Shared wire contracts for the Scrabble platform (module scrabble/pkg), imported by both backend and gateway. It carries no logic — only the generated message types and the schemas they come from.

Layout

proto/push/v1/    # backend -> gateway live-event gRPC channel (Push.Subscribe)
                  #   committed generated Go (*.pb.go, *_grpc.pb.go)
fbs/scrabble.fbs  # FlatBuffers edge payloads (one `scrabblefb` namespace)
fbs/scrabblefb/   # committed generated Go for the schema

proto/push/v1 is the single gRPC server-stream the backend exposes and the gateway subscribes to (Event{user_id, kind, payload, event_id}); the payload is an opaque FlatBuffers body the gateway forwards verbatim.
proto/telegram/v1 is the Telegram connector's RPC contract (Stage 9; Stage 11 added ValidateLoginWidget for the web Login Widget sign-in).
fbs holds the client↔gateway request/response and event payloads as FlatBuffers tables. The backend encodes the push payloads from these types; the gateway transcodes the rest to and from the backend's JSON; the UI generates TypeScript from the same .fbs (Stage 7).

Generated code

Committed (CI only builds it); regenerate dev-time after editing the schemas:

make -C pkg tools   # go install protoc-gen-go + protoc-gen-go-grpc
make -C pkg gen     # buf generate (proto) + flatc (fbs)

flatc is pinned to 23.5.26 to match the github.com/google/flatbuffers Go runtime in go.mod; generating with another version is refused.

Workspace wiring

scrabble/pkg is a bare-path module (no dot), so — like scrabble-solver — it cannot be fetched as a versioned dependency. go.work carries use ./pkg and replace scrabble/pkg v0.0.0 => ./pkg; consumers require scrabble/pkg v0.0.0.