Contract mechanics and settlement rules reflect venue documentation as of August 2026 and are actively changing — one venue altered its settlement method the day this was written. The vulnerability spectrum and cost-to-flip model are stylized: constants are illustrative and chosen to rank designs, not to price a live trade. The strongest empirical results cited come from a 2026 preprint and are labelled as such. This is market-structure analysis of settlement design; describing how a settlement window could be pushed is not an endorsement, instruction, or recommendation to attempt it, and manipulating a settlement price is unlawful in most jurisdictions and prohibited by the venues discussed. Nothing here is a recommendation for or against any venue or contract. Research and education, not investment advice.