diff --git a/scripts/patch-ap-interactions-cleanup-preserve.mjs b/scripts/patch-ap-interactions-cleanup-preserve.mjs
new file mode 100644
index 00000000..590d3e52
--- /dev/null
+++ b/scripts/patch-ap-interactions-cleanup-preserve.mjs
@@ -0,0 +1,112 @@
+/**
+ * Patch: preserve liked/bookmarked/boosted items during timeline cleanup.
+ *
+ * Root cause:
+ *   cleanupTimeline() removes old remote posts from ap_timeline and also
+ *   deletes their ap_interactions entries. Any post the user has liked,
+ *   bookmarked, or boosted disappears from GET /api/v1/favourites and
+ *   GET /api/v1/bookmarks after the next daily cleanup run.
+ *
+ * Fix:
+ *   Before deleting, fetch the set of objectUrls that have ap_interactions
+ *   entries (likes, bookmarks, boosts). Filter those out of the deletion
+ *   candidate list so they are preserved in ap_timeline (and their
+ *   ap_interactions entries are never touched).
+ */
+
+import { access, readFile, writeFile } from "node:fs/promises";
+
+const MARKER = "// [patch] ap-interactions-cleanup-preserve";
+
+const candidates = [
+  "node_modules/@rmdes/indiekit-endpoint-activitypub/lib/timeline-cleanup.js",
+  "node_modules/@indiekit/indiekit/node_modules/@rmdes/indiekit-endpoint-activitypub/lib/timeline-cleanup.js",
+];
+
+const OLD_SNIPPET = `  const removedUids = toDelete.map((item) => item.uid).filter(Boolean);
+
+  // Delete old timeline items by UID
+  const deleteResult = await collections.ap_timeline.deleteMany({
+    _id: { $in: toDelete.map((item) => item._id) },
+  });
+
+  // Clean up stale interactions for removed items
+  let interactionsRemoved = 0;
+  if (removedUids.length > 0 && collections.ap_interactions) {
+    const interactionResult = await collections.ap_interactions.deleteMany({
+      objectUrl: { $in: removedUids },
+    });
+    interactionsRemoved = interactionResult.deletedCount || 0;
+  }`;
+
+const NEW_SNIPPET = `  const removedUids = toDelete.map((item) => item.uid).filter(Boolean);
+
+  // Preserve items the user has interacted with (liked, bookmarked, boosted). ${MARKER}
+  // Deleting them would silently remove entries from the Favourites/Bookmarks pages.
+  let interactedUids = new Set();
+  if (removedUids.length > 0 && collections.ap_interactions) {
+    const interacted = await collections.ap_interactions.distinct("objectUrl");
+    interactedUids = new Set(interacted);
+  }
+  const itemsToDelete = toDelete.filter((item) => !interactedUids.has(item.uid));
+  const uidsToDelete = itemsToDelete.map((item) => item.uid).filter(Boolean);
+
+  if (!itemsToDelete.length) {
+    return { removed: 0, interactionsRemoved: 0 };
+  }
+
+  // Delete old timeline items by UID
+  const deleteResult = await collections.ap_timeline.deleteMany({
+    _id: { $in: itemsToDelete.map((item) => item._id) },
+  });
+
+  // Clean up stale interactions for removed items
+  let interactionsRemoved = 0;
+  if (uidsToDelete.length > 0 && collections.ap_interactions) {
+    const interactionResult = await collections.ap_interactions.deleteMany({
+      objectUrl: { $in: uidsToDelete },
+    });
+    interactionsRemoved = interactionResult.deletedCount || 0;
+  }`;
+
+async function exists(filePath) {
+  try {
+    await access(filePath);
+    return true;
+  } catch {
+    return false;
+  }
+}
+
+let checked = 0;
+let patched = 0;
+
+for (const filePath of candidates) {
+  if (!(await exists(filePath))) continue;
+  checked += 1;
+
+  const source = await readFile(filePath, "utf8");
+
+  if (source.includes(MARKER)) {
+    console.log(`[postinstall] patch-ap-interactions-cleanup-preserve: already applied to ${filePath}`);
+    continue;
+  }
+
+  if (!source.includes(OLD_SNIPPET)) {
+    console.warn(`[postinstall] patch-ap-interactions-cleanup-preserve: snippet not found in ${filePath}`);
+    continue;
+  }
+
+  const updated = source.replace(OLD_SNIPPET, NEW_SNIPPET);
+  await writeFile(filePath, updated, "utf8");
+  patched += 1;
+  console.log(`[postinstall] Applied patch-ap-interactions-cleanup-preserve to ${filePath}`);
+}
+
+if (checked === 0) {
+  console.log("[postinstall] patch-ap-interactions-cleanup-preserve: no target files found");
+} else if (patched === 0) {
+  console.log("[postinstall] patch-ap-interactions-cleanup-preserve: already up to date");
+} else {
+  console.log(`[postinstall] patch-ap-interactions-cleanup-preserve: patched ${patched} file(s)`);
+}