TacBuild · AkKoks · Aug 5, 2026 · Aug 5, 2026 · Aug 5, 2026 · Aug 5, 2026
diff --git a/contrib/localnet/init.sh b/contrib/localnet/init.sh
@@ -226,8 +226,8 @@ jq --arg GOV_MIN_EXPEDITED_DEPOSIT "$GOV_MIN_EXPEDITED_DEPOSIT" '
 # enable apis
 sed -i.bak "s/enable = false/enable = true/g" $HOMEDIR/config/app.toml
 
-# enable debug namespace in json-rpc
-sed -i.bak 's/api = "eth,net,web3"/api = "eth,net,web3,debug"/' $HOMEDIR/config/app.toml
+# enable debug and tac namespaces in json-rpc
+sed -i.bak 's/api = "eth,net,web3"/api = "eth,net,web3,debug,tac"/' $HOMEDIR/config/app.toml
 
 # enable rpc cors
 sed -i.bak "s/cors_allowed_origins = \[\]/cors_allowed_origins = \[\"*\"\]/g" $HOMEDIR/config/config.toml

diff --git a/docs/CHANGELOG-v160-v161.md b/docs/CHANGELOG-v160-v161.md
@@ -0,0 +1,183 @@
+# TacChain v1.6.1 — Changelog
+
+> **Status:** DRAFT
+> **Upgrade name:** `v1.6.1`
+> **Previous version:** v1.6.0
+> **Chain:** TacChain Mainnet
+
+---
+
+## Summary
+
+TacChain v1.6.1 is a maintenance release on top of v1.6.0. It carries **no state
+migration**: the upgrade handler exists only so the network can coordinate a
+version bump to ship binary-level fixes.
+
+Everything in this release comes from the `cosmos/evm` and `cosmos-sdk` forks:
+
+- Delegating vesting-locked tokens through the EVM staking precompile no longer
+  burns coins or panics
+- Historical EVM queries below the v1.6.0 store-migration height work again
+- New `tac_simulate` JSON-RPC method
+
+---
+
+## Breaking Changes
+
+None. No consensus-affecting change, no state migration, no parameter change.
+
+---
+
+## New Features
+
+### RPC
+
+- **`tac_simulate`** — a simulated, non-committing call that reports in one
+  round-trip what `eth_call`, `eth_estimateGas` and a log inspection would take
+  three of:
+
+  ```json
+  {
+    "success": true,
+    "output": "0x...",
+    "vmError": "",
+    "logs": [],
+    "gasEstimated": "0x..."
+  }
+  ```
+
+  Parameters mirror `eth_call`: call args, block number or hash, and state
+  overrides.
+
+  - **Event logs** emitted during the simulation are returned in `logs`.
+  - **`gasEstimated`** is a full `eth_estimateGas` binary search run against the
+    *same* overridden state as the call, so an estimate can be produced for state
+    that does not exist on chain yet.
+  - **A revert is a result, not an error.** Where `eth_call` turns a revert into
+    a JSON-RPC error, `tac_simulate` returns `success: false` together with
+    `vmError` and the revert data in `output`, so a caller can decode a custom
+    error instead of just seeing the request fail.
+
+  Served under the **`tac` namespace, which is not enabled by default** — it has
+  to be listed in `app.toml` under `[json-rpc] api` to be reachable.
+
+---
+
+## Bug Fixes
+
+### Vesting delegations via the EVM staking precompile
+
+Delegating vesting-**locked** tokens through the staking precompile either
+silently burned coins (when `amount <= spendable`) or aborted with an
+integer-overflow panic (when `amount > spendable`).
+
+The EVM balance handler subtracted the full `CoinSpent` amount from an EVM
+balance that only ever reflects the *spendable* portion, while a delegation from
+a vesting account is drawn from the locked portion and does not reduce spendable
+at all.
+
+`x/bank` now tags `coin_spent` with a `locked_amount` attribute
+(`cosmos-sdk` fork), and the handler subtracts only the spendable part
+(`amount - locked`). An inconsistent event where `locked > amount` is now an
+error rather than a silent clamp. `SubBalance` is additionally guarded against
+underflow (upstream `cosmos/evm` #1176).
+
+> Requires both fork bumps together — the EVM-side handler depends on the
+> `locked_amount` emission from the SDK side.
+
+### Historical EVM queries below the v1.6.0 migration height
+
+`eth_call`, `eth_estimateGas` and traces at heights **below** the v1.6.0 store
+migration failed or returned wrong results, because pre-migration state was
+being decoded with the current, incompatible layout:
+
+- **`x/vm` params** — proto field numbers shifted in v1.6.0 (old field 10
+  `active_static_precompiles` vs. new `history_serve_window`), so decoding
+  panicked with `wrong wireType = 2 for field HistoryServeWindow`.
