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Scrabble Game — implementation plan

Living plan and stage tracker. Each stage is implemented in its own session; the rules for starting and finishing a stage are in CLAUDE.md. The architecture/decision record is docs/ARCHITECTURE.md; behaviour is docs/FUNCTIONAL.md. When a stage produces a decision, bake it back here and into the affected docs/code in the same PR.

Context

Greenfield multiplatform Scrabble. Players arrive from a platform (Telegram first; later VK/MAX/iOS/Android) or standalone web (email / guest). Three executables — gateway, backend, ui — plus per-platform side-services. Deliberately simpler than the sibling ../galaxy-game (idea donor, not a template). The ../scrabble-solver engine is embedded in-process as a library.

Locked decisions (recap — full record in docs/ARCHITECTURE.md)

Stack: go.work monorepo, modules scrabble/<name>, Go 1.26.x, backend gin+pgx+Postgres(schema backend)+goose+zap+OTel (deps added when first used). Wire: Connect-RPC + FlatBuffers (client↔gateway), REST/JSON + X-User-ID (gateway↔backend), gRPC server-stream for live events. Auth: platform-native, thin opaque session token, no Ed25519/signing, likely no Redis. UI: pure HTML5/CSS, plain Svelte + Vite, Capacitor for native. MVP surfaces: Telegram + web (email + ephemeral guest) + link/merge. Variants: ru/en/Эрудит. Legality: validate-at-submit. End: empty bag+rack / 6 scoreless / 24h timeout. Hint: top-1. Word-check: unlimited + complaint. Robot: P(win)≈0.40, margin targeting, [2,90]min skewed timing, sleep 00:0007:00 opp-tz, nudge logic. Dictionary: pin per game. History: structured + GCG export, dictionary- independent (see ARCHITECTURE §9.1).

Stage tracker

# Stage Status
0 Scaffolding (go.work, backend skeleton, docs, CI) done
1 Backend foundation (config, server, Postgres+goose, sessions, accounts) done
2 Engine package over scrabble-solver done
3 Game domain (lifecycle, rules, hint, word-check, history+GCG, stats) done
4 Lobby & social (matchmaking, friends, block, chat, profile, nudge) done
5 Robot opponent done
6 Gateway edge (Connect/FB, platform auth, sessions, push bridge, admin) done
7 UI — playable slice + UX polish (Svelte+Vite, board, lobby, chat, hint/word-check, i18n) done
8 UI — social/account/history (friends, blocks, invitations, profile edit, stats, history/GCG) done
9 Telegram integration (bot side-service, deep-link, push) done
10 Admin & dictionary ops (complaint review, version reload) done
11 Account linking & merge done
12 Observability & performance (telemetry, metrics, guest GC) done
13 Alphabet on the wire (UI alphabet-agnostic) todo
14 CI & deploy (multi-service, dictionary artifacts) todo

Scaffolding is incremental: go.work lists only existing modules; each stage adds the modules it needs.

Stages

Each stage: read this plan + relevant docs, interview the owner on the open details below, implement within scope, then update plan/docs/code and get CI green before marking done.

Stage 0 — Scaffolding (done)

Scope: go.work (Go 1.26.3, use ./backend); minimal runnable backend (gin, zap, /healthz, /readyz, env config); docs skeleton; PLAN.md; CLAUDE.md; .gitea/workflows/go-unit.yaml; README; .gitignore. Acceptance: go build ./backend/... + go vet + gofmt clean + go test ./backend/... green; CI green on push.

Stage 1 — Backend foundation

Scope: config/server route groups (/api/v1/{public,user,internal,admin}, probes), Postgres (pgx) + embedded goose migrations + schema backend, telemetry (OTel) wiring, in-memory cache scaffolding, thin sessions + accounts + platform identities. Open details: Postgres version + DSN/search_path convention; jet vs sqlc/sqlx (default jet); migration naming; exact session-token shape (opaque random length, TTL, revocation); account/identity table shape; whether the admin bootstrap lands here or in Stage 10.

Stage 2 — Engine package

Scope: backend/internal/engine over scrabble-solver — versioned DAWG load/registry, GenerateMoves/ValidatePlay/ScorePlay wrappers, bag/rack, the dictionary-independent game-state model + decode helpers. Add replace scrabble-solver => ../scrabble-solver to go.work here and solve the CI sibling-checkout (clone gitea.iliadenisov.ru/.../scrabble-solver). Open details: how CI obtains the solver (clone sibling vs publish/tag the solver module); in-memory game-state representation; how blanks and exchanges are modelled; Эрудит specifics to verify against the solver.

Stage 3 — Game domain

Scope: create/join, turn order, submit play/pass/exchange/resign, validate-at-submit, scoring, end-conditions, 24h timeout/auto-resign, hint, word-check + complaint capture, structured history + GCG writer, stats on finish. Open details: GCG dialect details (blanks, exchanges, notation); exact stats edge cases; turn-timeout scheduler mechanism (cron vs per-game timer); complaint payload shape.

Stage 4 — Lobby & social

Scope: matchmaking pool, friends, block, per-game chat, profile + email confirm-code, nudge. Open details: pool fairness/keying confirmation; deep-link format per platform; chat length limit + retention; friend-request lifecycle; email-code provider (SMTP relay choice).

Stage 5 — Robot opponent

Scope: human-like player — balance ~0.40, margin targeting, skewed [2,90]min timing + sleep + nudge logic, friend/DM blocking, name pool. Open details: exact delay distribution + parameters; margin band; name pool source; how the scheduler drives robot moves; metrics for tuning balance.

Stage 6 — Gateway edge

Scope: Connect/gRPC-Web (h2c), Telegram initData validation → session → X-User-ID, in-memory rate-limit, admin Basic-Auth passthrough, FlatBuffers transcoding, in-app push stream bridging backend push gRPC stream, email + ephemeral-guest paths. Open details: FlatBuffers schema layout + message_type catalog; rate-limit classes/limits; admin surface routing; session cache shape at the gateway.

Stage 7 — UI

Scope: plain Svelte + Vite static; Connect-web + FlatBuffers client; lobby (my games, profile tabs); board (HTML5/CSS grid, drag-n-drop, no assets); chat; hint/word-check; in-app stream; i18n en/ru; in-memory session (+IndexedDB if available); Capacitor-ready structure. Open details: detailed game-board UX (deferred by the owner to this stage); client routing; offline/refresh behaviour; design system / theming.

Suggested layouts (lobby + game screen)

User note:

Detailed interview about UI/UX is strongly required. Too much to discuss.

