0039. Connection points on the whole border

Status: accepted (connector-border-points change, 13 October 2026)

Context

With 1.4, a dragged end snapped to the middle and quarters of each side, and connections started only from four dots at the middles of a selected box’s sides. The owner asked for more: any point of a box’s border should be a connection point, and recomputing the layout should let the engine choose the points again. arrange with scope all removed waypoints but kept every port and point, so a recomputed diagram still carried the hand-picked ends.

Decision

• Any point of the border. Within 12 screen pixels of a box’s border, inside or outside, a dragged end takes the pointer’s projection on the nearest side, to 1 %. Magnets win within 6 px: the middle of each side, the four corners and the named ports; Alt turns them off. Further inside the end is free. The overlay shows the outline, the magnets and the point taken.
• Starting on the border. Within 8 px outside a box’s border, where no handle or connector is, the canvas shows the point a connection would start from and a crosshair; a press there starts a connection pinned at that point. The canvas protocol’s connect pins its start and its end independently. Sequence diagrams and C4 views have no routes and pin nothing.
• Recompute frees the ends. arrange with scope all removes compass sides and points from route ends along with waypoints, keeps named ports, and removes routes left with nothing. Arranging only the unplaced elements leaves routes alone.

Alternatives considered

• More fixed points (eighths, sixteenths). Still a set of points, which is what the owner asked to go beyond, and harder to read on small boxes.
• A ring inside the box. It would compete with selecting and moving the box; outside the border a press can only mean a connection.
• Keeping pinned ends on Recompute. Hand-picked points often stop making sense once boxes move; undo restores them, and arranging the unplaced keeps them.

Consequences

• No language change: routes already took any percentage (decision 0038). No existing drawing changes.
• layout --all and Recompute Layout write fewer route statements; files that relied on them keeping compass sides get the engine’s choice instead.