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Steps to reproduce: set intrinsic quality bonus of a machine very high so that module changes cannot bring the chance below 100%. Start producing items from normal ingredients, note they're all above normal quality. Add a speed module mid-craft and note a single normal output appears. Also happens if there are quality modules in the machine and you remove one or you place a speed beacon.

Expected behavior: either quality is rolled when crafting begins and that result is locked in, or quality is rolled based on the machine's state at the moment the result is produced.

Admittedly a minor corner case based around giving things levels of stats they were not designed to have. This could e.g. cause belt contamination when switching out modules when using a mod that greatly boosts quality chances but limits maximum_quality_jump to 1 and having built a system without quality filters because they aren't needed during normal operation (which was what the mod I was testing when I discovered this does, and why it was so annoying)

planetfall wrote: Mon May 04, 2026 8:55 am Expected behavior: either quality is rolled when crafting begins and that result is locked in, or quality is rolled based on the machine's state at the moment the result is produced.

Both of these are exploitable by controlling speed beacons with power switches. Currently quality is rolled at the start and any loss in quality chance invalidates the quality roll (see this post).
(Ideally the quality roll would be evaluated according to the lowest chance observed during the craft, but that means storing that chance and the initial roll, which will require more memory, which is something that's frequently rejected by the devs.)

tl;dr: not a bug

This bug report lives in a grey area of "working as intended" for 2.0, and "fixed for 2.1" because this logic was already changed for 2.1 due to unrelated features.

Given there will be a behavior change that seems to align with your expected outcome, i will classify this as Fixed for 2.1 -> product will be based on lowest quality effect that was seen by the machine during the entire crafting process as to avoid abuses.