Deep understanding of EVM internals and Solidity (advanced patterns: upgradeable, diamond, minimal proxy, compliance hooks). Cross-chain and interoperability (LayerZero, Wormhole, CCIP, oracle strategy, bridge risk mitigation). Blockchain data engineering (nodes, archive, event decoding, reorg handling, custom indexers, ETL to lake/warehouse). Data stack expertise (Kafka, Flink/Spark, ClickHouse/Snowflake, columnar design, caching tiers, GraphQL/gRPC APIs). Performance and cost optimization (gas profiling, storage layout, node topology, capacity planning). Security and assurance (threat modeling, formal verification, Slither, MythX, Echidna, fuzzing with Foundry). Zero-knowledge and Layer 2 (rollups, prover integration patterns, fraud/validity proof considerations, MEV mitigation). Multi-language proficiency (Solidity plus Rust, Go, Java, Python, Node.js). Enterprise integration (PKI/mTLS, IAM, secrets/HSM/KMS, event-driven architectures, API gateway patterns). Cloud architecture (AWS/Azure networking, container orchestration, DevSecOps CI/CD pipelines). Observability and resilience (distributed tracing, metrics, log correlation for on/off-chain components). Formal architecture artifacts (C4, sequence diagrams, data flow, threat and recovery models). Global stakeholder management and strong communication skills. Experience with ALM tools like JIRA, Confluence, Jenkins, Git.