[UPGRADE] SPB Testnet Upgrade to v1.6.1

[AkKoks]

SPB Testnet Upgrade to v1.6.1

Proposal

Network: tacchain_2391-1
Current version: v1.6.0-spb-hotfix
Target upgrade name: v1.6.1
Target build tag: v1.6.1-beta.1
Target commit: 15450bf7

Overview

This proposal applies the v1.6.1 upgrade to the SPB testnet.

v1.6.1 ships binary-level fixes only — the upgrade handler performs no state migration (it just runs standard module migrations and returns).

The main fix allows delegating vesting-locked tokens via the EVM staking precompile (0x0000000000000000000000000000000000000800). Previously such delegations silently burned tokens (when within spendable) or overflow-panicked and left the transaction stuck (when beyond spendable), because the EVM state tracks only the spendable balance. The fix has x/bank tag the locked portion on the coin_spent event and the EVM balance handler subtract only the spendable part (amount − locked), so delegation works and total supply is conserved.

Dependency bumps carrying the fix: cosmos-sdk v0.53.6-tac.3, cosmos/evm v0.6.0-tac.10.

The same upgrade will be proposed for mainnet after it is validated on SPB.

Release Artifacts

Artifact	Value
Git tag / build tag	v1.6.1-beta.1
Commit	15450bf70e0aba87d12ae4c72a527de879f2c625
GitHub release	https://github.com/TacBuild/tacchain/releases/tag/v1.6.1-beta.1

The upgrade proposal plan.info uses .tar.gz binary archives for Cosmovisor compatibility:

Platform	Archive	SHA256
linux/amd64	tacchaind-linux-amd64.tar.gz	5f018f80883237e48c9639128ca8fb4f14d64a55033ba4bdaa78d6e56aab2e92
linux/arm64	tacchaind-linux-arm64.tar.gz	b8727acffa8f778cfab94706cf7382f4541374438a60eb4fb4056c11468fa380

If your Cosmovisor setup is configured to automatically download and switch binaries from the upgrade plan.info, it should be able to use these archive URLs automatically.

Upgrade Timeline

Event	Date (UTC)	Block
Governance proposal submitted	July 30, 2026, 10:00	-
Voting period ends	July 30, 2026, 13:00	-
Upgrade activation time	July 30, 2026, 14:00	23205042
Node update deadline	after upgrade height	-

Validator Actions

Validators should vote during the voting period and prepare the v1.6.1-beta.1 binary before the upgrade height.

At the upgrade height, the chain will halt with the upgrade name v1.6.1. After the halt:

1. Stop tacchaind.
2. Back up the node home directory.
3. Replace the binary with the v1.6.1-beta.1 build.
4. Start tacchaind.

The upgrade handler runs automatically on the first block after restart. No manual state migration is required.

[AkKoks]

Upgrade done.