From b8903615b57c2479fe4acda9d34cb5bc78f742dc Mon Sep 17 00:00:00 2001
From: "seidroid[bot]" <257742136+seidroid[bot]@users.noreply.github.com>
Date: Mon, 10 Aug 2026 00:21:34 +0000
Subject: [PATCH] skills: The eth_blobBaseFee JSON-RPC endpoint is now exposed
 on Sei but returns a JSON-RPC error (code -32000, "blobs not supported on
 this chain") since Sei does not support EIP-4844 blob transactions.
 (sei-protocol/sei-chain#3080)

---
 skill/references/evm/overview.md            |  2 +-
 skill/references/migration/from-ethereum.md | 12 ++++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/skill/references/evm/overview.md b/skill/references/evm/overview.md
index 7e95fc1..12ffb23 100644
--- a/skill/references/evm/overview.md
+++ b/skill/references/evm/overview.md
@@ -35,7 +35,7 @@ description: How Sei's EVM differs from Ethereum — opcodes, gas model, finalit
 | `BLOCKHASH` | Hash of Tendermint header | Keccak of Ethereum block header | Different encoding; usable for recent blocks |
 | `GASLIMIT` | 12,500,000 | 60,000,000 | Block gas limit |
 | `TIMESTAMP` | Tendermint block time | Proposer-chosen block time | Do not use as randomness source |
-| Blob opcodes | Not supported | Supported (post-Cancun) | No EIP-4844 blob transactions on Sei |
+| Blob opcodes | Not supported | Supported (post-Cancun) | No EIP-4844 blob transactions on Sei. `eth_blobBaseFee` is exposed but returns JSON-RPC error -32000 ("blobs not supported on this chain"), not -32601 method-not-found |
 
 ## Key Developer Rules
 
diff --git a/skill/references/migration/from-ethereum.md b/skill/references/migration/from-ethereum.md
index 56a24e6..665bae8 100644
--- a/skill/references/migration/from-ethereum.md
+++ b/skill/references/migration/from-ethereum.md
@@ -77,6 +77,18 @@ address proposer = block.coinbase;
 
 Sei runs Pectra EVM but without blob transactions (`BLOBHASH` / `BLOBBASEFEE`). If your contract uses blobs, you need to refactor.
 
+The `eth_blobBaseFee` JSON-RPC endpoint **is** exposed, but it deliberately returns a JSON-RPC error instead of a fee value — do not expect a usable blob base fee:
+
+```json
+// Request
+{"jsonrpc":"2.0","id":1,"method":"eth_blobBaseFee"}
+
+// Response
+{"jsonrpc":"2.0","id":1,"error":{"code":-32000,"message":"blobs not supported on this chain"}}
+```
+
+Migrating apps that call `eth_blobBaseFee` must handle the `-32000` "blobs not supported on this chain" error rather than parsing a returned fee.
+
 ### 6. SSTORE Costs Are Higher Than Ethereum
 
 Storage writes are far costlier than Ethereum's 20,000 gas: