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I'm not sure this is a bug; it looks like a deliberate change. I've noticed in 2.1 that labs are now eager consumers instead of lazy consumers.

Previously, with the setup below, science packs would've been moved all the way down to the lower-left. Now science packs are consumed by the first lab they encounter, and packs only move further when the current labs are full.

I haven't seen this in the notes for 2.1.7 or 2.1.8, so I'm curious when (and why) this was changed and whether it was intentional.

Not a bug.

I would note that with the previous lazy-consumer design, it was easier to know where to prioritize e.g. productivity modules: In the furthest-away labs.

With the new eager-consumer labs, which lab consumes a science pack seems somewhat less deterministic with the same setup.

boskid wrote: Sun Jun 28, 2026 9:14 amNot a bug.

OK, but when and why was it changed?

Still not a bug.

Change is that science packs are no longer tools so labs will consume science pack in 1 tick and then do reserach from internally tracked remaining durability. Previously the science packs would be partially used up by a lab on the top of the chain during that 1 tick but the item would stay in the inventory and inserter was able to move those partially used (often almost depleted) science packs down the chain. Having partially used up science packs moved between labs was causing problems with item production statistics (merging 2 partially used up science packs could lead to a science pack lost without tracking by statistics), would cause daisy chaining labs to suffer from transfer of used up science packs, would cause problems with recycling science packs allowing to get extra 25% science from a depleted science pack item, and science packs on belts were taking extra amount of memory just to track durability of each stack of science pack even if they were almost always full.

boskid wrote: Sun Jun 28, 2026 9:15 am Still not a bug.

I don't doubt your word.

Kyralessa wrote: Sun Jun 28, 2026 9:15 am ...but when and why was it changed?

Kyralessa wrote: Sun Jun 28, 2026 9:15 am OK, but when and why was it changed?

2.1.7 Changelog:

TechnologyPrototype and LabPrototype now accept any item type as research ingredients. Changed all science packs to be plain items.

And here are 4 reasons Why:

boskid wrote: Sun Jun 28, 2026 9:15 am

• Having partially used up science packs moved between labs was causing problems with item production statistics (merging 2 partially used up science packs could lead to a science pack lost without tracking by statistics)
• would cause daisy chaining labs to suffer from transfer of used up science packs
• would cause problems with recycling science packs allowing to get extra 25% science from a depleted science pack item
• science packs on belts were taking extra amount of memory just to track durability of each stack of science pack even if they were almost always full.

Good Luck!

eugenekay wrote: Sun Jun 28, 2026 2:39 pm And here are 4 reasons Why:

That was all edited in after I posted, which is why I asked the question instead of just reading that.

boskid wrote: Sun Jun 28, 2026 9:15 am Change is that science packs are no longer tools so labs will consume science pack in 1 tick and then do reserach from internally tracked remaining durability. Previously the science packs would be partially used up by a lab on the top of the chain during that 1 tick but the item would stay in the inventory and inserter was able to move those partially used (often almost depleted) science packs down the chain. Having partially used up science packs moved between labs was causing problems with item production statistics (merging 2 partially used up science packs could lead to a science pack lost without tracking by statistics), would cause daisy chaining labs to suffer from transfer of used up science packs, would cause problems with recycling science packs allowing to get extra 25% science from a depleted science pack item, and science packs on belts were taking extra amount of memory just to track durability of each stack of science pack even if they were almost always full.

Thank you for the info.