Extract the FlatBuffers builders for the wire tables shared by the backend push
encoder and the gateway edge transcoder — GameView, MoveRecord, StateView,
AccountRef, Invitation and their nested rows — into a new scrabble/pkg/wire
package. Both callers keep their local builder signatures (no call sites move)
but now map their own source types (the backend's notify.* payloads and the
decoded engine.MoveRecord; the gateway's backendclient.* REST DTOs) to neutral
wire.* structs and delegate the construction to package wire, the single
definition of the nested-table layout.
Behaviour-preserving: the verified-identical field sets mean the wire bytes
decode the same, and the notify + transcode round-trip tests pass unchanged. The
fiddly Start/Add/End + reverse-prepend vector boilerplate now lives once; the two
encode files shrink while pkg/wire carries the shared logic.
Enrich the in-app live stream into a delta channel so the UI renders a move from the event without a follow-up game.state, and make the matchmaking poll a stream-down fallback.
- pkg/fbs: trailing fields on opponent_moved (move+game+bag_len), your_turn (move_count), match_found (state), game_over (game), notify (account/invitation/state), MoveResult (rack+bag_len); regenerate Go + TS.
- backend: notify owns the FB encoding (encode.go + payload.go input structs); game/lobby/social map their domain types in. emitMove builds the move delta; game.Service.InitialState feeds match_found/game_started the recipient's initial StateView; friends/invitations notify carry their account/invitation. The move-commit response (submit_play/pass/exchange/resign) returns the actor's refilled rack + bag size.
- gateway: MoveResult transcode carries rack+bag_len.
- ui: pure lib/gamedelta.ts reducer advances the per-game cache keyed on move_count (idempotent + gap-safe); app.svelte seeds the cache on match_found/game_started; Game.svelte applies the delta (commit/pass/exchange/resign drop their load()); NewGame polls only while app.streamAlive is false.
- docs: ARCHITECTURE §10, FUNCTIONAL(+ru), backend/gateway/ui READMEs; PRERELEASE R4 marked done + Refinements.
Ilia Denisov