feat(telegram): bot support relay — per-user forum topics

Users who DM the bot anything but /start are relayed into a private
forum supergroup, one topic per user. Operators (the chat's admins)
reply in the topic and the bot copies it back to the user; an info card
opening each topic carries a Block/Unblock toggle and a Clear button.
State is a small JSON file on a new /data volume — the bot host has no
database. Off by default (TELEGRAM_SUPPORT_CHAT_ID=0): the prod bot is
unchanged until the operator sets the chat id and adds the bot as a
forum admin.

- internal/support: concurrency-safe JSON store (topic map, block list,
  relayed message ids) with field-targeted mutators and atomic save
- bot/support.go: relay both ways via copyMessage, short-TTL admin
  cache, callback buttons, per-user topic-create lock, loop guard
  (skip the bot's own posts), reopen a deleted topic on the next message
- config + compose + CI/prod-deploy: TELEGRAM_SUPPORT_CHAT_ID per
  contour + TELEGRAM_SUPPORT_STATE_DIR; bot-state named volume; /data
  pre-owned by UID 65532 so a fresh volume is writable under distroless
- docs: ARCHITECTURE §15 + decision record, FUNCTIONAL (+ru), README

.gitea/workflows/ci.yaml

@@ -267,6 +267,7 @@ jobs:
           TELEGRAM_MINIAPP_URL: ${{ vars.TEST_TELEGRAM_MINIAPP_URL }}
           TELEGRAM_GAME_CHANNEL_ID: ${{ vars.TEST_TELEGRAM_GAME_CHANNEL_ID }}
           TELEGRAM_CHAT_ID: ${{ vars.TEST_TELEGRAM_CHAT_ID }}
+          TELEGRAM_SUPPORT_CHAT_ID: ${{ vars.TEST_TELEGRAM_SUPPORT_CHAT_ID }}
           TELEGRAM_BOT_USERNAME: ${{ vars.TEST_TELEGRAM_BOT_USERNAME }}
           # The promo button reuses the UI's Mini App link variable.
           TELEGRAM_BOT_LINK: ${{ vars.TEST_VITE_TELEGRAM_LINK }}

.gitea/workflows/prod-deploy.yaml

@@ -179,6 +179,7 @@ jobs:
       TELEGRAM_MINIAPP_URL: ${{ vars.PROD_TELEGRAM_MINIAPP_URL }}
       TELEGRAM_GAME_CHANNEL_ID: ${{ vars.PROD_TELEGRAM_GAME_CHANNEL_ID }}
       TELEGRAM_CHAT_ID: ${{ vars.PROD_TELEGRAM_CHAT_ID }}
+      TELEGRAM_SUPPORT_CHAT_ID: ${{ vars.PROD_TELEGRAM_SUPPORT_CHAT_ID }}
       TELEGRAM_BOT_USERNAME: ${{ vars.PROD_TELEGRAM_BOT_USERNAME }}
       TELEGRAM_BOT_LINK: ${{ vars.PROD_VITE_TELEGRAM_LINK }}
     steps:
@@ -200,6 +201,7 @@ jobs:
           export TELEGRAM_MINIAPP_URL='$TELEGRAM_MINIAPP_URL'
           export TELEGRAM_GAME_CHANNEL_ID='$TELEGRAM_GAME_CHANNEL_ID'
           export TELEGRAM_CHAT_ID='$TELEGRAM_CHAT_ID'
+          export TELEGRAM_SUPPORT_CHAT_ID='$TELEGRAM_SUPPORT_CHAT_ID'
           export TELEGRAM_PROMO_BOT_TOKEN='$TELEGRAM_PROMO_BOT_TOKEN'
           export TELEGRAM_BOT_USERNAME='$TELEGRAM_BOT_USERNAME'
           export TELEGRAM_BOT_LINK='$TELEGRAM_BOT_LINK'

deploy/.env.example

@@ -47,6 +47,7 @@ AWG_CONF=                              # required; AmneziaWG sidecar config (the
 TELEGRAM_BOT_TOKEN=                    # required
 TELEGRAM_GAME_CHANNEL_ID=
 TELEGRAM_CHAT_ID=                      # moderated discussion chat (channel's linked group); empty disables gating
+TELEGRAM_SUPPORT_CHAT_ID=              # private forum supergroup for the support relay (topic per user); empty disables it
 TELEGRAM_PROMO_BOT_TOKEN=             # optional standalone promo bot token; empty disables it
 TELEGRAM_BOT_USERNAME=               # main bot @username without the @ (promo message); required when the promo token is set
 TELEGRAM_BOT_LINK=                    # main bot Mini App link for the promo button (reuse VITE_TELEGRAM_LINK); required when the promo token is set

deploy/docker-compose.bot.yml

@@ -23,6 +23,11 @@ services:
       TELEGRAM_BOT_TOKEN: ${TELEGRAM_BOT_TOKEN:?set TELEGRAM_BOT_TOKEN}
       TELEGRAM_GAME_CHANNEL_ID: ${TELEGRAM_GAME_CHANNEL_ID:-}
       TELEGRAM_CHAT_ID: ${TELEGRAM_CHAT_ID:-}
+      # Support relay: a private forum supergroup the bot relays direct user messages
+      # into (one topic per user). 0/unset disables it; the bot needs admin there with
+      # the manage-topics and delete-messages rights.
+      TELEGRAM_SUPPORT_CHAT_ID: ${TELEGRAM_SUPPORT_CHAT_ID:-}
+      TELEGRAM_SUPPORT_STATE_DIR: /data
       TELEGRAM_PROMO_BOT_TOKEN: ${TELEGRAM_PROMO_BOT_TOKEN:-}
       TELEGRAM_BOT_USERNAME: ${TELEGRAM_BOT_USERNAME:-}
       TELEGRAM_BOT_LINK: ${TELEGRAM_BOT_LINK:-}
@@ -46,8 +51,13 @@ services:
       GOMAXPROCS: "1"
     volumes:
       - ${SCRABBLE_CONFIG_DIR:-.}/certs:/certs:ro
+      # Support relay state (topic mapping, block list); survives redeploys.
+      - bot-state:/data
     deploy:
       resources:
         limits:
           cpus: "1.0"
           memory: 256M
+
+volumes:
+  bot-state:

deploy/docker-compose.yml

@@ -292,6 +292,11 @@ services:
       # only restricts (mutes the ineligible) — and the bot must be an admin there with the
       # "Ban users" right; chat_member updates are delivered only to a chat admin.
       TELEGRAM_CHAT_ID: ${TELEGRAM_CHAT_ID:-}
+      # The private forum supergroup the bot relays direct user messages into (one topic
+      # per user) and reads operator replies from. Empty disables the support relay; when
+      # set the bot must be an admin there with the manage-topics and delete-messages rights.
+      TELEGRAM_SUPPORT_CHAT_ID: ${TELEGRAM_SUPPORT_CHAT_ID:-}
+      TELEGRAM_SUPPORT_STATE_DIR: /data
       # The optional standalone promo bot (its own token) answering /start with a button
       # into the main bot's app. Empty disables it; when set it needs the main bot's
       # @username and the Mini App link (reused from the UI's VITE_TELEGRAM_LINK).
@@ -325,6 +330,8 @@ services:
       GOMAXPROCS: "1"
     volumes:
       - ${SCRABBLE_CONFIG_DIR:-.}/certs:/certs:ro
+      # Support relay state (topic mapping, block list); survives redeploys.
+      - bot-state:/data
     deploy:
       resources:
         limits:
@@ -496,3 +503,4 @@ volumes:
   prometheus-data:
   tempo-data:
   grafana-data:
+  bot-state:

docs/ARCHITECTURE.md

@@ -1200,3 +1200,25 @@ blocks **only** feedback submission (unlike a suspension, the whole-account bloc
 granted from the feedback section (the delete-with-block checkbox) and granted/revoked from the
 `/users` console card. Roles are validated against a known set in Go, so adding one needs no
 migration.
+
+**Telegram support relay.** Separate from the in-app Feedback above, the bot offers a direct
+support channel for users who message it on Telegram. Any message other than `/start` is relayed
+into a private **forum supergroup** (`TELEGRAM_SUPPORT_CHAT_ID`): a user's first message opens a
+dedicated **forum topic** whose first message is an info card (name, @username, language, premium,
+id, profile deep-link) carrying a Block/Unblock toggle and a Clear button; every message is then
+copied into that topic (`copyMessage`, so any content — text, media, voice, files — carries over).
+Any **administrator** of the support chat who writes in a user's topic has their message copied
+back to that user; non-admins and the bot's own posts are ignored (the loop guard). Block drops the
+user's incoming messages (the topic stays); Clear deletes the relayed messages, keeping the info
+card; a topic the operators delete is reopened on the next message. State (user→topic map, block
+list, relayed message ids) is a small JSON file on a writable volume — the bot host has no database
+and cannot reach Postgres. The relay is **bot-local**: it touches neither the backend, the gateway,
+nor `feedback_messages`. The bot must be an administrator in the forum group with the manage-topics
+and delete-messages rights.
+
+> **Decision (2026-06-23) — bot-local support relay over forum topics.** The direct Telegram
+> support channel lives entirely in the bot (no backend, no bot-link command), because the bot host
+> has no database. One forum **topic per user** (not a reply-to-header thread) gives native per-user
+> separation and survives message deletion; the topic id, not a fragile header message, anchors the
+> mapping. Operators are the support chat's administrators (no separate owner id); messages relay
+> both ways with `copyMessage`. State persists as JSON on a dedicated volume.

docs/FUNCTIONAL.md

@@ -272,6 +272,15 @@ marked read once the screen shows it and disappears a week later. A badge on the
 unanswered reply. Guests cannot send feedback (the entry is hidden). A player the operator has
 barred from feedback (a role, not a full account block) sees the send control disabled.
 
