Types, tuning constants ported from the prototype, a seeded PRNG and Emitter,
plus checkContract() — the tripwire that catches a lane drifting from its
interface at merge time instead of three lanes later.
createStubWind() ports the prototype's gust shape (telegraph 1.5s, ramp 0.8s,
hold 1.7s, fade 1.0s) so B and D can develop before Lane C lands weather.js.
Its schedule is precomputed at construction, which keeps sample() pure in t —
the selftest samples out of order and must get the same answer.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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