Productivity Modules cannot be used for some intermediate products

[BarkyMacDarbydale]

As in title, Productivity Modules cannot be used in some intermediate products - specifically I have found Acid Neutralisation and Steam Condensation to not allow it. These recipes are in the 'Intermediate Product' category, yet when I try to slot a production module into the Chemical Plant I am given the error message of "productivity module can only be used on intermediate products."

This might be to prevent loops that would allow you to get more output than input (which might classify this as a UI issue rather than outright bug), but in that case the error message is entirely misleading and there is no in-game indication as to why you cannot use the module. The error message states that they can be used on intermediate products without saying there are some intermediates that quietly don't count.

[IsaacOscar]

You also can't use them on the fluid barrelling recipes, which would allow you to generate extra fluids from nothing.

[BarkyMacDarbydale]

That makes sense again from a gameplay perspective, but the error message the game gives is simply misleading and wrong when those are classified as intermediate products.

[IsaacOscar]

So I wrote a script, and it seems these rules determine what can and can't be given a productivity module:

The general rule is that if productivity modules are allowed if and only if one of the outputs is a "fluid" or an "intermediate product" (i.e. in those factoriopedia tabs)

However, the above has the following exceptions:

Productivity is allowed for:

• Labs and Biolabs
• blueprint parameters
• Stone bricks
• Concrete from molten iron (but not the normal Concrete in an assembling machine!)
• Artificial & Overgrowth yumako & jellynut soil

Productivity is not allowed for:

• recycling recipes
• barrel emptying or filling recipes
• Biter Eggs (captive biter spawners don't even have module slots; also Nutrients from bitter eggs do allow productivity)
• Fish breeding and Nutrients from fish
• Cooling hot fluoroketone

[IsaacOscar]

I would be good to get confirmation from the devs that the above rules are intended and none of them are bugs.

[IsaacOscar]

Oh and FYI this is related to a similar issue with quality modules whose applicability is not well-documented, see viewtopic.php?p=646786#p646786 where I list the rules they follow.

[Rseding91]

Thanks for the report however we will not be changing the message. The message covers the majority of how productivity is limited without being just a huge list of allowed recipes.

The alternative is some super verbose message or just saying some generic “can’t be used with this recipe” which is less useful.

[IsaacOscar]

Thanks for the report however we will not be changing the message. The message covers the majority of how productivity is limited without being just a huge list of allowed recipes.

The alternative is some super verbose message or just saying some generic “can’t be used with this recipe” which is less useful.

Fair enough, it might be nice to list whether it's an exception or not in factoriopedia though.
Also things probably should obey the general rule unless there's a good reason not to (as is the case for barrelling, because then you can make fluids out of nothing).

Others however I'm not sure, for example I don't see why "Concrete from molten iron" should be treated any differently from the normal "Concrete" recipe.