+### Telegram support chat
+A user can also reach the operators straight from the Telegram bot: anything they send the bot
+other than `/start` — text, a photo, a voice message, a file — is forwarded into the operators'
+private support group, grouped into a per-user thread. The user sees no automatic reply; an
+operator answers from that thread and the bot delivers the answer back as an ordinary bot message,
+so to the user it is a quiet one-to-one conversation. Operators can block a user (the bot then
+silently ignores their messages) or clear a thread's messages. This is independent of the in-app
+Feedback above — it serves people who write to the bot directly rather than through the app.
+
 ### History & statistics
 Finished games are archived in a dictionary-independent form and exportable to
 GCG; the export is offered **only once a game is finished**, and never for an

docs/FUNCTIONAL_ru.md

@@ -278,6 +278,15 @@ UTC; при создании аккаунта она подставляется
 ответе. Гость отправлять обратную связь не может (пункт скрыт). Игрок, которому оператор запретил
 обратную связь (роль, а не полная блокировка аккаунта), видит кнопку отправки недоступной.
 
+### Чат поддержки в Telegram
+С операторами можно поговорить и прямо из Telegram-бота: всё, что пользователь присылает боту,
+кроме `/start` — текст, фото, голосовое, файл, — пересылается в закрытую группу поддержки операторов
+и собирается в отдельную ветку на пользователя. Пользователь не получает автоответа; оператор
+отвечает из этой ветки, и бот доставляет ответ обратно обычным сообщением — для пользователя это
+тихий диалог один на один. Операторы могут заблокировать пользователя (тогда бот молча игнорирует
+его сообщения) или очистить сообщения ветки. Это независимо от встроенной «Обратной связи» выше —
+канал для тех, кто пишет боту напрямую, а не через приложение.
+
 ### История и статистика
 Завершённые партии архивируются в независимом от словаря виде и экспортируются
 в GCG; экспорт доступен **только после завершения партии** и никогда — для

platform/telegram/Dockerfile

@@ -24,6 +24,11 @@ ARG VERSION=dev
 RUN CGO_ENABLED=0 GOOS=linux go build -trimpath -ldflags "-X scrabble/pkg/version.Version=${VERSION}" -o /out/validator ./platform/telegram/cmd/validator
 RUN CGO_ENABLED=0 GOOS=linux go build -trimpath -ldflags "-X scrabble/pkg/version.Version=${VERSION}" -o /out/bot ./platform/telegram/cmd/bot
 
+# The bot's support relay writes its JSON state under /data. Stage an empty directory
+# owned by the distroless nonroot UID so a fresh named volume mounted there inherits
+# writable ownership (Docker copies the image dir's mode/owner into an empty volume).
+RUN mkdir -p /out/data
+
 # --- validator (home) --------------------------------------------------------
 FROM gcr.io/distroless/static-debian12:nonroot AS validator
 COPY --from=build /out/validator /usr/local/bin/validator
@@ -32,4 +37,5 @@ ENTRYPOINT ["/usr/local/bin/validator"]
 # --- bot (remote) ------------------------------------------------------------
 FROM gcr.io/distroless/static-debian12:nonroot AS bot
 COPY --from=build /out/bot /usr/local/bin/bot
+COPY --from=build --chown=65532:65532 /out/data /data
 ENTRYPOINT ["/usr/local/bin/bot"]

platform/telegram/README.md

@@ -63,6 +63,19 @@ Telegram identity to an account from a browser. Both map a rejection to gRPC
   `getChatMember`, since bots cannot list members). The bot must be an **administrator** there
   with the **"Ban users"** right (the Bot API `can_restrict_members`), and it subscribes to
   `chat_member` updates, which Telegram delivers only to a chat admin.
+- **Support relay (optional).** When `TELEGRAM_SUPPORT_CHAT_ID` names a private **forum
+  supergroup**, the bot runs a direct support channel for users who message it. A user's first
+  non-`/start` message opens a dedicated **forum topic** whose first message is an info card (name,
+  @username, language, premium, id, `tg://user` profile link) carrying a **Block/Unblock** toggle
+  and a **Clear** button; each message is then copied into that topic (`copyMessage`, so any content
+  — text, media, voice, files — carries over). Any **administrator** of the support chat who writes
+  in a user's topic has it copied back to that user; the bot's own posts and non-admins are ignored
+  (the loop guard). **Block** drops a user's incoming messages (the topic stays); **Clear** deletes
+  the relayed messages, keeping the info card; a topic the operators delete is reopened on the next
+  message. State (user→topic map, block list, relayed ids) is a JSON file under
+  `TELEGRAM_SUPPORT_STATE_DIR` on a persistent volume — the bot host has no database. The bot must
+  be an **administrator** in the group with the **manage-topics** and **delete-messages** rights.
+  The relay is bot-local (no backend, no bot-link) and the user gets no automatic reply.
 - **Promo bot (optional).** When `TELEGRAM_PROMO_BOT_TOKEN` is set, the container also
   runs a **second, standalone** bot whose only job is to answer `/start` with a localized
   message and a button that opens the **main** bot's Mini App. The button is a **URL** to
@@ -132,6 +145,8 @@ Bot (`cmd/bot`):
 | `TELEGRAM_BOTLINK_TLS_CERT` / `_KEY` / `_CA` | — (required) | the bot client cert, its key, and the CA that signs the gateway server cert |
 | `TELEGRAM_GAME_CHANNEL_ID` | — | the bot's game channel chat id for `SendToGameChannel` |
 | `TELEGRAM_CHAT_ID` | — | the moderated discussion chat id (a channel's linked group); empty disables chat gating |
+| `TELEGRAM_SUPPORT_CHAT_ID` | — | the support relay's forum supergroup id (topic per user); empty disables the relay |
+| `TELEGRAM_SUPPORT_STATE_DIR` | `/data` | directory for the support relay's JSON state (a writable volume) |
 | `TELEGRAM_PROMO_BOT_TOKEN` | — | the optional standalone promo bot's token; empty disables it |
 | `TELEGRAM_BOT_USERNAME` | — | the main bot's @username without the @ (promo message); required when the promo bot runs |
 | `TELEGRAM_BOT_LINK` | — | the main bot's Mini App link for the promo button (the UI's `VITE_TELEGRAM_LINK`); required when the promo bot runs |

platform/telegram/cmd/bot/main.go

@@ -10,6 +10,7 @@ import (
 	"context"
 	"log"
 	"os/signal"
+	"path/filepath"
 	"sync"
 	"syscall"
 	"time"
@@ -23,6 +24,7 @@ import (
 	"scrabble/platform/telegram/internal/botlink"
 	"scrabble/platform/telegram/internal/config"
 	"scrabble/platform/telegram/internal/promobot"
+	"scrabble/platform/telegram/internal/support"
 )
 
 // telemetryShutdownTimeout bounds the OpenTelemetry flush during process exit.
@@ -65,6 +67,19 @@ func run(ctx context.Context, cfg config.BotConfig, logger *zap.Logger) error {
 		logger.Warn("telemetry: start runtime metrics", zap.Error(err))
 	}
 
+	// The support relay keeps its per-user state in a JSON file on a writable volume
+	// (the bot host has no database). A corrupt file is logged and the relay starts
+	// empty rather than crash-looping the bot.
+	var supportStore *support.Store
+	if cfg.SupportChatID != 0 {
+		statePath := filepath.Join(cfg.SupportStateDir, "support.json")
+		supportStore, err = support.Open(statePath)
+		if err != nil {
+			logger.Warn("support: state load failed, starting empty", zap.String("path", statePath), zap.Error(err))
+			supportStore = support.New(statePath)
+		}
+	}
+
 	b, err := bot.New(bot.Config{
 		Token:             cfg.Token,
 		APIBaseURL:        cfg.APIBaseURL,
@@ -73,6 +88,8 @@ func run(ctx context.Context, cfg config.BotConfig, logger *zap.Logger) error {
 		SendRatePerSecond: cfg.SendRatePerSecond,
 		ChatID:            cfg.ChatID,
 		GameChannelID:     cfg.GameChannelID,
+		SupportChatID:     cfg.SupportChatID,
+		SupportStore:      supportStore,
 	}, logger)
 	if err != nil {
 		return err
@@ -128,6 +145,7 @@ func run(ctx context.Context, cfg config.BotConfig, logger *zap.Logger) error {
 		zap.Bool("owns_updates", cfg.OwnsUpdates),
 		zap.Bool("test_env", cfg.TestEnv),
 		zap.Bool("chat_gating", cfg.ChatID != 0),
+		zap.Bool("support_relay", cfg.SupportChatID != 0),
 		zap.Bool("promo_bot", promo != nil))
 
 	var wg sync.WaitGroup

platform/telegram/internal/bot/bot.go

@@ -15,6 +15,8 @@ import (
 	"github.com/go-telegram/bot/models"
 	"go.uber.org/zap"
 	"golang.org/x/time/rate"
+
+	"scrabble/platform/telegram/internal/support"
 )
 
 // Config configures the bot wrapper.
@@ -39,6 +41,14 @@ type Config struct {
 	// GameChannelID is the game channel whose public @username the /start welcome links
 	// to (resolved from this id via getChat at startup); 0 omits that follow link.
 	GameChannelID int64
+	// SupportChatID is the private forum supergroup the bot relays direct user messages
+	// into (one topic per user) and reads operator replies from; 0 disables the support
+	// relay. The bot must be an administrator there with the manage-topics and
+	// delete-messages rights.
+	SupportChatID int64
+	// SupportStore persists the support relay's state (topic mapping, block list,
+	// relayed message ids); required when SupportChatID is set, ignored otherwise.
+	SupportStore *support.Store
 }
 
