Add EIP: Add blob schedule to EL config files

EIPS/eip-7840.md

@@ -0,0 +1,70 @@
+---
+eip: 7840
+title: Add blob schedule to EL config files
+description: Include a per-fork schedule of max and target blob counts in client configuration files
+author: lightclient (@lightclient)
+discussions-to: https://ethereum-magicians.org/t/add-blob-schedule-to-execution-client-configuration-files/22182
+status: Draft
+type: Standards Track
+category: Core
+created: 2024-12-12
+---
+
+
+## Abstract
+
+Add a new object to client configuration files `blobSchedule` which lists the
+target blob count per block and max blob count per block for each fork.
+
+## Motivation
+
+- ensure there is a way to dynamically adjust the target and max blob counts per
+  block
+- avoid complex handshake over engine API
+
+## Specification
+
+Extend the client configuration files with the object `blobSchedule` with the
+following shape:
+
+```json
+"blobSchedule": {
+  "cancun": {
+    "target": 3,
+    "max": 6
+  },
+  "prague": {
+    "target": 6,
+    "max": 9
+  }
+}
+```
+
+When there is no explicit configuration for the current fork, use the last
+specified fork value. If no last value is specified, set both to zero.
+
+## Rationale
+
+Although maintaining the target and max blob only in the consensus client is
+desirable, we acknowledge the reality that execution clients need these values
+for various activities. For example, the `eth_feeHistory` RPC method returns a
+field `blobGasUsedRatio` that does require the max, even though the core
+protocol doesn't specifically need such value. Passing this value over the
+engine API every block seem overkill so we believe a configuration value is a
+good middle ground.
+
+## Backwards Compatibility
+
+No backward compatibility issues found.
+
+## Test Cases
+
+TODO
+
+## Security Considerations
+
+Needs discussion.
+
+## Copyright
+
+Copyright and related rights waived via [CC0](../LICENSE.md).