feat: add player-scoped assignment recovery

server/api/service.go

@@ -40,6 +40,19 @@ type SessionIssuer interface {
 	Issue(context.Context, string, time.Duration, time.Time) (domain.Session, string, error)
 }
 
+type AssignmentView struct {
+	MatchID           string    `json:"match_id"`
+	ServerID          string    `json:"server_id"`
+	PlayerID          string    `json:"player_id"`
+	Slot              int       `json:"slot"`
+	ExpiresAt         time.Time `json:"expires_at"`
+	ProtocolVersion   int       `json:"protocol_version"`
+	Transport         string    `json:"transport"`
+	JoinAuthorisation string    `json:"join_authorisation"`
+}
+
+type AssignmentProvider func(context.Context, string, string, time.Time) (AssignmentView, error)
+
 type Service struct {
 	Sessions       *domain.SessionStore
 	SessionBackend SessionBackend
@@ -50,6 +63,7 @@ type Service struct {
 	CandidateV2    CandidateProviderV2
 	QueueBackend   QueueBackend
 	Probe          ProbeProvider
+	Assignment     AssignmentProvider
 	Now            func() time.Time
 	Proposals      map[string]*domain.Proposal
 	RankedProfiles map[string]domain.RankedProfile
@@ -64,6 +78,7 @@ func (s *Service) Handler() http.Handler {
 	mux.HandleFunc("/v1/queue", s.queueCreate)
 	mux.HandleFunc("/v1/queue/", s.queueMutation)
 	mux.HandleFunc("/v1/proposals/", s.proposalMutation)
+	mux.HandleFunc("/v1/assignments/", s.assignment)
 	mux.HandleFunc("/v1/profile/ranked", s.rankedProfile)
 	mux.HandleFunc("/v1/probes/", s.probe)
 	return mux
@@ -331,6 +346,37 @@ func (s *Service) proposalMutation(w http.ResponseWriter, r *http.Request) {
 	writeJSON(w, http.StatusOK, toProposalResponse(updated))
 }
 
+func (s *Service) assignment(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodGet {
+		writeError(w, http.StatusMethodNotAllowed, "method_not_allowed")
+		return
+	}
+	playerID, ok := s.authenticate(w, r)
+	if !ok {
+		return
+	}
+	parts := strings.Split(strings.TrimPrefix(r.URL.Path, "/v1/assignments/"), "/")
+	if len(parts) != 1 || parts[0] == "" {
+		writeError(w, http.StatusNotFound, "not_found")
+		return
+	}
+	if s.Assignment == nil {
+		writeError(w, http.StatusServiceUnavailable, "assignment_unavailable")
+		return
+	}
+	now := s.now()
+	view, err := s.Assignment(r.Context(), playerID, parts[0], now)
+	if err != nil || view.MatchID != parts[0] || view.PlayerID != playerID {
+		writeError(w, http.StatusNotFound, "not_found")
+		return
+	}
+	if view.ServerID == "" || view.Slot < 0 || view.Slot > 5 || view.ProtocolVersion < 1 || (view.Transport != "enet" && view.Transport != "steam_sdr") || view.JoinAuthorisation == "" || view.ExpiresAt.IsZero() || !now.Before(view.ExpiresAt) {
+		writeError(w, http.StatusServiceUnavailable, "assignment_unavailable")
+		return
+	}
+	writeJSON(w, http.StatusOK, view)
+}
+
 type rankedProfileResponse struct {
 	Rating      float64 `json:"rating"`
 	RD          float64 `json:"rd"`