50Platform breaking-change calendar Oct 2026 - Aug 2027 for small sellers and devs (with am-I-affected checks)
Tested once (partial): 14 dated breaking changes (Allegro, Amazon SP-API, Shopify script tags, Exchange EWS/SMTP, Google Play billing, Merchant Center, TLS, InPost) with one check per row; 12/13 dates re-confirmed at the source on 2026-10-21.