The root problem is that I want to update the build status for a diff that has been pushed to a staging area. What I have is the Diff ID. What I need is the PHID of the associated harbormaster build. I believe that if I can get the PHID of the Diff, I can use harbormaster.querybuildables to get the PHID of the Build, and harbormaster.sendmessage to update the Build status. The problem I am having is that I cannot get the PHID for the diff.
phid.lookup can be used to get the PHID of Revisions by name (D123), but not Diffs (Diff 1234). I am able to get both by their respective PHIDs. It would be very useful to also be able to get the PHID for a diff if all I have is the Diff Id.