scrabble-game/pkg/fbs/scrabble.fbs

// FlatBuffers payloads for the client <-> gateway edge transport.
//
// Every request and response that rides inside the Connect envelope
// (gateway/proto/edge) `payload` field, and every push Event payload, is one of
// these tables. They are the binary wire contract shared with the UI, which
// generates TypeScript from this same schema. A single namespace keeps
// nested tables (GameView inside MoveResult / MatchResult) free of
// cross-namespace imports. Keep this schema and the backend JSON DTOs in lockstep
// — the gateway transcodes one to the other.
//
// Generate Go with `make fbs` (flatc, version-pinned). The committed output lives
// in fbs/scrabblefb/.
namespace scrabblefb;

// --- shared building blocks ---

// TileRecord is one tile in a decoded move record (history, move result, hint): its
// board coordinate, the concrete letter ("?" when read from a hand for a blank) and
// whether it came from a blank. Inbound tiles to place use PlayTile (alphabet indices).
table TileRecord {
  row:int;
  col:int;
  letter:string;
  blank:bool;
}

// PlayTile is one inbound tile to place, addressed by its alphabet index rather than a
// concrete letter. For a blank, letter carries the designated letter's index
// and blank is true. The board coordinate is its target square.
table PlayTile {
  row:int;
  col:int;
  letter:ubyte;
  blank:bool;
}

// AlphabetEntry is one letter of a variant's alphabet, sent for display only:
// index is the engine alphabet-index byte the wire uses for this letter, letter is the
// concrete character and value is its tile score. The client caches the table per variant.
table AlphabetEntry {
  index:ubyte;
  letter:string;
  value:int;
}

// SeatView is one seat's public standing in a game. display_name is resolved by the
// backend from the account store (added trailing — backward-compatible).
table SeatView {
  seat:int;
  account_id:string;
  score:int;
  hints_used:int;
  is_winner:bool;
  display_name:string;
}

// GameView is the shared (non-private) game summary.
table GameView {
  id:string;
  variant:string;
  dict_version:string;
  status:string;
  players:int;
  to_move:int;
  turn_timeout_secs:int;
  multiple_words_per_turn:bool;
  move_count:int;
  end_reason:string;
  seats:[SeatView];
  // last_activity_unix is the lobby sort key: the current turn's start for an active
  // game, the finish time for a finished one.
  last_activity_unix:long;
  // vs_ai marks an honest-AI game: the opponent is shown as 🤖 and chat/nudge/add-friend
  // are disabled in the client. A robot-filled random game keeps vs_ai=false.
  vs_ai:bool;
  // unread_chat is a per-viewer flag: the requesting player has at least one unread chat
  // entry (message or nudge) in this game. It drives the lobby and in-game unread badge.
  unread_chat:bool;
  // unread_messages is a per-viewer flag: at least one of the unread entries is a real chat
  // message (not just a nudge). With unread_chat it colours the badge — both set is the regular
  // badge, unread_chat alone is the softer nudge-only badge.
  unread_messages:bool;
}

// MoveRecord is one decoded move (a committed play, or a hint preview).
table MoveRecord {
  player:int;
  action:string;
  dir:string;
  main_row:int;
  main_col:int;
  tiles:[TileRecord];
  words:[string];
  count:int;
  score:int;
  total:int;
}

// --- auth (unauthenticated) ---

// TelegramLoginRequest carries the platform launch data; the gateway validates
// its HMAC before forwarding the extracted identity to the backend. browser_tz is
// the client's detected UTC offset ("±HH:MM"), seeded into a brand-new account's
// time zone so the robot's sleep window and the turn-timeout away window are
// anchored to the player's real zone from first contact (first contact only).
table TelegramLoginRequest {
  init_data:string;
  browser_tz:string;
}

// VKLoginRequest carries a VK Mini App launch. params is the raw query string of the
// signed vk_* launch parameters plus the sign, which the gateway verifies in-process
// (HMAC-SHA256 over the sorted vk_* params under the app secret, base64url) before
// forwarding the extracted vk_user_id to the backend. display_name is the player's
// name read client-side via VKWebAppGetUserInfo — VK omits it from the signed params,
// so it is an untrusted, cosmetic seed for a brand-new account's display name.
// browser_tz is the client's detected UTC offset ("±HH:MM"), seeded into a brand-new
// account's time zone (see TelegramLoginRequest.browser_tz; first contact only).
table VKLoginRequest {
  params:string;
  browser_tz:string;
  display_name:string;
}

