What is a line

[placeholder] Body content for this entry will be written by the copy chat. The entry covers what a line is, why connections are first-class objects in Tree, and how they differ from the dependency fields you see in list-shaped tools.

In Tree, a line points from a prerequisite node to a dependent node. When the prerequisite completes, the dependent's lock can lift. Graph theory calls these edges; the product always says line or connection.

Because connections are stored as their own records rather than as fields on a node, every dependency-aware operation (critical path, reachability, topological sort) is a graph query rather than a special case.