{"changes":[{"id":"001-add-required-idempotency-key","category":"add-required-header","severity":"breaking","versionBump":"major","description":"Require Idempotency-Key header on POST /v1/charges. Naive callers will get 400 from header validation.","applied":false},{"id":"002-add-refunds-endpoint","category":"add-endpoint","severity":"additive","versionBump":"minor","description":"Add POST /v1/refunds. Existing callers unaffected.","applied":false},{"id":"003-tighten-amount-validation","category":"tighten-validation","severity":"breaking","versionBump":"major","description":"Tighten POST /v1/charges body schema: amount minimum raised from 1 to 50. Callers sending small test amounts will get 400.","applied":false}]}