locked-atomic-ws
A combination of fs-write-stream-atomic and node-proper-lockfile to ensure that no more than one (atomic) write stream can be used at a time for a certain file. Since atomically streaming to a file requires a temporary file (&& fs.rename afterwords), aquiring a lock means preventing work in vain.
Example
var fs = ;var getWriteStream = ; ; { throw err;}
Status
Alpha, read the source code for more info on how this works. Needs tests.