Arborist Call #115 | (12/11/2025) | Zcash Protocol Updates
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 12/11/2025
Since the last Arborist call, ZF shipped Zebra v3.1.0 with key improvements
fixed ARM64 Docker images, a new mempool dust filter, Configurable RPC response sizes, early support for the Bing RPC, Expanded Grafana metrics, and added support for pre-Canopy subsidy blocks bringing Zebra closer to full parity with zcashd, including on regtest.
Momentum continues on faster Zallet release cycles.
SLSA + reproducible build reviews are nearing completion, strengthening binary assurance.
With this in place, Zallet Alpha 3 is expected to ship very soon.
New Sapling and Orchard crate releases enable external PCZT signing, supporting constrained environments and hackathon use cases.
Halo 2 updates deliver ~20% faster proof creation and ~50% faster verification direct wins for Zebra and the wider Zcash ecosystem
lightwalletd now adds optional transparent data to compact blocks improving scan reliability without compromising privacy.
Core libraries also enable account and Keystone hardware wallet disconnect/reconnect for safer wallet workflows.
Lightwallet Protocol v0.4.0
v0.4.0 tagged
Adds optional transparent data in compact blocks + other protocol improvements
gRPC-backwards compatible wallets can upgrade immediately
Server capability signaling added
lightwalletd to advertise the protocol version it supports
Enables wallets to detect features like transparent data and FlyClient proofs in the future
Servers must fully support v0.4.0 before advertising it
Two parallel workstreams are nearing completion.
Chain Index integration is replacing the deprecated local cache, consolidating feedback paths and modernizing how chain data is accessed across the stack.
The migration effort is in its final stages.
Finalizing a new test framework for chain forks.
This improves confidence around fork-handling behavior and regression testing, strengthening reliability as the Zcash protocol and wallet infrastructure continue to evolve.
End-of-year focus has been on ecosystem readiness.
Outreach with exchanges, mining pools, and API providers gathered feedback on NU 6.1, plus early signals from large integrators using Zallet and the Z3 stack critical input for smoothing the transition off zcashd.
Progress is underway on a unified OpenRPC specification spanning Zebra, Zaino, and Zallet via a Rust router that transparently forwards calls across the stack.
This consolidation aims to simplify integration, documentation, and long-term maintenance for node operators and developers.
On timelines, zcashd deprecation remains feature driven.
Once feature-complete, the plan includes a ~16-week coexistence period where zcashd and the new stack run side-by-side, giving production users a safe migration window.
Early napkin estimates point toward 2026 milestones, all explicitly tentative.
Core Halo 2 work is complete and merged, with several releases already out.
The current focus is Orchard ZSA, now in active review. Once finalized, updates will flow through librustzcash and Zebra, completing the stack-level integration.Long-term features like ZSAs are now developed in dedicated integration branches within the main repos.
This model improves visibility, reduces maintenance burden, and makes large features easier to review and evolve before final merge.
Testnet strategy was a key discussion point.
An unofficial, public single-node ZSA testnet is already live, while consensus is forming around future feature testnets (or “staging nets”) to support builders ahead of mainnet.
Cross-org coordination is emerging as the next step.
Progress across supporting codebases continues:
Updates to Zcash test vectors and TX tooling now cover Transaction v6 and Orchard ZSAs, enabling realistic testing against modified Zebra nodes.
Review-driven refactors are improving maintainability and downstream reuse.
Least Authority has completed the ZIP 233 audit, with recommendations to add explicit requirements and privacy implications updates are in progress for review at the next ZIP editors meeting.
Engineering ownership has transitioned to Shielded Labs, with active work underway to rebase and update ZIPs 234 & 235, targeting completion before year end.
Workshop 4B is completed successfully, marking the first milestone where real testnet ZEC feeds into PoS staking weight.
Two demo wallets now exist,a desktop visualizer and an iOS wallet (with Zingo) plus a runnable Finalizer, making PoS tangible for the first time.
Next milestone (mid–late January) focuses on tightening PoS mechanics
The team is deliberately prioritizing experimentation, exploring trade-offs across UX, privacy (e.g. stake quantization), unbonding delays, and incentives using workshops and community feedback to guide design.
Shielded Labs has begun collaborating with Zechub on community-oriented experiments workshop goals, participation challenges, and lightweight rewards (badges/NFTs) to encourage hands-on testing.
By Q1 2026, the aim is a feature complete Crosslink prototype on a persistent feature testnet, paired with an independent, pre-registered design review.
Mark shared an early look at a dynamic fee mechanism via a new public lab meant as exploration, not final design.
The proposal builds on ZIP 317, uses recent block history to adjust fees, prioritizes privacy and UX, and keeps consensus changes intentionally minimal. Feedback is very welcome at this stage.
Good discussion followed on trade-offs.
Str4d and Nate highlighted that requiring transaction expiry heights (as part of the fee logic) would have real ecosystem impact especially for wallets and transparent tx tooling so this needs to be treated as a separate, explicit design choice and communicated clearly.
Conversation widened to ecosystem infrastructure.
Blake shared progress from http://zec.rocks lightwallet server operators grew from ~12 to 112, with ongoing rewards. That sparked discussion on reducing trust assumptions via FlyClient proofs, multi-server querying, and how this could dovetail with future efforts like Crosslink and Zaino.
Interesting discussion from http://Inversed.tech, a cryptography company, on the future of fully private light wallets for Zcash.
The ideas explore moving beyond linear scanning using PIR, homomorphic encryption, MPC, and private notifications reducing metadata leakage and improving mobile wallet scalability.
The conversation was very much exploratory, with broad interest from ECC and others.
There’s a clear appetite for research-first work benchmarks, simulations, and feasibility studies before any protocol proposals, with follow-up discussions expected on the Zcash R&D forum and Discord.
The Sapling crate updates for external PCZT signing are low-key huge for developer experience. Being able to handle signing in constrained environments opens up way more possibilities for hardware wallets and mobile implementations. The 20% faster proof creation and 50% faster verification from Halo 2 is also a solid win that'll compound across the whole stack. Been watching the zcashd deprecation timeline closely and the 16-week coexistence window seems like the right call.