feat: Ground fluid pickup + dirty fluid flag removal and fluid reaction framework

[YukariMindGap]

Purpose of change (The Why)

Currently, there's no way to pick up liquids on the floor; Once they're on the floor, they're impossible to get and is basically counted as lost. There's windows of frustration where you accidentally spill the gasoline your car needs, so it's an unacceptable flaw.

I also found out that the way the game handles ground fluids and dirty fluids needs to be reworked to fit the gameplay more, and the dirty flag from the old days has to go as a consequence. I also see the potential for a fluid transform framework for more interesting interactions with fluids.

Also Closes #9199

Describe the solution (The How)

Adds fluid_pickup iuse_actor types to recover some part of the spilled liquids. Adds three fluid pump-type items (hand, gasoline, and electric), each with distinct crafting recipe, itemgroup integration, and fuel requirements. Modifies sponge and mop to add these actions.

Removes the old "dirty" flag system from liquids and replace them with a "reacts_to" JSON field where a fluid can transform into other fluids when certain conditions are met. For this PR, only ground contamination will be implemented with clean/mineral water reacting into water and gasoline/diesel reacting into dirty gasoline/diesel (which can't be used to fuel vehicles) I also added an item that can clean those dirty fuel fluids through a crafting interaction and integrated them through itemgroups that make sense

As a consequence of the removal of the "dirty" flag, you can now drink liquids from the floor

Describe alternatives you've considered

keep the water puddle being an elusive item to get and keep the old dirtiness flag causing jank interactions.

Testing

• You walk up to a fluid spill on the floor.
• You activate the item with the "fluid_pickup" tag
• The menu for what to do with the fluid will open (the same menu for when you're filling or unfilling fluid containers, in fact)

Additional context

Look at this guy trying to pick up the puddle with their bare hands

Originally you can't do anything to the puddle after it's on the ground, but now a new friend the sponge!!

The sponge picks up the liquid and asks the guy where to put it

The guy, still wanting that liquid, pours it into the bottle.

Checklist

Mandatory

• I linked any relevant issues using github keyword syntax like closes #1234 in Summary of the PR so it can be closed automatically.

Optional

• This PR used AI assistance.
  • I added an Assisted-by: trailer to every AI-assisted commit in the Linux kernel format.
• This is a C++ PR that modifies JSON loading or behavior.
  • I have documented the changes in the appropriate location in the docs/ folder.
  • If documentation for this feature does not exist, please write it or at least note its lack in PR description.
  • New localizable fields need to be added to the lang/bn_extract_json_strings.sh script if it does not support them yet.
  • If applicable, add checks on game load that would validate the loaded data.
  • If it modifies format of save files, please add migration from the old format.

Translations

post	changed	stale	missing
mod/json/reference/items/item_creation.md	en	ja, ko

Build Artifacts

PR build for commit 2482abf (Merge remote-tracking branch 'origin/main' into spongeroberts-cubictrousers) on 2026-08-26 20:51:33

• ✅ Linux tiles — download
• ❌ Windows tiles — build failed
• ✅ macOS tiles — download
• ✅ Android tiles — download

[autofix-ci]

Autofix has formatted code style violation in this PR.

I edit commits locally (e.g: git, github desktop) and want to keep autofix

1. Run git pull. this will merge the automated commit into your local copy of the PR branch.
2. Continue working.

I do not want the automated commit

1. Format your code locally, then commit it.
2. Run git push --force to force push your branch. This will overwrite the automated commit on remote with your local one.
3. Continue working.

If you don't do this, your following commits will be based on the old commit, and cause MERGE CONFLICT.

[mkrutov]

Hi! I kind of like this conceptually, but have a question: What is the plan for (dirty) liquid results? I don't think its reasonable from gameplay perspective to pour dirty gasoline into car, for instance, but it is reasonable to use it for something like a handmade weapon.

I also kind of think that may be the gasoline version of tool should be considerably slower (not just 1s slower than electric).

[YukariMindGap]

Hi! I kind of like this conceptually, but have a question: What is the plan for (dirty) liquid results? I don't think its reasonable from gameplay perspective to pour dirty gasoline into car, for instance, but it is reasonable to use it for something like a handmade weapon.

I also kind of think that may be the gasoline version of tool should be considerably slower (not just 1s slower than electric).

I still have no idea of what to do with the dirty liquids. That's for a future PR to solve. Only one that's sure is dirty water having more potential to be sickening than normal water.

[mkrutov]

Does this also work for modded liquids? (Dragon Blood comes to mind - I dont' recall if it exists in MagicNights or only in Magiclysm..)

[YukariMindGap]

Does this also work for modded liquids? (Dragon Blood comes to mind - I dont' recall if it exists in MagicNights or only in Magiclysm..)

Should work with modded liquids.

