diff --git a/services/web/scripts/attach_dangling_comments_to_doc.mjs b/services/web/scripts/attach_dangling_comments_to_doc.mjs
new file mode 100644
index 0000000000..e8b34fdc93
--- /dev/null
+++ b/services/web/scripts/attach_dangling_comments_to_doc.mjs
@@ -0,0 +1,146 @@
+// @ts-check
+
+import minimist from 'minimist'
+import process from 'node:process'
+import ChatApiHandler from '../app/src/Features/Chat/ChatApiHandler.js'
+import DocumentUpdaterHandler from '../app/src/Features/DocumentUpdater/DocumentUpdaterHandler.js'
+import DocstoreManager from '../app/src/Features/Docstore/DocstoreManager.js'
+import HistoryManager from '../app/src/Features/History/HistoryManager.js'
+import { db, ObjectId } from '../app/src/infrastructure/mongodb.js'
+
+const OPTS = parseArgs()
+
+function usage() {
+  console.error('Attach dangling threads to the beginning of a document')
+  console.error('')
+  console.error('Usage: node attach_dangling_comments_to_doc.mjs')
+  console.error('   --project   PROJECT_ID')
+  console.error('   --doc       DOC_ID')
+  console.error('   [--commit]')
+}
+
+function parseArgs() {
+  const args = minimist(process.argv.slice(2), {
+    boolean: ['commit'],
+    string: ['project', 'doc'],
+  })
+  const projectId = args.project
+  const docId = args.doc
+  if (!projectId || !docId) {
+    usage()
+    process.exit(0)
+  }
+  return { projectId, docId, commit: args.commit }
+}
+
+/**
+ * @typedef {{ id: string, content: string, timestamp: number, user_id: string }} Message
+ * @typedef {{ id: string, messages: Message[] }} Thread
+ */
+
+/**
+ * @param {string} projectId
+ * @returns {Promise<Thread[]>}
+ */
+async function getDanglingThreads(projectId) {
+  const docRanges = await DocstoreManager.promises.getAllRanges(projectId)
+  const threads = await ChatApiHandler.promises.getThreads(projectId)
+
+  const threadsInDoc = new Set()
+  for (const doc of docRanges) {
+    for (const comment of doc.ranges?.comments ?? []) {
+      threadsInDoc.add(comment.op.t)
+    }
+  }
+
+  const danglingThreads = Object.keys(threads)
+    .filter(threadId => !threadsInDoc.has(threadId))
+    .map(id => ({ ...threads[id], id }))
+
+  console.log(`Found:`)
+  console.log(`  - ${Object.keys(threads).length} threads`)
+  console.log(`  - ${threadsInDoc.size} threads in docRanges`)
+  console.log(`  - ${danglingThreads.length} dangling threads`)
+
+  return danglingThreads
+}
+
+const ensureDocExists = async (projectId, docId) => {
+  const doc = await DocstoreManager.promises.getDoc(projectId, docId)
+  if (!doc) {
+    console.error(`Document ${docId} not found`)
+    process.exit(1)
+  }
+}
+
+/**
+ * @param {Thread[]} threads
+ */
+const ensureThreadsHaveMessages = async threads => {
+  const threadsWithoutMessages = threads.filter(
+    thread => !thread.messages || thread.messages.length === 0
+  )
+  if (threadsWithoutMessages.length > 0) {
+    console.error(`The following threads have no messages:`)
+    console.error(threadsWithoutMessages.join(','))
+    process.exit(1)
+  }
+}
+
+/**
+ * @param {string} projectId
+ * @param {string} docId
+ */
+async function processProject(projectId, docId) {
+  console.log(`Processing project ${projectId}`)
+
+  await DocumentUpdaterHandler.promises.flushProjectToMongoAndDelete(projectId)
+
+  const danglingThreads = await getDanglingThreads(projectId)
+
+  await ensureDocExists(projectId, docId)
+  await ensureThreadsHaveMessages(danglingThreads)
+
+  for (const thread of danglingThreads) {
+    const firstMessage = thread.messages[0]
+    if (!firstMessage) {
+      console.error(`Thread ${thread.id} has no messages`)
+      continue
+    }
+    const rangeComment = newRangeComment(thread, firstMessage)
+
+    console.log(`Attaching thread ${thread.id} to doc ${docId}`)
+
+    if (OPTS.commit) {
+      await db.docs.updateOne(
+        { _id: new ObjectId(docId) },
+        { $push: { 'ranges.comments': rangeComment } }
+      )
+    }
+  }
+
+  if (OPTS.commit) {
+    console.log(`Resyncing history for project ${projectId}`)
+    await HistoryManager.promises.resyncProject(projectId)
+  }
+}
+
+/**
+ * @param {Thread} thread
+ * @param {Message} message
+ */
+const newRangeComment = (thread, message) => ({
+  id: new ObjectId(thread.id),
+  op: { t: new ObjectId(thread.id), p: 0, c: '' },
+  metadata: {
+    user_id: new ObjectId(message.user_id),
+    ts: new Date(message.timestamp),
+  },
+})
+
+await processProject(OPTS.projectId, OPTS.docId)
+
+if (!OPTS.commit) {
+  console.log('This was a dry run. Rerun with --commit to apply changes')
+}
+process.exit(0)