+- **`x/erc20` precompiles** — the native/dynamic lists moved from a single
+  concatenated-blob key to per-address keys, so precompiles looked unregistered
+  at historical heights and calls executed the decoy ERC20 bytecode instead of
+  the precompile. In practice `gTAC.balanceOf` at an old height returned `0`
+  instead of the real balance.
+
+A lazy, height-gated shim now decodes the legacy layout on the read path below
+the migration height. The height is resolved from the applied `x/upgrade`
+done-height and cached; the caches are warmed in the `x/vm` `BeginBlock`.
+
+> **Query path only.** At current heights the code path is byte-for-byte
+> unchanged, so this is not consensus-affecting.
+
+### Gas estimation with a balance override
+
+The upper bound of the gas estimation binary search is capped by what the sender
+can pay for gas, and that balance was read straight off the bank keeper — the
+state override never reached it. Pricing a call for an account that is not funded
+yet therefore returned no estimate at all: the call itself succeeded on the
+overridden state while `gasEstimated` came back `0`.
+
+The balance now comes from the override when it carries one for the sender, the
+way go-ethereum reads it off the overridden state. Without an override nothing
+changes, so `eth_estimateGas` keeps its behaviour.
+
+> Only observable when the caller passes a gas price; otherwise the fee cap
+> defaults to `0` and the recap is skipped entirely.
+
+---
+
+## Upgrade Handler Details
+
+`v1.6.1` is a **no-op state upgrade**. The handler runs the standard module
+migrations and returns:
+
+- No `StoreUpgrades` — no store added, renamed or deleted.
+- No KV migration.
+- No parameter change.
+- No `ConsensusVersion` bump in any module.
+
+A vesting schedule shift and an account migration were considered for this
+release and **dropped** — they were not approved — so no vesting logic ships in
+the handler.
+
+---
+
+## Documentation & Tooling
+
+- Cosmovisor setup guide now covers migrating an already running node.
+- Deprecated Turin testnet (`tacchain_2390-1`) removed: `NETWORKS.md` section and
+  the `networks/tacchain_2390-1/` directory (genesis, compose file, env).
+- The localnet script now lists `tac` in `json-rpc.api`, so `tac_simulate` is
+  reachable out of the box on a locally initialised chain.
+
+---
+
+## Dependency Versions
+
+| Dependency | v1.6.0 | v1.6.1 |
+|------------|--------|--------|
+| `cosmos/evm` | fork @ `v0.6.0-tac.8` | fork @ `v0.6.0-tac.12` |
+| `cosmos/cosmos-sdk` | fork @ `v0.53.6-tac.2` | fork @ `v0.53.6-tac.3` |
+| `ethereum/go-ethereum` | `v1.16.2-cosmos-1` | unchanged |
+| `cometbft/cometbft` | `v0.38.21` | unchanged |
+| `cosmos/ibc-go/v10` | `v10.3.1` | unchanged |
+| Go | 1.23.8 | unchanged |
+
+### Fork changes in detail
+
+**`cosmos/evm` `v0.6.0-tac.8` → `v0.6.0-tac.12`**
+
+| Commit | Change |
+|--------|--------|
+| `6fac41af` | Allow delegating locked vesting tokens via the staking precompile |
+| `a585881b` | Tests for vesting-locked delegation via the staking precompile |
+| `993cc964` | Decode pre-migration EVM state for historical queries |
+| `436c16e0` | Warm the legacy-decode height cache from live state |
+| `9d115d6c` | Move the per-block cache warming into the `x/vm` `BeginBlock` |
+| `5796b415` | Guard nil `erc20Keeper` in `BeginBlock` cache warming |
+| `9a602662` | Add the `tac_simulate` JSON-RPC method |
+| `5f530858` | Let a balance override reach the gas estimation |
+
+**`cosmos/cosmos-sdk` `v0.53.6-tac.2` → `v0.53.6-tac.3`**
+
+| Commit | Change |
+|--------|--------|
+| `7bb449d6` | `x/bank` emits `locked_amount` on `coin_spent` for vesting delegations |
diff --git a/go.mod b/go.mod
@@ -293,7 +293,8 @@ replace (
 	// fix ed25519 precompile gas cost. See: https://github.com/TacBuild/evm/pull/11
 	// bump to v0.6.0
 	// tac.10: allow delegating vesting-locked tokens via staking precompile (amount-locked; needs cosmos-sdk tac.3).
-	github.com/cosmos/evm => github.com/TacBuild/evm v0.6.0-tac.10
+	// tac.12: add the tac_simulate rpc (state overrides, event logs and gas estimate in one call).
+	github.com/cosmos/evm => github.com/TacBuild/evm v0.6.0-tac.12
 
