snap/2 - BAL-Based State Healing

The five-minute read

One action, walked through

1. Open EIP 8189 and read the status line before the examples.
2. Write down the rule in one sentence. A fair version of that sentence is: This EIP upgrades the snap protocol from version 1 to version 2, removing GetTrieNodes (0x06) / TrieNodes (0x07) and adding GetBlockAccessLists (0x08) / BlockAccessLists (0x09) to enable BAL-based state healing during snap sync.
3. Name the object that changes: BAL, B_32.
4. Ask what an old client, an old contract, or an offline counterparty does. If the document is silent, the silence is part of the design.

The argument, unpacked

What has to be true

• You are implementing EIP 8189 at the status the text itself states: Review.
• The object that has to change is BAL, B_32. A neighbouring document with a similar name is not this one.
• Measurements of delay in one year do not travel with the specification.

What happened after the paper

The source marks this review. It is not a live consensus rule just because it has a number. Later documents can narrow, replace, or ignore this one. Cite the number you mean.

What to check before you use the idea

• Which message does snap/2 - BAL-Based State Healing add, and which old peer must still be answered?
• What does a node do when the short form fails and the full object is required?
• Which names are normative: BAL, B_32?

Terms

EIP 8189

The public text titled snap/2 - BAL-Based State Healing.

Review

The document's own label for how finished the text is. It is not a market fact.

The problem the paper names

A node that cannot fetch, filter, or relay the data it is supposed to validate is not a peer of the network the paper describes.

What the design proposes

• This EIP upgrades the snap protocol from version 1 to version 2, removing GetTrieNodes (0x06) / TrieNodes (0x07) and adding GetBlockAccessLists (0x08) / BlockAccessLists (0x09) to enable BAL-based state healing during snap sync.
• EIP-7928 introduces block-level access lists (BALs) that capture all state changes per block, committed to block headers via block-access-list-hash.
• With BALs available, the snap sync healing phase — which iteratively fetches individual Merkle trie nodes via GetTrieNodes to resolve state inconsistencies — can be replaced entirely.

How the mechanism is specified

• Taken from the specification, the next constraint is: EIP-7928 introduces block-level access lists (BALs) that capture all state changes per block, committed to block headers via block-access-list-hash.
• Locate BAL, B_32 in EIP 8189 and apply it to one transaction or call.
• Then check the failure the class of rule always has: a node that did not upgrade, a reverted call, a replayed signature, or a peer that does not speak the message.

What this page does not treat as proven

• A peer protocol is not a consensus rule. A peer can disconnect. A block is still valid or not on its own.
• Measurements of delay in one year do not travel with the specification.
• The source marks this review. It is not a live consensus rule just because it has a number.

Why a venture studio still reads it

Use EIP 8189 when a pitch says 'snap/2 - BAL-Based State Healing' without saying whether the rule is consensus, policy, or an interface. The number is the citation. The pitch is not.