 // EligibilityResolver answers whether the Telegram user identified by externalID
@@ -66,11 +76,21 @@ type Bot struct {
 	channelUsername string
 	chatUsername    string
 	// botID is the bot's own Telegram user id (resolved at startup); it skips the
-	// chat_member updates the bot's own restrict actions generate — the grant loop guard.
+	// chat_member updates the bot's own restrict actions generate — the grant loop guard —
+	// and the bot's own relayed copies in the support chat.
 	botID int64
 	// eligibility resolves a joining user's chat write eligibility; nil leaves a
 	// joiner muted (fail-closed) until it is wired.
 	eligibility EligibilityResolver
+	// supportChatID is the support relay's forum supergroup (0 disables the relay).
+	supportChatID int64
+	// support persists the support relay's per-user state; nil when the relay is off.
+	support *support.Store
+	// supportLocks serialises per-user topic creation so a burst of a new user's
+	// messages opens exactly one topic.
+	supportLocks *keyedMutex
+	// admins caches the support chat's administrator ids (who may reply and act).
+	admins *adminCache
 }
 
 // New builds the bot wrapper, registering the /start handler and a default handler
@@ -80,7 +100,14 @@ func New(cfg Config, log *zap.Logger) (*Bot, error) {
 	if log == nil {
 		log = zap.NewNop()
 	}
-	t := &Bot{miniAppURL: cfg.MiniAppURL, log: log, chatID: cfg.ChatID, channelID: cfg.GameChannelID}
+	t := &Bot{
+		miniAppURL:    cfg.MiniAppURL,
+		log:           log,
+		chatID:        cfg.ChatID,
+		channelID:     cfg.GameChannelID,
+		supportChatID: cfg.SupportChatID,
+		support:       cfg.SupportStore,
+	}
 	if cfg.SendRatePerSecond > 0 {
 		t.limiter = rate.NewLimiter(rate.Limit(cfg.SendRatePerSecond), cfg.SendRatePerSecond)
 	}
@@ -89,15 +116,26 @@ func New(cfg Config, log *zap.Logger) (*Bot, error) {
 		tgbot.WithDefaultHandler(t.handleUpdate),
 		tgbot.WithMessageTextHandler("/start", tgbot.MatchTypePrefix, t.handleStart),
 	}
+	if t.supportEnabled() {
+		t.supportLocks = newKeyedMutex()
+		t.admins = &adminCache{}
+		// The info-card buttons are callback_query updates; route them to the support
+		// callback handler by their "sup:" data prefix.
+		opts = append(opts, tgbot.WithCallbackQueryDataHandler(supportCallbackPrefix, tgbot.MatchTypePrefix, t.handleSupportCallback))
+	}
+	// Allowed updates default to "all except chat_member". Specify an explicit set only
+	// when we need chat_member (moderated chat) — and then re-add callback_query (which
+	// the explicit set would otherwise drop) when the support relay needs it.
 	if cfg.ChatID != 0 {
-		// chat_member updates are off by default; subscribe explicitly (alongside
-		// messages) so the bot sees joins in the moderated chat. The bot must also be an
-		// administrator there for Telegram to deliver them.
-		opts = append(opts, tgbot.WithAllowedUpdates(tgbot.AllowedUpdates{
+		allowed := tgbot.AllowedUpdates{
 			models.AllowedUpdateMessage,
 			models.AllowedUpdateMyChatMember,
 			models.AllowedUpdateChatMember,
-		}))
+		}
+		if t.supportEnabled() {
+			allowed = append(allowed, models.AllowedUpdateCallbackQuery)
+		}
+		opts = append(opts, tgbot.WithAllowedUpdates(allowed))
 	}
 	if cfg.TestEnv {
 		// Route to the Bot API test environment (.../bot<token>/test/METHOD).
@@ -134,6 +172,9 @@ func (t *Bot) Run(ctx context.Context) {
 	if t.chatID != 0 {
 		t.logChatAdminStatus(ctx)
 	}
+	if t.supportEnabled() {
+		t.initSupport(ctx)
+	}
 	t.resolveWelcomeHandles(ctx)
 	t.api.Start(ctx)
 }
@@ -305,6 +346,19 @@ func (t *Bot) handleUpdate(ctx context.Context, api *tgbot.Bot, update *models.U
 		t.handleChatMember(ctx, update.ChatMember)
 		return
 	}
+	// Support relay (when enabled): a non-/start message — /start has its own handler —
+	// is either an operator's reply in the support chat or a user's direct message to
+	// relay. Everything else falls through to the Mini App launch reply.
+	if t.supportEnabled() && update.Message != nil {
+		switch {
+		case update.Message.Chat.ID == t.supportChatID:
+			t.handleSupportGroupMessage(ctx, update.Message)
+			return
+		case update.Message.Chat.Type == models.ChatTypePrivate:
+			t.handleSupportUserMessage(ctx, update.Message)
+			return
+		}
+	}
 	t.handleStart(ctx, api, update)
 }
 

