react18-upgrade

Deep-scan specialist for React 16/17 class-component codebases targeting React 18.3.1. Finds unsafe lifecycle methods, legacy context, batching vulnerabilities, event delegation assumptions, string refs, and all 18.3.1 deprecation surface. Reads everything, touches nothing. Saves .github/react18-audit.md.

Automatic batching regression specialist. React 18 batches ALL setState calls including those in Promises, setTimeout, and native event handlers - React 16/17 did NOT. Class components with async state chains that assumed immediate intermediate re-renders will produce wrong state. This agent finds every vulnerable pattern and fixes with flushSync where semantically required.

Class component migration specialist for React 16/17 → 18.3.1. Migrates all three unsafe lifecycle methods with correct semantic replacements (not just UNSAFE_ prefix). Migrates legacy context to createContext, string refs to React.createRef(), findDOMNode to direct refs, and ReactDOM.render to createRoot. Uses memory to checkpoint per-file progress.

Master orchestrator for React 16/17 → 18.3.1 migration. Designed for class-component-heavy codebases. Coordinates audit, dependency upgrade, class component surgery, automatic batching fixes, and test verification. Uses memory to gate each phase and resume interrupted sessions. 18.3.1 is the target - it surface-exposes every deprecation that React 19 will remove, so the output is a codebase ready for the React 19 orchestra next.

Dependency upgrade specialist for React 16/17 → 18.3.1. Pins to 18.3.1 exactly (not 18.x latest). Upgrades RTL to v14, Apollo 3.8+, Emotion 11.10+, react-router v6. Detects and blocks on Enzyme (no React 18 support). Returns GO/NO-GO to commander.

Test suite fixer and verifier for React 16/17 → 18.3.1 migration. Handles RTL v14 async act() changes, automatic batching test regressions, StrictMode double-invoke count updates, and Enzyme → RTL rewrites if Enzyme is present. Loops until zero test failures. Invoked as subagent by react18-commander.

Provides the complete, verified grep scan command library for auditing React codebases before a React 18.3.1 or React 19 upgrade. Use this skill whenever running a migration audit - for both the react18-auditor and react19-auditor agents. Contains every grep pattern needed to find deprecated APIs, removed APIs, unsafe lifecycle methods, batching vulnerabilities, test file issues, dependency conflicts, and React 19 specific removals. Always use this skill when writing audit scan commands - do not rely on memory for grep syntax, especially for the multi-line async setState patterns which require context flags.

Provides exact patterns for diagnosing and fixing automatic batching regressions in React 18 class components. Use this skill whenever a class component has multiple setState calls in an async method, inside setTimeout, inside a Promise .then() or .catch(), or in a native event handler. Use it before writing any flushSync call - the decision tree here prevents unnecessary flushSync overuse. Also use this skill when fixing test failures caused by intermediate state assertions that break after React 18 upgrade.

React 18.3.1 and React 19 dependency compatibility matrix.

Provides exact Enzyme → React Testing Library migration patterns for React 18 upgrades. Use this skill whenever Enzyme tests need to be rewritten - shallow, mount, wrapper.find(), wrapper.simulate(), wrapper.prop(), wrapper.state(), wrapper.instance(), Enzyme configure/Adapter calls, or any test file that imports from enzyme. This skill covers the full API mapping and the philosophy shift from implementation testing to behavior testing. Always read this skill before rewriting Enzyme tests - do not translate Enzyme APIs 1:1, that produces brittle RTL tests.

Provides the complete migration pattern for React legacy context API (contextTypes, childContextTypes, getChildContext) to the modern createContext API. Use this skill whenever migrating legacy context in class components - this is always a cross-file migration requiring the provider AND all consumers to be updated together. Use it before touching any contextTypes or childContextTypes code, because migrating only the provider without the consumers (or vice versa) will cause a runtime failure. Always read this skill before writing any context migration - the cross-file coordination steps here prevent the most common context migration bugs.

Provides exact before/after migration patterns for the three unsafe class component lifecycle methods - componentWillMount, componentWillReceiveProps, and componentWillUpdate - targeting React 18.3.1. Use this skill whenever a class component needs its lifecycle methods migrated, when deciding between getDerivedStateFromProps vs componentDidUpdate, when adding getSnapshotBeforeUpdate, or when fixing React 18 UNSAFE_ lifecycle warnings. Always use this skill before writing any lifecycle migration code - do not guess the pattern from memory, the decision trees here prevent the most common migration mistakes.

Provides exact migration patterns for React string refs (ref="name" + this.refs.name) to React.createRef() in class components. Use this skill whenever migrating string ref usage - including single element refs, multiple refs in a component, refs in lists, callback refs, and refs passed to child components. Always use this skill before writing any ref migration code - the multiple-refs-in-list pattern is particularly tricky and this skill prevents the most common mistakes. Use it for React 18.3.1 migration (string refs warn) and React 19 migration (string refs removed).