preseed.tides.state — the TIDES shared contract

Everything that crosses a lane boundary in part 9 ("THE FARJAN"), as pure functions of part-local t and nothing else. No state, no side effects, no entity lookups, no ctx.

local State = require("preseed.tides.state")

State.ship(t)     --> { pos = {x,y,z}, forward = {x,0,z}, speed, headingDeg }
State.sea(t)      --> { windSpeed, windDirection, choppiness, amplitude,
                        standingWaveRatio, foamDecay, significantHeight }
State.weather(t)  --> { squall01, coverage, cloudBase, cloudTop, wetness, rain01 }
State.light(t)    --> { sunElevDeg, sunAzimuthDeg, timeOfDay, sunColor, sunIntensity,
                        ambientColor, ambientIntensity, keyOcclusion01, exposure }
State.palette(t)  --> { skyHorizon, skyZenith, skyGround, cloudLit, cloudShadow,
                        waterBody, foam, fogColor, hullRed, upperworksWhite,
                        antifoul, bootTop, cabinEmissive }

Why pure

Hot-reload rebinds a module's function bodies without re-running its module-level chunk. Module-level mutable state in a shared file therefore keeps the old build's values while running the new build's code, and the bug looks like it is in whichever lane read it last. A file of pure functions cannot do that.

It is also what makes the wake derivable. Because ship(t) is pure, the wake at time t is exactly the locus { ship(t - a) : a in [0, 26] } — sample it and a scrub, a seek or a hot-reload all produce the identical wake. An accumulating wake is empty after every seek, and this demo is scrubbed constantly.

No lane may add module-level mutable state to this file.

Ownership

Function	Owner (may retune the numbers)	Readers
ship	SEA (track & speed)	CAMERA, SEA, FERRY
sea	SEA	SKY, CAMERA
weather	SKY	LIGHT, SEA, FERRY
light	LIGHT	SKY, SEA, FERRY
palette	LIGHT	everyone

A lane needing a new field appends it. Nobody renames or removes one.

Fixed facts

• Axes: +X = ahead (bow), -X = astern, +Y = up, -Z = port, +Z = starboard. The sun sits just off her starboard bow.
• Music: 192 BPM, 4/4 — BAR = 1.25 s. Thirty seconds is exactly 24 bars. Nothing changes on a number that is not a multiple of 1.25.
• pos.y is the calm-water datum, not her true height. preseed.Buoyant owns her vertical; read the entity for her real y.
• ProceduralSky owns the sun's direction via timeOfDay. sunAzimuthDeg is the intended bearing the clouds are lit against, not an instruction to write a direction onto the Light.