// GuestLoginRequest bootstraps an ephemeral guest session. locale is an optional
// preferred-language hint; browser_tz is the detected UTC offset seeded into the
// guest account's time zone (see TelegramLoginRequest.browser_tz).
table GuestLoginRequest {
  locale:string;
  browser_tz:string;
}

// EmailRequestRequest asks the backend to send a login confirm-code to email. It
// also provisions the account on first contact, so browser_tz (the detected UTC
// offset) is seeded into its time zone here, not at the later login step.
table EmailRequestRequest {
  email:string;
  browser_tz:string;
}

// EmailLoginRequest logs in to the account owning email (provisioned at the
// request step), verifying the confirm-code.
table EmailLoginRequest {
  email:string;
  code:string;
}

// Session is the minted credential returned by every auth operation.
table Session {
  token:string;
  user_id:string;
  is_guest:bool;
  display_name:string;
}

// Ack is a simple success acknowledgement (e.g. an email-code request).
table Ack {
  ok:bool;
}

// --- advertising banner ---

// BannerCampaign is one campaign in the rotation feed: a GCD-reduced show weight
// (the client runs a smooth weighted round-robin over campaigns by this weight)
// and its messages in display order, each already resolved to the viewer's bot
// language (the stored en/ru pair is picked server-side).
table BannerCampaign {
  weight:int;
  messages:[string];
}

// BannerInfo is the advertising-banner block of an eligible viewer's profile: the
// campaigns to rotate and the global display timings the client rotator reads.
// It is present (set on Profile.banner) only when the viewer is eligible to see a
// banner; absent otherwise. The transition between messages is fade_out_ms, then
// gap_ms, then fade_in_ms.
table BannerInfo {
  campaigns:[BannerCampaign];
  hold_ms:int;
  edge_pause_ms:int;
  scroll_px_per_sec:int;
  fade_out_ms:int;
  gap_ms:int;
  fade_in_ms:int;
}

// --- profile (authenticated) ---

// Profile is the authenticated account's own profile view. away_start/away_end are
// the "HH:MM" daily away-window bounds. notifications_in_app_only (default true)
// suppresses out-of-app platform push, leaving only the in-app live stream. banner
// carries the advertising-banner block for an eligible viewer, absent otherwise
// (all added trailing — backward-compatible).
table Profile {
  user_id:string;
  display_name:string;
  preferred_language:string;
  time_zone:string;
  hint_balance:int;
  block_chat:bool;
  block_friend_requests:bool;
  is_guest:bool;
  away_start:string;
  away_end:string;
  notifications_in_app_only:bool = true;
  banner:BannerInfo;
  // variant_preferences is the set of game variants the player allows themselves to be
  // matched into (engine.Variant labels), Erudit-first; the New Game picker is gated by it.
  variant_preferences:[string];
}

// BlockStatus reports the caller's current manual block. The UI fetches it after any operation
// returns the "account_blocked" result code, then replaces every screen with the terminal blocked
// screen and stops all push/poll. permanent is false for a temporary block; until is an RFC3339
// UTC instant for a temporary block and empty for a permanent one; reason is the operator-set text
// resolved to the account's language, empty when none was cited.
table BlockStatus {
  blocked:bool;
  permanent:bool;
  until:string;
  reason:string;
}

// --- game (authenticated) ---

// SubmitPlayRequest places tiles on the player's turn; the backend infers the play's
// orientation from the tiles and the board. tiles are addressed by alphabet index.
table SubmitPlayRequest {
  game_id:string;
  tiles:[PlayTile];
}

// MoveResult is the outcome of a committed move: the move and the post-move game. rack and
// bag_len carry the actor's own post-move private state — their refilled rack (alphabet indices,
// a blank is the sentinel index 255) and the bag size after drawing — so the mover
// renders the next state straight from this response without a follow-up game.state (added
// trailing — backward-compatible).
table MoveResult {
  move:MoveRecord;
  game:GameView;
  rack:[ubyte];
  bag_len:int;
}

