site-builder/craft/src/state/ProjectExtrasContext.tsx

import React, { createContext, useCallback, useContext, useMemo, useRef, ReactNode } from 'react';
import { useSaveGuard } from './SaveGuardContext';

/**
 * Feature data that is not Craft state (style presets, custom sections, ...),
 * persisted as the top-level `extras` key of project.json. Held in a ref, not
 * React state: nothing renders from it directly, and a save queued behind
 * another must read the latest value at send time.
 */
interface ProjectExtrasValue {
  get<T>(key: string, fallback: T): T;
  set(key: string, value: unknown): void;
  update<T>(key: string, fn: (prev: T) => T, fallback: T): void;
  all(): Record<string, unknown>;
  /** Load hydration. Does NOT mark the editor dirty. */
  replaceAll(extras: Record<string, unknown>): void;
}

const noop: ProjectExtrasValue = {
  get: (_k, fallback) => fallback,
  set: () => {},
  update: () => {},
  all: () => ({}),
  replaceAll: () => {},
};

const ProjectExtrasContext = createContext<ProjectExtrasValue>(noop);

export const useProjectExtras = () => useContext(ProjectExtrasContext);

export const ProjectExtrasProvider: React.FC<{ children: ReactNode }> = ({ children }) => {
  const { markDirty } = useSaveGuard();
  const store = useRef<Record<string, unknown>>({});
  const markRef = useRef(markDirty);
  markRef.current = markDirty;

  const value = useMemo<ProjectExtrasValue>(() => ({
    get: <T,>(key: string, fallback: T): T => (key in store.current ? (store.current[key] as T) : fallback),
    set: (key, v) => {
      store.current = { ...store.current, [key]: v };
      markRef.current();
    },
    update: <T,>(key: string, fn: (prev: T) => T, fallback: T) => {
      const prev = (key in store.current ? store.current[key] : fallback) as T;
      store.current = { ...store.current, [key]: fn(prev) };
      markRef.current();
    },
    all: () => store.current,
    replaceAll: (extras) => { store.current = { ...extras }; },
  }), []);

  return <ProjectExtrasContext.Provider value={value}>{children}</ProjectExtrasContext.Provider>;
};