diff --git a/src/main/java/com/google/devtools/build/lib/remote/logging/BUILD b/src/main/java/com/google/devtools/build/lib/remote/logging/BUILD
index 46a9b5f..b9fced4 100644
--- a/src/main/java/com/google/devtools/build/lib/remote/logging/BUILD
+++ b/src/main/java/com/google/devtools/build/lib/remote/logging/BUILD
@@ -19,6 +19,7 @@
         "//src/main/java/com/google/devtools/build/lib/util/io",
         "//src/main/protobuf:remote_execution_log_java_proto",
         "//third_party:flogger",
+        "//third_party:guava",
         "//third_party:jsr305",
         "//third_party/grpc:grpc-jar",
         "//third_party/protobuf:protobuf_java",
diff --git a/src/main/java/com/google/devtools/build/lib/remote/logging/LoggingInterceptor.java b/src/main/java/com/google/devtools/build/lib/remote/logging/LoggingInterceptor.java
index c673894..8cffbae 100644
--- a/src/main/java/com/google/devtools/build/lib/remote/logging/LoggingInterceptor.java
+++ b/src/main/java/com/google/devtools/build/lib/remote/logging/LoggingInterceptor.java
@@ -74,6 +74,8 @@
       return new ReadHandler(); // <ReadRequest, ReadResponse>
     } else if (method == ByteStreamGrpc.getWriteMethod()) {
       return new WriteHandler(); // <WriteRequest, WriteResponse>
+    } else if (method == ByteStreamGrpc.getQueryWriteStatusMethod()) {
+      return new QueryWriteStatusHandler(); // <QueryWriteStatusRequest, QueryWriteStatusResponse>
     } else if (method == CapabilitiesGrpc.getGetCapabilitiesMethod()) {
       return new GetCapabilitiesHandler(); // <GetCapabilitiesRequest, ServerCapabilities>
     }
diff --git a/src/main/java/com/google/devtools/build/lib/remote/logging/QueryWriteStatusHandler.java b/src/main/java/com/google/devtools/build/lib/remote/logging/QueryWriteStatusHandler.java
new file mode 100644
index 0000000..26ec94f
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/remote/logging/QueryWriteStatusHandler.java
@@ -0,0 +1,41 @@
+// Copyright 2021 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.devtools.build.lib.remote.logging;
+
+import com.google.bytestream.ByteStreamProto.QueryWriteStatusRequest;
+import com.google.bytestream.ByteStreamProto.QueryWriteStatusResponse;
+import com.google.devtools.build.lib.remote.logging.RemoteExecutionLog.QueryWriteStatusDetails;
+import com.google.devtools.build.lib.remote.logging.RemoteExecutionLog.RpcCallDetails;
+
+/** LoggingHandler for {@link google.bytestream.QueryWriteStatus} gRPC call. */
+public class QueryWriteStatusHandler
+    implements LoggingHandler<QueryWriteStatusRequest, QueryWriteStatusResponse> {
+  private final QueryWriteStatusDetails.Builder builder = QueryWriteStatusDetails.newBuilder();
+
+  @Override
+  public void handleReq(QueryWriteStatusRequest message) {
+    builder.setRequest(message);
+  }
+
+  @Override
+  public void handleResp(QueryWriteStatusResponse message) {
+    builder.setResponse(message);
+  }
+
+  @Override
+  public RpcCallDetails getDetails() {
+    return RpcCallDetails.newBuilder().setQueryWriteStatus(builder).build();
+  }
+}
diff --git a/src/main/java/com/google/devtools/build/lib/remote/logging/WriteHandler.java b/src/main/java/com/google/devtools/build/lib/remote/logging/WriteHandler.java
index 67e9e37..b506295 100644
--- a/src/main/java/com/google/devtools/build/lib/remote/logging/WriteHandler.java
+++ b/src/main/java/com/google/devtools/build/lib/remote/logging/WriteHandler.java
@@ -16,24 +16,40 @@
 
 import com.google.bytestream.ByteStreamProto.WriteRequest;
 import com.google.bytestream.ByteStreamProto.WriteResponse;
+import com.google.common.collect.Iterables;
 import com.google.devtools.build.lib.remote.logging.RemoteExecutionLog.RpcCallDetails;
 import com.google.devtools.build.lib.remote.logging.RemoteExecutionLog.WriteDetails;
+import java.util.ArrayList;
 import java.util.LinkedHashSet;
+import java.util.List;
 import java.util.Set;
 