     ┌────────────────────┐                   
     │ Display_Name      =│- Profile          
     ├────────────────────┤- Settings         
     │ Invitations        │- About            
     │ - list             │                   
     ├────────────────────┤                   
     │ Active games       │                   
     │ - list             │                   
     ├────────────────────┤                   
     │ Finished games     │                   
     │ - list             │                   
     │                    │                   
     │                    │                   
     │                    │                   
     │                    │                   
     │                    │                   
     │                    │                   
     │                    │                   
     ├────────────────────┤                   
     │ ┌───┐  ┌───┐  ┌───┐│                   
     │ New │  Stats  Tourn│                   
     │ └───┘  └───┘  └───┘│                   
     └────────────────────┘                   
     ┌────────────────────┐                   
Lobby│◄                 ==│- History          
     ├────────────────────┤- Chat             
     │You  Ann  Kaya  Rick│- Check word       
     │136  700   179    39│- Drop game        
     ├────────────────────┤                   
     │                    │                   
     │                    │                   
     │                    │                   
     │        c           │                   
     │      words         │                   
     │        o           │                   
     │        s           │                   
     │        s           │                   
     │                    │                   
     │                    │                   
     ├──┬──┬──┬──┬──┬──┬──┤ ┌──┐              
     │A │Q │Z │* │N │I │W │◄│  │MakeMove/Reset
     ├──┴──┴──┴──┴──┴──┴──┤ └──┘              
     │  ┌───┐ ┌───┐ ┌───┐ │                   
     │  Draw│ Skip│ Shfl│ │                   
     │  └───┘ └───┘ └───┘ │                   
     └────────────────────┘                   

Stage 8 — UI: social, account & history surfaces

Scope: the UI surfaces deferred from Stage 7's playable slice, wiring the matching backend/gateway operations as each screen needs them (the Stage 6 vertical-slice pattern): friends (request/accept/decline/list), per-user blocks, friend-game invitations (create 24 player, accept/decline, invitations list), profile editing (account.UpdateProfile + the email confirm-code binding UI), the statistics screen, and the history viewer with GCG export/download. Open details: friends/invitations UX; stats presentation; history/GCG viewer + download mechanics; any new validation the profile-editing forms need.

Stage 9 — Telegram integration

Scope: bot side-service, deep-link invites, platform push (your-turn / nudge), Mini App launch/auth; backend↔platform internal API. Open details: bot framework/library; deep-link scheme; push message templates; internal API contract; Mini App hosting/origin.

Stage 10 — Admin & dictionary ops

Scope: admin endpoints (users, games, complaint review queue, dictionary versions + reload), complaint→dictionary update pipeline. Open details: whether a server-rendered console is wanted or JSON-only; the dictionary rebuild/deploy pipeline; complaint resolution workflow.

Stage 11 — Account linking & merge

Scope: link-via-confirm; merge-into-A (stats sum, transfer games/friends, dedupe). High blast-radius — focused regression tests. Open details: conflict resolution (active games on both, duplicate friends, display-name collisions); irreversibility/audit; confirm-flow per platform.

Stage 12 — Observability & performance

Scope: wire a configurable OTLP exporter (alongside none/stdout), shared in a new pkg/telemetry; add telemetry to the gateway and the Telegram connector (providers + otelgrpc on the gRPC hops) for parity with the backend; add domain/operational metrics close to the business (game replay/validate timings, started/abandoned games, live-cache size, chat/nudge counts, the edge roundtrip, Go runtime metrics); discharge TODO-3 (abandoned-guest GC). The OTLP collector and dashboards are stood up with the deploy (Stage 14); the default exporter stays none, so CI needs no collector. Performance is operational-metric instrumentation, not speculative optimisation (the standing "evidence first" rule — no measured hotspot yet). Open details: exporter default and whether a collector is stood up now; the metric set and its attributes; the guest-reaper trigger given revoke-only sessions.

Stage 13 — Alphabet on the wire (TODO-4)

Scope: make the UI alphabet-agnostic. On game-screen load the client receives the variant's alphabet table (letter, index, value) for display only, caches it in memory by variant (a request flag gates whether the table is included, so it is not resent on every state poll); live play then exchanges letter indices both ways, and word-check sends indices, constraining input to the variant's alphabet. The engine already works in alphabet-index bytes, so the wire does less decoding in live play; the durable journal / history / GCG stay decoded concrete characters (the §9.1 dictionary-independent invariant is untouched). The alphabet comes from the solver's rules (not the DAWG), so the wire table is pinned by the solver version. Index-drift caveat: the running solver, the DAWGs (built against it — Stage 14 / TODO-2) and the wire table must agree, or letter indexing silently corrupts. Blast radius: pkg/fbs (a new Alphabet table; index fields in StateView/rack and in SubmitPlay/Exchange/check_word) → backend DTO encode/decode → UI codec.ts/premiums.ts → board/rack render, the move/exchange/word-check senders, the mock transport and the Vitest tests. Open details: the fbs shape and include_alphabet flag placement; whether to keep concrete-letter fields during the transition; whether tile exchange moves fully to indices; the premiums.ts parity-test rework.

Stage 14 — CI & deploy

Scope: the full multi-service production deploy plus the observability backend, also discharging TODO-1 and TODO-2. Backend + gateway Dockerfiles (multi-stage distroless, mirroring the Stage 9 connector image); the gateway gains static UI serving (the §13 single-origin model — mini-landing at /, Mini App under /telegram/), documented since Stage 9 but not yet implemented; prod UI build vars (VITE_TELEGRAM_BOT_ID for the Login Widget, the Mini App URL / share link); a root deploy/docker-compose.yml (backend + gateway + Postgres + connector + the OTLP collector / Grafana stack) on the external edge network behind the host caddy, the VPN sidecar only for the connector; a deploy workflow mirroring ../15-puzzle (host-mode runner, docker compose up -d --build, no external registry, env from Gitea secrets, a post-deploy probe). Stand up the OTLP collector + dashboards (the export wiring landed in Stage 12).

  • TODO-1 — publish & version the solver: tag/publish scrabble-solver, drop the go.work replace + the CI clone, pin a version in backend/go.mod (or keep cloning the sibling as the minimal-diff fallback). The DAWGs are delivered separately regardless.
  • TODO-2 — versioned dictionary artifacts: a new versioned repo for the wordlist parsers + built DAWGs, delivered as a release artifact (Gitea release / OCI / object store — not go get; DAWGs are data). One semver label vX.Y.Z for the whole set, additive: a deploy drops a new BACKEND_DICT_DIR/<version>/ subdir; engine.OpenWithVersions loads every present subdir at boot; BACKEND_DICT_VERSION selects the default for new games. A new version never breaks a running backend (each game pins its dict_version; versions are additive); only active games need a dictionary (validate-at-submit — finished games replay the dictionary-independent journal), so a version is safe to retire once no active game pins it. The dict repo must build against the same dafsa/alphabet/solver the backend runs, or letter indexing drifts (ties into Stage 13). Open details: embed-vs-mount for the UI build and the DAWG set; the OTLP collector / dashboard stack; solver-publish vs clone-in-build; load expectations.

Refinements logged during implementation

  • Stage 0: solver replace deferred to Stage 2 (nothing imports it yet; adding the path now would break CI, which checks out only this repo). Docker / compose deferred to a stage that has something to deploy. Trunk is master (owner preference); feature/* + PR from Stage 1; the genesis commit lands on master by necessity.