platform/telegram/internal/bot/support.go

@@ -0,0 +1,438 @@
+package bot
+
+import (
+	"context"
+	"fmt"
+	"html"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+
+	tgbot "github.com/go-telegram/bot"
+	"github.com/go-telegram/bot/models"
+	"go.uber.org/zap"
+)
+
+// Support relay: the bot forwards a user's direct messages into a per-user forum
+// topic in the operators' private support chat, and relays operator replies in that
+// topic back to the user. The info card opening each topic carries a Block/Unblock
+// toggle and a Clear button. State (topic mapping, block list, relayed message ids)
+// lives in a small JSON file via internal/support.
+const (
+	// supportCallbackPrefix namespaces the info-card button callbacks
+	// ("sup:<action>:<userID>").
+	supportCallbackPrefix = "sup:"
+	supportActionBlock    = "block"
+	supportActionUnblock  = "unblock"
+	supportActionClear    = "clear"
+	// supportAdminTTL is how long the support chat's administrator set is cached.
+	supportAdminTTL = time.Minute
+	// supportTopicNameMax bounds the forum topic name (the Telegram limit is 128).
+	supportTopicNameMax = 128
+	// supportDeleteBatch is the maximum message ids per deleteMessages call (the
+	// Telegram limit is 100).
+	supportDeleteBatch = 100
+)
+
+// supportEnabled reports whether the support relay is configured.
+func (t *Bot) supportEnabled() bool {
+	return t.supportChatID != 0 && t.support != nil
+}
+
+// initSupport prepares the support relay at startup: it resolves the bot's own user
+// id (getMe) for the loop guard, unless the chat-gating self-check already did, and
+// logs readiness. The loop guard also tests From.IsBot, so an unresolved id is not
+// fatal.
+func (t *Bot) initSupport(ctx context.Context) {
+	if t.botID == 0 {
+		if me, err := t.api.GetMe(ctx); err != nil {
+			t.log.Warn("support: getMe failed; relying on is_bot for the loop guard", zap.Error(err))
+		} else {
+			t.botID = me.ID
+		}
+	}
+	t.log.Info("support relay ready", zap.Int64("support_chat_id", t.supportChatID))
+}
+
+// keyedMutex serialises work per int64 key (here, per user id) so two concurrent
+// updates from the same user — the go-telegram/bot library runs handlers in
+// goroutines — cannot both open a forum topic.
+type keyedMutex struct {
+	mu sync.Mutex
+	m  map[int64]*sync.Mutex
+}
+
+func newKeyedMutex() *keyedMutex { return &keyedMutex{m: map[int64]*sync.Mutex{}} }
+
+// lock acquires the per-key mutex and returns its unlock function.
+func (k *keyedMutex) lock(key int64) func() {
+	k.mu.Lock()
+	mu, ok := k.m[key]
+	if !ok {
+		mu = &sync.Mutex{}
+		k.m[key] = mu
+	}
+	k.mu.Unlock()
+	mu.Lock()
+	return mu.Unlock
+}
+
+// adminCache caches the support chat's administrator ids for a short TTL, so the bot
+// does not call getChatAdministrators on every operator action.
+type adminCache struct {
+	mu        sync.Mutex
+	ids       map[int64]bool
+	fetchedAt time.Time
+}
+
+// isSupportAdmin reports whether userID administers the support chat, refreshing the
+// cache when stale. On a refresh failure it falls back to the last known set
+// (fail-closed when nothing is cached yet).
+func (t *Bot) isSupportAdmin(ctx context.Context, userID int64) bool {
+	t.admins.mu.Lock()
+	if t.admins.ids != nil && time.Since(t.admins.fetchedAt) < supportAdminTTL {
+		ok := t.admins.ids[userID]
+		t.admins.mu.Unlock()
+		return ok
+	}
+	t.admins.mu.Unlock()
+
+	members, err := t.api.GetChatAdministrators(ctx, &tgbot.GetChatAdministratorsParams{ChatID: t.supportChatID})
+	if err != nil {
+		t.log.Warn("support: getChatAdministrators failed; using cached admin set", zap.Error(err))
+		t.admins.mu.Lock()
+		defer t.admins.mu.Unlock()
+		return t.admins.ids[userID] // a nil map yields false (fail-closed)
+	}
+	ids := make(map[int64]bool, len(members))
+	for _, m := range members {
+		if u := chatMemberUser(m); u != nil {
+			ids[u.ID] = true
+		}
+	}
+	t.admins.mu.Lock()
+	t.admins.ids = ids
+	t.admins.fetchedAt = time.Now()
+	t.admins.mu.Unlock()
+	return ids[userID]
+}
+
+// handleSupportUserMessage relays a user's direct message into their forum topic in
+// the support chat, opening the topic (and its info card) on first contact. A blocked
+// user's message is dropped silently, and the user receives no reply — operators
+// answer from the topic.
+func (t *Bot) handleSupportUserMessage(ctx context.Context, m *models.Message) {
+	if m.From == nil || m.From.IsBot {
+		return
+	}
+	uid := m.From.ID
+	unlock := t.supportLocks.lock(uid)
+	defer unlock()
+
+	rec, ok := t.support.Get(uid)
+	if ok && rec.Blocked {
+		return
+	}
+	topicID := 0
+	if ok {
+		topicID = rec.TopicID
+	}
+	if topicID == 0 {
+		var err error
+		if topicID, err = t.openSupportTopic(ctx, m.From); err != nil {
+			t.log.Warn("support: open topic failed", zap.Int64("user_id", uid), zap.Error(err))
+			return
+		}
+	}
+
+	newID, err := t.copyToTopic(ctx, m.Chat.ID, m.ID, topicID)
+	if err != nil && isTopicMissingErr(err) {
+		// The operators deleted the whole topic; reopen it and retry once.
+		t.log.Info("support: topic gone, reopening", zap.Int64("user_id", uid), zap.Int("topic_id", topicID))
+		if topicID, err = t.openSupportTopic(ctx, m.From); err == nil {
+			newID, err = t.copyToTopic(ctx, m.Chat.ID, m.ID, topicID)
+		}
+	}
+	if err != nil {
+		t.log.Warn("support: relay to topic failed", zap.Int64("user_id", uid), zap.Error(err))
+		return
+	}
+	if err := t.support.AppendMsg(uid, newID); err != nil {
+		t.log.Warn("support: persist relayed id failed", zap.Int64("user_id", uid), zap.Error(err))
+	}
+}
+
+// handleSupportGroupMessage relays an operator's reply in a user's topic back to that
+// user. It ignores the bot's own posts (the loop guard), messages outside a topic,
+// unknown topics, and non-administrators. The operator's message is tracked too, so a
+// later clear removes it.
+func (t *Bot) handleSupportGroupMessage(ctx context.Context, m *models.Message) {
+	if m.From == nil || m.From.IsBot {
+		return // the bot's own relayed copies (and other bots) — never loop them back
+	}
+	if t.botID != 0 && m.From.ID == t.botID {
+		return
+	}
+	if m.MessageThreadID == 0 {
+		return // the chat's general area, not a user's topic
+	}
+	uid, ok := t.support.ByTopic(m.MessageThreadID)
+	if !ok {
+		return
+	}
+	if !t.isSupportAdmin(ctx, m.From.ID) {
+		return // only operators reach the user
+	}
+	if err := t.support.AppendMsg(uid, m.ID); err != nil {
+		t.log.Warn("support: persist operator msg id failed", zap.Int64("user_id", uid), zap.Error(err))
+	}
+	if _, err := t.copyToUser(ctx, m.ID, uid); err != nil {
+		t.log.Warn("support: relay reply to user failed", zap.Int64("user_id", uid), zap.Error(err))
+	}
+}
+
+// handleSupportCallback handles the info-card buttons (block/unblock/clear). Only
+// support-chat administrators may act; others get a denial. It always answers the
+// callback query so the client's spinner clears.
+func (t *Bot) handleSupportCallback(ctx context.Context, _ *tgbot.Bot, update *models.Update) {
+	cq := update.CallbackQuery
+	if cq == nil {
+		return
+	}
+	action, uid, ok := parseSupportCallback(cq.Data)
+	if !ok {
+		t.answerSupportCallback(ctx, cq.ID, "")
+		return
+	}
+	if !t.isSupportAdmin(ctx, cq.From.ID) {
+		t.answerSupportCallback(ctx, cq.ID, "Недостаточно прав")
+		return
+	}
+	switch action {
+	case supportActionBlock:
+		t.setSupportBlocked(ctx, cq, uid, true)
+	case supportActionUnblock:
+		t.setSupportBlocked(ctx, cq, uid, false)
+	case supportActionClear:
+		t.clearSupportTopic(ctx, cq, uid)
+	default:
+		t.answerSupportCallback(ctx, cq.ID, "")
+	}
+}
+
+// setSupportBlocked sets the user's block state, flips the info-card toggle to match,
