docs: reconcile SSTORE gas to 72,000 (same on both networks, Prop #109)

ai/sei-skill/index.mdx

@@ -17,7 +17,7 @@ AI assistants are trained on broad Ethereum knowledge, not Sei's specifics. With
 |---|---|
 | `maxFeePerGas` in transactions | Legacy `gasPrice` (Sei doesn't use EIP-1559 basefee) |
 | "Finality takes ~12 confirmations" | Instant finality — 1 confirmation is final |
-| SSTORE costs 20,000 gas | SSTORE varies: 72,000 on testnet, 20,000 on mainnet (governance-adjustable) |
+| SSTORE costs 20,000 gas | SSTORE costs 72,000 gas — the same on mainnet and testnet (governance-adjustable on-chain parameter; [reference](/evm/differences-with-ethereum#sstore-gas-cost)) |
 | `PREVRANDAO` for randomness | PREVRANDAO is not random on Sei — use Pyth VRF or Chainlink VRF |
 | Generic ERC-20 patterns | Sei precompiles, pointer contracts, dual-address UX |
 | `@sei-js/evm` imports | `@sei-js/precompiles` (the current package name) |

ai/sei-skill/prompts.mdx

@@ -19,7 +19,7 @@ Deploy a Solidity contract to Sei mainnet and verify it on Seiscan
 How do I call the Staking precompile from Solidity to delegate SEI?
 ```
 ```
-Why is SSTORE so expensive on Sei testnet compared to mainnet?
+Why does SSTORE cost more on Sei than on Ethereum, and how should I budget gas for storage writes?
 ```
 ```
 How do I use the Bank precompile to query a native denom balance?

evm/differences-with-ethereum.mdx

@@ -47,7 +47,7 @@
   - User accounts on Sei have [two addresses](/learn/accounts) derived from the same public key (Cosmos Bech32 and EVM-compatible 0x…)
   - Interoperability between EVM and Cosmos-SDK modules is governed and navigated via [precompiles](/evm/precompiles/example-usage) and [pointer contracts](/learn/pointers)
 
 ## Sei EVM Release
 
 Sei EVM was originally deployed at the following block heights and versions:
 
@@ -63,7 +63,7 @@
 - **Height:** `79123881`
 - **Changelog:** https://github.com/sei-protocol/sei-chain/blob/main/CHANGELOG.md#v552
 
 ## Opcode Differences
 
 | Opcode | Sei EVM | Ethereum | Notes |
 | --- | --- | --- | --- |
@@ -77,7 +77,7 @@
 | Blob‑related opcodes | Not supported (Pectra without blobs) | Supported post‑Cancun (EIP‑4844) | Blob transactions are not enabled on Sei. |
 
 
 ### PREVRANDAO
 
 Since Sei doesn't rely on the same pseudo‑randomness way of determining the next
 validator like Proof of Stake (PoS) Ethereum does, it doesn't have the
@@ -91,19 +91,19 @@
 Coinbase address on Sei is always set to (the EVM address of) the global fee
 collector.
 
 ## State Root
 
 Since Sei uses AVL-tree instead of Merkle Patricia Trie (MPT) for data storage,
 Sei doesn't have per-account state root. The global state root is the AVL-tree
 root which is also not equivalent to Ethereum's overall state root (which is a
 MPT root)
 
 ## Block Hash
 
 The block hash on Sei is computed based on the block header in Tendermint data
 format, and is different from Ethereum's block Hash as a result.
 