  • Stage 1 (interview + implementation):

    • Query layer: go-jet over database/sql (pgx stdlib) + otelsql; a cmd/jetgen tool regenerates the committed code from a throwaway container. Postgres 17 pinned for jetgen, tests and prod.
    • Sessions: opaque token stored only as a SHA-256 hash (kept as hex text, not bytea — avoids jet bytea-literal friction), revoke-only (no TTL); revocation-audit table deferred. Backend keeps a warmed write-through session cache that gates /readyz.
    • Data model: UUIDv7 PKs; one unified identities table (kind ∈ telegram|email, widen to vk/max later); no soft-delete / actor-audit columns yet.
    • HTTP surface: service/store/cache layer only. /api/v1/{public,user, internal,admin} groups + X-User-ID middleware are scaffolding (exposed via Server group accessors); the session/account REST handlers land with the gateway in Stage 6. Admin bootstrap deferred to Stage 10.
    • Telemetry: providers + request-timing middleware + otelsql; exporters none (default) / stdout; OTLP + dashboards deferred to Stage 12.
    • Tests/CI: integration tests behind the integration build tag in backend/internal/inttest + new integration.yaml (testcontainers, Ryuk off, serial), firing on push and PR. Backend now hard-depends on Postgres at boot (migrations at startup) — a deliberate contract change from Stage 0, documented in both READMEs. All code stays in the existing backend module under internal/ (+ cmd/jetgen); go.work untouched.
  • Stage 2 (interview + implementation):

    • Scope: internal/engine is a self-contained library (registry, bag, Game state machine, decode/replay). No config/main/server wiring this stage — there is no consumer yet; wiring lands in Stage 3, mirroring Stage 1's deferred handlers.
    • Pure rules engine (interview): the engine owns the in-memory Game, pure transitions (play/pass/exchange/resign + draw) and end-condition detection, including the standard end-game rack-adjustment scoring — a deliberate slice of Stage 3's "scoring/end-conditions" that the pure-engine boundary implies. Stage 3 keeps scheduling, the 24h timeout, persistence and GCG.
    • Solver wiring: replace scrabble-solver => ../scrabble-solver in go.work; backend/go.mod requires scrabble-solver (placeholder version, redirected by the replace) and github.com/iliadenisov/dafsa directly (for dawg.Load). CI clones the public solver repo at master HEAD anonymously into ../scrabble-solver (no token); both Go workflows gained the step (the engine's untagged tests run under the integration workflow too) and set BACKEND_DICT_DIR.
    • Dictionaries: registry loads the committed DAWGs from a directory parameter; dict_version is an explicit string label; the latest version per variant is tracked. Smoke tests validate a known word per variant (English/Russian/Эрудит). Эрудит is handled uniformly — every real difference is already in rules.Erudit(); the move.go "single orientation per turn" note needs no special code (any single play is one-directional).
    • Bag/blanks/exchange: own deterministic Bag (Draw + Return) because selfplay.Bag cannot return tiles; exchange is legal only when the bag holds at least a rack and draws replacements before returning the swapped tiles. A blank is Placement{Blank:true} carrying its designated letter; the history keeps the concrete letter plus a blank flag (decoded via Alphabet.Character / Decode). ReplayBoard reuses scrabble.Apply, so no internal/encoding dependency.
    • Deviation from the approved plan: docs/FUNCTIONAL.md (+_ru) was left unchanged. Stage 2 adds no user-visible behaviour; the variant, per-game dictionary and dictionary-independent-history user stories already live in Stages 34, so a "light touch" here would have duplicated or pre-empted them.
  • Stage 3 (interview + implementation):

    • Scope, as in Stages 12: domain service/store layer + engine wiring, no HTTP (internal/game). The gateway↔backend REST surface lands in Stage 6; the only active driver this stage is a background turn-timeout sweeper started from main. The robot (Stage 5) will consume the same service API.
    • Persistence = event-sourcing + warm cache (interview): durable state is the games row plus an append-only decoded move journal (game_moves); the live position is an engine.Game kept in an in-memory cache with a ~24h idle TTL and rebuilt by replaying the journal on a miss (the seeded bag makes replay exact). Each game is serialised by a per-game mutex; a persistence failure evicts the live game so the next access rebuilds. §9 reworded from "stored structurally" to this model.
    • Resign/timeout split (interview): 2-player resign/timeout only this stage (the other player wins); multiplayer drop-out-and-continue + resigned-tiles disposition deferred to Stage 4. Per-game turn-timeout duration setting (5/10/15/30 min, 1/2/3/6/12/24 h; default 24 h) and a per-user away window (accounts.away_start/away_end, default 00:0007:00 local, honoured by the sweeper with midnight-cross handling) added now; profile editing of the away window is Stage 4 and the robot's sleep (Stage 5) reuses it.
    • Engine Resign fix (interview, in internal/engine): the resigner keeps their accumulated score (no end-game rack adjustment) and never wins; winner excludes the resigner, so a two-player resign/timeout gives the win to the other player regardless of score. Timeout reuses Resign, so the game domain needs no winner override.
    • Additive engine domain API: Direction, Game.SubmitPlay/SubmitExchange/ EvaluatePlay/HintView/Hand, MoveRecord.{Dir,MainRow,MainCol}, Registry.Lookup, ParseVariant — so internal/game never imports scrabble-solver (keeps the §5 single-importer invariant).
    • Create = atomic with seats (interview): Create seats all accounts and starts; lobby seat-filling is Stage 4. Sweeper = periodic goroutine (interview; default 60 s, BACKEND_GAME_TIMEOUT_SWEEP_INTERVAL).
    • Hint = settings + wallet (interview): per-game hints_allowed + hints_per_player, plus a profile wallet accounts.hint_balance (spent after the allowance; purchases later). Category defaults (random 1 / tournament 0 / friendly 1-or-0) are the caller's job (lobby/tournaments).
    • Stats (interview): account_stats with draws added beyond §9's wins/losses; max_word_points = best single move score; ties draw, resign/timeout is a loss, guests get no stats.
    • Complaint (interview): full payload with game_id; word-check is scoped to the game's pinned (variant, dict_version). Stage 10 owns the resolution lifecycle, so the status column carries no value CHECK yet.
    • GCG (interview): standard Poslfit dialect (UTF-8, #player/#lexicon pragmas, 8G/H8 coordinates, lower-case blanks, . pass-throughs, -TILES exchange) plus #note lines for resign/timeout; derived from the journal, so dictionary-independent.
    • Engine wiring + config: main loads the registry (engine.Open, a hard boot dependency like migrations) and starts the sweeper. New config: BACKEND_DICT_DIR (required), BACKEND_DICT_VERSION (default v1), BACKEND_GAME_TIMEOUT_SWEEP_INTERVAL (60 s), BACKEND_GAME_CACHE_TTL (24 h). No CI change — both Go workflows already clone the solver sibling and export BACKEND_DICT_DIR. accounts gained away_start/away_end/hint_balance and the account package gained SpendHint (it owns its table).
  • Stage 4 (interview + implementation):

