8. A non-transitory computer-readable medium including one or more sequences of instructions that, when executed by one or more processors of a content management system, causes: storing, in the content management system, a first reference to a document managed by a collaboration system remote from the content management system, where the content management system is distinct from the collaboration system and stored therein; receiving a first message from the collaboration system, the first message including document metadata corresponding to the document in the collaboration system; synchronizing the first reference to the document with a first client device, such that the first reference is stored via a local file system managed by the first client as a first local reference to the document; mapping the first reference in the content management system to the first local reference in the first client device; in response to receiving the first message, saving, in the content management system, the document metadata received in the first message as metadata for the first reference; synchronizing the first reference metadata with the first client device detecting, by the processor of the content management system, a second reference to the document in the collaboration system as a result of the first client device sharing the first local reference with a second client device; updating the mapping between the first reference and the first local reference, such that the second reference is stored via a second local file system managed by the second client as a second local reference to the document; and upon detecting a change by the first client device to the first reference to the document, synchronizing the change with the second local reference to the document.
13. The non-transitory computer-readable medium of claim 8 , wherein the content management system and the collaboration system are distinct systems.