Bottleneck explainer for production networks

No technique in the dataset is linked to production chains, yet one of the mechanic's documented failure modes is diagnosis: starvation far upstream is hard to see, so players blame the wrong building. Differentiable or finite-difference sensitivity of output to each machine, buffer, and route identifies the binding constraint exactly; a constrained language layer turns that into a short explanation with links to the machines involved. The same tool supports designers checking recipe balance.

A bottleneck lens colors every producer by how much one more unit of it would raise the selected output, and a sentence explains the top constraint ('circuits are limited by copper cable, which is starved because the smelter column shares a belt with iron'). Clicking jumps to the machine.

Implement sensitivity analysis over a factory prototype's production graph and test whether players fix an injected bottleneck faster with the lens. Success: 50 percent faster fixes with no drop in reported satisfaction among experienced players when the lens is optional.

• Players who enjoy diagnosis lose the puzzle; must be optional or costly.
• Nonlinear buffers make one-step sensitivity misleading.
• Explanations wrong in edge cases erode trust.

The text above states findings about this dataset. The build fails (E032) if any of these stops holding.

• derived.production-chain.technique_count == 0