Pectra user fees notice

pages/notices/_meta.json

@@ -1,4 +1,5 @@
 {
+  "pectra-fees": "Pectra user fees notice",
   "superchain-withdrawal-pause-test": "Superchain withdrawal pause test",
   "upgrade-15": "Upgrade 15: Isthmus Hard Fork",
   "upgrade-14": "Upgrade 14: MT-Cannon and Isthmus L1 Contracts",

pages/notices/pectra-fees.mdx

@@ -0,0 +1,84 @@
+---
+title: L1 Pectra user fees and chain profitability
+description: L1 Pectra affect on user fees and chain profitability analysis
+lang: en-US
+content_type: notice
+topic: pectra-fees
+personas:
+ - chain-operator
+ - node-operator
+categories:
+ - security
+ - protocol
+ - infrastructure
+ - l1-contracts
+is_imported_content: 'false'
+---
+
+# Pectra impact on user fees and chain profitability
+
+The Ethereum L1 Pectra upgrade has introduced changes to calldata gas costs via EIP-7623 that will affect OP Stack chain profitability in specific configurations. This notice outlines the potential impact on your chain and recommends specific actions.
+
+The Optimism protocol's current fee pricing formula does not account for the Pectra upgrade's 10/4 increase in calldata costs (from 16 gas per byte to 40 gas per byte). While most chains using blob data availability remain unaffected, chains with specific configurations will experience reduced profitability.
+
+## Actions required
+
+Review your chain configuration if your chain uses a zero blob fee scalar (`sB=0`), meaning it's configured to price for calldata only, AND your chain uses calldata (not blobs) to post batches to L1.
+
+No action is needed if your chain uses blob data availability (the default and recommended configuration) or your ecotone scalars already account for blob pricing.
+
+## Technical background
+
+Since the Ecotone upgrade, the Optimism protocol prices L2 transactions using a function that incorporates L1 base fee, L1 blob base fee, and estimated data availability costs. "Ecotone scalars" in the SystemConfig contract determine this pricing.
+
+The current fee pricing formula is:
+
+```
+c = e(16sC·C + sB·B)·10^-6
+```
+
+Where:
+
+*   e = estimated transaction size
+*   C = L1 base fee
+*   B = L1 blob base fee
+*   sC = L1 base fee scalar
+*   sB = L1 blob base fee scalar
+*   16 = calldata cost per byte (pre-Pectra)
+
+## Impact on chains
+
+The Pectra upgrade through EIP-7623 increases calldata gas costs by a factor of 10/4 (from 16 to 40 gas per byte).
+
+**No impact for chains that:**
+
+*   Use blob data availability (most OP Stack chains)
+*   Have ecotone scalars configured for a healthy profit margin (\~5%)
+
+**Potential impact for chains that:**
+
+*   Use calldata exclusively for batch posting
+*   Have scalars configured only for calldata pricing (sB=0)
+
+In extreme cases of unchecked negative profitability, a batcher might eventually exhaust its funds, resulting in a safe head stall.
+
+### Detection
+
+Chain operators should monitor their profitability by tracking the L1 Fee Vault balance and comparing this to the batcher balance.
+
+### Mitigation
+
+If adjustments are needed:
+
+1.  **For chains using calldata by design:**  // What is the fix here??
+
+2.  **For chains using or able to use blobs:** Ensure your blob fee scalar (sB) properly accounts for blob pricing, as the Pectra changes do not affect blob transactions.
+
+Chain operators can update their ecotone scalars through the standard governance process for their deployment.
+
+### Technical References
+
+*   [Optimism Protocol Specification - Ecotone L1 Cost Fee Changes](https://specs.optimism.io/protocol/exec-engine.html#ecotone-l1-cost-fee-changes-eip-4844-da)
+*   [Optimism Protocol Specification - Fjord Execution Engine Fees](https://specs.optimism.io/protocol/fjord/exec-engine.html#fees)
+*   [Implementation Source Code](https://github.com/ethereum-optimism/op-geth/blob/3d7afdc2701b74c5987e31521e2c336c4511afdf/core/types/rollup_cost.go#L527)
+*   [EIP-7623](https://eips.ethereum.org/EIPS/eip-7623)