[WishDuck]

I'm not sure this is good in the current state
Gasoline zombies for instance will with this PR be a simple infinite source of fuel.
Let alone removing any punishment from fragile objects being destroyed, so that becomes less threatening.
Adding checks for is_dirty everywhere would also get scrungly fast.

Additional request: percentage return, some of these dont get 100% back for at least some resemblance of balance...

[YukariMindGap]

I'm not sure this is good in the current state Gasoline zombies for instance will with this PR be a simple infinite source of fuel. Let alone removing any punishment from fragile objects being destroyed, so that becomes less threatening. Adding checks for is_dirty everywhere would also get scrungly fast.

Additional request: percentage return, some of these dont get 100% back for at least some resemblance of balance...

The item requirement is kind of a balancing point for the ability to get ground fluids, with the heavier the item, the more it can pick up, and also dirty fluids having (yet-unimplemented) bad effects compared to non-dirty fluids. I imagine dirty water would be more sickening than normal, untreated water. Dirty gasoline/diesel being less efficient than clean gasoline/diesel and increased chance of the engine failing to start.

Also I assume gasoline zombies would drop their gasoline at death or is it a constant +1 unit of gasoline puddles?

[WishDuck]

Each time gasoline zombies move they have a 1/5 chance to drop gasoline on the ground. There is no cap
See monmove.cpp line 2632

[YukariMindGap]

Each time gasoline zombies move they have a 1/5 chance to drop gasoline on the ground. There is no cap See monmove.cpp line 2632

How much do they drop anyways? One unit per proc? I imagine gasoline zombies would be quite rare. I should nerf gasoline zombies at a later PR

[YukariMindGap]

I have completely reworked the PR and now the dirty flag is officially no more.
It's now replaced with a system of fluid reactions that can transform a liquid to another when certain criterias are met. For this pr, it's ground contamination.

[chaosvolt]

Is the weird hack with dirty fuel types actually necessary? We'd have to specify dirty versions of every fuel in the game for this to make sense, which includes fuels not yet converted like ethanol since gasoline and turbine engines can use them.

In addition, got this error on trying to mop up some spilled mutagen into a container:

 DEBUG    : Failed to remove emptied liquid item from stack

 FUNCTION : use
 FILE     : D:\a\Cataclysm-BN\Cataclysm-BN\src\iuse_actor.cpp
 LINE     : 8641
 VERSION  : BN 535b6a7 (2026-08-03)

[shmakota]

Just wanted to let you know I'm working on fixing this up so it's a bit better in regards to the above requested changes and upcoming fluid fields, so you can hold back on changes for now (might require me to open a separate PR though)

[YukariMindGap]

Is the weird hack with dirty fuel types actually necessary? We'd have to specify dirty versions of every fuel in the game for this to make sense, which includes fuels not yet converted like ethanol since gasoline and turbine engines can use them.

In addition, got this error on trying to mop up some spilled mutagen into a container:

 DEBUG    : Failed to remove emptied liquid item from stack

 FUNCTION : use
 FILE     : D:\a\Cataclysm-BN\Cataclysm-BN\src\iuse_actor.cpp
 LINE     : 8641
 VERSION  : BN 535b6a7 (2026-08-03)

Well, the alternative would be the old "dirty" flag that someone suggested to be removed. The implementation is too jank and weird so i replaced it with a fluid reaction system that you can extend with more than just ground contamination. Here is the quote from Wishduck:

I'm going to be completely honest. A magic filter which can filter anything, which mod authors could not block from filtering something is scrungly, merely because it is a large shift in balance without a way to say "this liquid cannot be used after being spilled.

We already have this in the form of "water" and "clean water." I could see certain liquids maybe getting a variable for a clean variant that they revert to

This was a suggestion from shmakota for a replacement of the dirty flag, which honestly makes more sense then the magic "Put dirty alpha mutagen in and get clean alpha mutagen out" filter.

This way cleaning is done via the crafting menu, as a recipe that takes the unclean itype and returns a clean itype. It doesn't break mod balance as mods have to opt into having a cleaning path.

It also allows for more expensive cleaning methods to be made. And above was

I don't think its reasonable from gameplay perspective to pour dirty gasoline into car, for instance, but it is reasonable to use it for something like a handmade weapon.

If we do it this way, it could become part of the ammotype used by handmade gasoline weapons, but not something engines which can use. Allowing for restrictions in our current systems without needing to add is_dirty checks to places.

For instance crafting, reloading, cloning, and I'm sure there are many others I cant think of would all need these checks, in comparison to this route.

Also Shmakota:

Just wanted to let you know I'm working on fixing this up so it's a bit better in regards to the above requested changes and upcoming fluid fields, so you can hold back on changes for now (might require me to open a separate PR though)

i've fixed what Chaosvolt requested and i think it's actually ready for merging. Please check this newly-updated PR and see if it needs improvement.

[chaosvolt]

Shmakota said they were going to push some fixes and to hold off on tweaking it, bleh. :/