    • Scope, as in Stages 13: domain service/store layer, no HTTP — REST/stream is Stage 6. Chat and nudges are persisted now; live delivery (push / in-app stream) is Stage 6/8. New packages internal/social (friends, blocks, chat+nudge) and internal/lobby (matchmaking + invitations); profile editing and the email confirm-code extend internal/account. The services have no active driver this stage, so main builds them and hands them to the server, which exposes them via accessors (the Stage 1 scaffolding-accessor pattern) for the Stage 6 handlers.
    • Friends (interview): request → accept on a single friendships table; decline/cancel delete the pending row; blocking severs any friendship.
    • Blocks (interview): the existing global toggles plus a per-user blocks table; block effects are mutual (a block either way suppresses chat visibility and prevents requests/invitations between the pair).
    • Friend games (interview): invitation → accept; the game starts only when all invitees accept, any decline cancels it, and a pending invitation lazily expires after 7 days (checked on access — no new sweeper).
    • Chat (interview): ≤ 60 runes, stored with the game forever, the sender IP kept for moderation (as text, following Stage 1's no-bytea precedent; the gateway forwards it in Stage 6), input content-filtered (links/emails/phone numbers incl. obfuscated forms) via mvdan.cc/xurls/v2 plus a compact leet/separator normaliser and a ≥7-digit phone heuristic — the one new dependency. Nudge is a chat message (kind='nudge'), rate-limited to once per hour per game per sender.
    • Matchmaking (interview): an in-memory FIFO pool keyed by variant only (variant fixes the board language), pairing two humans (seat order randomised). The 10 s wait and robot substitution are deferred to Stage 5. The pool does not consult blocks (auto-match is anonymous) — a deliberate simplification of the plan's optional block-skip that also avoids a DB call under the pool lock.
    • Email confirm-code (interview): 6-digit code, 15-min TTL, ≤ 5 attempts, stored as a SHA-256 hash; a Mailer seam with an SMTP relay (BACKEND_SMTP_*) and a default log mailer. It binds an email to the current account; an email already confirmed by another account → ErrEmailTaken (merge is Stage 11); email-as-login is Stage 6 and reuses this mechanism.
    • Multi-player drop-out (interview; discharges the Stage 3 deferral): the engine's Resign now drops a seat and the rest play on while ≥ 2 are active, finishing (last-survivor wins) when one remains; winner excludes all resigned seats. A per-game dropout_tiles setting (remove default | return) governs the leaver's rack, which is never revealed to the others. Timeout reuses Resign, so a multi-player timeout drops one seat and play continues; game.commit/timeoutGame were already keyed on g.Over(), so they only needed the setting threaded through create/replay.
    • Build/deps: go mod tidy is not run — the bare-path scrabble-solver replace lives only in go.work, so tidy/go get cannot resolve it; the xurls dependency was added with go mod edit -require + go mod download, its checksums recorded in the committed go.work.sum. No CI workflow change (both Go workflows already clone the solver sibling and export BACKEND_DICT_DIR).
  • Stage 5 (interview + implementation):

    • Scope, as in Stages 14: domain layer, no HTTP — the robot consumes the public game API as an ordinary seated player (internal/robot), so only internal/engine still imports the solver. New: engine.Candidates() (decoded ranked plays) and a thin game.Service.Candidates + RobotTurns read.
    • Account model (interview): a pool of durable accounts, each a single identities row kind='robot' (migration 00004 widens the kind CHECK — a CHECK-only change, no jetgen). A curated ~16-name pool in code; EnsurePool provisions them idempotently at boot (a hard dependency, like the registry) with block_chat/block_friend_requests set, which is all the friend/DM blocking needs (no special-casing).
    • Driver + state (interview): a background sweeper goroutine (robot.Service.Run/Drive, mirroring the timeout sweeper); every per-game and per-turn choice is derived deterministically from the game seed (FNV-1a mix, restart-stable — not hash/maphash), so the robot keeps no extra state. playToWin = mix(seed,"win")%100 < 40; per-turn delay; sleep drift.
    • Timing (interview): per-move delay 2 + 88·u^k minutes, u~U(0,1), k≈3.5 → median ~10 min, clamped to [2,90]. A daytime nudge on the robot's turn pulls the move into a 210 min reply window; the robot proactively nudges after 12 h idle on the human's turn (reusing social.Nudge's once-per-hour guard; social.LastNudgeAt added to detect the human's nudge).
    • Sleep (interview — resolves the §7-vs-account.go mismatch): the robot sleeps 00:0007:00 in the opponent's timezone shifted by a per-game drift ∈ [3,+3]h (so its night overlaps the human's rather than running anti-phase), computed on the fly per game — no profile mutation, no concurrency cap. The account.go away-window comment was corrected accordingly.
    • Margin (interview): pick the candidate whose resulting margin (own+moveopp) is closest to [1,30] when playing to win / [30,1] when playing to lose, tie-broken toward the conservative edge; no legal play → exchange the full rack when the bag can refill it, else pass.
    • Substitution (interview): a matchmaker reaper (Reap/RunReaper) substitutes a pooled robot after a 10 s wait (BACKEND_LOBBY_ROBOT_WAIT), NewMatchmaker now takes a RobotProvider. A waiter learns of a match — human pairing or substitution — through a new Poll + results map; production delivery is a match-found notification (session/in-app push + side-service), Stage 6/8 — noted in §10.
    • Metrics (interview, 1+2): robots are durable accounts, so account_stats is the authoritative, complete balance ground-truth (target ~40% robot wins); an OTel counter (robot_games_finished_total, exporter none today) and a structured log cover robot-finished games for live observation.
    • Config: BACKEND_ROBOT_DRIVE_INTERVAL (30 s), BACKEND_LOBBY_ROBOT_WAIT (10 s), BACKEND_LOBBY_REAPER_INTERVAL (1 s). No CI change (both Go workflows already clone the solver sibling and export BACKEND_DICT_DIR).
  • Stage 6 (interview + implementation):

    • Scope = framework + vertical slice (interview): the whole edge mechanism is built and the backend's REST surface + the live-event seam are opened for the first time, but only a representative slice of operations is wired end-to-end — auth (auth.telegram/auth.guest/auth.email.request/ auth.email.login), profile.get, game.submit_play/game.state, lobby.enqueue/lobby.poll, chat.post, all five push events, and the admin passthrough. The remaining domain operations reuse the identical transcode pattern and are wired as the UI needs them: the play-loop ops (pass/exchange/ resign, hint, evaluate, word-check/complaint, history, my-games list, chat list/nudge) in Stage 7; the social/account ops (friends, blocks, invitations, profile editing, stats, GCG export) in Stage 8.
    • Wire contracts in a new shared scrabble/pkg module (interview): the backend push proto (pkg/proto/push/v1) and the FlatBuffers edge payloads (pkg/fbs, one scrabblefb namespace) live here with committed generated Go, imported by both backend and gateway. The Connect envelope proto lives in gateway/proto/edge/v1. Codegen is dev-time (buf generate with local plugins + flatc, driven by per-module Makefiles, mirroring cmd/jetgen); CI only builds the committed output. pkg and gateway are bare-path modules like scrabble-solver, so go.work carries use ./pkg, use ./gateway and a replace scrabble/pkg v0.0.0 => ./pkg (the no-dot path is not VCS-fetchable); deps were added with go mod edit + go work sync (the established no-tidy pattern). flatc is pinned to 23.5.26 to match the flatbuffers Go runtime.
    • Guest = durable account + is_guest (interview): migration 00005 adds accounts.is_guest; a guest is a durable row with no identity (so the sessions/game_players foreign keys hold) that is excluded from statistics (the finish-time recompute skips guest seats) and from friends/history. The earlier "guests never reach this table" comments and §3/§9 were softened to "no profile/friends/stats persisted". Guest-row GC is a logged TODO (TODO-3).
    • Push = in-process Publisher + backend gRPC listener (interview): a new internal/notify hub (a Publisher interface defaulting to Nop, installed on game/social/lobby via SetNotifier during boot — additive, existing tests unchanged) is drained by a new backend gRPC server (internal/pushgrpc, BACKEND_GRPC_ADDR default :9090) serving Push.Subscribe. Emission lives in game.commit (so robot-driver and timeout-sweep moves emit your_turn/ opponent_moved too — the background sources a handler-only design would miss), social (chat_message/nudge) and the matchmaker (match_found). Event payloads are FlatBuffers-encoded in the backend (it imports pkg/fbs); the gateway forwards them verbatim. Revoke/session-invalidation and cursor-resume are deferred (single-instance MVP).
    • Edge envelope = minimal, token in header (interview): the Gateway Connect service is Execute(message_type, payload, request_id) + Subscribe; the session token rides in Authorization: Bearer; auth ops are unauthenticated and return the token in the FlatBuffers Session. Domain outcomes ride back in the ExecuteResponse.result_code (HTTP 200); only edge failures (rate limit, missing session, unknown type, internal) are Connect error codes. No Ed25519/signing (the galaxy donor's crypto stack was dropped, per §3).
    • Admin = gateway validates Basic-Auth (interview): the gateway checks GATEWAY_ADMIN_USER/_PASSWORD and reverse-proxies to backend /api/v1/admin/*; the backend admin surface is a single ping until Stage 10.
    • Rate-limit = 2 dimensions, 3 classes (interview): public per-IP (30/min, burst 10), authenticated per-user (120/min, burst 40), admin per-IP (60/min, burst 20), plus an email-code per-IP sub-limit (5/10 min); token bucket (golang.org/x/time/rate) with a lazy stale-bucket sweep.
    • Email-as-login (discharges the Stage 4 deferral): account.EmailService gained RequestLoginCode/LoginWithCode, reusing the confirm-code mechanism but provisioning-or-finding the account by email identity (it does not refuse an already-confirmed address — that is the returning user).
    • CI: both Go workflows gained gateway/** (and pkg/** where backend depends on it) path filters and now build/vet/test ./backend/... ./pkg/... ./gateway/... (unit) — integration stays ./backend/... (the only module with tagged tests). The solver clone + BACKEND_DICT_DIR steps are unchanged.
  • Stage 7 (interview + implementation):

