The ITAD v2 API requires POST (not GET) for /games/overview/v2, and expects ITAD game UUIDs in the JSON body rather than Steam app IDs. Added a lookup step via GET /games/lookup/v1 to convert Steam app IDs to ITAD UUIDs before calling the overview endpoint. Updated preflight check to use the lookup endpoint for API key validation. https://claude.ai/code/session_01B7YPGrE3NatkwadCXVjv2j