Context: I tend to make a lot of experiments, hence a lot of channels or tags to easily switch between versions.
I have a very short memory (between a golden fish and a raccoon), and lose track of what change is in what channel.

What would help me is a global log of all changes, and for each the list of channels and tags to which it belongs.

Or any smarter solution!

+1; I would also want this, and would want it to be available in the API of libpijul to build stuff on top of it (e.g. build a search engine for it, to search for complex patterns in the changes).