Ruin-preventing guardian mechanisms for online gambling and outcome markets

Online outcome markets spanning gambling platforms, prediction markets, sports-betting sites, crypto exchanges, and retail brokerages now form a fragmented ecosystem in which individuals can take leveraged positions on events ranging from minutes to decades. Existing harm-minimisation tools, such as deposit limits, self-exclusion, and platform-specific loss caps, operate in isolation and ignore cross-platform exposure and time structure of outstanding bets. We study a ruin-preventing mechanism for retail users: a cross-platform, time-aware guardian that aggregates speculative exposure across venues, tracks realised losses and time-discounted open risk, and restricts or modifies actions to keep probability of financial ruin below a prescribed threshold. The interaction between user and guardian is formalised in a discrete time model with heterogeneous contract maturities and tilt-prone behaviour, and we characterise a family of guardian policies that enforce behaviour-adjusted budgets on realised loss and time-weighted open risk. We also describe an implementable, device-level architecture that combines read-only connections to financial and platform services with local parsing of app and web interfaces on user's own devices, enabling cross-platform risk monitoring even when operators expose only coarse or adversarial interfaces. Guardian design is cast as a constrained mechanism-design and Stackelberg problem, in which a designer chooses loss and risk budgets, discounting, and behavioural-sensitivity parameters to maximise a stakeholder objective such as user utility subject to an ex-ante bound on ruin probability. From a game-theoretic perspective, the guardian can be viewed as a ruin-aware allocation rule in an online outcome-market game, with a stylised Stackelberg analysis characterising maximally permissive constant-fraction caps.