1. A computer-implemented method comprising: receiving, from a first user device associated with a first user, a signal stream automatically generated by the first user device, the signal stream including first data that identifies a second user device detected by a sensor of the first user device as being present within a detection range of the sensor of the first user device; receiving, from the first user device, a first event stream including a first event associated with the first user, the first event generated by the first user device based upon first activities of the first user, the first activities of the first user determined by the first user device based on the signal stream; determining a second user associated with the second user device based on the first data included in the signal stream; determining whether the second user has a connection with the first user on an online service; responsive to determining that the second user has the connection with the first user on the online service and the second user device is detected by the sensor of the first user device as being present within the detection range of the sensor of the first user device, retrieving a second event stream associated with the second user and including one or more events generated by the second user device; identifying, from the one or more events in the second event stream, a second event based on a comparison to the first event associated with the first user; transmitting, to the first user device, the second event associated with the second user and an instruction that causes the first user device to include the second event associated with the second user in the first event stream associated with the first user on the first user device; updating the first event stream of the first user with the second event associated with the second user to generate a third event stream; and transmitting, to the first user device, the third event stream and an instruction that causes the first user device to synchronize the first event stream on the first user device with the third event stream.