--- remote_execution.proto.orig	1970-01-01 01:00:00.000000000 +0100
+++ remote_execution.proto	2023-11-03 13:32:37.502134562 +0100
@@ -406,6 +406,29 @@
   rpc GetTree(GetTreeRequest) returns (stream GetTreeResponse) {
     option (google.api.http) = { get: "/v2/{instance_name=**}/blobs/{root_digest.hash}/{root_digest.size_bytes}:getTree" };
   }
+
+  // Split a blob into chunks.
+  //
+  // Clients can use this API before downloading a blob to determine which parts
+  // of the blob are already present locally and do not need to be downloaded
+  // again.
+  //
+  // The blob is split into chunks which are individually stored in the CAS. A
+  // list of the chunk digests is returned in the order in which the chunks have
+  // to be concatenated to assemble the requested blob.
+  //
+  // Using this API is optional but it allows clients to download only the
+  // missing parts of a blob instead of the entire blob data, which in turn can
+  // considerably reduce network traffic.
+  //
+  // Errors:
+  //
+  // * `NOT_FOUND`: The requested blob is not present in the CAS.
+  // * `RESOURCE_EXHAUSTED`: There is insufficient disk quota to store the blob
+  //   chunks.
+  rpc SplitBlob(SplitBlobRequest) returns (SplitBlobResponse) {
+    option (google.api.http) = { get: "/v2/{instance_name=**}/blobs/{blob_digest.hash}/{blob_digest.size_bytes}:splitBlob" };
+  }
 }
 
 // The Capabilities service may be used by remote execution clients to query
@@ -1601,6 +1624,27 @@
 }
 
 // A request message for
+// [ContentAddressableStorage.SplitBlob][build.bazel.remote.execution.v2.ContentAddressableStorage.SplitBlob].
+message SplitBlobRequest {
+  // The instance of the execution system to operate against. A server may
+  // support multiple instances of the execution system (with their own workers,
+  // storage, caches, etc.). The server MAY require use of this field to select
+  // between them in an implementation-defined fashion, otherwise it can be
+  // omitted.
+  string instance_name = 1;
+
+  // The digest of the blob to be splitted.
+  Digest blob_digest = 2;
+}
+
+// A response message for
+// [ContentAddressableStorage.SplitBlob][build.bazel.remote.execution.v2.ContentAddressableStorage.SplitBlob].
+message SplitBlobResponse {
+  // The digests of the chunks into in which the blob was splitted.
+  repeated Digest chunk_digests = 1;
+}
+
+// A request message for
 // [Capabilities.GetCapabilities][build.bazel.remote.execution.v2.Capabilities.GetCapabilities].
 message GetCapabilitiesRequest {
   // The instance of the execution system to operate against. A server may