I still support the elimination of the classical concept of stockpiles. More ideas:
Food: On-planet stockpiles, or the illusion of this. If running low on food begins to deplete population health, this would accomplish the same thing as long as those citizens can survive for a little while. In the real world, if our grocery stores become empty then the citizens will still survive for a reasonable period of time, perhaps indefinitely. Maybe food-rich climates can be more survivable once food resources become scarce..? I like the idea of a standardized 1-jump range for distribution between systems 'automagically'
resources on a per-planet basis! Your mineral focus changes the rate
at which minerals are extracted. Later tech advances could allow better mining and refining or whatever, increasing not only total available mineral resources on any given planet but also increasing extraction rate. Apply techs like 'recycling' to gain a free +1 mineral per turn on a planet. This means that mineral stockpiles are intrinsic to planet status; capturing a planet allows you to capture that 'stockpile' without really taking anything from the defending player's empire.
Production: No stockpiles at all, simply a speed limit for planetary production based on total infrastructure. Does unused production currently increase the rate of infrastructure-building?
Research: Centrally collected as long as every planet is within communication range.
Trade: Centrally collected as is research.
If planets within a system could instantly share Food then I would be happy. But why not industry? In this vision of the future, why couldn't Earth and Mars collaborate on the building of in-system projects? This would reduce the impact of removing stockpiles by adding an easy-to-apply sharing option. A simple % penalty can reflect the inefficiency of shuttling raw materials between planets. Late-game tech could even allow collaboration between systems! Example:
A ship costs "100".
Earth produces 10 minerals and 25 production, and can build a ship in 10 turns.
Mars produces 30 minerals and 5 production; it would take 20 turns to build the ship.
If Earth and Mars decide to collaborate, they collectively have 40 minerals and 30 production.
The social tech that allows intra-system collaboration is somewhat developed, and there is only a -15% penalty.
After the penalty, the Sol system has access to 34 minerals and 25 production if the planets collaborate.
The ship can now be constructed in 4 turns, occupying the build queue of both Earth and Mars.
A ship is added to the build queue on Earth.
The player presses 'collaborate' on the ship's queue icon and selects Mars from a list of in-system colonies.
The ship is added to the Mars build queue.
Four turns later, the ship is produced at Earth (where it was initially queued).