Unable to use Google Well Known Types with @grpc/reflection and @grpc/proto-loader

[LeoWesterberg]

Problem description

When using @grpc/proto-loader to load a .proto file that imports Google Well-Known Types (for example, google/protobuf/struct.proto), the server reflection fails to recognize those types at runtime.

Although proto-loader correctly builds and adds the Google WKTs to the packageDefinition object, running grpcurl with service reflection enabled produces the following error:

cannot resolve type: "*.google.protobuf.Duration" not found
A similar issue has been discussed here: fullstorydev/grpcurl#459

Reproduction Steps

Proto:

syntax = "proto3";

package multiply_function;

import "google/protobuf/duration.proto";

message Request {
  int32 op1 = 1;
  int32 op2 = 2;
}

message Response {
  int32 prod = 1;
  google.protobuf.Duration processing_time = 3;  // How long the calculation took
}

service Multiply {
  rpc multiply (Request) returns (Response);
}

// Load a .proto file that imports a Google well-known type
const packageDefinition = await load(protoFile);

// Create and register the ReflectionService
const reflectionService = new ReflectionService(packageDefinition);
reflectionService.addToServer(grpcServer);

Environment

Node.js: v22.14.0

Dependencies:
@grpc/grpc-js: 1.13.3
@grpc/proto-loader: 0.7.15
@grpc/reflection: 1.0.4

Additional context

I’ve also tried supplying complete file descriptors—including the Google WKTs, but the issue persists. Any help would be greatly appreciated!