Create: CAES

First release. Compressed Air Energy Storage for Create.

• Air Engine — a dual-mode kinetic block. It compresses air into a vessel while its network has stress capacity to spare, and acts as a motor to supply capacity when the rest of the network cannot carry its own load. It picks a mode from the network balance measured excluding its own contribution, so it settles rather than oscillating, and a configurable margin keeps two engines on one shaft from charging each other.
• Generation follows Create's Steam Engine. Vessel size decides an efficiency the way boiler size does, efficiency picks one of four speed tiers (16/32/48/64 RPM), and the total stress supplied is flat across the tier — so gearing a network up does not multiply what an engine is worth. Engines sharing one vessel split it between them, as Steam Engines split a boiler. An engine joins a shaft that is already turning rather than fighting it.
• Pressure Vessel — a multiblock that stores Compressed Air, formed and split by Create's own connectivity handler. Footprints up to 3x3 and up to 32 tall, one cap for every width as with Create's Fluid Tank. Placing against a wide vessel lays a whole course at once. Capacity scales with the number of blocks; fill level reads out on a comparator and under goggles. Stacked vessels connect their textures and render as one tank.
• Ponder scene for the Air Engine, with its structure and lang generated from one place, and Create's native item tooltips — summary, Hold Shift for behaviours, and the stress bar — on both blocks.
• An idle engine says why. Goggles report no supply / empty / full / not turning / not enough spare, and for the last one it quotes what it needs against what is going spare.
• Compressed Air — a real fluid, so Create's pipes, pumps and gauges all work on it. It has no bucket and no block: it only exists inside something built to hold it.