    • Scope = playable slice (interview): the whole UI shell plus the core play loop end-to-end; the social/account/history surfaces were split out into a new Stage 8 and the later stages shifted +1 (Telegram→9, Admin→10, Linking→11, Polish→12). Stage 7 wires only the operations the slice needs (the Stage 6 "as the UI needs them" pattern): the new gateway/transcode + backend-REST ops games.list, game.{pass,exchange,resign,hint,evaluate,check_word,complaint, history}, chat.{list,nudge}. The only new domain code is game.ListForAccount (the "my games" query) and seat display_name resolution (server DTO layer); SeatView gained a trailing display_name. Friends/blocks/invitations, profile-editing, stats and the history/GCG viewer are Stage 8.
    • Stack (interview): plain Svelte 5 (runes) + TypeScript + Vite, no SvelteKit; @connectrpc/connect-web + the flatbuffers runtime, with the edge TS bindings generated from the same edge.proto (protoc-gen-es) and scrabble.fbs (flatc --ts) and committed under ui/src/gen/ (dev-time codegen, like cmd/jetgen / pkg/Makefile; CI builds the committed output).
    • No board on the wire (discovered): StateView carries no grid, so the client replays the decoded move journal (game.history, newly wired) onto an empty board; premium squares + tile values are a client-side map ported from scrabble-solver/rules/rules.go with a Vitest parity test.
    • Board UX (interview): full-width, borderless; tiles placed by Pointer-Events drag or tap (no HTML5 DnD — it has no touch support); a contextual MakeMove control (short tap → make/reset popup, ~1 s press-and-hold → commit); per-tile recall by tapping a pending tile; a two-state zoom (15↔9 cells) on touch only (auto-zoom-in on placement, double-tap / pinch manual); a blank-letter chooser. All board/tiles/effects are pure HTML5/CSS + Unicode — no image/font/SVG asset.
    • Theming (interview): own CSS custom-property tokens, light/dark via prefers-color-scheme, Telegram-themeParams-ready (a runtime hook can override the tokens; the SDK is wired in the Telegram stage). Navigation (interview): dependency-free hash router; session token in memory + IndexedDB, re-resolved on reload (reopen Subscribe, refetch the open game); stream reconnect on focus. i18n en/ru is a hand-rolled typed catalog (compile-time key parity + a test).
    • Mock transport (owner request): a build-flagged in-memory fake (VITE_MOCK, pnpm start) drives lobby → active game → board with no backend, tree-shaken out of production; it is the same fixture the Playwright smoke uses.
    • Tests/CI (interview): Vitest units (board replay, placement machine, premium parity, i18n parity, FlatBuffers codec) + a Playwright smoke against the mock; a new ui-test.yaml workflow (type-check, unit, build with a bundle-size budget — prod is ~67 KB gzip JS — and a chromium e2e). The Go workflows already cover the new backend/gateway/pkg code; a game.ListForAccount integration test and gateway transcode tests for the new ops were added.
    • UX polish (follow-up PR): a mobile-app app shell (growing nav bar, content pinned to the bottom) + a one-line announcement banner (client-side mock rotation now; server-driven channel later — §10); a mobile-OS tab bar and a reusable HoldConfirm press-and-hold control (MakeMove 🏁 + game-action confirms); board zoom reworked to a width-based zoom in a fixed viewport (real native scroll, double-tap; pinch/swipe dropped) with constant cqw labels, corner-letter tiles, contrasting grid lines, last-word dark-tile highlight, and a Settings bonus-label style (beginner/ classic/none); hint lays its tiles on the board (no spend when no move — a new no_hint_available result code); the history opens as an in-place slide-down (not a modal); word-check is alphabet/length-limited, cached and throttled. Design details live in the new docs/UI_DESIGN.md.
  • Stage 8 (interview + implementation):