+// and answers the callback. Blocking does not delete the topic — it stays.
+func (t *Bot) setSupportBlocked(ctx context.Context, cq *models.CallbackQuery, uid int64, blocked bool) {
+	if err := t.support.SetBlocked(uid, blocked); err != nil {
+		t.log.Warn("support: set blocked failed", zap.Int64("user_id", uid), zap.Error(err))
+		t.answerSupportCallback(ctx, cq.ID, "Ошибка")
+		return
+	}
+	if rec, ok := t.support.Get(uid); ok && rec.HeaderMsgID != 0 {
+		if _, err := t.api.EditMessageReplyMarkup(ctx, &tgbot.EditMessageReplyMarkupParams{
+			ChatID:      t.supportChatID,
+			MessageID:   rec.HeaderMsgID,
+			ReplyMarkup: supportCardMarkup(uid, blocked),
+		}); err != nil {
+			t.log.Debug("support: update card markup failed", zap.Error(err))
+		}
+	}
+	msg := "Разблокирован"
+	if blocked {
+		msg = "Заблокирован"
+	}
+	t.answerSupportCallback(ctx, cq.ID, msg)
+}
+
+// clearSupportTopic deletes the messages relayed into the user's topic (keeping the
+// info card) and answers the callback.
+func (t *Bot) clearSupportTopic(ctx context.Context, cq *models.CallbackQuery, uid int64) {
+	ids, err := t.support.ClearMsgs(uid)
+	if err != nil {
+		t.log.Warn("support: clear failed", zap.Int64("user_id", uid), zap.Error(err))
+		t.answerSupportCallback(ctx, cq.ID, "Ошибка")
+		return
+	}
+	t.deleteSupportMessages(ctx, ids)
+	t.answerSupportCallback(ctx, cq.ID, "Очищено")
+}
+
+// openSupportTopic creates a forum topic for the user and posts its info card with
+// the block/clear buttons, persisting both. It returns the new topic id. A failure to
+// persist is logged but not fatal: the in-memory mapping still lets the relay proceed.
+func (t *Bot) openSupportTopic(ctx context.Context, u *models.User) (int, error) {
+	topic, err := t.api.CreateForumTopic(ctx, &tgbot.CreateForumTopicParams{
+		ChatID: t.supportChatID,
+		Name:   supportTopicName(u),
+	})
+	if err != nil {
+		return 0, fmt.Errorf("create forum topic: %w", err)
+	}
+	headerID := 0
+	header, err := t.api.SendMessage(ctx, &tgbot.SendMessageParams{
+		ChatID:          t.supportChatID,
+		MessageThreadID: topic.MessageThreadID,
+		Text:            supportCardText(u),
+		ParseMode:       models.ParseModeHTML,
+		ReplyMarkup:     supportCardMarkup(u.ID, false),
+	})
+	if err != nil {
+		t.log.Warn("support: post info card failed (topic opened without it)", zap.Error(err))
+	} else {
+		headerID = header.ID
+	}
+	if err := t.support.SetTopic(u.ID, topic.MessageThreadID, headerID, u.FirstName, u.LastName, u.Username); err != nil {
+		t.log.Warn("support: persist topic state failed (kept in memory)", zap.Int64("user_id", u.ID), zap.Error(err))
+	}
+	return topic.MessageThreadID, nil
+}
+
+// copyToTopic copies a message into the user's forum topic and returns the new
+// message id.
+func (t *Bot) copyToTopic(ctx context.Context, fromChatID int64, messageID, topicID int) (int, error) {
+	if err := t.throttle(ctx); err != nil {
+		return 0, err
+	}
+	res, err := t.api.CopyMessage(ctx, &tgbot.CopyMessageParams{
+		ChatID:          t.supportChatID,
+		MessageThreadID: topicID,
+		FromChatID:      fromChatID,
+		MessageID:       messageID,
+	})
+	if err != nil {
+		return 0, err
+	}
+	return res.ID, nil
+}
+
+// copyToUser copies a support-chat message to the user's private chat and returns the
+// new message id.
+func (t *Bot) copyToUser(ctx context.Context, messageID int, userID int64) (int, error) {
+	if err := t.throttle(ctx); err != nil {
+		return 0, err
+	}
+	res, err := t.api.CopyMessage(ctx, &tgbot.CopyMessageParams{
+		ChatID:     userID,
+		FromChatID: t.supportChatID,
+		MessageID:  messageID,
+	})
+	if err != nil {
+		return 0, err
+	}
+	return res.ID, nil
+}
+
+// deleteSupportMessages best-effort deletes the given support-chat messages in
+// batches; individual failures (for example a message already removed) are ignored.
+func (t *Bot) deleteSupportMessages(ctx context.Context, ids []int) {
+	for start := 0; start < len(ids); start += supportDeleteBatch {
+		end := min(start+supportDeleteBatch, len(ids))
+		if _, err := t.api.DeleteMessages(ctx, &tgbot.DeleteMessagesParams{
+			ChatID:     t.supportChatID,
+			MessageIDs: ids[start:end],
+		}); err != nil {
+			t.log.Debug("support: delete batch failed", zap.Error(err))
+		}
+	}
+}
+
+// answerSupportCallback answers a callback query, logging a failure at debug (the
+// only effect of a miss is a lingering client spinner).
+func (t *Bot) answerSupportCallback(ctx context.Context, id, text string) {
+	if _, err := t.api.AnswerCallbackQuery(ctx, &tgbot.AnswerCallbackQueryParams{
+		CallbackQueryID: id,
+		Text:            text,
+	}); err != nil {
+		t.log.Debug("support: answer callback failed", zap.Error(err))
+	}
+}
+
+// parseSupportCallback parses "sup:<action>:<userID>" callback data.
+func parseSupportCallback(data string) (action string, userID int64, ok bool) {
+	rest, found := strings.CutPrefix(data, supportCallbackPrefix)
+	if !found {
+		return "", 0, false
+	}
+	action, idStr, found := strings.Cut(rest, ":")
+	if !found {
+		return "", 0, false
+	}
+	userID, err := strconv.ParseInt(idStr, 10, 64)
+	if err != nil {
+		return "", 0, false
+	}
+	return action, userID, true
+}
+
+// supportCardMarkup builds the info-card buttons: a Block/Unblock toggle reflecting
+// the current state, and a Clear button.
+func supportCardMarkup(userID int64, blocked bool) *models.InlineKeyboardMarkup {
+	toggleText, toggleAction := "Заблокировать", supportActionBlock
+	if blocked {
+		toggleText, toggleAction = "Разблокировать", supportActionUnblock
+	}
+	return &models.InlineKeyboardMarkup{
+		InlineKeyboard: [][]models.InlineKeyboardButton{{
+			{Text: toggleText, CallbackData: fmt.Sprintf("%s%s:%d", supportCallbackPrefix, toggleAction, userID)},
+			{Text: "Очистить", CallbackData: fmt.Sprintf("%s%s:%d", supportCallbackPrefix, supportActionClear, userID)},
+		}},
+	}
+}
+
+// supportTopicName builds the forum topic title for a user: full name and @username,
+// trimmed to the Telegram length limit.
+func supportTopicName(u *models.User) string {
+	name := strings.TrimSpace(u.FirstName + " " + u.LastName)
+	if name == "" {
+		name = "user " + strconv.FormatInt(u.ID, 10)
+	}
+	if u.Username != "" {
+		name += " @" + u.Username
+	}
+	if r := []rune(name); len(r) > supportTopicNameMax {
+		return string(r[:supportTopicNameMax])
+	}
+	return name
+}
+
+// supportCardText renders the info card describing the user. User-controlled fields
+// are HTML-escaped because the card uses HTML parse mode for the profile link.
+func supportCardText(u *models.User) string {
+	name := html.EscapeString(strings.TrimSpace(u.FirstName + " " + u.LastName))
+	if name == "" {
+		name = "—"
+	}
+	username := "—"
+	if u.Username != "" {
+		username = "@" + html.EscapeString(u.Username)
+	}
+	lang := u.LanguageCode
+	if lang == "" {
+		lang = "—"
+	}
+	premium := "нет"
+	if u.IsPremium {
+		premium = "да"
+	}
+	var b strings.Builder
+	fmt.Fprintf(&b, "<b>%s</b>\n", name)
+	fmt.Fprintf(&b, "Username: %s\n", username)
+	fmt.Fprintf(&b, "ID: <code>%d</code>\n", u.ID)
+	fmt.Fprintf(&b, "Язык: %s · Premium: %s\n", html.EscapeString(lang), premium)
+	fmt.Fprintf(&b, `<a href="tg://user?id=%d">Открыть профиль</a>`, u.ID)
+	return b.String()
+}
+
+// isTopicMissingErr reports whether err is Telegram's deleted/absent forum-topic
+// error, signalling the topic must be reopened.
+func isTopicMissingErr(err error) bool {
+	if err == nil {
+		return false
+	}
+	s := strings.ToLower(err.Error())
+	return strings.Contains(s, "thread not found") ||
+		strings.Contains(s, "thread_not_found") ||
+		strings.Contains(s, "topic deleted") ||
+		strings.Contains(s, "topic_deleted")
+}

