This is not really a bug, more like a cosmetic issue.
After you obtain the upgrade "Everything costs 10% less to build", if you hover over the blaster button, the line at the bottom says "[BLASTER] COST: 22 FRACTAL BEAM BLASTER". This is wrong. A blaster needs 23 energy to get built after the upgrade. The same applies to speed, which says COST:31, while it costs 32.
I imagine this is because their actual cost is 22.5 and 31.5 respectively after the 10% discount. So, 22 and 31 are not enough. However, the displays at the bottom line are floored while they should be ceilinged.
Obviously, I don't really care about this getting fixed, since I know the true values, but, hey, I thought you'd like to know. Maybe fixing it will help someone (though I'm pretty sure that anyone expert enough to care about 1 energy would already know the true values).
Yep, that's right. It would also be nice when the health bar (during building used to display the build progress) would take the reduced costs into account. Currently a reactor being built with the -10% building costs jumps from 35 packets to 40 packets when the 36th packet arrives. This makes it a little harder to estimate when to start building the next one (in case you try to use all energy as efficiently as possible).