    • Scope = vertical slice continued: the social/account/history operations were opened end-to-end (UI → gateway transcode → backend REST → existing domain services). The only new backend logic is lobby.ListInvitations, account.Store.GetStats, a game.SharedGame seam (self-join on game_players), the friend-code mechanism, and the friendships declined-status change.
    • Friends — two add paths (interview, a deliberate plan change): one-time friend codes (the player to be added issues a 6-digit numeric code, 12 h TTL, SHA-256-hashed like email codes, single active per issuer, single-use, redeem rate-limited) and a play-gated request (SendFriendRequest now requires a shared game — active or finished). An explicit decline is permanent (blocks re-send), an ignored request lazily expires after 30 days and may be re-sent, and a code from the same person bypasses a prior decline. This supersedes Stage 4's "declining/cancelling deletes the row" (cancel by the requester still deletes; decline now sets status='declined'). Migration 00006 widens friendships_status_chk and adds friend_codes (jetgen regen). No public ID or name search — discovery is codes + befriend-an-opponent.
    • Badges = poll + push (interview): a new generic notify push event (notify.KindNotification, sub-kinds friend_request/friend_added/invitation/ game_started) drives the lobby hamburger + "Friends" badge; emitted on friend- request and invitation create and on the invitation's game start. The client polls incoming requests + open invitations on lobby open and on focus (a missed push while hidden), and re-polls on the notify event. Cursor-resume stays deferred (single-instance MVP, §10).
    • Language single-control (interview): the Settings language control writes through to the durable account's preferred_language (profile.update); guests keep only the client preference. Seeding the language from the platform/client on first provider login is a Stage 9 forward-note.
    • Guests = durable-only (interview): friends/blocks/invitations/statistics and history management are durable-account-only; a guest sees a sign-in prompt. Binding an email to an existing guest (account linking) stays Stage 11.
    • GCG = finished-only + share (interview): game.ExportGCG refuses an active game (game.ErrGameActive) to avoid leaking the live journal mid-play; the client exports via the Web Share API where available, else a Blob download (game-<id>.gcg). Capacitor-native file save lands with the native wrapper.
    • IA = as the mockup (interview): Friends (friends + blocks) is its own screen from the lobby menu; Invitations is a lobby section + a "play with friends" mode in New game; Stats is a lobby tab-bar button; profile editing is on Profile; history + GCG stay in the game.
    • Wire/codegen: new fbs tables (friends/blocks/invitations/profile-update/email- bind/stats/gcg + NotificationEvent; Profile gained trailing away fields) in pkg/fbs, regenerated to committed Go + TS; ~21 new gateway transcode ops; new REST handlers under /api/v1/user/{friends,blocks,invitations,profile,email,stats} and …/games/:id/gcg. UI grows to ~82 KB gzip JS (budget 100 KB). No CI workflow change (the Go and UI workflows already cover the new code).
    • UI polish (owner review follow-up): a copyable friend code (📋 + toast); the lobby notification badge fixed (it had inherited the hamburger-bar style) and made a proper count dot; Safari flex inputs given min-width:0; profile-edit validation on both UI and backend — display-name format (letters + single /./_, ≤ 32 runes), a UTC-offset timezone picker (account.ResolveZone parses ±HH:MM or IANA; DST is traded for the simple picker), a 10-minute away grid capped at 12 h (wrap-aware), email format — with Save disabled and invalid fields red-bordered while any field is invalid; language stays in Settings; in a game, an "add to friends" item flips to a disabled "request sent"; chat send/nudge became ⬆️/🛎️ icons; a finished game drops its last-word highlight, hides Check word / Drop game, disables zoom, and draws an inert footer (greyed rack + tab bar) instead of hiding it. Two iPhone-simulator passes then made the chat and modals keyboard-aware (dvh plus a visualViewport listener that sizes the modal backdrop to the area above the keyboard), reserved the rack height so a finished footer does not collapse, and compacted the play-with-friends form (a searchable bounded-scroll friend list, a pinned invite, and an explicit, required game type — a smart default is TODO-6). On the owner's call, every profile / new-game picker is a native <select> (the away window as hour + 10-minute selects, the timezone as a UTC-offset select): native time/wheel inputs render differently per OS and can't be forced to match, and a select also avoids the iOS "clear" button that would empty a time field.
  • Stage 9 (interview + implementation):

    • Connector as its own container (interview): the Telegram side-service is a standalone module platform/telegram (binary cmd/telegram) holding the bot token only there; gateway and backend reach it by unauthenticated gRPC on the trusted internal network, and it egresses to api.telegram.org through a VPN sidecar (deploy/docker-compose.yml, mirroring ../15-puzzle). Bot library github.com/go-telegram/bot (one new dep), long-poll updates.
    • initData validation moved off the gateway (interview): the gateway's HMAC validator was relocated into the connector (internal/initdata, now also returning language_code); the gateway calls connector.ValidateInitData over gRPC during auth.telegram. The hop is negligible (loopback gRPC, once per login). GATEWAY_TELEGRAM_BOT_TOKEN is gone; GATEWAY_CONNECTOR_ADDR replaces it. The gateway/internal/auth package was deleted.
    • Connector gRPC API (pkg/proto/telegram/v1, service Telegram): the generic methods are platform-agnostic, keyed by the identity external_id (so a future VK/MAX connector reuses them); only ValidateInitData is Telegram-specific. Methods: ValidateInitData, Notify (the out-of-app push — renders a localized message + a Mini App deep-link button from the FlatBuffers payload), SendToUser and SendToGameChannel (arbitrary admin messages — built and unit-tested now, wired to the admin surface in Stage 10; the game channel id lives only in connector config).
    • Push = fallback, gateway-routed, de-dup by presence (interview): the gateway already consumes the firehose and knows in-app presence (push.Hub.HasSubscribers), so it decides in-app vs out-of-app atomically: for a recipient with no live in-app stream it fetches a new backend /internal/push-target ({external_id, language, notifications_in_app_only}) and calls connector.Notify only when they have a Telegram identity and have not set the new flag. Push set: your_turn, nudge, match_found, and the notify sub-kinds invitation/ friend_request (the connector skips the rest). Delivery runs in a goroutine so a slow connector never stalls the firehose; best-effort (no cursor resume — single instance, §10).
    • Profile flag notifications_in_app_only (interview, default true → push is opt-in): migration 00007 (+ jetgen), threaded through account.Profile/UpdateProfile, the REST DTOs, the fbs Profile/ UpdateProfileRequest (default true in the schema so an unset field reads conservatively), and a Profile-screen toggle. Flagged at review: the channel is silent until a user turns it off.
    • Language seeding from the platform (discharges the Stage 8 forward-note): account.ProvisionTelegram seeds a brand-new account's preferred_language from the Telegram language_code and its display name from first_name/ username (existing accounts untouched); the UI's adoptSession already adopts the server language when the user has not locked a locale, so no extra UI seeding was needed. The gateway forwards the fields from ValidateInitData.
    • Mini App = /telegram/ + guard (interview): the gateway serves the one SPA build under /telegram/ (Vite relative base; the hash router is path-agnostic). The UI detects a Telegram launch by Telegram.WebApp.initData, applies themeParams, authenticates via the existing auth.telegram op (UI authTelegram codec/client/transport/mock added), and routes the deep-link start_param (g/i/f → game / lobby-invitation / friend-code redeem). On the /telegram/ path without initData it redirects to the site root. The official telegram-web-app.js loads from index.html (harmless outside Telegram).
    • Deep-link scheme (shared Go platform/telegram/internal/deeplink ↔ TS ui/src/lib/deeplink.ts): g<game uuid> / i<invitation uuid> / f<6-digit code> / empty = lobby. A friend-code share-to-Telegram link is shown when VITE_TELEGRAM_LINK is configured (partially discharges TODO-5; QR still open). The Notify button and the bot /start reply both wrap the payload as <MiniAppURL>?startapp=<payload>.
    • Test environment (interview nuance): the Bot API base is overridable for Telegram's test environment — TELEGRAM_TEST_ENV=true suffixes the token with /test so the client hits /bot<token>/test/METHOD (TELEGRAM_API_BASE_URL overrides the host for a mock/self-hosted server).
    • Deploy groundwork (interview): platform/telegram/Dockerfile (builds the connector standalone — drops backend/gateway and the solver replace from a copy of go.work, validated with docker build) + the connector-scoped compose with the VPN sidecar; a root .dockerignore. No public ingress for the connector (long-poll + sidecar egress); the host reverse proxy routes only to the gateway port, which serves the Mini App. The full multi-service deploy is Stage 12.
    • Wire/codegen/CI: new proto pkg/proto/telegram/v1 (committed Go); fbs Profile/UpdateProfileRequest gained notifications_in_app_only (committed Go
      • TS). go.work gains use ./platform/telegram; deps via go mod edit + go work sync (no-tidy). go-unit.yaml gained the platform/** path filter and builds/vets/tests ./platform/telegram/.... UI grows to ~86 KB gzip JS (budget 100 KB). The connector's unit tests use an httptest fake Bot API; a Playwright smoke drives the Mini App launch + guard with an injected window.Telegram.
    • Stage 10 forward-note: the admin surface will wire connector.SendToUser/ SendToGameChannel (backend gains its own connector client) for operator broadcasts to a user and the game channel.
    • Verification-time fixes (caught by the CI gate): (1) the gateway transcode dropped notifications_in_app_only in four places (ProfileResp, encodeProfile, profileUpdateHandler, the UpdateProfile body) so the toggle never reached the backend — fixed, with a round-trip transcode test added. (2) The e2e suite was made hermetic (a shared ui/e2e/fixtures.ts blocks the real telegram-web-app.js): the render-blocking CDN <script> hung every page load on the CI runner, where telegram.org is unreachable, timing out all non-Telegram specs. (3) A pre-existing time-of-day flake in TestTimeoutSweep (the default 00:0007:00 away window made the sweeper skip when CI ran with now-1h inside it) was made deterministic by clearing the test account's away window.
  • Stage 10 (interview + implementation):