// StateRequest asks for the requesting player's view of a game. include_alphabet asks the
// backend to embed the variant's AlphabetEntry table in the reply; the client
// sets it only on a per-variant cache miss so the table is not resent on every poll.
table StateRequest {
  game_id:string;
  include_alphabet:bool = false;
}

// StateView is a player's view of a game: the shared summary plus their private rack, the
// bag size and their remaining hint budget. rack carries alphabet indices; a
// blank tile is the sentinel index 255. alphabet is present only when the request set
// include_alphabet (a display table the client caches per variant).
table StateView {
  game:GameView;
  seat:int;
  rack:[ubyte];
  bag_len:int;
  hints_remaining:int;
  alphabet:[AlphabetEntry];
  // wallet_balance is the requesting player's global hint-wallet balance, sent apart from
  // hints_remaining (which folds the wallet in with the per-game allowance) so the client can
  // separate the two: the per-game allowance remaining is hints_remaining - wallet_balance, and
  // the wallet is a single global figure the client keeps live across games (added trailing —
  // backward-compatible).
  wallet_balance:int;
}

// GameActionRequest carries just a game id (pass / resign / hint / history).
table GameActionRequest {
  game_id:string;
}

// ExchangeRequest swaps the listed rack tiles back into the bag. tiles are alphabet
// indices; a blank is the sentinel index 255.
table ExchangeRequest {
  game_id:string;
  tiles:[ubyte];
}

// EvalRequest previews a tentative play without committing it. tiles are addressed by
// alphabet index; the backend infers the play's orientation from the tiles and the board.
table EvalRequest {
  game_id:string;
  tiles:[PlayTile];
}

// EvalResult is an unlimited move preview: legality, score, the words formed (main word
// first) and the orientation the backend inferred (dir is "H"/"V", empty when illegal).
table EvalResult {
  legal:bool;
  score:int;
  words:[string];
  dir:string;
}

// CheckWordRequest looks a word up in the game's pinned dictionary. word is a sequence of
// alphabet indices; the client constrains input to the variant's alphabet.
table CheckWordRequest {
  game_id:string;
  word:[ubyte];
}

// WordCheckResult is the dictionary lookup outcome.
table WordCheckResult {
  word:string;
  legal:bool;
}

// ComplaintRequest disputes a word-check result.
table ComplaintRequest {
  game_id:string;
  word:string;
  note:string;
}

// HintResult is the top-ranked move plus the remaining hint budget. wallet_balance is the
// global hint-wallet balance after spending (see StateView.wallet_balance), so the client
// refreshes its live wallet and re-derives the per-game allowance (added trailing —
// backward-compatible).
table HintResult {
  move:MoveRecord;
  hints_remaining:int;
  wallet_balance:int;
}

// DraftRequest saves the player's client-side composition for a game: a single
// JSON string of {rack_order, board_tiles} the client serializes itself, so the wire carries
// no tile array. The gateway forwards json verbatim to the backend, which owns its shape.
table DraftRequest {
  game_id:string;
  json:string;
}

// DraftView returns the player's stored composition as the same opaque JSON string (empty
// when none is stored). A draft get reuses GameActionRequest for its game id.
table DraftView {
  json:string;
}

// History is a game's decoded move journal — the source for client board replay.
table History {
  game_id:string;
  moves:[MoveRecord];
}

// GameList is the caller's games (active and finished) for the lobby. at_game_limit is
// true when the caller has reached the simultaneous quick-game cap, so the lobby
// disables "New Game" and shows a notice.
table GameList {
  games:[GameView];
  at_game_limit:bool;
}

// --- lobby (authenticated) ---

// EnqueueRequest starts a quick game for a variant under a per-turn word rule.
// multiple_words_per_turn true is standard Scrabble; false is the single-word rule.
// vs_ai true starts an honest-AI game against a robot instead of human auto-match.
table EnqueueRequest {
  variant:string;
  multiple_words_per_turn:bool;
  vs_ai:bool;
}