 /** LoggingHandler for {@link google.bytestream.Write} gRPC call. */
 public class WriteHandler implements LoggingHandler<WriteRequest, WriteResponse> {
   private final WriteDetails.Builder builder = WriteDetails.newBuilder();
   private final Set<String> resources = new LinkedHashSet<>();
+  private final List<Long> offsets = new ArrayList<>();
+  private final List<Long> finishWrites = new ArrayList<>();
+  private long bytesSentInSequence = 0;
   private long numWrites = 0;
   private long bytesSent = 0;
 
   @Override
   public void handleReq(WriteRequest message) {
     resources.add(message.getResourceName());
+    long writeOffset = message.getWriteOffset();
+    if (numWrites == 0 || Iterables.getLast(offsets) + bytesSentInSequence != writeOffset) {
+      offsets.add(writeOffset);
+      bytesSentInSequence = 0;
+    }
+    int size = message.getData().size();
+    if (message.getFinishWrite()) {
+      finishWrites.add(writeOffset + size);
+    }
 
     numWrites++;
-    bytesSent += message.getData().size();
+    bytesSent += size;
+    bytesSentInSequence += size;
   }
 
   @Override
@@ -44,6 +60,8 @@
   @Override
   public RpcCallDetails getDetails() {
     builder.addAllResourceNames(resources);
+    builder.addAllOffsets(offsets);
+    builder.addAllFinishWrites(finishWrites);
     builder.setNumWrites(numWrites);
     builder.setBytesSent(bytesSent);
     return RpcCallDetails.newBuilder().setWrite(builder).build();
diff --git a/src/main/protobuf/remote_execution_log.proto b/src/main/protobuf/remote_execution_log.proto
index 84a07d6..b3f265a 100644
--- a/src/main/protobuf/remote_execution_log.proto
+++ b/src/main/protobuf/remote_execution_log.proto
@@ -16,11 +16,11 @@
 
 package remote_logging;
 
-import "build/bazel/remote/execution/v2/remote_execution.proto";
-import "google/protobuf/timestamp.proto";
 import "google/bytestream/bytestream.proto";
 import "google/longrunning/operations.proto";
+import "google/protobuf/timestamp.proto";
 import "google/rpc/status.proto";
+import "build/bazel/remote/execution/v2/remote_execution.proto";
 
 option java_package = "com.google.devtools.build.lib.remote.logging";
 
@@ -83,7 +83,7 @@
 // Details for a call to
 // build.bazel.remote.execution.v2.ActionCache.UpdateActionResult.
 message UpdateActionResultDetails {
-  // The build.bazel.remote.execution.v2.GetActionResultRequest sent by
+  // The build.bazel.remote.execution.v2.UpdateActionResultRequest sent by
   // the call.
   build.bazel.remote.execution.v2.UpdateActionResultRequest request = 1;
 
@@ -128,10 +128,24 @@
 message WriteDetails {
   // The names of resources requested to be written to in this call in the order
   // they were first requested in. If the ByteStream protocol is followed
-  // according to specification, this should only contain have a single element,
-  // which is the resource name specified in the first message of the stream.
+  // according to specification, this should contain at most two elements:
+  // The resource name specified in the first message of the stream, and an
+  // empty string specified in each successive request if num_writes > 1.
   repeated string resource_names = 1;
 
+  // The offsets sent for the initial request and any non-sequential offsets
+  // specified over the course of the call. If the ByteStream protocol is
+  // followed according to specification, this should contain a single element
+  // which is the starting point for the write call.
+  repeated int64 offsets = 5;
+
+  // The effective final size for each request sent with finish_write true
+  // specified over the course of the call. If the ByteStream protocol is
+  // followed according to specification, this should contain a single element
+  // which is the total size of the written resource, including the initial
+  // offset.
+  repeated int64 finish_writes = 6;
+
   // The number of writes performed in this call.
   int64 num_writes = 2;
 
