How React's Render and Commit Phases Cause Stale State and Context Bugs

React applications can exhibit confusing behavior when state appears stale or context values fail to update as expected, often due to how React internally manages its rendering pipeline. React separates work into a render phase, where it calculates UI changes without touching the DOM, and a commit phase, where it applies those changes and runs effects. In Concurrent Mode, React can pause, discard, and restart render work mid-flight, meaning a component's hooks may execute multiple times before any result is committed. This causes effects and closures to sometimes capture outdated context or state values from an earlier, discarded render attempt. Developers can mitigate these issues by keeping render functions pure, memoizing context values, and carefully managing hook dependencies to prevent stale closures.