platform/telegram/internal/bot/support_test.go

@@ -0,0 +1,404 @@
+package bot
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"path/filepath"
+	"strings"
+	"sync"
+	"testing"
+
+	"github.com/go-telegram/bot/models"
+	"go.uber.org/zap"
+
+	"scrabble/platform/telegram/internal/support"
+)
+
+const supportChatID = -1001000000000
+
+// copyRec records one copyMessage call.
+type copyRec struct {
+	chatID, fromChatID, threadID, messageID string
+}
+
+// supportAPI is a fake Bot API for the support-relay handlers: it answers the
+// methods they call with incrementing ids and records the requests for assertions.
+type supportAPI struct {
+	mu           sync.Mutex
+	adminIDs     []int64
+	nextThread   int
+	nextMsg      int
+	topicsOpened int
+	copies       []copyRec
+	headerThread string // message_thread_id of the last header sendMessage
+	deleted      [][]int
+	editedMsgIDs []string
+	answers      []string
+}
+
+func newSupportAPI(adminIDs ...int64) *supportAPI {
+	return &supportAPI{adminIDs: adminIDs, nextThread: 1000, nextMsg: 5000}
+}
+
+func (s *supportAPI) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	path := r.URL.Path
+	switch {
+	case strings.HasSuffix(path, "/getMe"):
+		io.WriteString(w, `{"ok":true,"result":{"id":1,"is_bot":true,"first_name":"bot","username":"b"}}`)
+	case strings.HasSuffix(path, "/createForumTopic"):
+		s.topicsOpened++
+		tid := s.nextThread
+		s.nextThread++
+		fmt.Fprintf(w, `{"ok":true,"result":{"message_thread_id":%d,"name":%q}}`, tid, r.FormValue("name"))
+	case strings.HasSuffix(path, "/sendMessage"):
+		s.headerThread = r.FormValue("message_thread_id")
+		mid := s.nextMsg
+		s.nextMsg++
+		fmt.Fprintf(w, `{"ok":true,"result":{"message_id":%d}}`, mid)
+	case strings.HasSuffix(path, "/copyMessage"):
+		s.copies = append(s.copies, copyRec{
+			chatID:     r.FormValue("chat_id"),
+			fromChatID: r.FormValue("from_chat_id"),
+			threadID:   r.FormValue("message_thread_id"),
+			messageID:  r.FormValue("message_id"),
+		})
+		mid := s.nextMsg
+		s.nextMsg++
+		fmt.Fprintf(w, `{"ok":true,"result":{"message_id":%d}}`, mid)
+	case strings.HasSuffix(path, "/deleteMessages"):
+		var ids []int
+		_ = json.Unmarshal([]byte(r.FormValue("message_ids")), &ids)
+		s.deleted = append(s.deleted, ids)
+		io.WriteString(w, `{"ok":true,"result":true}`)
+	case strings.HasSuffix(path, "/editMessageReplyMarkup"):
+		s.editedMsgIDs = append(s.editedMsgIDs, r.FormValue("message_id"))
+		io.WriteString(w, `{"ok":true,"result":{"message_id":1}}`)
+	case strings.HasSuffix(path, "/answerCallbackQuery"):
+		s.answers = append(s.answers, r.FormValue("text"))
+		io.WriteString(w, `{"ok":true,"result":true}`)
+	case strings.HasSuffix(path, "/getChatAdministrators"):
+		var b strings.Builder
+		b.WriteString(`{"ok":true,"result":[`)
+		for i, id := range s.adminIDs {
+			if i > 0 {
+				b.WriteString(",")
+			}
+			fmt.Fprintf(&b, `{"status":"administrator","user":{"id":%d,"is_bot":false}}`, id)
+		}
+		b.WriteString(`]}`)
+		io.WriteString(w, b.String())
+	default:
+		io.WriteString(w, `{"ok":true,"result":true}`)
+	}
+}
+
+func (s *supportAPI) copyCount() int {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	return len(s.copies)
+}
+
+// newSupportBot builds a support-enabled bot against the fake API and returns it with
+// its backing store.
+func newSupportBot(t *testing.T, api http.Handler) (*Bot, *support.Store) {
+	t.Helper()
+	srv := httptest.NewServer(api)
+	t.Cleanup(srv.Close)
+	st := support.New(filepath.Join(t.TempDir(), "support.json"))
+	b, err := New(Config{
+		Token:         "123:ABC",
+		APIBaseURL:    srv.URL,
+		MiniAppURL:    "https://example.com/telegram/",
+		SupportChatID: supportChatID,
+		SupportStore:  st,
+	}, zap.NewNop())
+	if err != nil {
+		t.Fatalf("new support bot: %v", err)
+	}
+	return b, st
+}
+
+// userMsg builds a private direct message from the given user.
+func userMsg(userID int64, text string) *models.Message {
+	return &models.Message{
+		ID:   int(userID)*10 + 1,
+		Chat: models.Chat{ID: userID, Type: models.ChatTypePrivate},
+		From: &models.User{ID: userID, FirstName: "Ann", Username: "annlee", LanguageCode: "ru"},
+		Text: text,
+	}
+}
+
+func TestSupportFirstContactOpensTopicAndRelays(t *testing.T) {
+	api := newSupportAPI()
+	b, st := newSupportBot(t, api)
+
+	b.handleSupportUserMessage(context.Background(), userMsg(7, "hello"))
+
+	if api.topicsOpened != 1 {
+		t.Fatalf("topics opened = %d, want 1", api.topicsOpened)
+	}
+	rec, ok := st.Get(7)
+	if !ok || rec.TopicID != 1000 || rec.HeaderMsgID != 5000 {
+		t.Fatalf("store = %+v ok=%v, want topic 1000 / header 5000", rec, ok)
+	}
+	if api.headerThread != "1000" {
+		t.Errorf("header posted to thread %q, want 1000", api.headerThread)
+	}
+	if len(api.copies) != 1 {
+		t.Fatalf("copies = %d, want 1", len(api.copies))
+	}
+	c := api.copies[0]
+	if c.threadID != "1000" || c.fromChatID != "7" || c.chatID != fmt.Sprint(supportChatID) {
+		t.Errorf("copy = %+v, want thread 1000 from 7 into the support chat", c)
+	}
+	if len(rec.RelayedMsgIDs) != 1 {
+		t.Errorf("relayed ids = %v, want 1 tracked", rec.RelayedMsgIDs)
+	}
+}
+
+func TestSupportSubsequentReusesTopic(t *testing.T) {
+	api := newSupportAPI()
+	b, st := newSupportBot(t, api)
+
+	b.handleSupportUserMessage(context.Background(), userMsg(7, "first"))
+	b.handleSupportUserMessage(context.Background(), userMsg(7, "second"))
+
+	if api.topicsOpened != 1 {
+		t.Errorf("topics opened = %d, want 1 (topic reused)", api.topicsOpened)
+	}
+	if len(api.copies) != 2 {
+		t.Errorf("copies = %d, want 2", len(api.copies))
+	}
+	rec, _ := st.Get(7)
+	if len(rec.RelayedMsgIDs) != 2 {
+		t.Errorf("relayed ids = %v, want 2", rec.RelayedMsgIDs)
+	}
+}
+
+func TestSupportBlockedUserDropped(t *testing.T) {
+	api := newSupportAPI()
+	b, st := newSupportBot(t, api)
+	if err := st.SetTopic(7, 1000, 5000, "Ann", "", "annlee"); err != nil {
+		t.Fatalf("seed topic: %v", err)
+	}
+	if err := st.SetBlocked(7, true); err != nil {
+		t.Fatalf("block: %v", err)
+	}
+
+	b.handleSupportUserMessage(context.Background(), userMsg(7, "hello?"))
+
+	if api.copyCount() != 0 {
+		t.Errorf("a blocked user's message was relayed (%d copies)", api.copyCount())
+	}
+	if api.topicsOpened != 0 {
+		t.Errorf("a blocked user opened a topic (%d)", api.topicsOpened)
+	}
+}
+
+// supportGroupMsg builds an operator message inside a topic of the support chat.
+func supportGroupMsg(fromID int64, threadID int, isBot bool) *models.Message {
+	return &models.Message{
+		ID:              700 + threadID,
+		Chat:            models.Chat{ID: supportChatID, Type: models.ChatTypeSupergroup},
+		From:            &models.User{ID: fromID, IsBot: isBot},
+		MessageThreadID: threadID,
+		Text:            "operator reply",
+	}
+}
+
+func TestSupportOperatorReplyRelayed(t *testing.T) {
+	api := newSupportAPI(50) // user 50 is an admin
+	b, st := newSupportBot(t, api)
+	if err := st.SetTopic(7, 1000, 5000, "Ann", "", "annlee"); err != nil {
+		t.Fatalf("seed topic: %v", err)
+	}
+
+	b.handleSupportGroupMessage(context.Background(), supportGroupMsg(50, 1000, false))
+
+	if len(api.copies) != 1 {
+		t.Fatalf("copies = %d, want 1 (reply relayed to user)", len(api.copies))
+	}
+	if api.copies[0].chatID != "7" || api.copies[0].fromChatID != fmt.Sprint(supportChatID) {
+		t.Errorf("copy = %+v, want from the support chat to user 7", api.copies[0])
+	}
+	rec, _ := st.Get(7)
+	if len(rec.RelayedMsgIDs) != 1 {
+		t.Errorf("operator message not tracked for clear: %v", rec.RelayedMsgIDs)
+	}
+}
+
+func TestSupportGroupMessageIgnored(t *testing.T) {
+	cases := []struct {
+		name   string
+		msg    *models.Message
+		admins []int64
+	}{
+		{"bot's own copy (loop guard)", supportGroupMsg(1, 1000, true), []int64{50}},
+		{"non-admin sender", supportGroupMsg(999, 1000, false), []int64{50}},
+		{"outside any topic", supportGroupMsg(50, 0, false), []int64{50}},
+		{"unknown topic", supportGroupMsg(50, 4242, false), []int64{50}},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			api := newSupportAPI(tc.admins...)
+			b, st := newSupportBot(t, api)
+			if err := st.SetTopic(7, 1000, 5000, "Ann", "", "annlee"); err != nil {
+				t.Fatalf("seed topic: %v", err)
+			}
+			b.handleSupportGroupMessage(context.Background(), tc.msg)
+			if api.copyCount() != 0 {
+				t.Errorf("message relayed (%d copies); it should be ignored", api.copyCount())
+			}
+		})
+	}
+}
+
+// supportCallback builds a callback-query update for the given data and presser.
+func supportCallback(data string, fromID int64) *models.Update {
+	return &models.Update{CallbackQuery: &models.CallbackQuery{
+		ID:   "cb1",
+		From: models.User{ID: fromID},
+		Data: data,
+	}}
+}
+
+func TestSupportCallbackBlockToggle(t *testing.T) {
+	api := newSupportAPI(50)
+	b, st := newSupportBot(t, api)
+	if err := st.SetTopic(7, 1000, 5000, "Ann", "", "annlee"); err != nil {
+		t.Fatalf("seed topic: %v", err)
+	}
+
+	b.handleSupportCallback(context.Background(), b.api, supportCallback("sup:block:7", 50))
+	if !st.Blocked(7) {
+		t.Error("user not blocked after sup:block")
+	}
+	if len(api.editedMsgIDs) != 1 || api.editedMsgIDs[0] != "5000" {
+		t.Errorf("edited markup msg ids = %v, want [5000]", api.editedMsgIDs)
+	}
+
+	b.handleSupportCallback(context.Background(), b.api, supportCallback("sup:unblock:7", 50))
+	if st.Blocked(7) {
+		t.Error("user still blocked after sup:unblock")
+	}
+	if len(api.answers) != 2 || api.answers[0] != "Заблокирован" || api.answers[1] != "Разблокирован" {
+		t.Errorf("answers = %v, want [Заблокирован Разблокирован]", api.answers)
+	}
+}
+
+func TestSupportCallbackNonAdminDenied(t *testing.T) {
+	api := newSupportAPI(50)
+	b, st := newSupportBot(t, api)
+	if err := st.SetTopic(7, 1000, 5000, "Ann", "", "annlee"); err != nil {
+		t.Fatalf("seed topic: %v", err)
+	}
+
+	b.handleSupportCallback(context.Background(), b.api, supportCallback("sup:block:7", 999))
+
+	if st.Blocked(7) {
+		t.Error("a non-admin managed to block the user")
+	}
+	if len(api.answers) != 1 || api.answers[0] != "Недостаточно прав" {
+		t.Errorf("answers = %v, want a permission denial", api.answers)
+	}
+}
+
+func TestSupportCallbackClearDeletesTracked(t *testing.T) {
+	api := newSupportAPI(50)
+	b, st := newSupportBot(t, api)
+	if err := st.SetTopic(7, 1000, 5000, "Ann", "", "annlee"); err != nil {
+		t.Fatalf("seed topic: %v", err)
+	}
+	for _, id := range []int{501, 502, 503} {
+		if err := st.AppendMsg(7, id); err != nil {
+			t.Fatalf("append: %v", err)
+		}
+	}
+
+	b.handleSupportCallback(context.Background(), b.api, supportCallback("sup:clear:7", 50))
+
+	if len(api.deleted) != 1 || len(api.deleted[0]) != 3 {
+		t.Fatalf("deleted batches = %v, want one batch of 3", api.deleted)
+	}
+	rec, _ := st.Get(7)
+	if len(rec.RelayedMsgIDs) != 0 {
+		t.Errorf("relayed ids after clear = %v, want empty", rec.RelayedMsgIDs)
+	}
+	if rec.HeaderMsgID != 5000 {
+		t.Errorf("clear disturbed the header (%d)", rec.HeaderMsgID)
+	}
+}
+
+func TestParseSupportCallback(t *testing.T) {
+	cases := []struct {
+		data       string
+		wantAction string
+		wantUID    int64
+		wantOK     bool
+	}{
+		{"sup:block:7", "block", 7, true},
+		{"sup:clear:-100", "clear", -100, true},
+		{"sup:unblock:42", "unblock", 42, true},
+		{"block:7", "", 0, false},
+		{"sup:block", "", 0, false},
+		{"sup:block:notanumber", "", 0, false},
+	}
+	for _, tc := range cases {
+		t.Run(tc.data, func(t *testing.T) {
+			action, uid, ok := parseSupportCallback(tc.data)
+			if action != tc.wantAction || uid != tc.wantUID || ok != tc.wantOK {
+				t.Errorf("parseSupportCallback(%q) = %q,%d,%v; want %q,%d,%v",
+					tc.data, action, uid, ok, tc.wantAction, tc.wantUID, tc.wantOK)
+			}
+		})
+	}
+}
+
+func TestSupportCardTextEscapes(t *testing.T) {
+	u := &models.User{ID: 7, FirstName: "<b>Ann</b>", Username: "ann", LanguageCode: "ru", IsPremium: true}
+	card := supportCardText(u)
+	if strings.Contains(card, "<b>Ann</b>") {
+		t.Error("user-supplied first name was not HTML-escaped in the card")
+	}
+	if !strings.Contains(card, "&lt;b&gt;Ann&lt;/b&gt;") {
+		t.Errorf("card = %q, want the escaped name", card)
+	}
+	if !strings.Contains(card, "tg://user?id=7") {
+		t.Error("card missing the profile deep link")
+	}
+	if !strings.Contains(card, "Premium: да") {
+		t.Error("card missing the premium flag")
+	}
+}
+
+func TestSupportTopicName(t *testing.T) {
+	if got := supportTopicName(&models.User{ID: 7, FirstName: "Ann", LastName: "Lee", Username: "annlee"}); got != "Ann Lee @annlee" {
+		t.Errorf("topic name = %q, want %q", got, "Ann Lee @annlee")
+	}
+	if got := supportTopicName(&models.User{ID: 7}); got != "user 7" {
+		t.Errorf("nameless topic = %q, want %q", got, "user 7")
+	}
+	long := strings.Repeat("x", 200)
+	if got := supportTopicName(&models.User{ID: 7, FirstName: long}); len([]rune(got)) != supportTopicNameMax {
+		t.Errorf("topic name length = %d, want %d (trimmed)", len([]rune(got)), supportTopicNameMax)
+	}
+}
+
+func TestSupportDisabledFallsThrough(t *testing.T) {
+	// With no SupportChatID the relay is off and supportEnabled is false.
+	srv := httptest.NewServer(&supportAPI{nextThread: 1000, nextMsg: 5000})
+	t.Cleanup(srv.Close)
+	b, err := New(Config{Token: "123:ABC", APIBaseURL: srv.URL, MiniAppURL: "https://example.com/"}, zap.NewNop())
+	if err != nil {
+		t.Fatalf("new bot: %v", err)
+	}
+	if b.supportEnabled() {
+		t.Error("supportEnabled() = true without a SupportChatID")
+	}
+}