// MatchResult reports whether the caller has been paired into a game yet.
table MatchResult {
  matched:bool;
  game:GameView;
}

// --- chat (authenticated) ---

// ChatPostRequest posts a per-game chat message.
table ChatPostRequest {
  game_id:string;
  body:string;
}

// ChatMessage is one stored chat message or nudge.
table ChatMessage {
  id:string;
  game_id:string;
  sender_id:string;
  kind:string;
  body:string;
  created_at_unix:long;
}

// ChatList is a game's chat history.
table ChatList {
  messages:[ChatMessage];
}

// --- feedback (authenticated) ---

// FeedbackSubmitRequest submits a feedback message with an optional single
// attachment. attachment is the raw file bytes (empty for none); attachment_name
// carries the original file name (its extension keys the allow-list); channel is
// the submitting platform (telegram/ios/android/web). The response is an Ack.
table FeedbackSubmitRequest {
  body:string;
  attachment:[ubyte];
  attachment_name:string;
  channel:string;
  version:string;
  browser_tz:string;
}

// FeedbackReply is the operator's answer shown back to the player.
table FeedbackReply {
  body:string;
  replied_at_unix:long;
}

// FeedbackState is the player's feedback screen state. blocked_reason is "" (can
// send), "pending" or "banned"; reply is null when there is none to show. Fetching
// it (feedback.get) delivers any pending reply, clearing the badge.
table FeedbackState {
  can_send:bool;
  blocked_reason:string;
  reply:FeedbackReply;
}

// FeedbackUnread reports whether the player has an undelivered operator reply, for
// the lobby/Info badge (feedback.unread; no side effect).
table FeedbackUnread {
  reply_unread:bool;
}

// --- account, statistics, friends, blocks, invitations, history ---

// AccountRef is a referenced account with its display name resolved — the shared
// shape for friends, blocked users and invitation participants.
table AccountRef {
  account_id:string;
  display_name:string;
}

// UpdateProfileRequest overwrites the full editable profile (the client sends the
// complete desired profile). away_start/away_end are "HH:MM" bounds.
// notifications_in_app_only (trailing — backward-compatible) toggles out-of-app
// platform push off when set.
table UpdateProfileRequest {
  display_name:string;
  preferred_language:string;
  time_zone:string;
  away_start:string;
  away_end:string;
  block_chat:bool;
  block_friend_requests:bool;
  notifications_in_app_only:bool = true;
  variant_preferences:[string];
}

// --- account linking & merge (authenticated) ---

// LinkEmailRequest mails a confirm-code to email for a later link or merge. The
// code is always sent (no pre-send "taken" signal), so a probe cannot enumerate
// registered addresses.
table LinkEmailRequest {
  email:string;
}

// LinkEmailConfirm carries the email and its confirm code, for both the confirm
// (preview) and the explicit merge step.
table LinkEmailConfirm {
  email:string;
  code:string;
}

// LinkTelegramRequest carries Telegram Login Widget data (a URL query string) for
// attaching a Telegram identity to the current account.
table LinkTelegramRequest {
  data:string;
}

// LinkResult is the unified result of a confirm or merge step. status is "linked"
// (bound to the caller), "merge_required" (the identity belongs to another account —
// the secondary_* fields summarise it for the irreversible confirmation), or
// "merged" (done). session is present only when the active account switched (a guest
// initiator whose durable counterpart won) — the client adopts it.
table LinkResult {
  status:string;
  secondary_user_id:string;
  secondary_display_name:string;
  secondary_games:int;
  secondary_friends:int;
  session:Session;
}

// BestMoveTile is one letter cell of a best-move word: its concrete letter (the designated
// letter for a blank), its tile point value (0 for a blank) and whether it is a blank. It
// lets the client render the word as game tiles without the variant's alphabet table.
table BestMoveTile {
  letter:string;
  value:int;
  blank:bool;
}

// BestMoveView is an account's highest-scoring single play within one game variant: the
// variant label, the play's total score (matching max_word_points for that variant) and its
// main word as ordered tiles.
table BestMoveView {
  variant:string;
  score:int;
  word:[BestMoveTile];
}

