Hyperlanes Save Scenario
Hyperlanes join systems. You can draw them one at a time, in broad strokes with a brush, or between every system you select.
Draw a hyperlane
Zoom in until a ring appears around a star, then drag from the ring to another system. Shift+drag from the star works at any zoom.

Cut a hyperlane
Hover a lane and click the "×" at its middle. Right-click a system and select "Isolate" to remove all its lanes.
Right-clicking a lane also offers Cut.

Link or cut several systems at once
With two or more systems selected, the Inspector's Hyperlanes section can add lanes between them or cut them. It has an Add lanes block and a Remove lanes block.
In Add lanes, the Link choice sets which lanes the button adds. Every pair links each selected system to every other one, and works on up to 5 systems. Nearby connects each system to the systems near it, so it suits a large selection. Its Density slider sets how many lanes it adds. The left end lays the fewest lanes, and the new lanes form no loops of their own. At the right end, each system links to every neighbour. Like the game is ticked by default. It links the selection in small clusters joined by single lanes, as the game does. Untick it for an even spread of lanes. Point at the "Add N lanes" button to preview the new lanes on the map.
Remove lanes has "Cut lanes between them" and "Isolate them". Cut lanes removes only the lanes that join two selected systems. Isolate removes every lane from each selected system, including lanes to systems outside the selection. Each button shows how many lanes or systems it changes.
The right-click menu on a selected system has the same actions: "Link every pair", "Link nearby", "Cut lanes between them" and "Isolate them". Each shows a count in brackets.
Join a split galaxy
When the galaxy is in separate pieces, click "Join" beside Components in the Inspector. It connects the pieces with the shortest hyperlanes that don't cross any others.
Reset a lane's length Save
The game uses a hyperlane's stored length as its travel cost. A lane's page marks the length with "!" when it doesn't match the distance between its systems. Click "Reset length" on the lane's page, or right-click the lane and select "Reset length". Either sets the length to that distance. With several systems selected, "Reset lane lengths" in the Inspector's Hyperlanes section resets the lanes of those systems whose length is off.
Prevent a lane Scenario
Right-click a hyperlane and select "Cut and prevent" so the game never generates it. Right-click a prevented lane and select "Allow" to undo that.