New Zealand agritech in 2026 lands the AI architecture conversation hardest on the constraints mainstream cloud-AI tutorials assume away: solar-powered devices on the cow's collar, intermittent cellular and satellite connectivity, the welfare envelope that takes precedence over production, and the data co-governance arrangement under the Algorithm Charter and Te Tiriti o Waitangi. This article walks the engineering deliverables for an agritech AI architecture in 2026: edge-first inference with welfare envelope on-device, multispectral pasture-vision with fixed-tower-drone-satellite fusion, behaviour-model training with the labelling discipline as the value-creating activity, store-and-forward synchronisation with explicit conflict resolution, federated learning across farms, Te Tiriti and Algorithm Charter compliance engineered into the architecture. NZ-anchored to Halter, Fonterra, Gallagher, LIC, AgResearch and globally portable. 8 anti-patterns, 5-stage maturity ladder.