Release v1.9.1

This patch release updates the v1.9.x release line with follow-mode stability fixes, payload-builder latency fixes, Reth/Rust dependency updates, and transaction-pool/RPC improvements.

Update Priority

User Class	Priority
Validators	High
RPC Nodes	High

Operators running v1.9.0 should upgrade to v1.9.1.

What's Changed

• Fixed follower upstream event handling by making certified follow the default, keeping the deprecated certify flag accepted, and resubscribing after upstream event stream errors or termination (#5845, #5964, #6051).
• Improved payload builder and consensus latency by keeping executor-owned payload jobs running to completion and deferring block/state provider drops off the response path (#5625, #6012, #6046).
• Enabled builder cache sharing by default again, with --engine.disable-execution-cache-sharing-with-builder available as the opt-out flag (#5529).
• Fixed snapshot manifest/download logging by initializing tracing before running snapshot commands (#5982).
• Updated Reth/Alloy dependencies, the workspace MSRV and CI toolchains to Rust 1.96, and Rust Docker base images used by release builds (#5564, #5822, #5876, #6035, #6025).
• Improved transaction-pool validation and maintenance performance by sharing EVM/state reads, caching active hardfork state, reducing AA insertion and fee-payer lookups, narrowing TIP-20 transfer decoding, and batching maintenance work (#5572, #5602, #5603, #5621, #5622, #5645, #5646, #5648, #5649).
• Added developer/API improvements for programmatic node overrides, transaction-pool validation hooks, AA signer recovery, and consistent tempo_simulateV1 metadata block selection (#5910, #5628, #5664, #5658).
• Added future-fork implementation work for dynamic base fees, the StorageCredits precompile, and TIP-20 rewards deprecation behind later hardfork activation (#5153, #5228, #5433).
• Bumped workspace and SDK crate versions to v1.9.1 (#6040, #6089).

Full Changelog: v1.9.0...v1.9.1