Real-time L2 sequencer health across 12 chains (Base, Arbitrum, Optimism, zkSync, Blast, Linea, Mantle, Mode, Scroll, Taiko, Polygon zkEVM, Casper). Returns kernel-level P99/P95 RTT from eBPF probes, revert ratios (Base and Arbitrum via eth_getBlockReceipts), gas pressure, and execution recommendation.