[UI] Filter and Highlight Valid Fuels for Vehicles/Burners

[kizrak]

TL;DR

When opening a vehicle or burner's fuel tab, filter the ghost-selection grid (or highlight the engineer's physical inventory) to only show valid fuels, and apply a red background to requested fuels missing from the network.

What?

I suggest improving the UI when interacting with fuel slots, both when setting remote logistics requests and when the normal engineer is manually inserting fuel.

• When setting a ghost/logistics request, filter the selection grid so it only displays valid, accepted fuels for that specific entity.
• When interacting physically as the normal engineer, dim out non-fuel items in the character's inventory grid, highlighting only what can actually be inserted.
• Apply a red background highlight to fuels that are currently unavailable in the local logistics network, mimicking the existing personal logistics UI.
• Dim/remove tabs that don't have any valid (fuel) options.
• Note: The strict filtering/highlighting is the core feature here. The red network-status background would be an amazing bonus.

Why?

Currently, figuring out which fuels are accepted often requires opening Factoriopedia, checking the "Accepted fuel" list, and then visually hunting for those specific icons. This is tedious visual clutter in both remote and local play.

Example in the remote view logistics selection:

05-30-2026, 14-04-01.png (1.36 MiB) Viewed 60 times

And similarly, when playing as the normal engineer trying to manually load a locomotive from a full backpack:

05-30-2026, 13-58-13.png (378.89 KiB) Viewed 60 times

With the expanded variety of fuels in Space Age, parsing a wall of unsorted items in your character inventory or a massive ghost grid to find the right fuel requires unnecessary mental overhead. Automatically filtering the request menu—and highlighting the valid items right in the normal engineer's pockets—completely removes that visual clutter. Additionally, the red network-status background would prevent players from requesting a fuel type that doesn't currently exist, saving them from discovering a stalled train hours later.

How?

This could be implemented by applying existing UI logic to fuel slots:

• When a fuel inventory or request slot is clicked, apply an item-filter mask to the GUI that checks against the entity's burner prototype requirements (exactly like how module slots filter the UI to only show valid modules).
• For the character inventory, apply the same "dimming" visual mask used when holding an item over a chest, but trigger it dynamically based on the burner's accepted fuel list.
• For the logistics check, if the item count is zero, render the slot with the existing red-background sprite used in the logistics UI.

[kizrak]

I'm not entirely sure if this should be a separate feature request—while the core UX philosophy is identical ("If an item cannot be used in a given interface/interaction, don't show it"), the underlying code for these different entities might be completely separate.
If a moderator feels this warrants its own thread, please feel free to split this reply off, or just let me know and I can create a new topic!

To expand on my original idea

This UX improvement shouldn't be limited just to fuel slots. It would be incredibly helpful to apply this same "restrictive display" logic to any entity that has highly specific inventory limitations.

Three major examples:

• Roboports: When opening a roboport, the ghost-selection or inventory highlight should only show Logistic Bots, Construction Bots, and Repair Packs. (As a side note, with fewer items displayed, this filtering might even allow the UI tabs to be collapsed into one cleaner view).

  

  05-30-2026, 14-35-33.png (748.97 KiB) Viewed 43 times

• Smelters / Furnaces: When clicking the ingredient slot for a furnace, the UI should strictly filter out everything except valid, smeltable ores (Iron, Copper, Stone, etc.), fuels, modules† and outputs.

  

  05-30-2026, 14-35-26.png (364.7 KiB) Viewed 43 times

  For example, why am I seeing inserters in this interaction menu? They cannot be used as input, output, or fuel.
  (A minor caveat on my screenshot†: I highlighted modules because they would be displayed for electric furnaces, but strictly speaking, they shouldn't be shown for burner furnaces!)
• Biochambers: If none of the recipes allow something as input/output/fuel/spoil or module, then hide it.

  

  05-30-2026, 15-00-43.png (908.79 KiB) Viewed 26 times

Applying the exact same filtering mask discussed for fuels to these other restricted entities would make factory management significantly cleaner and drastically reduce visual noise when setting requests.