The Zcash Arborist Calls are bi-weekly protocol development meetings focused on tracking upcoming protocol deployment logistics, consensus node implementation issues, and protocol research.
This summary focuses on the last call that took place on 06/25/2026
Highlights
Zebra advances with Ironwood development and key infrastructure improvements.
Zallet Alpha 4 enters release, bringing zcashd wallet migration support.
Dynamic Fees gain momentum as more wallets prepare to support Priority Lane transactions.
Zaino, Crosslink, ZSAs, and a new open-source wallet (ZecD) continue expanding the ecosystem.
A proposal to formally verify Zebra's core using Lean was also presented.
Release workflow is now automated with signed binaries attached to every release.
Non-finalized reorg window increased from 100 → 1000 blocks, improving rollback resilience.
Added fork point detection, resumable block streaming for Index RPC, and began work on NU6.3 (Ironwood) value balance pools. Block notify support is also in development
Ironwood Progress
V6 transaction format specification continues to advance.
V6 transaction & signature implementations from the Velar team have been reviewed and merged.
Ironwood PRs for librustzcash and Keystone multi-signature fund migration have also been reviewed.
Draft NU6.3 deployment and V6 transaction ZIPs are now available for community review.
NU6.3 Testnet Update
Target activation remains July 1, with the final activation height to be announced closer to launch due to unpredictable testnet mining activity.
The team is also preparing wallet migration guidance, updating ZIP 317 (fees), documenting recent consensus changes, and has merged the NU6.3 circuit updates into the Orchard crate.
Zallet & Core Libraries
The zcash_primitives v0.25 dependency upgrade has been completed across the stack.
Zallet Alpha 4 is now entering release, bringing support for zcashd wallet migration. The team is encouraging community testing on both mainnet and testnet to validate wallet balances, migration flows, and report any issues before wider adoption.
Zaino Updates
Released v0.4.1 with NU6.2 support and sync fixes.
Development continues on v0.5.0, introducing optional database indexing for faster startup.
The team replaced Zingolib with DevTool in its test harness, upgraded to Zebra’s latest features, and is shifting release testing towards real-world zallet use cases.
Zallet will soon support both Zaino and Zebra as backend options, giving users greater flexibility during the transition away from zcashd.
The team also highlighted Zebra's upcoming block notify configuration option, improving compatibility with existing workflows that rely on chain tip notifications.
QEDIT has updated its ZSA branch to incorporate NU6.2 changes and is finalizing Orchard integration.
The team has also submitted a Zebra PR for architectural review while continuing to track Ironwood, extensible transactions, quantum recoverability, and other protocol changes to ensure ZSAs remain compatible with the evolving Zcash protocol.
Shielded Labs has completed two FeatureNet workshops, using the current stalled network to strengthen tooling, improve diagnostics, and better handle rollback and fork scenarios rather than simply resetting the network.
The first round of mainnet rewards for participants is now being distributed.
Crosslink Development
- Shielded Labs is prototyping a user-driven slashing tool, drafting ZIPs for the Proof-of-Stake subsystem, and implementing protocol improvements ahead of the next FeatureNet iteration. Workshop 3 is tentatively scheduled for July 23.
Wallet support for Priority Lane and Speed Up transactions is expanding, with Cipher Wallet and Noir Wallet integrating the experimental features.
A new Zebra getstandardfee RPC has also been proposed, paving the way for future fee estimation while encouraging early ecosystem adoption.
Formal Verification Proposal
A proposal was presented to formally verify Zebra’s arithmetic and parsing layer using Lean proofs generated from Rust code.
The initial 4-week pilot targets consensus-critical components to mathematically verify correctness beyond what conventional testing can provide.
The proposal sparked discussion on prioritizing elliptic curve parsing, coordinating with existing formal verification efforts, and ensuring proofs remain maintainable as Zebra evolves. the team expressed support for aligning its work with the broader Zcash verification strategy.
Crosslink Discussion
- The team reviewed lessons from the first Crosslink FeatureNet iteration, focusing on fork recovery, rollback behavior, and improving node resilience. The discussion highlighted how future Crosslink designs could make fork detection more explicit and recovery more reliable.
New Open-Source Wallet
- Blake announced ZecD, an open-source server-side Zcash wallet built as a lightweight alternative to zcashd. Designed for commerce, it communicates directly with Zebra, follows a Bitcoin-style RPC model, and is already powering Overpay in production.
ZecD Highlights
- ZecD is designed to be stateless, recoverable from a seed phrase and optimized for large scale deployments. Transparent address support is also being added, while the project remains focused on providing a modern server-side wallet for the post-zcashd era.
zcashd Deprecation Debate
- The community discussed whether some infrastructure providers should receive a temporary bridge beyond NU6.3 to complete migration from zcashd. While some supported a short transition period, others argued that completing the deprecation sooner would reduce security risks and simplify long-term maintenance.