// StatsView is a durable account's lifetime statistics (games-played and win-rate
// are derived client-side). best_moves breaks the best move down per variant, carrying the
// word itself; it is empty for an account with no recorded play and lists only variants the
// account has played (added trailing — backward-compatible).
table StatsView {
  wins:int;
  losses:int;
  draws:int;
  max_game_points:int;
  max_word_points:int;
  best_moves:[BestMoveView];
  // moves is the player's lifetime play count (tile placements); hints_used is their lifetime
  // hint count. The screen shows the hint share = hints_used / moves (added trailing).
  moves:int;
  hints_used:int;
}

// TargetRequest names a single counterpart account (friend request/cancel/unfriend,
// block/unblock). game_id is set only by an in-game block of a disguised-robot opponent,
// so the backend can record the per-game robot block (the seat name the player saw)
// against that game; every other path leaves it empty (FlatBuffers-optional).
table TargetRequest {
  account_id:string;
  game_id:string;
}

// FriendRespondRequest accepts or declines a pending request from a requester.
table FriendRespondRequest {
  requester_id:string;
  accept:bool;
}

// FriendList is the caller's accepted friends.
table FriendList {
  friends:[AccountRef];
}

// IncomingRequestList is the friend requests awaiting the caller's response.
table IncomingRequestList {
  requests:[AccountRef];
}

// RobotFriendRef is one per-game friend request to a disguised-robot opponent: a
// per-game record (not a real account) carrying the game name the player saw and the
// game/seat it was sent in, so the in-game card can re-mark that seat as already
// requested. Its id is the robot_friend_requests row.
table RobotFriendRef {
  id:string;
  display_name:string;
  game_id:string;
  seat:int;
}

// OutgoingRequestList is the accounts the caller has already requested and cannot
// (re-)request: a live pending request or one the addressee declined. The game's
// "add to friends" item reads it to stay disabled across reloads. robots are the
// per-game disguised-robot requests (not real accounts), added trailing.
table OutgoingRequestList {
  requests:[AccountRef];
  robots:[RobotFriendRef];
}

// FriendCode is a freshly issued one-time add-a-friend code (returned once).
table FriendCode {
  code:string;
  expires_at_unix:long;
}

// RedeemCodeRequest redeems a friend code, befriending its issuer.
table RedeemCodeRequest {
  code:string;
}

// RedeemResult reports the new friend gained by redeeming a code.
table RedeemResult {
  friend:AccountRef;
}

// RobotBlockRef is one blocked disguised-robot opponent: a per-game record (not a real
// account) carrying the game name the player saw and the game/seat it was blocked in, so
// the blocked list shows it as a distinct personality and the in-game card can re-mark
// that seat. Its id is the robot_blocks row, used to unblock it.
table RobotBlockRef {
  id:string;
  display_name:string;
  game_id:string;
  seat:int;
}

// BlockList is the accounts the caller has blocked, plus the per-game disguised-robot
// blocks (robots) which are not real accounts.
table BlockList {
  blocked:[AccountRef];
  robots:[RobotBlockRef];
}

// InvitationInvitee is one invitee's seat and response, name resolved.
table InvitationInvitee {
  account_id:string;
  display_name:string;
  seat:int;
  response:string;
}

// Invitation is a friend-game invitation with its settings and invitees.
table Invitation {
  id:string;
  inviter:AccountRef;
  invitees:[InvitationInvitee];
  variant:string;
  turn_timeout_secs:int;
  hints_allowed:bool;
  hints_per_player:int;
  multiple_words_per_turn:bool;
  dropout_tiles:string;
  status:string;
  game_id:string;
  expires_at_unix:long;
}

// CreateInvitationRequest proposes a 2-4 player friend game to the named invitees.
table CreateInvitationRequest {
  invitee_ids:[string];
  variant:string;
  turn_timeout_secs:int;
  hints_allowed:bool;
  hints_per_player:int;
  dropout_tiles:string;
  multiple_words_per_turn:bool;
}

// InvitationActionRequest accepts / declines / cancels an invitation by id.
table InvitationActionRequest {
  invitation_id:string;
}