@@ -142,6 +156,15 @@
   google.bytestream.WriteResponse response = 4;
 }
 
+// Details for a call to google.bytestream.QueryWriteStatus.
+message QueryWriteStatusDetails {
+  // The google.bytestream.QueryWriteStatusRequest sent by the call.
+  google.bytestream.QueryWriteStatusRequest request = 1;
+
+  // The received google.bytestream.QueryWriteStatusResponse.
+  google.bytestream.QueryWriteStatusResponse response = 2;
+}
+
 // Contains details for specific types of calls.
 message RpcCallDetails {
   reserved 1 to 4, 11;
@@ -152,6 +175,7 @@
     FindMissingBlobsDetails find_missing_blobs = 10;
     ReadDetails read = 5;
     WriteDetails write = 6;
+    QueryWriteStatusDetails query_write_status = 14;
     GetCapabilitiesDetails get_capabilities = 12;
     UpdateActionResultDetails update_action_result = 13;
   }
diff --git a/src/test/java/com/google/devtools/build/lib/remote/logging/LoggingInterceptorTest.java b/src/test/java/com/google/devtools/build/lib/remote/logging/LoggingInterceptorTest.java
index 17ee021..3b1ca9a 100644
--- a/src/test/java/com/google/devtools/build/lib/remote/logging/LoggingInterceptorTest.java
+++ b/src/test/java/com/google/devtools/build/lib/remote/logging/LoggingInterceptorTest.java
@@ -49,6 +49,8 @@
 import com.google.bytestream.ByteStreamGrpc.ByteStreamBlockingStub;
 import com.google.bytestream.ByteStreamGrpc.ByteStreamImplBase;
 import com.google.bytestream.ByteStreamGrpc.ByteStreamStub;
+import com.google.bytestream.ByteStreamProto.QueryWriteStatusRequest;
+import com.google.bytestream.ByteStreamProto.QueryWriteStatusResponse;
 import com.google.bytestream.ByteStreamProto.ReadRequest;
 import com.google.bytestream.ByteStreamProto.ReadResponse;
 import com.google.bytestream.ByteStreamProto.WriteRequest;
@@ -58,6 +60,7 @@
 import com.google.devtools.build.lib.remote.logging.RemoteExecutionLog.GetActionResultDetails;
 import com.google.devtools.build.lib.remote.logging.RemoteExecutionLog.GetCapabilitiesDetails;
 import com.google.devtools.build.lib.remote.logging.RemoteExecutionLog.LogEntry;
+import com.google.devtools.build.lib.remote.logging.RemoteExecutionLog.QueryWriteStatusDetails;
 import com.google.devtools.build.lib.remote.logging.RemoteExecutionLog.ReadDetails;
 import com.google.devtools.build.lib.remote.logging.RemoteExecutionLog.RpcCallDetails;
 import com.google.devtools.build.lib.remote.logging.RemoteExecutionLog.UpdateActionResultDetails;
@@ -854,6 +857,10 @@
                         WriteDetails.newBuilder()
                             .addResourceNames("test1")
                             .addResourceNames("test2")
+                            .addOffsets(0)
+                            .addOffsets(0)
+                            .addOffsets(0)
+                            // finish write is empty
                             .setResponse(response)
                             .setBytesSent(9)
                             .setNumWrites(3)))
@@ -866,6 +873,81 @@
   }
 
