feat: add verified gacha flows and native client studio

go/internal/server/player/gacha_batch.go

@@ -0,0 +1,37 @@
+package player
+
+import "errors"
+
+// GachaBatchResponse returns the immutable result of a completed batch. The
+// digest binds the full ordered request, including repeated gacha IDs.
+func (s *CollectionStore) GachaBatchResponse(identity, digest string) ([]byte, bool, error) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	grant, found := s.data.Grants[identity]
+	if !found {
+		return nil, false, nil
+	}
+	if grant.GachaRequestDigest != digest || len(grant.GachaResponse) == 0 {
+		return nil, true, errors.New("player: gacha batch request identity conflict")
+	}
+	return append([]byte(nil), grant.GachaResponse...), true, nil
+}
+
+// RecordGachaBatch participates in the caller's account operation alongside
+// every reward, daily allowance and fixed-pity update in the batch.
+func (s *CollectionStore) RecordGachaBatch(identity, digest string, response []byte) error {
+	if identity == "" || digest == "" || len(response) == 0 {
+		return errors.New("player: invalid gacha batch result")
+	}
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if prior, found := s.data.Grants[identity]; found {
+		if prior.GachaRequestDigest != digest {
+			return errors.New("player: gacha batch request identity conflict")
+		}
+		return nil
+	}
+	next := cloneCollection(s.data)
+	next.Grants[identity] = CollectionGrant{GachaRequestDigest: digest, GachaResponse: append([]byte(nil), response...)}
+	return s.commit(next)
+}