This Month in Forest - April 2026

[LesnyRumcajs]

This Month in Forest 🌲

Welcome to the April edition of This Month in Forest!

Highlights

NV28 upgrade

Forest joins Lotus and Venus in supporting the NV28 upgrade. See the post for details regarding the new features brought to the network. The calibration network upgrade is scheduled for May 7th - make sure to upgrade your Forest node before that date to avoid any issues; the v0.33.2 Night Mare is already available.

Finality calculator integration

New Forest releases integrate the finality calculator. This allows Forest to provide a safe finality estimate for the latest block, especially in cases where fast finality is not available (currently on mainnet). See Lotus finality docs for more details.

This is already available in /v1 and /v2 APIs, no additional configuration is needed.

Development

Strict JSON validation

JSON-RPC is a quite forgiving protocol when it comes to parsing JSON. This can lead to some unexpected behaviour, e.g., when missing fields are silently ignored or when map key are not unique. Setting FOREST_STRICT_JSON will catch some of these issues, punishing technically-correct-but-probably-broken JSON with an error instead of silently accepting it. Useful in development and testing, but adds some overhead, so it's not enabled by default.

State Tree snapshots

We're tinkering with a different approach to archival snapshots. @hanabi1224 came up with a leaner snapshot format that would improve archival snapshot ergonomics and reduce the amount of disk space needed. Check out his proposal.

Random improvements and fixes

fix n. & v. trans. [Latin figere "to attack with reproaches, to render immovable."] 1 n. A palliative shot in the system's arm f, becoming less effective with each application 2 v. trans. To remove [a bug] by redefining the program specification in order to take advantage of an unexpected feature.
The Computer Contradictionary, Stan Kelly-Bootle

Lots of small improvements and fixes, including:

• adaptive compression for RPC responses, see this PR. This significantly reduces latency for small RPC responses, while still providing compression benefits for larger responses.
• snapshot export and GC improvements, see this PR. This trades off some disk space and time for less memory usage, which is especially beneficial for users with limited resources.
• improvements in the P2P layer (here and there) to reduce memory usage and improve stability.
• lots of mempool improvements (and we're not done yet).

See the CHANGELOG for details. Note that it primarily contains client-facing changes, so if you're interested in the nitty-gritty details, you'll need to review the commit history. 🤓

Upcoming work

Our immediate focus is on:

• making sure the NV28 upgrade goes smoothly, including monitoring the network and providing support to users as needed.
• more mempool improvements and internal refactors.
• we'll likely start looking into archival node use case; while Forest can be used as one, the performance of it has lots of room for optimisation.

And then, of course, we will continue with our regular maintenance and improvements.

Outside of Forest

This is for reporting purposes only.

FVM maintenance

Quite a bit of work around FVM-related releases, including:

• chore(release): prepare FVM 4.8.1 filecoin-project/ref-fvm#2280
• chore(release): prepare amt@0.7.5 hamt@0.10.5 filecoin-project/ref-fvm#2279
• chore(release): prepare release 2.12.0 filecoin-project/ref-fvm#2278
• chore(release): prepare release 3.14.0 filecoin-project/ref-fvm#2277
• chore(release): prepare 4.8.0 filecoin-project/ref-fvm#2276
• chore: deprecate nv28-dev feature in favor of nv29-dev filecoin-project/ref-fvm#2282
• chore: bump multihash-codetable to get rid of core2 filecoin-project/ref-fvm#2281

builtin-actors and builtin-actors-bundler maintenance

• fix: misc bugs found by AI filecoin-project/builtin-actors#1733
• chore: bump deps to remove core2, upgrade to Rust 1.88.0 filecoin-project/builtin-actors-bundler#29

lotus and lotus-gateway fixes

Fix to lotus discovered during RPC parity testing with Forest.

• fix(api): StateSearchMsg should respect lookbackLimit filecoin-project/lotus#13562

go-state-types maintenance

• Include v18 miner actors methods and types filecoin-project/go-state-types#441

rust-libp2p maintenance

• feat: make wasm features implicit libp2p/rust-libp2p#6102

multiformats org

Various necessary maintenance:

• remove no_std_io2 from dep tree multiformats/rust-cid#187
• Embed minimal required no_std_io2 traits multiformats/rust-multihash#411
• chore: bump MSRV and remove no_std_io2 from multihash-derive multiformats/rust-multihash#410
• feat: add digest-traits feature to implement digest:Update for all hashers multiformats/rust-multihash#405