Constant GLOBAL_SCRIPT_CONTENTS 

pub const GLOBAL_SCRIPT_CONTENTS: &str = "(function() {\n  // Only initialize once, even if this script appears multiple times in the DOM\n  if (window.__columbo) return;\n  window.__columbo = true;\n\n  // Optional user config: window.__columboConfig = { swap: (placeholder, nodes) => { ... } }\n  const config = window.__columboConfig || {};\n\n  // Default swap: replace the placeholder span with the resolved nodes\n  const defaultSwap = (placeholder, nodes) => placeholder.replaceWith(...nodes);\n  const swapFn = typeof config.swap === \'function\' ? config.swap : defaultSwap;\n\n  // Track templates waiting to be swapped in\n  const pendingIds = new Set();\n  // Prevent scheduling multiple microtasks for the same batch of swaps\n  let transitionScheduled = false;\n\n  // Swap placeholder with template content and clean up\n  const performSwap = (id) => {\n    const p = document.querySelector(`[data-columbo-p-id=\"${id}\"]`);\n    const r = document.querySelector(`[data-columbo-r-id=\"${id}\"]`);\n    \n    if (p && r) {\n      swapFn(p, [...r.content.childNodes]);\n      r.remove();\n    }\n  };\n\n  // Process all pending swaps\n  const processQueue = () => {\n    transitionScheduled = false;\n    \n    // Snapshot and clear the queue\n    const ids = Array.from(pendingIds);\n    pendingIds.clear();\n\n    ids.forEach(performSwap);\n  };\n\n  // Watch for new template elements being added to the DOM\n  const observer = new MutationObserver((mutations) => {\n    for (const mutation of mutations) {\n      for (const node of mutation.addedNodes) {\n        // Check if this is a columbo replacement template\n        if (node.nodeType === 1 && node.hasAttribute(\'data-columbo-r-id\')) {\n          pendingIds.add(node.getAttribute(\'data-columbo-r-id\'));\n        }\n      }\n    }\n\n    // Schedule processing if we have new templates and haven\'t already scheduled\n    if (pendingIds.size > 0 && !transitionScheduled) {\n      transitionScheduled = true;\n      queueMicrotask(processQueue);\n    }\n  });\n\n  // Observe the entire document to catch streamed chunks as they arrive\n  observer.observe(document.documentElement, { childList: true, subtree: true });\n})();\n";

The contents of the script that performs the on-the-fly replacements.