Add internal onRollbackCommit callback API for rollback events

[DZakh]

Summary

Adds an internal, unstable ~internalAndWillBeRemovedSoon_onRollbackCommit API that allows indexers to register callbacks fired once per chain affected by a reorg rollback, after the rollback is durably written to the database.

Key Changes

• New RollbackCommit module (packages/envio/src/RollbackCommit.res): Manages callback registration and firing for rollback commit events. Callbacks receive the chain ID and the last valid block number for that chain.

• Integration in InMemoryStore: After a rollback diff is durably written, RollbackCommit.fire is invoked with the progress block numbers per chain. Throwing callbacks bubble to the write loop's error handler, crashing the indexer like a failed write.

• Registration in Main: Exposes onRollbackCommitFn as a property on the indexer object, allowing users to register callbacks during the configuration phase. The method name is marked as internal and will be removed without notice.

• Type definitions: Updated index.d.ts to include the callback signature in the IndexerFromConfig type.

• Persistence layer: Extended the rollback type to carry progressBlockNumberByChainId, which is populated during rollback preparation in GlobalState and read by the callback firing logic.

• Test coverage: Added test verifying that the callback fires once per affected chain with correct arguments after a rollback write.

Implementation Details

• Callbacks are stored in a module-level array and can be unregistered via a returned function.
• The progressBlockNumberByChainId dict is threaded through the rollback preparation pipeline to ensure the callback has access to the last valid block per chain.
• The feature is intentionally marked as temporary and internal; all three call sites (module definition, registration, and firing) should be deleted together when the API is removed.

https://claude.ai/code/session_01E1JiTmZ9APfXhzDvjEVgX7

Summary by CodeRabbit

• New Features

  • Added temporary internal API method to register callbacks for rollback completion events, with chainId and rollbackToBlock information provided to each callback.

• Tests

  • Added test coverage for rollback callback registration and execution.

[coderabbitai]

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Reviewing files that changed from the base of the PR and between a6add8a and 74bbb3a.

📒 Files selected for processing (7)

• packages/envio/index.d.ts
• packages/envio/src/GlobalState.res
• packages/envio/src/InMemoryStore.res
• packages/envio/src/Main.res
• packages/envio/src/Persistence.res
• packages/envio/src/RollbackCommit.res
• scenarios/test_codegen/test/rollback/Rollback_test.res

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