React Reconciler for Custom Renderers

react-reconciler is an experimental, low-level package provided by the React team for developers who wish to build custom React renderers for non-standard environments, such as WebGL, terminal UIs, or native desktop applications. It encapsulates the core reconciliation logic (the 'Fiber' architecture since React 16) responsible for efficiently diffing component trees and determining the minimal set of changes needed to update the UI. The package, currently at version 0.33.0, is designed to be pluggable with a custom `HostConfig` object, allowing developers to define platform-specific operations for creating, updating, and deleting nodes. Its API is explicitly unstable and does not adhere to React's standard versioning scheme, meaning breaking changes can occur in minor versions. It requires `react` as a peer dependency, specifically `>=19.2.0` for this version. It supports two primary modes: 'mutation mode' for environments that modify existing nodes (like the DOM) and 'persistent mode' for immutable tree structures.