Draft informational EIP-8252 sets REORG_RETENTION_WINDOW to 262,144 blocks,
about 8,192 epochs or 36.4 days.
Proposed rule
For every canonical block from head - 262,144 through head, an execution
client can reconstruct that block's post-state without sync. It may use full
snapshots, reverse diffs, or another equivalent form in memory or on disk.
The rule covers state needed to execute a branch after a reorganization. It does not set retention for headers, bodies, or receipts.
Failure handling
A reorganization within the window must not fail only because the client pruned ancestor state. State older than the window may require sync or another recovery path. An implementation must not claim local reorg support deeper than the state it can reconstruct.
Status
The EIP is informational and Draft. It does not prove that current clients meet this floor.
Design rationale
A fixed reconstructible window gives fork choice a clear local recovery bound without requiring one storage layout.