diff --git a/craft/src/utils/orphan-repair.test.ts b/craft/src/utils/orphan-repair.test.ts
new file mode 100644
index 0000000..5110b8e
--- /dev/null
+++ b/craft/src/utils/orphan-repair.test.ts
@@ -0,0 +1,106 @@
+import { describe, test, expect } from 'vitest';
+import { findUnreachableNodeIds, repairOrphanNodes } from './orphan-repair';
+
+/** Minimal Craft-shaped node. */
+function node(over: Record<string, any> = {}) {
+  return {
+    type: { resolvedName: 'Container' },
+    isCanvas: false,
+    props: {},
+    displayName: 'Container',
+    custom: {},
+    hidden: false,
+    nodes: [],
+    linkedNodes: {},
+    parent: 'ROOT',
+    ...over,
+  };
+}
+
+const healthy = JSON.stringify({
+  ROOT: node({ isCanvas: true, parent: null, nodes: ['a'] }),
+  a: node({ parent: 'ROOT' }),
+});
+
+describe('findUnreachableNodeIds', () => {
+  test('a healthy tree has no unreachable nodes', () => {
+    expect(findUnreachableNodeIds(JSON.parse(healthy))).toEqual([]);
+  });
+
+  test('a node ROOT does not list is unreachable even when its parent says ROOT', () => {
+    const nodes = JSON.parse(healthy);
+    nodes.stray = node({ parent: 'ROOT', displayName: 'HTML' });
+    expect(findUnreachableNodeIds(nodes)).toEqual(['stray']);
+  });
+
+  test('a node whose parent no longer exists is unreachable', () => {
+    const nodes = JSON.parse(healthy);
+    nodes.stray = node({ parent: 'ghost' });
+    expect(findUnreachableNodeIds(nodes)).toEqual(['stray']);
+  });
+
+  test('children of an unreachable node are also unreachable', () => {
+    const nodes = JSON.parse(healthy);
+    nodes.stray = node({ parent: 'ghost', nodes: ['strayChild'] });
+    nodes.strayChild = node({ parent: 'stray' });
+    expect(findUnreachableNodeIds(nodes).sort()).toEqual(['stray', 'strayChild']);
+  });
+
+  test('linkedNodes children count as reachable', () => {
+    const nodes = JSON.parse(healthy);
+    nodes.ROOT.linkedNodes = { inner: 'linked' };
+    nodes.linked = node({ parent: 'ROOT' });
+    expect(findUnreachableNodeIds(nodes)).toEqual([]);
+  });
+
+  test('a cycle among orphans terminates instead of hanging', () => {
+    const nodes = JSON.parse(healthy);
+    nodes.x = node({ parent: 'y', nodes: ['y'] });
+    nodes.y = node({ parent: 'x', nodes: ['x'] });
+    expect(findUnreachableNodeIds(nodes).sort()).toEqual(['x', 'y']);
+  });
+});
+
+describe('repairOrphanNodes', () => {
+  test('a healthy tree is returned byte-identical with nothing repaired', () => {
+    const out = repairOrphanNodes(healthy);
+    expect(out.repaired).toEqual([]);
+    expect(out.state).toBe(healthy);
+  });
+
+  test('an orphan is appended to the end of ROOT.nodes and reparented', () => {
+    const nodes = JSON.parse(healthy);
+    nodes.stray = node({ parent: 'ghost', displayName: 'HTML' });
+    const out = repairOrphanNodes(JSON.stringify(nodes));
+
+    expect(out.repaired).toEqual(['stray']);
+    const parsed = JSON.parse(out.state);
+    expect(parsed.ROOT.nodes).toEqual(['a', 'stray']);
+    expect(parsed.stray.parent).toBe('ROOT');
+  });
+
+  test('only the top of an orphan subtree is reattached; its children ride along', () => {
+    const nodes = JSON.parse(healthy);
+    nodes.stray = node({ parent: 'ghost', nodes: ['strayChild'] });
+    nodes.strayChild = node({ parent: 'stray' });
+    const out = repairOrphanNodes(JSON.stringify(nodes));
+
+    expect(out.repaired).toEqual(['stray']);
+    const parsed = JSON.parse(out.state);
+    expect(parsed.ROOT.nodes).toEqual(['a', 'stray']);
+    expect(parsed.strayChild.parent).toBe('stray');
+  });
+
+  test('malformed JSON comes back unchanged rather than throwing', () => {
+    const out = repairOrphanNodes('{not json');
+    expect(out.state).toBe('{not json');
+    expect(out.repaired).toEqual([]);
+  });
+
+  test('state with no ROOT comes back unchanged', () => {
+    const orphanOnly = JSON.stringify({ a: node({ parent: null }) });
+    const out = repairOrphanNodes(orphanOnly);
+    expect(out.state).toBe(orphanOnly);
+    expect(out.repaired).toEqual([]);
+  });
+});
diff --git a/craft/src/utils/orphan-repair.ts b/craft/src/utils/orphan-repair.ts
new file mode 100644
index 0000000..3811a06
--- /dev/null
+++ b/craft/src/utils/orphan-repair.ts
@@ -0,0 +1,79 @@
+/**
+ * Editor-state integrity: every node must be reachable from ROOT.
