As of block #224# 201 091, Sei v6.6 is officially live. V6.6 includes nearly 400 pull requests, including the first mainnet components of Sei Giga. This is the largest upgrade to Sei since EVM support was added in May 2024. Here are the most important takeaways: Execution and storage - The Ares Upgrade begins: the v2 executor is being retired. The Giga hybrid executor is now the default execution path on mainnet, with roughly 10x the throughput. Every upgraded node runs it. v2 stays on as a per-transaction fallback, and a full v2 node runs on every network comparing results block by block. - The Eidos Upgrade begins: state separation. Two years of chain state, unpicked one block at a time, with EVM history moving into its own database instead of sharing one with Cosmos state. This is the most error-prone part of shipping Giga, engineered to be a non-event for operators. Security - Over 30 issues fixed across DoS and resource exhaustion, P2P attack surface, and supply-chain hardening. Closer to 50 counting race conditions and upstream security backports. Node operators - Network synchrony is significantly improved. Consensus timeout parameters were retuned, with devnet showing up to 15% fewer vote misses and block proposal latency cut in half. More predictable block times, less bandwidth spent on catchup. - Two configuration footguns are gone. Both have caused validator outages in the past. Simpler values, less to get wrong. - Pruning no longer drags nodes behind the chain. It now compacts the deleted key range as soon as each prune finishes, holding prune runs at a steady ~5 minutes and head lag under 60 blocks. Builders - Receipts are backed by Giga+OCC by default: invisible txs no longer get receipts, state-transition errors that bump the nonce now do, and EIP-1559 effective gas price lands on the receipt. - JSON-RPC error handling is now spec-correct; query surfaces are bounded, with proper pagination. - Historical debug_trace sits behind a config flag, with a 10,000 block default lookback.

The Sei 6.6 proposal is live. 6.6 starts two of the biggest pieces of the Sei Giga Upgrade. Ares, execution engine rebuilt for Giga, becomes the default on mainnet. Eidos, the new storage layer, begins moving chain history into its own database.