Marketplace-reseller AI in 2026 fails differently per platform and the cross-platform mitigation pattern is to separate AI-on-listing-copy (broadly safe across Etsy, Marktplaats, Vinted) from AI-on-listing-images (increasingly penalised on all three platforms via different mechanisms: Etsy's Creativity Standards and AI-disclosure requirement; Marktplaats's photo-fingerprint deduplication; Vinted's image-similarity penalty for resale-of-resold). The 'AI does the entire listing' workflow is the procurement pattern that produces the account-suspension report 6-12 months later. The defensible reseller workflow uses real photos, AI-assisted copy with platform-required disclosure, and per-platform performance tracking on impressions and sales.

Sibling to OPS-041 (parent platform-algorithm-penalties piece, this is the marketplace-specific cut) and OPS-032 (chatgpt-vs-claude-vs-gemini-smb-content). Verified primary references: Etsy seller handbook stance on AI creations (human input, disclosure, authenticity as the three pillars); Etsy Creativity Standards (governing what is acceptable creative output, with explicit AI-assisted vs AI-generated guidance); 2025-2026 Etsy disclosure requirements tightened materially. Marktplaats's seller-rules framework (Adevinta-published photo-fingerprint deduplication; threshold tight enough that AI-generated background variations trip rather than evade). Vinted's seller policy targeting counterfeits, scams, resale-of-resold via image-similarity penalty. EU DSA and EU AI Act enforcement noted as the forward-looking pressure on marketplace platforms to enforce AI-disclosure rules more aggressively in 2026. 60-day review cadence; trigger conditions include Etsy policy updates, Marktplaats policy updates, Vinted policy updates, EU DSA enforcement actions on marketplace seller transparency, EU AI Act Aug 2026 enforcement effects.