    • Admin console = backend-rendered /_gm, gateway Basic-Auth (interview, two rounds): the owner chose a dedicated web console but, pointing at ../galaxy-game and asking to keep it simple, the deliverable is server-rendered Go html/template + one embedded CSS (backend/internal/adminconsole: a framework-agnostic renderer + page view-models, //go:embed templates/assets, zero JS, no build step), not a SPA. It lives in the backend on its own route /_gm/*; the gateway (the project's built-in reverse proxy) gates /_gm/* with the existing GATEWAY_ADMIN_USER/PASSWORD Basic-Auth on its public listener and proxies verbatim to backend /_gm/* (mounted on the edge mux below the h2c wrap so Connect keeps working). This supersedes Stage 6's gateway-fronts- /api/v1/admin model: the separate admin port GATEWAY_ADMIN_ADDR is dropped (only the port — user/password stay), the backend /api/v1/admin group + ping are removed, and gateway/internal/admin is repurposed to the verbatim proxy. The backend keeps no operator identity and no admin_accounts table; CSRF on the console's POSTs is a same-origin check (Origin/Referer vs Host, the gateway preserves the inbound Host) — no token. Discharges Stage 1's "admin bootstrap" (it is config, not a DB seed).
    • Complaint resolution + dictionary pipeline (interview): migration 00008 (+ jetgen) adds disposition/resolution_note/resolved_at/applied_in_version to complaints and the deferred status CHECK (open|resolved) — discharges Stage 3's deferral (no resolved_by: operator identity is not tracked). Resolution sets a disposition (reject/accept_add/accept_remove); accepted complaints are derived by query into a pending dictionary-change list (no new table), stamped applied_in_version once a rebuilt version is loaded. New game reads ListComplaints/GetComplaint/CountComplaints/ResolveComplaint/ DictionaryChanges/MarkChangesApplied; admin list/count reads account.ListAccounts/CountAccounts/Identities and game.ListGames/CountGames/ GameByID.
    • Dictionary hot-reload = per-version subdir (interview): the launch version stays in the flat BACKEND_DICT_DIR (CI/dev untouched); a reloaded version X loads from BACKEND_DICT_DIR/X/ via the new Registry.LoadAvailable (present variants only), and boot re-loads every subdirectory via engine.OpenWithVersions so reloaded versions survive a restart. Partially addresses TODO-2 (the runtime reload contract; the offline DAWG generator stays future work).
    • Operator broadcasts (discharges Stage 9's forward-note): the backend gains its own connector gRPC client (backend/internal/connector, BACKEND_CONNECTOR_ADDR, nil when unset) over the existing pkg/proto/telegram/v1; the console messages a user by account_id (backend resolves the Telegram external_id) and posts to the game channel via SendToUser/SendToGameChannel.
    • Config/CI: backend adds BACKEND_CONNECTOR_ADDR; gateway drops GATEWAY_ADMIN_ADDR (keeps user/password). No new module and no fbs/proto/UI codegen (the console is server-rendered Go). The Go workflows already span ./backend/... ./gateway/... ./pkg/...; integration stays ./backend/....
  • Stage 11 (interview + implementation):

    • Scope = link-via-confirm + merge for email and Telegram (interview): the current account is the merge primary; a linked identity that already has its own account is merged into the current one and the secondary is retired as an audit tombstone (accounts.merged_into/merged_at, migration 00009
      • jetgen). Linkable this stage: email (the existing confirm-code) and Telegram via the Login Widget (the web sign-in). New internal/accountmerge (the single-transaction data merge) and internal/link (the orchestrator over account + accountmerge + session).
    • Tombstone, not delete (interview): the secondary row is kept so a shared finished game's no-cascade game_players/chat/complaints foreign keys stay valid; its seat in such a game is left in place. The merge is refused (ErrActiveGameConflict) only when the two share an active game.
    • Merge algorithm (one tx): stats summed (wins/losses/draws) + max kept; hint_balance summed; identities repointed; non-shared game_players transferred (shared kept); chat_messages/complaints reassigned; friendships/blocks repointed with self-edge drop and dedupe (friendships by status precedence accepted>pending>declined); invitations: secondary's as inviter deleted, invitee rows deduped; secondary's email_confirmations/friend_codes dropped; secondary tombstoned. Sessions are handled one layer up: session.Service.RevokeAllForAccount (+ Cache.RemoveByAccount) retires the secondary's sessions after the tx.
    • Primary direction + guest inversion (interview): primary = the current account, except when the initiator is a guest and the linked identity already has a durable owner — then the durable account wins, the guest's active games transfer into it, the guest is retired, and a fresh session for the durable account is minted and returned (the client adopts it). Binding a free identity to a guest is a plain upgrade (clear is_guest, same session). Discharges Stage 8's "guest email-binding is Stage 11".
    • API/UX = dedicated ops; reveal only after the code (interview): new edge ops link.email.request/confirm/merge (Email-rate-limited) and link.telegram.confirm/merge. request always mails a code (no pre-send "taken" signal, so a probe cannot enumerate registered addresses); a required merge is revealed only after the code is verified, gating an explicit irreversible merge step (the Profile screen's confirmation dialog). This supersedes Stage 8's email.bind.* ops (and their fbs EmailBindRequest/EmailConfirmRequest tables), which were retired from the gateway/UI for that reason; the backend EmailService.RequestCode/ConfirmCode primitives stay (still covered by inttest).
    • Field policy (interview): display_name = primary's; profile prefs/flags (language, timezone, away window, block toggles, notifications_in_app_only) = primary's; hint_balance = sum. A new service column paid_account (bool, default false; lifetime one-time-payment marker, no purchase flow yet) is added in 00009 and ORed on merge (true always wins). It is not user-editable and is shown read-only on the admin account-detail page.
    • Telegram Login Widget (interview, owner chose the broader scope): the connector validates it (internal/loginwidget, secret = SHA-256(bot_token), distinct from initData) via a new Telegram.ValidateLoginWidget RPC; the gateway validates the widget payload and passes the trusted external_id to the backend link route (same trust model as auth.telegram). The UI offers "Link Telegram" only in a plain web context (loginWidgetAvailable), driving the popup Telegram.Login.auth; it is inert in production until BotFather /setdomain registers the site domain and VITE_TELEGRAM_BOT_ID is configured (a deploy concern, Stage 12). e2e mocks the widget (telegram.org is blocked on CI).
    • Wire/CI: new fbs LinkEmailRequest/LinkEmailConfirm/LinkTelegramRequest/ LinkResult (committed Go + TS); new proto RPC (committed Go); new REST routes under /api/v1/user/link/*. The Go workflows already span ./backend/... ./gateway/... ./pkg/... ./platform/telegram/...; integration stays ./backend/.... UI ~90 KB gzip JS (budget 100 KB). New error code merge_active_game_conflict.
  • Stage 12 (interview + implementation):

