# Overlay Network Transaction History Tracking Ty Everett () ## Abstract This document proposes a solution for tracking transaction histories within UTXO-based overlay networks by extending the BRC-22 submission result model to identify which spent topical coins should be retained for history and by extending BRC-24 lookup behavior to return BEEF that preserves source-transaction ancestry. This allows clients to traverse the lifecycle of topical outputs directly from returned transaction data. The older notion of extending BRC-36 JSON envelopes is now historical and is not the current interoperable mechanism. ## Motivation BRC-22 successfully enables the tracking and synchronization of UTXOs across various topics in overlay networks, yet it does not accommodate the preservation of UTXO histories which can hold valuable network data. Transaction histories are key to understanding the full lifecycle of UTXOs, acting as a crucial component for certain applications in areas like network analysis and auditability. The absence of a history tracking standard leads to information gaps, preventing a comprehensive understanding of network state changes. This document presents a solution to this problem by providing a clear and standardized mechanism for maintaining and accessing transaction histories in UTXO-based overlay networks. ## Specification We introduce extensions to the BRC-22 and BRC-24 standards to encapsulate the input history of network transactions. Topic managers in BRC-22 can prescribe which transaction inputs should be conserved and linked with admitted transaction outputs, designating inputs pertinent for later history traversal. BRC-24 lookups then return enough BEEF to reconstruct those relationships. ### Changes to the BRC-22 Standard Topic managers in overlay networks now perform the following additional steps: * Verify the inputs from the transaction tagged with their topic labels to determine their relevance. * Return `coinsToRetain` input indices for any spent topical predecessors that should remain queryable for history. * Optionally return `coinsRemoved` input indices for spent topical predecessors that are removed from the live topical set. * Preserve enough transaction ancestry to later reconstruct source transactions for those retained historical coins. ### Changes to the BRC-24 Standard The lookup services specified under BRC-24 can now: * Accept queries for the previous renditions of specific UTXOs (formats for these queries depend on the specific lookup service). * Assemble and return BEEF sufficient to reconstruct the responsive outputs and their ancestry. * Optionally associate service-defined `context` bytes with each returned output when that helps identify the role of a historical rendition. Current SDK-side historical reconstruction is performed by traversing `Transaction.inputs[].sourceTransaction` ancestry. Implementations that wish to support interoperable history traversal SHOULD therefore ensure that returned BEEF is rich enough for clients to rebuild this chain. ## Implementation Developers should adapt their existing BRC-22 based systems to collect and preserve pertinent transaction inputs when admitting new transaction outputs. Lookup services following BRC-24 should return BEEF with sufficient ancestry for clients to traverse historical state transitions. The older BRC-36-envelope approach SHOULD be considered deprecated for new interoperable implementations. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://bsv.brc.dev/overlays/0064.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.