Hydrant and GitHub Issues
GitHub Issues keeps tasks beside code and pull requests; Hydrant gives a small human-and-agent team a separate delivery workspace.
Hydrant and Linear
Both trackers work with agents. The useful choice is about the size and shape of the work around them.
Hydrant and Markdown files
Markdown task files are cheap, portable and reviewable; Hydrant supplies shared state and coordination that a repository must otherwise maintain.
Atom feed. For people who still own an RSS reader, and agents.