   @Test
+  public void testWriteCallOffsetAndFinishWriteCompounding() {
+    WriteRequest request1 =
+        WriteRequest.newBuilder()
+            .setResourceName("test1")
+            .setData(ByteString.copyFromUtf8("abc"))
+            .setWriteOffset(10)
+            .build();
+    WriteRequest request2 =
+        WriteRequest.newBuilder()
+            .setData(ByteString.copyFromUtf8("def"))
+            .setWriteOffset(request1.getWriteOffset() + request1.getData().size())
+            .build();
+    WriteResponse response = WriteResponse.newBuilder().setCommittedSize(6).build();
+    serviceRegistry.addService(
+        new ByteStreamImplBase() {
+          @Override
+          public StreamObserver<WriteRequest> write(StreamObserver<WriteResponse> streamObserver) {
+            return new StreamObserver<WriteRequest>() {
+              @Override
+              public void onNext(WriteRequest writeRequest) {}
+
+              @Override
+              public void onError(Throwable throwable) {}
+
+              @Override
+              public void onCompleted() {
+                streamObserver.onNext(response);
+                streamObserver.onCompleted();
+              }
+            };
+          }
+        });
+    ByteStreamStub stub = ByteStreamGrpc.newStub(loggedChannel);
+    @SuppressWarnings("unchecked")
+    StreamObserver<WriteResponse> responseObserver = Mockito.mock(StreamObserver.class);
+
+    clock.advanceMillis(10000);
+    // Request three writes, the first identical with the third, but offset correctly and
+    // finish_writing
+    StreamObserver<WriteRequest> requester = stub.write(responseObserver);
+    requester.onNext(request1);
+    clock.advanceMillis(100);
+    requester.onNext(request2);
+    clock.advanceMillis(200);
+    requester.onNext(
+        request1.toBuilder()
+            .setWriteOffset(request2.getWriteOffset() + request2.getData().size())
+            .setFinishWrite(true)
+            .build());
+    clock.advanceMillis(100);
+    requester.onCompleted();
+
+    LogEntry expectedEntry =
+        LogEntry.newBuilder()
+            .setMethodName(ByteStreamGrpc.getWriteMethod().getFullMethodName())
+            .setDetails(
+                RpcCallDetails.newBuilder()
+                    .setWrite(
+                        WriteDetails.newBuilder()
+                            .addResourceNames("test1")
+                            .addResourceNames("")
+                            .addOffsets(request1.getWriteOffset())
+                            .addFinishWrites(
+                                10 + request1.getData().size() * 2 + request2.getData().size())
+                            .setResponse(response)
+                            .setBytesSent(9)
+                            .setNumWrites(3)))
+            .setStatus(com.google.rpc.Status.getDefaultInstance())
+            .setStartTime(Timestamp.newBuilder().setSeconds(10))
+            .setEndTime(Timestamp.newBuilder().setSeconds(10).setNanos(400000000))
+            .build();
+    verify(logStream).write(expectedEntry);
+  }
+
+  @Test
   public void testWriteCallFail() {
     WriteRequest request =
         WriteRequest.newBuilder()
@@ -881,7 +963,6 @@
             return Mockito.mock(StreamObserver.class);
           }
         });
-
     ByteStreamStub stub = ByteStreamGrpc.newStub(loggedChannel);
     @SuppressWarnings("unchecked")
     StreamObserver<WriteResponse> responseObserver = Mockito.mock(StreamObserver.class);
@@ -894,7 +975,6 @@
     requester.onError(error.asRuntimeException());
 
     Status expectedCancel = Status.CANCELLED.withCause(error.asRuntimeException());
-
     LogEntry expectedEntry =
         LogEntry.newBuilder()
             .setMethodName(ByteStreamGrpc.getWriteMethod().getFullMethodName())
@@ -907,12 +987,50 @@
                     .setWrite(
                         WriteDetails.newBuilder()
                             .addResourceNames("test")
+                            .addOffsets(0)
                             .setNumWrites(1)
                             .setBytesSent(3)))
             .setStartTime(Timestamp.newBuilder().setSeconds(10000000))
             .setEndTime(Timestamp.newBuilder().setSeconds(20000000))
             .build();
+    verify(logStream).write(expectedEntry);
+  }
 
+  @Test
+  public void testQueryWriteStatusCallOk() {
+    QueryWriteStatusRequest request =
+        QueryWriteStatusRequest.newBuilder().setResourceName("test").build();
+    QueryWriteStatusResponse response =
+        QueryWriteStatusResponse.newBuilder().setCommittedSize(10).build();
+    serviceRegistry.addService(
+        new ByteStreamImplBase() {
+          @Override
+          public void queryWriteStatus(
+              QueryWriteStatusRequest request,
+              StreamObserver<QueryWriteStatusResponse> responseObserver) {
+            clock.advanceMillis(22222);
+            responseObserver.onNext(response);
+            responseObserver.onCompleted();
+          }
+        });
+    ByteStreamBlockingStub stub = ByteStreamGrpc.newBlockingStub(loggedChannel);
+
+    clock.advanceMillis(11111);
+    stub.queryWriteStatus(request);
+
+    LogEntry expectedEntry =
+        LogEntry.newBuilder()
+            .setMethodName(ByteStreamGrpc.getQueryWriteStatusMethod().getFullMethodName())
+            .setDetails(
+                RpcCallDetails.newBuilder()
+                    .setQueryWriteStatus(
+                        QueryWriteStatusDetails.newBuilder()
+                            .setRequest(request)
+                            .setResponse(response)))
+            .setStatus(com.google.rpc.Status.getDefaultInstance())
+            .setStartTime(Timestamp.newBuilder().setSeconds(11).setNanos(111000000))
+            .setEndTime(Timestamp.newBuilder().setSeconds(33).setNanos(333000000))
+            .build();
     verify(logStream).write(expectedEntry);
   }
 }