Arborist Call #108 R&D Summary (08/21/2025)
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 08/212025
Core stack update:
Zebra 2.5.0 now live w/ NU6.1 on testnet
CI hardened (nextest + Docker optimizations), Orchard batch validation enabled via librustzcash, funding streams configurable on custom nets, and smarter state restores on restart.
In-flight Zebra work:
feature-gated NU upgrades, expanded getrawtransaction fields (Orchard + JoinSplit), pre-generated Coinbase txns in getblocktemplate w/ long-polling, plus Sapling verifier integration. More robust consensus.
ECC Core Stack update:
Major push on P2SH support in zcash_script crate → vital for NU6.1 & lockbox disbursements.
Work underway to ensure compatibility w/ Ledger & Keystone.
Also marching towards Zallet alpha ,just few issues left before release.
Across the stack:
zaino updated to latest Zebra + librustzcash
Confirmations policies added to client backend (low/zero conf shielding)
Qedit’s Halo2 PRs merged; ZSA work advancing in Orchard
opreturn support landed in primitives for partner integrations
Extra fixes & polish:
Hotfix in Zcash Keys for transparent secret key encoding
Protocol & API cleanup in Zaino + librustzcash
Grant support work + reviews moving ZSA & primitives forward
Zaino update:
Chain Index API nearing completion (crucial for Zallet & crosslink non-finalized state).
Grant deliverables almost wrapped, with core code re-architecture + quality upgrades underway.
Block explorer RPC support also in progress.
Priorities update:
Focus on wrapping Zallet MVP tasks, chain index refactor, & block explorer APIs.
Zingo Labs driving proper explorer RPCs, while compact block protocol tweaks improve handling of transparent data.
Huge kudos to Zebra + infra teams for heavy lifting.
DAG & deprecation:
some inaccuracies in NU7 dependency mapping being corrected; CI rendering now cleaner via GitHub Pages.
Conrado upgraded RPC method tracking for zcashd deprecation → cross-referenced on site.
Open Q: policy for bug-for-bug vs correct RPC outputs.
Halo2 & ZSAs:
PR merged w/ full ZSA modifications; Orchard PR in review .
ZIP updates landed for SIG hash versioning + issuance key encoding. Changes now in test vectors & Python ref impl, rolling through Orchard → librustzcash → Zebra
Progress across stack:
Orchard simplifications + draft PR moving toward review
librustzcash catching up w/ upstream (pczt + ZSA integration)
Zebra branch near parity (2.4.2) w/ ZSA support pending state mgmt
v6 txn tool & CI improvements ongoing.
NSM progress:
ZIP-233 PR rebased on latest librustzcash & ready for review.
Test vector PR (101) updated w/ addressed comments, also pending review.
Review coordination underway w/ Daira & team.
Shielded Labs Milestone 3 updates:
crosslink now runs on both consensus protocols, with finality ensuring PoW rollbacks can’t affect validity.
Docs going into Zebra Book + ADRs. Release + tag coming soon.
Next week’s Shielded Labs workshop will tackle testnet fixes + community Q&A.
Formal verification is advancing too, w/ automated proofs for crosslink + incentives, in collab w/ Informal Systems (Quint).
New visualizer boosts design validation
Debate on a proposed “smaller Nu7” upgrade:
Shielded Labs argues it could speed protocol cadence, de-risk delays, and introduce NSM + explicit fees sooner.
Critics warn it risks disruption, delays ZSAs, and adds fragile transaction format changes.
Broader concern:
Zcash upgrades often slip despite past 6-month cadence goals.
Some advocate smaller, incremental releases; others stress one major, yearly upgrade is more realistic.
Consensus: process changes are needed to avoid repeating delays.