syntax = "proto3";

// Package scrabble.push.v1 is the backend -> gateway live-event control channel.
// The gateway opens Subscribe once at startup and keeps the stream open; the
// backend pushes one Event per notification intent. The payload is an opaque
// FlatBuffers message (the scrabblefb.* tables) that the gateway forwards to the
// client without re-interpreting it. The transport is plain gRPC server-stream
// (ARCHITECTURE.md §2); the client edge is Connect-RPC (gateway/proto/edge).
package scrabble.push.v1;

option go_package = "scrabble/pkg/proto/push/v1;pushv1";

// Push is the unidirectional live-event channel from backend to gateway.
service Push {
  // Subscribe opens the single backend -> gateway event stream. The backend
  // sends every event for every user; the gateway fans them out to the active
  // client subscriptions by user_id.
  rpc Subscribe(SubscribeRequest) returns (stream Event);
}

// SubscribeRequest opens a push subscription. gateway_id identifies the gateway
// instance for logging; the MVP backend keeps no per-gateway state.
message SubscribeRequest {
  string gateway_id = 1;
}

// Event is one live-event frame. kind is the notification catalog kind
// (your_turn, opponent_moved, chat_message, nudge, match_found). payload is the
// FlatBuffers-encoded body for that kind. event_id is a correlation id the
// gateway carries through to the client envelope.
message Event {
  string user_id = 1;
  string kind = 2;
  bytes payload = 3;
  string event_id = 4;
}