One build. See all 3 kept builds.
Two puzzles you flagged, both fixed rather than struck, plus the bench being less annoying to test with.
You were right, and it was worst at the EASIEST rung. Measured over twenty seeds a difficulty:
difficulty 1: 9 boards in 20 had NO solution at all difficulty 3: 3 with none, and 7 more solvable only by a pair cut difficulty 5: none unsolvable, but 9 in 20 needed a pair
Unsolvable boards were dealt anyway. And the "pair" ones were arguably worse, because they looked fine: the generator proved those by cutting two ropes AT THE SAME INSTANT, which hands cannot do. You cut one, the rig swings, and the second cut happens in a different world.
The cause was doing it backwards - roll a random target port, then go hunting for a cut that reaches it. It now simulates each cut, sees where the payload actually lands, and makes one of those the target. Every board is solvable by construction, always with ONE cut. 150 seeds across all five difficulties, zero failures.
Two-tether boards are gone as well. With two ropes the only cut that releases the payload is cutting both, which is the "slash everything" answer this puzzle exists to refuse. Two tethers was not an easy version of it, it was a broken one.
Each node you could step to showed "-26 +40". Two numbers, no units, and nothing on screen saying which was the cost and which the gain - while that pair IS the whole decision. The node's kind was a single initial in its own colour on a dark disc, which read as a smudge, and nothing said what winning was.
Now the numbers are labelled, every legible node names its kind in the colour of its meter in the WATCHING row, and the goal is stated. At difficulty 3 the trade-off reads at a glance: CORE at 26 noise for +40 progress, against RELAY at 6 for +6. That was always the puzzle. None of it was reaching you.
Still tell me if it earns its place. That part is a play call and I have only made it legible, not proved it is fun.
Without it a falling-block well is a reaction test - you cannot decide where THIS piece goes without knowing what follows it.
At every board size. They were being stretched to fill a fixed rectangle, worst at the low difficulties.