• Private keys and seed phrases never enter the app.
• Login uses a short-lived one-time nonce and Nimiq signed-message verification.
• Sessions are signed and stored in an httpOnly cookie.
• Run IDs are bound to the authenticated wallet and consumed once.
• Seeds are generated by the server and are not sent to the client as authoritative scores.
• Replay timing, event order, event values, and puzzle solutions are validated server-side.
• Practice scores remain local and are not accepted by ranked endpoints.
• Reward requests require a verified daily score and are unique per wallet/day.
• Scores are calculated from server-replayed events. Ranked submission bodies do not contain an authoritative score field.
• Each run is consumed before replay evaluation, preventing a valid event trace from being replayed after submission.
• Per-IP request limiting protects authentication, run creation, and replay submission endpoints. Responses include Retry-After when limited.
• Unhandled API failures are logged as structured events and return a generic error response.

Production requirements:

• Set a strong SESSION_SECRET and DAILY_SECRET.
• Configure durable Postgres with DATABASE_URL.
• Production startup rejects SQLite fallback when DATABASE_URL is missing.
• Set WEB_ORIGIN to the deployed frontend origin.
• Configure a funded payout worker before enabling on-chain reward settlement.