    • Re-scoped & split (interview): the original "Polish (observability + perf + deploy)" was too large for one session, so it was split — Stage 12 = observability
      • performance + guest GC; Stage 13 = alphabet-on-the-wire (TODO-4); Stage 14 = CI & deploy (TODO-1, TODO-2, the collector + dashboards). The latter two were written into the plan now as the agreed baseline (each still re-interviews at its own start).
    • Shared telemetry (interview): a new pkg/telemetry owns the OTel provider bootstrap (exporter selection, W3C propagators, shutdown, Go runtime metrics); the backend internal/telemetry is now a thin facade over it (keeping its gin middleware), and the gateway and connector gained telemetry runtimes. A configurable otlp exporter was added alongside none/stdout; the default stays none, the OTLP endpoint comes from the standard OTEL_EXPORTER_OTLP_* env, and the collector + dashboards are Stage 14 (so CI needs none). otelgrpc instruments the backend push server, the gateway's backend + connector clients, and the connector's gRPC server. New config GATEWAY_SERVICE_NAME/GATEWAY_OTEL_* and TELEGRAM_SERVICE_NAME/ TELEGRAM_OTEL_*; the backend's existing BACKEND_OTEL_* gained the otlp value.
    • Metrics = operational, business-near (interview): histograms game_replay_duration and game_move_validate_duration; counters games_started_total, games_abandoned_total (a turn-timeout seat drop) and chat_messages_total (kind=message/nudge); an observable gauge game_cache_active; the gateway edge_request_duration (message_type/result); plus Go runtime/heap metrics. Game-scoped metrics carry a variant attribute (english/russian_scrabble/erudit — chosen over a coarser language, which it subsumes); the gateway edge metric is variant-agnostic. Optional wiring uses the established SetMetrics/SetNotifier setter pattern (default no-op meter), so existing constructors and tests are untouched. No speculative optimisation — there is no measured hotspot; the deliverable is the instrumentation (the standing "performance only with evidence" rule). pprof was not added (reframed away by the owner).
    • Guest GC (interview, TODO-3): age-based, no-seat-only — see the discharged TODO-3 below; new config BACKEND_GUEST_REAP_INTERVAL/BACKEND_GUEST_RETENTION.
    • Deps/CI: new OTel modules (the OTLP exporters, contrib/instrumentation/runtime, otelgrpc) added with the no-tidy pattern (go mod edit + go mod download + go work sync; pkg carries no bare-path dep, so it tidies cleanly). No workflow change — the Go workflows already span ./backend/... ./gateway/... ./pkg/... ./platform/telegram/..., integration stays ./backend/..., and the default none exporter keeps CI collector-free.

Deferred TODOs (cross-stage)

  • TODO-1 — publish & version the solver. Once scrabble-solver is stable, give it a real module URL and switch backend to a versioned dependency, dropping the go.work replace and the CI clone. Removes the floating master dependency accepted for now (Stage 2 interview). Planned for Stage 14 (it cleans up the backend Docker build; a clone-in-build fallback stays available).
  • TODO-2 — split the solver into engine vs dictionary generator + versioned dictionary artifacts. Owner's idea, with the caveats agreed at the Stage 2 interview: the split is sound (build-time wordlist→DAWG vs runtime load have different lifecycles and shrink the runtime dependency surface), but the generator must pin the same dafsa/alphabet versions and alphabet definitions as the runtime engine or the on-disk format / letter indexing drifts and silently corrupts validation. For delivery prefer Git LFS or an artifact store (Gitea releases / OCI artifact / object storage) over a raw git submodule (the ~0.50.7 MB DAWGs are regenerated wholesale and bloat git history); pin by tag/hash for a reproducible startup set. A submodule/LFS pull is a deploy-time way to populate the directory, not the runtime dynamic-reload mechanism (implemented in Stage 10: a per-version subdirectory BACKEND_DICT_DIR/<version>/ loaded via Registry.LoadAvailable, restart-restored by engine.OpenWithVersions) — keep the BACKEND_DICT_DIR directory as the runtime contract: a new .dawg appears in it and is loaded with dawg.Load. Planned for Stage 14, agreed resolution: a new versioned repo for the parsers + built DAWGs, delivered as a release artifact (not go get), versioned with one semver label for the whole set (additive; old versions retired once no active game pins them — see Stage 14). The generator must build against the same dafsa/alphabet/solver as the runtime (the index-drift caveat, shared with TODO-4).
  • TODO-3 — garbage-collect abandoned guest accounts. Done in Stage 12. A periodic account.GuestReaper deletes guests (is_guest) with no game seat at all whose account age exceeds BACKEND_GUEST_RETENTION (default 30 d, swept every BACKEND_GUEST_REAP_INTERVAL, default 1 h). Two schema facts shaped this, narrowing the original sketch: (1) game_players/chat_messages/complaints reference accounts without ON DELETE CASCADE, and a finished game belongs to the other players' history, so a guest with any seat is retained (a delete would be blocked anyway) — hence "no seat", not "no active game"; (2) sessions are revoke-only with no maintained last_seen_at, so a lingering session never expires and account age is the abandonment trigger, not "last session gone". The reaped guest's sessions/identities/ account_stats fall away via their own ON DELETE CASCADE.
  • TODO-4 — put the per-game alphabet on the wire (owner's idea, Stage 7). Today the client hardcodes each variant's letters/values (ported into ui/src/lib/premiums.ts from scrabble-solver/rules/rules.go) and the edge exchanges plays/hints by concrete letters. Consider extending game.state to carry the variant's (letter, index, value) table so the UI stops duplicating it, and optionally moving tile exchange to letter indices end-to-end. Caveat (as for the dictionaries, TODO-2): the wire table must stay pinned to the same rules.Alphabet the engine uses, or indices drift. Planned for Stage 13, expanded (owner) to a fully alphabet-agnostic UI: the client caches the per-variant table (display only) behind an include_alphabet request flag and exchanges indices both ways, word-check included; the durable journal stays concrete characters (§9.1). See Stage 13.
  • TODO-5 — QR friend codes (owner's idea, Stage 8). Partially done in Stage 9: the deep-link scheme now exists (f<code>, shared Go ↔ TS), the bot redeems it on launch, and the UI shows a share-to-Telegram link for an issued code when VITE_TELEGRAM_LINK is configured. Still open: render the link as a QR so a friend can add you by scanning rather than tapping/typing. The code semantics (12 h TTL, single use, one active per issuer) stay as-is; only the delivery changes.
  • TODO-6 — smart default for the friend-game "game type" (owner's idea, Stage 8). The play-with-friends form has no preselected variant today (an empty, required pick). Default it from the player's history (the variant they play most, from account_stats or a games query), falling back to their interface language (en → English, ru → Russian/Эрудит). Until then the explicit pick avoids guessing wrong.