// InvitationList is the caller's open invitations.
table InvitationList {
  invitations:[Invitation];
}

// GcgExport is a finished game's GCG transcript: a suggested filename and the text.
table GcgExport {
  game_id:string;
  filename:string;
  content:string;
}

// ExportUrlRequest asks for a signed download URL of a finished game's export artifact.
// kind is "png" or "gcg". For the PNG the client passes its presentation context — the
// UI-localized non-play move labels (pass, exchange, resign, timeout, in that order),
// the device date locale and the device IANA time zone — which ride the signed URL so
// the server render matches what the player would have seen locally.
table ExportUrlRequest {
  game_id:string;
  kind:string;
  date_locale:string;
  action_labels:[string];
  time_zone:string;
}

// ExportUrl is the minted download link: a relative, signed, short-lived path the client
// resolves against its own origin (the SPA and the gateway share it), plus the filename
// the download will carry.
table ExportUrl {
  path:string;
  filename:string;
}

// --- push event payloads ---

// YourTurnEvent signals that it is now the recipient's turn. The trailing fields enrich the
// out-of-app push: opponent_name is the player who just moved, last_action is their
// move kind ("play"/"pass"/"exchange"/...), last_word is the main word of a scoring play (empty
// otherwise), and score_line is the recipient-first running score (e.g. "120:95:80"). They are
// appended (FlatBuffers-optional), so an older reader that only needs game_id/deadline is unaffected.
// move_count is the post-move count (matching the opponent_moved GameView): the client uses it to
// tell whether its cached game already reflects the move, falling back to a refetch on a gap.
table YourTurnEvent {
  game_id:string;
  deadline_unix:long;
  opponent_name:string;
  last_action:string;
  last_word:string;
  score_line:string;
  move_count:int;
}

// GameOverEvent signals that a game the recipient is seated in has finished, driving the
// out-of-app "game over" push. result is the outcome from the recipient's own
// perspective ("won"/"lost"/"draw"); score_line is the recipient-first final score. game is the
// final post-game summary (adjusted scores after rack penalties + the winner flag), so the client
// settles the finished game from the event without a refetch (added trailing).
table GameOverEvent {
  game_id:string;
  result:string;
  score_line:string;
  game:GameView;
}

// OpponentMovedEvent carries a move another seat just committed as a delta the client applies to
// its cached game without a refetch: move is the decoded play/pass/exchange (the same record
// game.history returns), game is the post-move summary (per-seat scores, to_move, move_count,
// status) and bag_len is the bag size after the draw.
table OpponentMovedEvent {
  game_id:string;
  move:MoveRecord;
  game:GameView;
  bag_len:int;
}

// NudgeEvent signals that a player nudged the recipient. sender_name is the nudger's seat
// display-name snapshot, so the toast and the out-of-app push can name them (added trailing —
// an older reader still reads just game_id + from_user_id, and falls back to the plain phrase).
table NudgeEvent {
  game_id:string;
  from_user_id:string;
  sender_name:string;
}

// MatchFoundEvent signals that an auto-match pairing (or robot substitution) started a game the
// recipient is seated in. state is the recipient's full initial view of the new game (empty board,
// dealt rack), so the client navigates straight in from the event with no follow-up fetch (added
// trailing — an older reader still reads just game_id).
table MatchFoundEvent {
  game_id:string;
  state:StateView;
}

// NotificationEvent is a lightweight "something changed, re-poll" signal that
// drives the lobby badge (incoming friend requests, invitations). kind is a sub-
// discriminator ("friend_request", "friend_added", "friend_declined", "invitation",
// "game_started"); the client re-fetches its lobby counters (and, for a requester
// watching a game, its friend state) on any of them. To let the client update its lobby without a
// follow-up fetch, each event also carries the payload its kind changed: account for the
// friend_* kinds (the requester/friend), invitation for "invitation" (the new invitation) and
// state for "game_started" (the started game's initial view, like match_found). Only the field
// matching kind is set (all added trailing — backward-compatible).
table NotificationEvent {
  kind:string;
  account:AccountRef;
  invitation:Invitation;
  state:StateView;
}