 	// replace with our fork using geth v1.16.2
 	github.com/ethereum/go-ethereum => github.com/cosmos/go-ethereum v1.16.2-cosmos-1

diff --git a/go.sum b/go.sum
@@ -685,8 +685,8 @@ github.com/Shopify/sarama v1.19.0/go.mod h1:FVkBWblsNy7DGZRfXLU0O9RCGt5g3g3yEuWX
 github.com/Shopify/toxiproxy v2.1.4+incompatible/go.mod h1:OXgGpZ6Cli1/URJOF1DMxUHB2q5Ap20/P/eIdh4G0pI=
 github.com/TacBuild/cosmos-sdk v0.53.6-tac.3 h1:tKkYpmiVGrCFy3V11fCy/AP+JOu3duawBzQVOIQgl5s=
 github.com/TacBuild/cosmos-sdk v0.53.6-tac.3/go.mod h1:N6YuprhAabInbT3YGumGDKONbvPX5dNro7RjHvkQoKE=
-github.com/TacBuild/evm v0.6.0-tac.10 h1:XJuFhP+eZK48NgNY2ywnHTdi0tGNJMrjSHMlxGzPezc=
-github.com/TacBuild/evm v0.6.0-tac.10/go.mod h1:9DaIfOYirXAQplL677tYEmy0crZWLI4glre84+qi5FQ=
+github.com/TacBuild/evm v0.6.0-tac.12 h1:AQC/scOXohqzCfFuh6a8WVBE3H6xybnv41Qfu4ctmXo=
+github.com/TacBuild/evm v0.6.0-tac.12/go.mod h1:9DaIfOYirXAQplL677tYEmy0crZWLI4glre84+qi5FQ=
 github.com/VictoriaMetrics/fastcache v1.12.2 h1:N0y9ASrJ0F6h0QaC3o6uJb3NIZ9VKLjCM7NQbSmF7WI=
 github.com/VictoriaMetrics/fastcache v1.12.2/go.mod h1:AmC+Nzz1+3G2eCPapF6UcsnkThDcMsQicp4xDukwJYI=
 github.com/VividCortex/gohistogram v1.0.0 h1:6+hBz+qvs0JOrrNhhmR7lFxo5sINxBCGXrdtl/UvroE=