platform/telegram/internal/config/config.go

@@ -42,6 +42,16 @@ type BotConfig struct {
 	// (TELEGRAM_CHAT_ID, optional; 0 disables chat gating). The bot must be an admin
 	// there with the "Ban users" right, and "chat_member" in its allowed updates.
 	ChatID int64
+	// SupportChatID is the chat id of the private forum supergroup the bot relays
+	// direct user messages into — one forum topic per user — and reads operator
+	// replies from (TELEGRAM_SUPPORT_CHAT_ID, optional; 0 disables the support relay).
+	// The bot must be an administrator there with the manage-topics and
+	// delete-messages rights. Distinct from ChatID (the moderated discussion chat).
+	SupportChatID int64
+	// SupportStateDir is the directory holding the support relay's JSON state file
+	// (TELEGRAM_SUPPORT_STATE_DIR, default /data). It must be writable by the
+	// container user (UID 65532) and backed by a persistent volume.
+	SupportStateDir string
 	// PromoBotToken is the API token of the optional standalone promo bot run in this
 	// container — a second bot whose only job is to answer /start with a button that
 	// opens the main bot's Mini App (TELEGRAM_PROMO_BOT_TOKEN, optional; empty disables
@@ -135,6 +145,7 @@ func LoadBot() (BotConfig, error) {
 		PromoBotToken:     os.Getenv("TELEGRAM_PROMO_BOT_TOKEN"),
 		BotUsername:       strings.TrimPrefix(os.Getenv("TELEGRAM_BOT_USERNAME"), "@"),
 		BotLinkURL:        os.Getenv("TELEGRAM_BOT_LINK"),
+		SupportStateDir:   envOr("TELEGRAM_SUPPORT_STATE_DIR", "/data"),
 		LogLevel:          envOr("TELEGRAM_LOG_LEVEL", "info"),
 		BotLink: BotLinkClientConfig{
 			GatewayAddr: os.Getenv("TELEGRAM_GATEWAY_ADDR"),
@@ -152,6 +163,9 @@ func LoadBot() (BotConfig, error) {
 	if cfg.ChatID, err = envInt64("TELEGRAM_CHAT_ID", 0); err != nil {
 		return BotConfig{}, err
 	}
+	if cfg.SupportChatID, err = envInt64("TELEGRAM_SUPPORT_CHAT_ID", 0); err != nil {
+		return BotConfig{}, err
+	}
 	if cfg.SendRatePerSecond, err = envInt("TELEGRAM_SEND_RATE_PER_SECOND", defaultSendRatePerSecond); err != nil {
 		return BotConfig{}, err
 	}

platform/telegram/internal/config/config_test.go

@@ -151,6 +151,48 @@ func TestLoadBotChatAndPromo(t *testing.T) {
 	})
 }
 
+// TestLoadBotSupportRelay verifies the support-relay chat id parses, the state
+// directory defaults to /data, and the relay is disabled (chat id 0) by default.
+func TestLoadBotSupportRelay(t *testing.T) {
+	t.Run("parsed", func(t *testing.T) {
+		setBotRequired(t)
+		t.Setenv("TELEGRAM_SUPPORT_CHAT_ID", "-1001234567890")
+		t.Setenv("TELEGRAM_SUPPORT_STATE_DIR", "/srv/state")
+		c, err := LoadBot()
+		if err != nil {
+			t.Fatalf("LoadBot: %v", err)
+		}
+		if c.SupportChatID != -1001234567890 {
+			t.Errorf("SupportChatID = %d, want -1001234567890", c.SupportChatID)
+		}
+		if c.SupportStateDir != "/srv/state" {
+			t.Errorf("SupportStateDir = %q, want /srv/state", c.SupportStateDir)
+		}
+	})
+
+	t.Run("defaults", func(t *testing.T) {
+		setBotRequired(t)
+		c, err := LoadBot()
+		if err != nil {
+			t.Fatalf("LoadBot: %v", err)
+		}
+		if c.SupportChatID != 0 {
+			t.Errorf("SupportChatID = %d, want 0 (relay disabled)", c.SupportChatID)
+		}
+		if c.SupportStateDir != "/data" {
+			t.Errorf("SupportStateDir = %q, want /data", c.SupportStateDir)
+		}
+	})
+
+	t.Run("malformed chat id rejected", func(t *testing.T) {
+		setBotRequired(t)
+		t.Setenv("TELEGRAM_SUPPORT_CHAT_ID", "not-a-number")
+		if _, err := LoadBot(); err == nil {
+			t.Fatal("LoadBot: expected an error for a malformed support chat id, got nil")
+		}
+	})
+}
+
 // TestLoadRejectsUnsupportedExporter verifies an exporter outside the supported set
 // fails validation (the validator path).
 func TestLoadRejectsUnsupportedExporter(t *testing.T) {

platform/telegram/internal/support/store.go

@@ -0,0 +1,227 @@
+// Package support persists the Telegram bot's support-relay state. For each user
+// who direct-messages the bot it records the dedicated forum topic the bot opened
+// in the operators' support chat, whether the user is blocked, and the ids of the
+// messages relayed into that topic — so an operator's "clear" can delete them while
+// keeping the topic's info card. The state is a small JSON file on a writable
+// volume: the bot host has no database.
+//
+// The store is concurrency-safe. The go-telegram/bot library dispatches each update
+// in its own goroutine, so every exported method locks. Mutators update only their
+// own fields (SetTopic never touches Blocked, SetBlocked never touches the relayed
+// ids) so a topic recreate cannot clobber a concurrent block toggle.
+package support
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+	"sort"
+	"sync"
+	"time"
+)
+
+// User is one user's support-relay state.
+type User struct {
+	// UserID is the user's Telegram user id (the private chat id the bot relays to).
+	UserID int64 `json:"user_id"`
+	// TopicID is the forum topic's message_thread_id in the support chat; 0 means no
+	// topic has been created yet.
+	TopicID int `json:"topic_id"`
+	// HeaderMsgID is the info-card message that opens the topic and carries the
+	// block/clear buttons; it is never deleted by a clear.
+	HeaderMsgID int `json:"header_msg_id"`
+	// Blocked reports whether the bot drops this user's incoming messages.
+	Blocked bool `json:"blocked"`
+	// FirstName, LastName and Username snapshot the user's Telegram profile at the
+	// time the topic was created or last refreshed (for the topic name and info card).
+	FirstName string `json:"first_name,omitempty"`
+	LastName  string `json:"last_name,omitempty"`
+	Username  string `json:"username,omitempty"`
+	// RelayedMsgIDs are the ids of the messages posted into the topic after the header
+	// (the user's relayed messages and the operators' replies); a clear deletes them.
+	RelayedMsgIDs []int `json:"relayed_msg_ids,omitempty"`
+	// CreatedAt is when the topic was first opened for this user.
+	CreatedAt time.Time `json:"created_at"`
+}
+
+// Store is the concurrency-safe, JSON-backed support-relay state. The zero value is
+// not usable; build one with Open or New.
+type Store struct {
+	mu      sync.Mutex
+	path    string
+	users   map[int64]*User
+	byTopic map[int]int64 // TopicID -> UserID, for resolving operator replies
+}
+
+// file is the on-disk shape: a flat list of users. A JSON object keyed by user id
+// would force the int64 keys through strings; a list keeps the ids typed.
+type file struct {
+	Users []*User `json:"users"`
+}
+
+// New returns an empty store that persists to path, creating the parent directory
+// when missing. Use it as the fallback when Open reports a corrupt file.
+func New(path string) *Store {
+	_ = os.MkdirAll(filepath.Dir(path), 0o755)
+	return &Store{path: path, users: map[int64]*User{}, byTopic: map[int]int64{}}
+}
+
+// Open loads the store from path. A missing file yields an empty store and no
+// error; an unreadable or malformed file returns an error so the caller can decide
+// whether to start empty.
+func Open(path string) (*Store, error) {
+	s := New(path)
+	b, err := os.ReadFile(path)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return s, nil
+		}
+		return nil, fmt.Errorf("support: read state %s: %w", path, err)
+	}
+	var f file
+	if err := json.Unmarshal(b, &f); err != nil {
+		return nil, fmt.Errorf("support: parse state %s: %w", path, err)
+	}
+	for _, u := range f.Users {
+		if u == nil || u.UserID == 0 {
+			continue
+		}
+		s.users[u.UserID] = u
+		if u.TopicID != 0 {
+			s.byTopic[u.TopicID] = u.UserID
+		}
+	}
+	return s, nil
+}
+
+// Get returns a detached copy of the user's state and whether it exists.
+func (s *Store) Get(userID int64) (User, bool) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	u, ok := s.users[userID]
+	if !ok {
+		return User{}, false
+	}
+	cp := *u
+	cp.RelayedMsgIDs = append([]int(nil), u.RelayedMsgIDs...)
+	return cp, true
+}
+
+// ByTopic returns the user id owning the given forum topic, and whether one is known.
+func (s *Store) ByTopic(topicID int) (int64, bool) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	uid, ok := s.byTopic[topicID]
+	return uid, ok
+}
+
+// Blocked reports whether the user's incoming messages are dropped.
+func (s *Store) Blocked(userID int64) bool {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if u, ok := s.users[userID]; ok {
+		return u.Blocked
+	}
+	return false
+}
+
+// SetTopic records the forum topic and info-card message opened for the user and
+// refreshes the profile snapshot, creating the record on first contact. It rebuilds
+// the topic index when the topic changes (a recreate) and preserves the block state
+// and the relayed-message ids. It persists the result.
+func (s *Store) SetTopic(userID int64, topicID, headerMsgID int, firstName, lastName, username string) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	u, ok := s.users[userID]
+	if !ok {
+		u = &User{UserID: userID, CreatedAt: time.Now().UTC()}
+		s.users[userID] = u
+	} else if u.TopicID != 0 && u.TopicID != topicID {
+		delete(s.byTopic, u.TopicID)
+	}
+	u.TopicID = topicID
+	u.HeaderMsgID = headerMsgID
+	u.FirstName, u.LastName, u.Username = firstName, lastName, username
+	if topicID != 0 {
+		s.byTopic[topicID] = userID
+	}
+	return s.save()
+}
+
+// SetBlocked sets the user's blocked flag, creating a minimal record when none
+// exists, and persists the result.
+func (s *Store) SetBlocked(userID int64, blocked bool) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	u, ok := s.users[userID]
+	if !ok {
+		u = &User{UserID: userID, CreatedAt: time.Now().UTC()}
+		s.users[userID] = u
+	}
+	u.Blocked = blocked
+	return s.save()
+}
+
+// AppendMsg records a message posted into the user's topic (for a later clear) and
+// persists the result. It is a no-op when the user has no record yet.
+func (s *Store) AppendMsg(userID int64, msgID int) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	u, ok := s.users[userID]
+	if !ok {
+		return nil
+	}
+	u.RelayedMsgIDs = append(u.RelayedMsgIDs, msgID)
+	return s.save()
+}
+
+// ClearMsgs empties and returns the user's relayed-message ids (the info card is not
+// among them) and persists the result, so the caller can delete them from the chat.
+func (s *Store) ClearMsgs(userID int64) ([]int, error) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	u, ok := s.users[userID]
+	if !ok || len(u.RelayedMsgIDs) == 0 {
+		return nil, nil
+	}
+	ids := u.RelayedMsgIDs
+	u.RelayedMsgIDs = nil
+	if err := s.save(); err != nil {
+		// Roll back so the ids are not lost if the write fails.
+		u.RelayedMsgIDs = ids
+		return nil, err
+	}
+	return ids, nil
+}
+
+// save writes the state atomically (temp file in the same directory, then rename).
+// The caller must hold s.mu.
+func (s *Store) save() error {
+	f := file{Users: make([]*User, 0, len(s.users))}
+	for _, u := range s.users {
+		f.Users = append(f.Users, u)
+	}
+	sort.Slice(f.Users, func(i, j int) bool { return f.Users[i].UserID < f.Users[j].UserID })
+	b, err := json.MarshalIndent(f, "", "  ")
+	if err != nil {
+		return fmt.Errorf("support: marshal state: %w", err)
+	}
+	tmp, err := os.CreateTemp(filepath.Dir(s.path), ".support-*.json")
+	if err != nil {
+		return fmt.Errorf("support: create temp state: %w", err)
+	}
+	tmpName := tmp.Name()
+	defer func() { _ = os.Remove(tmpName) }() // no-op once the rename succeeds
+	if _, err := tmp.Write(b); err != nil {
+		_ = tmp.Close()
+		return fmt.Errorf("support: write temp state: %w", err)
+	}
+	if err := tmp.Close(); err != nil {
+		return fmt.Errorf("support: close temp state: %w", err)
+	}
+	if err := os.Rename(tmpName, s.path); err != nil {
+		return fmt.Errorf("support: replace state %s: %w", s.path, err)
+	}
+	return nil
+}

