fatalf("ClientAppName(%q) = %q, want %q", platform, got, want)
@@ -62,3 +63,55 @@ func TestClientPresentationNames(t *testing.T) {
 		t.Fatalf("UserVisibleClientPlatform() = %q, want weba", got)
 	}
 }
+
+func TestConfigureInstallsCompleteBrandSnapshot(t *testing.T) {
+	previous := Current()
+	t.Cleanup(func() {
+		if err := Configure(previous); err != nil {
+			t.Fatalf("restore branding: %v", err)
+		}
+	})
+
+	cfg := Config{
+		ProductName:     "Example Chat",
+		ProductUsername: "@Example_Chat",
+		DesktopAppName:  "Example Workstation",
+		AndroidAppName:  "Example Droid",
+		IOSAppName:      "Example Phone",
+		MacOSAppName:    "Example Mac",
+		WebAAppName:     "Example Web Alpha",
+		WebKAppName:     "Example Web Kappa",
+		PremiumName:     "Example Plus",
+		StarsName:       "Example Credits",
+		PublicBaseURL:   "https://links.example.test/root/",
+	}
+	if err := Configure(cfg); err != nil {
+		t.Fatalf("Configure: %v", err)
+	}
+	if got := Current(); got.ProductUsername != "example_chat" || got.PublicBaseURL != "https://links.example.test/root" {
+		t.Fatalf("Current() = %+v", got)
+	}
+	if got := ClientAppName("android"); got != "Example Droid" {
+		t.Fatalf("ClientAppName(android) = %q", got)
+	}
+	if got := UserVisibleText("Telegram at t.me/example", ""); got != "Example Chat at links.example.test/example" {
+		t.Fatalf("UserVisibleText() = %q", got)
+	}
+}
+
+func TestValidateRejectsIncompleteOrUnsafeBranding(t *testing.T) {
+	for name, mutate := range map[string]func(*Config){
+		"blank product": func(cfg *Config) { cfg.ProductName = "   " },
+		"control":       func(cfg *Config) { cfg.StarsName = "bad\nname" },
+		"username":      func(cfg *Config) { cfg.ProductUsername = "3bad" },
+		"public URL":    func(cfg *Config) { cfg.PublicBaseURL = "file:///tmp/brand" },
+	} {
+		t.Run(name, func(t *testing.T) {
+			cfg := DefaultConfig()
+			mutate(&cfg)
+			if _, err := Validate(cfg); err == nil {
+				t.Fatal("Validate accepted invalid branding")
+			}
+		})
+	}
+}

internal/domain/login_code_delivery.go

@@ -8,9 +8,9 @@ import (
 	"telesrv/internal/branding"
 )
 
-const officialLoginCodeMessageTemplate = `Login code: %s. Do not give this code to anyone, even if they say they are from ` + branding.ProductName + `!
+var officialLoginCodeMessageTemplate = `Login code: %s. Do not give this code to anyone, even if they say they are from ` + branding.ProductName() + `!
 
-This code can be used to log in to your ` + branding.ProductName + ` account. We never ask it for anything else.
+This code can be used to log in to your ` + branding.ProductName() + ` account. We never ask it for anything else.
 
 If you didn't request this code by trying to log in on another device, simply ignore this message.`
 

internal/domain/system.go

@@ -172,8 +172,8 @@ func OfficialSystemUser() User {
 		ID:         OfficialSystemUserID,
 		AccessHash: 6599886787491911851,
 		Phone:      "42777",
-		FirstName:  branding.ProductName,
+		FirstName:  branding.ProductName(),
-		Username:   branding.ProductUsername,
+		Username:   branding.ProductUsername(),
 		Verified:   true,
 		Support:    true,
 	}

internal/rpc/aicompose_webpage.go

@@ -43,7 +43,7 @@ func (r *Router) resolveAIComposeStyleWebPage(ctx context.Context, rawURL string
 		Hash:               aiComposeToneWebPageHash(tone),
 		Date:               int(now.Unix()),
 		Type:               aiComposeToneWebPageType,
-		SiteName:           branding.ProductName,
+		SiteName:           branding.ProductName(),
 		Title:              tone.Title,
 		Description:        tone.Prompt,
 		ComposeToneEmojiID: tone.EmojiID,

internal/rpc/help.go

@@ -26,7 +26,7 @@ func (r *Router) registerHelp(d *tlprofile.Dispatcher) {
 		}, nil
 	})
 	registerRPC[*tg.HelpGetInviteTextRequest](d, tlprofile.SemanticMethodHelpGetInviteText, func(ctx context.Context, layerRequest *tg.HelpGetInviteTextRequest) (any, error) {
-		return &tg.HelpInviteText{Message: "Join me on " + branding.ProductName + "."}, nil
+		return &tg.HelpInviteText{Message: "Join me on " + branding.ProductName() + "."}, nil
 	})
 	registerRPC[*tg.HelpSaveAppLogRequest](d, tlprofile.SemanticMethodHelpSaveAppLog, func(ctx context.Context, _ *tg.HelpSaveAppLogRequest) (any, error) {
 		return r.onHelpSaveAppLog(ctx)
@@ -186,7 +186,7 @@ func (r *Router) onHelpDismissSuggestion(ctx context.Context, req *tg.HelpDismis
 // dead payment URLs. All six TL fields are mandatory.
 func (r *Router) onHelpGetPremiumPromo(ctx context.Context) (*tg.HelpPremiumPromo, error) {
 	promo := &tg.HelpPremiumPromo{
-		StatusText:     branding.PremiumName + " is not active on this account.",
+		StatusText:     branding.PremiumName() + " is not active on this account.",
 		StatusEntities: []tg.MessageEntityClass{},
 		VideoSections:  []string{},
 		Videos:         []tg.DocumentClass{},
@@ -215,7 +215,7 @@ func (r *Router) onHelpGetPremiumPromo(ctx context.Context) (*tg.HelpPremiumProm
 	}
 	if u.PremiumActiveAt(r.clock.Now().Unix()) {
 		until := time.Unix(int64(u.PremiumUntil), 0)
-		promo.StatusText = branding.PremiumName + " is active until " + until.Format("2006-01-02") + "."
+		promo.StatusText = branding.PremiumName() + " is active until " + until.Format("2006-01-02") + "."
 	}
 	if r.deps.PremiumPromo != nil {
 		catalog, found, err := r.deps.PremiumPromo.PremiumPromo(ctx)

internal/webauthn/webauthn.go

@@ -101,7 +101,7 @@ func BuildRegistrationOptions(p RegistrationParams) ([]byte, error) {
 		exclude = append(exclude, map[string]any{"type": "public-key", "id": b64.EncodeToString(id)})
 	}
 	pub := map[string]any{
-		"rp":        map[string]any{"id": p.RPID, "name": orDefault(p.RPName, branding.ProductName)},
+		"rp":        map[string]any{"id": p.RPID, "name": orDefault(p.RPName, branding.ProductName())},
 		"user":      map[string]any{"id": b64.EncodeToString(p.UserID), "name": p.UserName, "displayName": orDefault(p.UserDisplay, p.UserName)},
 		"challenge": b64.EncodeToString(p.Challenge),
 		"pubKeyCredParams": []map[string]any{