 ## Base Fee & Tips
 
 Sei supports all non‑blob transaction types, including the Pectra `SetCode` transaction (EIP‑7702). However for a legacy (non EIP‑1559) type
 transaction, you must specify a gas price at or above Sei's governance-set minimum gas price (currently `50 gwei` on mainnet). Query the live value with `eth_gasPrice` rather than hard-coding it. In addition to this, excess
@@ -128,7 +128,7 @@
 value: '"0.007500000000000000"'
 ```
 
 ## Non-EVM Transactions
 
 On Sei there exists non-EVM transactions which may update states accessible by
 EVM transactions. The simplest example would be bank balances, which may be
@@ -142,7 +142,7 @@
 committed (~400 ms) — meaning that commitment levels of "safe", "latest",
 "justified", and "finalized" on Ethereum are all the same thing on Sei.
 
 ## Pending State
 
 On Ethereum the block proposer would execute its proposed block first (and
 update its local state) before broadcasting the proposal to others (the updated
@@ -153,7 +153,7 @@
 the same time), so Sei does not have a window when "pending state"
 exists.
 
 ## Gas Model & Fees
 
 Sei does not implement base‑fee burning. There is no base‑fee burn; all transaction fees accrue to validators. Fees are calculated as:
 
@@ -175,17 +175,19 @@
 
 </Info>
 
 ## SSTORE Gas Cost
 
 On Sei, the `SSTORE` opcode gas cost is configurable as an on-chain parameter, meaning it can be adjusted via governance proposal without requiring a chain upgrade.
 
 This provides flexibility to tune storage costs based on EVM state size and network conditions.
 
-Currently, the `SSTORE` gas cost is set to the non-standard value of **72,000 gas**.
+Currently, the `SSTORE` gas cost is set to the non-standard value of **72,000 gas**, and this is the same on both mainnet (`pacific-1`) and testnet (`atlantic-2`) — it does not vary by network. It was set by governance [Proposal #109](https://www.mintscan.io/sei/proposals/109) ("Update EVM SSTORE set gas to 72000"), which changed the `evm` module parameter `KeySeiSstoreSetGasEIP2200` to `72000`.
+
+To confirm the real cost yourself, use a live `eth_estimateGas` call against a Sei RPC. Note that a Foundry `forge test --gas-report --fork-url <sei rpc>` report forks chain *state* but applies revm's standard EVM gas schedule, so it reports the Ethereum cost (~22,100) rather than Sei's — it is useful for relative profiling of your own logic, not for the absolute storage-write cost.
 
 <Info>Since `SSTORE` is a governance-controlled parameter, this value may change in the future through a governance proposal.</Info>
 
 ## ERC Token Standards Compatibility
 
 Sei’s EVM fully supports the common token standards:
 
@@ -195,7 +197,7 @@
 
 Existing OpenZeppelin contracts and tools work unchanged.
 
 ## Testing & Migration Checklist
 
 - ✅ Re‑deploy your Solidity code to Sei testnet; most contracts need no changes.
 - ✅ If you used SELFDESTRUCT, refactor to a soft‑close pattern.

evm/evm-parity/gas-and-fees.mdx

@@ -3,11 +3,11 @@
 description: 'Sei gas price floor, EIP-1559 fee model differences, and SSTORE cost'
 ---
 
 # Gas and Fees
 
 Sei supports both legacy and EIP-1559 transactions, but the fee model differs from Ethereum in three ways that affect how you estimate and set gas.
 
 ## Legacy Gas Price Floor
 
 Legacy transactions (type 0) on Sei must meet a minimum gas price set by on-chain governance. This floor can change via governance proposals — do not hard-code a specific value.
 
@@ -33,7 +33,7 @@
 
 </CodeGroup>
 
 ## EIP-1559 Fee Model
 
 Sei supports EIP-1559 transactions (type 2), but does not burn the base fee. Fees go entirely to validators rather than being partially burned as on Ethereum.
 
@@ -53,9 +53,9 @@
 
 </CodeGroup>
 
 ## SSTORE Cost
 
-The gas cost of `SSTORE` (writing to contract storage) is governance-adjustable on Sei. Do not hard-code storage write estimates in your application.
+The gas cost of `SSTORE` (writing to contract storage) is governance-adjustable on Sei. It is currently **72,000 gas** — the same on mainnet and testnet (see [Divergence from Ethereum](/evm/differences-with-ethereum#sstore-gas-cost)) — but treat that as the current value, not a constant: do not hard-code storage write estimates in your application.
 
 Always use `eth_estimateGas` for any transaction that writes to storage:
 
@@ -82,6 +82,8 @@
 
 </CodeGroup>
 
+<Warning>A Foundry `forge test --gas-report --fork-url <sei rpc>` report forks chain *state* but runs revm's standard EVM gas schedule, so it shows `SSTORE` at the Ethereum cost (~22,100) rather than Sei's ~72,000. Use it for relative profiling of your own logic; estimate the absolute storage-write cost with a live `eth_estimateGas` against a Sei RPC.</Warning>
+
 ## Summary
 
 | Behavior | Ethereum | Sei |

skill.md

@@ -21,7 +21,7 @@
   parent: https://github.com/sei-protocol/sei-skill
 ---
 
 # Sei Developer Documentation
 
 Full technical reference for building on Sei. This is the docs.sei.io-resident skill — for the offline AI coding-assistant skill (a Claude Code skill loaded directly into your editor), see **[github.com/sei-protocol/sei-skill](https://github.com/sei-protocol/sei-skill)**.
 
@@ -38,7 +38,7 @@
 ## Critical facts — apply to every answer
 
 1. **400ms block time, instant finality** — use `tx.wait(1)`, never `tx.wait(12)`
-2. **SSTORE gas is 72,000 on Sei** — both mainnet (pacific-1) and testnet (atlantic-2): 72,000 gas per cold write (governance proposal #240; governance-adjustable)
+2. **SSTORE gas is 72,000 on Sei** — the same on both mainnet (pacific-1) and testnet (atlantic-2); it does not vary by network. Set via governance (mainnet Proposal #109, "Update EVM SSTORE set gas to 72000", which set the `evm` param `KeySeiSstoreSetGasEIP2200` to `72000`), so it is adjustable and can change — confirm the live value at https://docs.sei.io/evm/differences-with-ethereum#sstore-gas-cost
 3. **Use legacy `gasPrice`** — Sei has no base fee burn; prefer `gasPrice` over EIP-1559 `maxFeePerGas` / `maxPriorityFeePerGas`
 4. **Minimum gas price: 50 gwei**
 5. **Block gas limit: 12.5M per block**
@@ -94,7 +94,7 @@
 
 Once connected: address lookup, balance checks, transaction status, contract reads, block data.
 
 ## Precompile addresses
 
 | Precompile | Address |
 |---|---|