Really interesting approach — you're essentially building an ad bidding layer on top of the Nostr relay protocol, using signed events, PoW-based deterrents, and programmatic Lightning payouts.

The fact that ad selection happens client-side, avoiding centralized profiling, is crucial for preserving user privacy. Also, leveraging the kind:0 metadata event to define the payout lud06/16 address is an elegant reuse of existing Nostr primitives without introducing new ones.

The negotiation mechanism with opt-out and PoW penalties introduces a lightweight but effective anti-spam / anti-sybil measure. The delegate service abstraction for payout logic and fraud heuristics adds flexibility, allowing things like whitelist enforcement or behavior-based scoring.

What stands out is the multi-model compatibility — supporting anything from classic app-specific ad delivery to Brave-style opt-in user rewards or even Satogram-style open broadcast.