+ *
+ * A node that exists in `SerializedNodes` but appears in no parent's `nodes`
+ * or `linkedNodes` list is invisible to the Layers tree AND to Craft's own
+ * selection machinery -- it renders somewhere on the canvas but can't be
+ * selected or deleted, which is exactly the "dropped outside the page"
+ * report. Reachability is computed from the PARENT'S child lists, not from
+ * each node's own `parent` pointer: a stale `parent: 'ROOT'` on a node ROOT
+ * never lists is precisely the broken case we're looking for.
+ *
+ * Pure functions over serialized state -- no React, no Craft instance.
+ */
+
+const ROOT_ID = 'ROOT';
+
+function childIdsOf(node: any): string[] {
+  const nodes: string[] = Array.isArray(node?.nodes) ? node.nodes : [];
+  const linked: string[] = node?.linkedNodes ? Object.values(node.linkedNodes) : [];
+  return [...nodes, ...linked];
+}
+
+/** Ids of nodes present in `nodes` whose parent chain does not reach 'ROOT'. */
+export function findUnreachableNodeIds(nodes: Record<string, any>): string[] {
+  if (!nodes || typeof nodes !== 'object' || !nodes[ROOT_ID]) return [];
+
+  const reachable = new Set<string>([ROOT_ID]);
+  const queue: string[] = [ROOT_ID];
+
+  while (queue.length > 0) {
+    const id = queue.shift()!;
+    for (const childId of childIdsOf(nodes[id])) {
+      // The `reachable` guard also terminates on a cycle among real nodes.
+      if (typeof childId === 'string' && nodes[childId] && !reachable.has(childId)) {
+        reachable.add(childId);
+        queue.push(childId);
+      }
+    }
+  }
+
+  return Object.keys(nodes).filter((id) => !reachable.has(id));
+}
+
+/** Reattach every unreachable node to the end of ROOT.nodes. Returns the
+ *  possibly-rewritten serialized state and the ids that were moved. Never
+ *  throws: malformed input comes back unchanged with an empty `repaired`. */
+export function repairOrphanNodes(serialized: string): { state: string; repaired: string[] } {
+  let nodes: Record<string, any>;
+  try {
+    nodes = JSON.parse(serialized);
+  } catch {
+    // A page must never fail to load because the repair pass couldn't parse
+    // it -- hand the original string straight back to deserialize().
+    return { state: serialized, repaired: [] };
+  }
+
+  if (!nodes || typeof nodes !== 'object' || !nodes[ROOT_ID]) {
+    return { state: serialized, repaired: [] };
+  }
+
+  const unreachable = findUnreachableNodeIds(nodes);
+  if (unreachable.length === 0) return { state: serialized, repaired: [] };
+
+  // Reattach only the TOP of each orphan subtree. An orphan whose parent is
+  // itself an orphan keeps its existing parent and rides along.
+  const orphanSet = new Set(unreachable);
+  const tops = unreachable.filter((id) => {
+    const parent = nodes[id]?.parent;
+    return !(typeof parent === 'string' && orphanSet.has(parent));
+  });
+
+  if (!Array.isArray(nodes[ROOT_ID].nodes)) nodes[ROOT_ID].nodes = [];
+  for (const id of tops) {
+    nodes[id].parent = ROOT_ID;
+    nodes[ROOT_ID].nodes.push(id);
+  }
+
+  return { state: JSON.stringify(nodes), repaired: tops };
+}