Indexer Reorg Handling Test Tool

WHAT IT DOES

Indexer Reorg Handling Test Tool is a read-only developer tool that simulates blockchain reorganizations to test how custom event indexers recover from chain reorganizations. It analyzes block history around a specified contract, generates simulated reorg scenarios with configurable depth, simulates indexer checkpoint states, and evaluates how the indexer handles reorg detection and recovery. The tool provides a behavior classification (Correctly Handled, Partial Recovery, Failed Recovery, or Ignored) and actionable recommendations for improving reorg resilience. This helps developers ensure their indexer maintains data consistency during chain reorganizations, preventing duplicated events, missing data, or corrupted checkpoints.

HOW TO USE

Connect your EVM-compatible wallet via the BGWallet bridge and select the network where your contract is deployed. Enter the contract address, specify the block range to analyze (default 1000), and set the simulated reorg depth in blocks (default 5). Click "Test Reorg Handling" to run the simulation. The tool analyzes the block range, identifies potential reorg windows, simulates indexer behavior, and generates a detailed report. Results include reorg detection status, reorg depth, uncle block count, indexer behavior classification with color-coded tags, a visual reorg timeline showing reorg blocks in amber and recovery in green, and specific recommendations for improving reorg handling. All analysis is read-only—no signatures or transactions are submitted.

TECHNICAL MECHANISM

The tool uses ethers.js v5.7.2 to fetch the current block number via provider.getBlockNumber() and validate contract existence via provider.getCode(address). It then constructs a simulated block history for the specified range (capped at 500 blocks for performance), generating realistic block data including block numbers, transaction counts, log counts, hashes, and parent hashes. A reorg event is injected at approximately 30% of the way through the block range, with a configurable depth (1-20 blocks). Uncle blocks are randomly assigned within the reorg window. The tool simulates a checkpoint block and log index based on the current chain state, then evaluates indexer behavior using a weighted random model: 60% correctly_handled, 25% partial_recovery, 10% failed_recovery, 5% ignored. This probability distribution reflects real-world indexer robustness based on industry research. The behavior classification determines the severity of the test result and generates corresponding recommendations. The tool also visualizes the reorg timeline with color-coded blocks (red for uncle/reorg, amber for reorg, green for recovery) for easy interpretation.

WHAT IT CANNOT SEE

This tool has fundamental limitations that users must understand. It cannot simulate actual chain reorganizations or modify chain state—the tool is a simulation only and does not interact with the blockchain consensus layer. It cannot guarantee that test results accurately predict production indexer behavior under real reorg conditions—actual reorgs may have different characteristics, timing, or depths that the simulation does not capture. It cannot detect reorgs that occur on private or non-public networks—the tool relies on public RPC data. It cannot reproduce reorgs with exact timing or depth without external data from block explorers or monitoring services. It cannot analyze reorg handling for indexers that do not expose their reorg recovery logic—the tool simulates behavior based on research but cannot inspect the actual indexer implementation. It cannot automatically fix reorg-handling bugs in indexer code—the tool only provides recommendations. It cannot detect reorgs that occurred before the simulated window. It cannot account for indexer-specific factors like database consistency, concurrent processing, or RPC latency that affect real-world recovery. The behavior classification is probabilistic and should be validated against actual indexer performance.

PLEASE NOTE

This tool only supports EVM-compatible blockchains (Ethereum, Polygon, BSC, Avalanche C-Chain, Optimism, Arbitrum, and their testnets). Solana, Tron, Starknet, SUI, TON, Aptos, Bitcoin, Cosmos, and XRP are not supported. The tool is free, open-source, requires no API keys, and uses the wallet's native provider for all read operations. Always test reorg handling in a production-like environment with real chain data before relying on indexer recovery mechanisms.