Prop 379: Juno v31 Software Upgrade

Upgrade juno-1 to Juno v31.0.0 at block height 42452000 (estimated Wednesday 7 October 2026 around 12:00 UTC, based on an average block time of about 2.71s; the exact time depends on block production).

Changes:

• wasmd v0.61.15 and wasmvm v3.0.8: CosmWasm security release. wasmvm changes can affect deterministic execution, so all validators must switch binaries at the upgrade height.
• Ante fee-grant fixes (PR #1222): the fee-grant keeper is wired into the custom fee decorator, and a fee granter is rejected when the keeper is unset.
• No module stores are added, deleted or renamed. The handler only runs module migrations.

Testnet: uni-7 upgraded at height 18425000 on 2026-10-01. Smoke tests passed: bank, wasm store/instantiate/execute/migrate, existing code instantiation, fee-grant, feeshare, feepay, clock, tokenfactory, staking.

Release: https://github.com/CosmosContracts/juno/releases/tag/v31.0.0 Binary (linux/amd64) sha256: 46fddb2c8c3fadcded48c63f72d88e9452cfd8a1da282892878a9f05d47f873c Build from source: git checkout v31.0.0 && make install (Go 1.25.2).

Validators: install the v31 binary before the upgrade height. With Cosmovisor, place it in cosmovisor/upgrades/v31/bin/junod. Coordination happens in the Juno Discord validator channels.