We provide a complete source snapshots for every release of UGENE. Usual release period is ~ 6 weeks so you are always have fresh sources.

There are no public SVN repository today due to several reasons.
The most important one: the source code base of UGENE v1.x is not stable enough and our local repository is not correctly organized today, it contains a lot of alpha-stage plugins that are not planned to be released at all.

We plan to do the required repository cleanup and API stabilization in v2.0 of UGENE. This version is expected during the next year. Before that we are ready to accept source-level patches for the snapshot or just a feature/api requests from our users.