FYEO Custom Fuzz Testing is a blockchain-focused security testing service that combines static analysis with bespoke fuzzing harnesses tailored to a client's specific codebase and threat model. The service generates and mutates transactions, simulates adversarial users, and drives protocols through thousands of stateful executions to uncover logic, math, and state-transition errors. It also collects evidence that key security invariants hold under extreme conditions. Coverage spans multiple layers of the blockchain stack: - Layer-1 Protocols: consensus mechanisms, state transitions, validator logic, and networking - Smart Contracts: Solana, EVM, CosmWasm, Move, Sui, and other environments - DeFi Protocols: AMMs, lending protocols, governance systems, and bridges - Custom Runtimes: VMs, execution environments, and interpreters Key technical components include bespoke fuzzing harnesses built to match the client's protocol and deployment assumptions, stateful execution with shadow-state tracking and invariant checking, high-coverage mutation strategies tuned to DeFi and protocol logic, and reproducible seeds for every discovered issue enabling regression testing. An optional CI integration allows fuzz suites to be rerun on every release. Deliverables include custom fuzzing harnesses, thousands of test iterations with state verification and coverage insights, reproducible test cases for identified bugs and edge cases, and detailed reports with verification evidence and remediation guidance.