We have several SVN repositories set up to be pulled/monitored.
When we create a differential revision within Phabricator from a diff patch created from a local checkout, context is not available.
Even after setting the repository in the revision there is not context available.
We haven not tried using arc yet.

Should this work?
Are there requirements for context to be provided? Do the paths between patch and tracked repository have to match 100 % (rather than sub-paths being identified)?

The repository does not have a “Import Only” set. Thus, its content are folders like trunk and branches. (Our branches are in subfolders of branches e.g. branches/features - which should not matter here though.)