Arborist Call #103 | R&D Summary (06/12/2025)
Core Team Updates, Research & Implementation Updates, Open Announcements & Discussion.
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 06/12/2025
Big updates from Zebra since the last Arborist Call! CI improvements, debug crate flexibility, and a new NU6.1 variant now exist in main.
Zebra also now supports deserialization tests + pinned LightwalletD for stability.
Zebra just rolled out a major DB format upgrade to support getaddressbalance + getblock RPCs.
Added: New received field addnode RPC Local outbound config for regtest Initial shielded address config (no coinbase yet)
New PRs Live: One-Time Lockbox disbursement support for NU6.1 Cleaned Zebra RPC API—now usable without Zebra State/server deps Added value pools + block sizes to getblock RPC The protocol is evolving fast.
ECC has implemented NU6.1 consensus changes in zcashd, including support for one-time lockbox disbursements. Major milestone for enhancing fund control + upgrade readiness.
Progress on the Zashi & Zallet fronts: Improved Tor support in Zashi via Librustzcash crate updates New z_gettotalbalance RPC merged for Zallet Continuous dev underway to push Zallet forward.
Zallet Alpha is on the horizon! This early release will support: Zcashd wallet migration Syncing transaction history It's API-forward, but legacy Bitcoin-style RPCs will remain limited.
Key management in Zallet Alpha: Initial support will include importing Zcashd wallets. Support for transparent & legacy Sapling key import is feasible — but not yet exposed via RPC. A CLI command to add accounts without a running lightwallet server is in the works.
Zallet devs are working toward better testability:
Proposal to add a CLI flag for wallet init to skip default account creation
Enables smoother integration with test setups like Zebra
Ticket to be opened soon—community collaboration in action
ZIP 233 integration is progressing! All 3 PRs (Librustzcash, Zcash test vectors, Zebra) have been rebased Updates reflect latest feedback from Daira Emma Zebra PR ties it all together for unified test coverage.
Issue discovered during testing: ZIP 233’s Digest header change breaks Zebra tests involving older testnet/mainnet blocks. Root cause? Header writing not conditioned on tx version.
Confirmed as a bug — fix underway.
Once ZIP 233 is finalized and merged, the team plans to move ahead with ZIP 234 and ZIP 235. If you’re reviewing the PRs — now’s the time to provide feedback!
Every test passed brings Zcash closer to robust protocol upgrades.
Shielded Labs Crosslink Update (Milestone 3): We're transitioning from research to implementation! This milestone introduces changes to PoW consensus, with Crosslink blocks linking PoW & BFT subprotocols — moving closer to hybrid consensus for Zcash.
Progress on Crosslink Milestone 3 includes: Design + testing of hybrid PoW+BFT blockchains Exploring objective validity for snapshots Early test harness to validate hybrid chain state Community workshops reveal current network fragility
Although PoS isn’t part of Milestone 3, design is underway: Drafting a FAQ based on validator/staker feedback Learning from Cosmos Hub, Penumbra, Namada Collaborating with Informal Systems & Anoma → Early feedback = better staking design!
Testing framework update: Designing test vectors for hybrid nodes (PoW & BFT blocks) Sequencing independent subprotocols with cross-references Reusable logic ensures future upgrades don't break tests Goal: Robust validation before full PoS rollout.
Discussion touched on funding key derivation work for FROST & passkey support. ECC emphasized the urgency of finalizing FROST key derivation spec to enable post-quantum recovery paths before NU7. Key infra decisions are needed now
Lockbox Update: Initial keyholders for the Lockbox disbursement (NU6.1) must generate P2SH multisig keys for testnet ASAP. Both Zebra & Zcashd are near testnet-ready pending those keys.
