A collection-synchronizing system synchronizes a local data collection with a remote device. During operation, the system can detect the remote device, and receives collection summaries for one or more data collections stored at the remote device. A collection summary can include at least one additive hash value that represents one or more content items of a data collection. Then, for a data collection that exists at the local device and the remote device, the system compares a remote additive hash value for the remote data collection with a local additive hash value for the local data collection. If the system determines that the local additive hash value does not match the remote additive hash value, the system synchronizes structured names for the data collection at the local device and the remote device.