# Fork and reorg watch

Research: detect indexers that follow a stale tip or a fork, from the experience of an atomicals indexer stuck on an orphan at block 966,500.

URL: https://blockspace.wiki/research/fork-and-reorg-watch/

**Status on [blockspacelabs.com](https://blockspacelabs.com): Research.**

## What it studies

The Labs site describes it as a study that "detects indexers that follow a stale tip or a fork, from our experience with an atomicals indexer stuck on an orphan at block 966,500."

An [indexer](https://blockspace.wiki/glossary/indexer/) reads every block and builds its own view of a protocol. In a [reorg](https://blockspace.wiki/glossary/reorg/), a competing chain replaces recent blocks, and a replaced block becomes an orphan. An indexer that does not follow the reorg keeps building on the orphan: its height can look current while its view has left the chain the node follows.

That happened to the atomicals indexer, which serves [ARC-20](https://blockspace.wiki/glossary/arc-20/): it stayed on an orphan at block 966,500. The study turns that lesson into a check.

## The data it will use

"Indexer cursors against bitcoind": compare the height and block each indexer says it has reached with the chain the Bitcoin node follows. A cursor whose block is not on the node's chain marks an indexer on a fork. block.space already publishes the cursors of BTI's three tiers beside the chain tip; [the frontier](/concepts/the-frontier/) page explains them.

## Where it stands

It is a descriptive card: it says what the check is and what it would compare. No watch is built yet and no results are claimed.

Sources:

- The blockspacelabs.com page (index.html) · https://blockspacelabs.com
- Blockspace Holdings records
- block.space frontier API (the three tier cursors and the chain tip) · https://block.space/api/frontier

Updated: 2026-10-20