platform/telegram/internal/support/store_test.go

@@ -0,0 +1,178 @@
+package support
+
+import (
+	"os"
+	"path/filepath"
+	"sync"
+	"testing"
+)
+
+// statePath returns a path inside a fresh temp directory for a store file.
+func statePath(t *testing.T) string {
+	t.Helper()
+	return filepath.Join(t.TempDir(), "support.json")
+}
+
+func TestOpenMissingReturnsEmpty(t *testing.T) {
+	s, err := Open(statePath(t))
+	if err != nil {
+		t.Fatalf("Open missing: %v", err)
+	}
+	if _, ok := s.Get(42); ok {
+		t.Error("Get on an empty store returned a record")
+	}
+}
+
+func TestOpenCorruptReturnsError(t *testing.T) {
+	path := statePath(t)
+	if err := os.WriteFile(path, []byte("{not json"), 0o600); err != nil {
+		t.Fatalf("write corrupt: %v", err)
+	}
+	if _, err := Open(path); err == nil {
+		t.Fatal("Open on a corrupt file: expected an error, got nil")
+	}
+}
+
+func TestSetTopicPersistsAndReloads(t *testing.T) {
+	path := statePath(t)
+	s := New(path)
+	if err := s.SetTopic(7, 100, 101, "Ann", "Lee", "annlee"); err != nil {
+		t.Fatalf("SetTopic: %v", err)
+	}
+
+	// In-memory view.
+	got, ok := s.Get(7)
+	if !ok || got.TopicID != 100 || got.HeaderMsgID != 101 || got.Username != "annlee" {
+		t.Fatalf("Get = %+v ok=%v, want topic 100 / header 101 / annlee", got, ok)
+	}
+	if got.CreatedAt.IsZero() {
+		t.Error("CreatedAt not set on first contact")
+	}
+	if uid, ok := s.ByTopic(100); !ok || uid != 7 {
+		t.Errorf("ByTopic(100) = %d ok=%v, want 7/true", uid, ok)
+	}
+
+	// Reloaded from disk.
+	reload, err := Open(path)
+	if err != nil {
+		t.Fatalf("Open: %v", err)
+	}
+	got, ok = reload.Get(7)
+	if !ok || got.TopicID != 100 || got.FirstName != "Ann" {
+		t.Fatalf("reloaded Get = %+v ok=%v, want topic 100 / Ann", got, ok)
+	}
+	if uid, ok := reload.ByTopic(100); !ok || uid != 7 {
+		t.Errorf("reloaded ByTopic(100) = %d ok=%v, want 7/true", uid, ok)
+	}
+}
+
+func TestSetTopicRecreateReindexes(t *testing.T) {
+	s := New(statePath(t))
+	if err := s.SetTopic(7, 100, 101, "Ann", "", ""); err != nil {
+		t.Fatalf("SetTopic: %v", err)
+	}
+	if err := s.SetTopic(7, 200, 201, "Ann", "", ""); err != nil {
+		t.Fatalf("SetTopic recreate: %v", err)
+	}
+	if _, ok := s.ByTopic(100); ok {
+		t.Error("ByTopic(100) still resolves after recreate; the stale topic was not dropped")
+	}
+	if uid, ok := s.ByTopic(200); !ok || uid != 7 {
+		t.Errorf("ByTopic(200) = %d ok=%v, want 7/true", uid, ok)
+	}
+}
+
+// TestBlockSurvivesTopicRecreate is the field-isolation guarantee: a topic recreate
+// (SetTopic) must not clear a block set concurrently from the buttons.
+func TestBlockSurvivesTopicRecreate(t *testing.T) {
+	s := New(statePath(t))
+	if err := s.SetTopic(7, 100, 101, "Ann", "", "annlee"); err != nil {
+		t.Fatalf("SetTopic: %v", err)
+	}
+	if err := s.SetBlocked(7, true); err != nil {
+		t.Fatalf("SetBlocked: %v", err)
+	}
+	if err := s.SetTopic(7, 200, 201, "Ann", "", "annlee"); err != nil {
+		t.Fatalf("SetTopic recreate: %v", err)
+	}
+	if !s.Blocked(7) {
+		t.Error("block was cleared by a topic recreate")
+	}
+}
+
+func TestAppendAndClearMsgs(t *testing.T) {
+	s := New(statePath(t))
+	if err := s.SetTopic(7, 100, 101, "Ann", "", ""); err != nil {
+		t.Fatalf("SetTopic: %v", err)
+	}
+	for _, id := range []int{500, 501, 502} {
+		if err := s.AppendMsg(7, id); err != nil {
+			t.Fatalf("AppendMsg %d: %v", id, err)
+		}
+	}
+	got, _ := s.Get(7)
+	if len(got.RelayedMsgIDs) != 3 {
+		t.Fatalf("RelayedMsgIDs = %v, want 3 ids", got.RelayedMsgIDs)
+	}
+
+	ids, err := s.ClearMsgs(7)
+	if err != nil {
+		t.Fatalf("ClearMsgs: %v", err)
+	}
+	if len(ids) != 3 || ids[0] != 500 || ids[2] != 502 {
+		t.Errorf("ClearMsgs = %v, want [500 501 502]", ids)
+	}
+	got, _ = s.Get(7)
+	if len(got.RelayedMsgIDs) != 0 {
+		t.Errorf("RelayedMsgIDs after clear = %v, want empty", got.RelayedMsgIDs)
+	}
+	if got.HeaderMsgID != 101 || got.TopicID != 100 {
+		t.Errorf("clear disturbed the topic/header: %+v", got)
+	}
+
+	// A second clear is a no-op.
+	if ids, err := s.ClearMsgs(7); err != nil || ids != nil {
+		t.Errorf("second ClearMsgs = %v, %v, want nil, nil", ids, err)
+	}
+}
+
+func TestGetReturnsDetachedCopy(t *testing.T) {
+	s := New(statePath(t))
+	if err := s.SetTopic(7, 100, 101, "Ann", "", ""); err != nil {
+		t.Fatalf("SetTopic: %v", err)
+	}
+	if err := s.AppendMsg(7, 500); err != nil {
+		t.Fatalf("AppendMsg: %v", err)
+	}
+	got, _ := s.Get(7)
+	got.RelayedMsgIDs[0] = 999 // mutate the copy
+	again, _ := s.Get(7)
+	if again.RelayedMsgIDs[0] != 500 {
+		t.Error("Get returned a slice that aliases the store's state")
+	}
+}
+
+// TestConcurrentMutationsSafe exercises the mutex under parallel writers; run with
+// -race to catch data races.
+func TestConcurrentMutationsSafe(t *testing.T) {
+	s := New(statePath(t))
+	if err := s.SetTopic(7, 100, 101, "Ann", "", ""); err != nil {
+		t.Fatalf("SetTopic: %v", err)
+	}
+	var wg sync.WaitGroup
+	for i := range 20 {
+		wg.Add(1)
+		go func(n int) {
+			defer wg.Done()
+			_ = s.AppendMsg(7, 1000+n)
+			_ = s.SetBlocked(7, n%2 == 0)
+			_, _ = s.Get(7)
+			_, _ = s.ByTopic(100)
+		}(i)
+	}
+	wg.Wait()
+	got, ok := s.Get(7)
+	if !ok || len(got.RelayedMsgIDs) != 20 {
+		t.Errorf("after concurrent appends: %d ids, want 20", len(got.RelayedMsgIDs))
+	}
+}