Circular Buffer Pipeline Management using In-Place Array Mutations in Svelte Subscriptions

import { writable } from 'svelte/store';
 
export function createCircularBufferStore(capacity) {
  const buffer = new Array(capacity).fill(null);
  let head = 0;
  let count = 0;
  const store = writable([]);
 
  return {
    subscribe: store.subscribe,
    push(item) {
      buffer[head] = item;
      head = (head + 1) % capacity;
      if (count < capacity) count++;
      const ordered = new Array(count);
      for (let i = 0; i < count; i++) {
        ordered[i] = buffer[(head - count + i + capacity) % capacity];
      }
      store.set(ordered);
    }
  };
}