fix(editor-ext): dedupe colliding unique ids on import/normalize (#206)

editor-pm-7: addUniqueIdsToDoc only FILLED missing ids and never deduplicated
existing ones, so a copy/paste or bulk-JSON duplicate that kept its attrs.id
produced two nodes sharing an id. MCP addressed edits (patch_node /
delete_node "before/after id") then hit the wrong node or both.

Walk the configured-type nodes in document order: the first occurrence of an
id keeps it (stable anchor), later duplicates are reassigned a fresh id.
transclusionSource ids are cross-reference keys (references resolve a source by
this id), so they are only filled-when-missing, never reassigned, to avoid
orphaning their references.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/editor-ext/src/lib/unique-id/unique-id.util.test.ts

@@ -0,0 +1,55 @@
+import { describe, it, expect } from "vitest";
+import StarterKit from "@tiptap/starter-kit";
+import { addUniqueIdsToDoc } from "./unique-id.util";
+import { UniqueID } from "./unique-id";
+
+// Minimal extension set: StarterKit (paragraph/heading) + the UniqueID config
+// the server uses for the addressing anchors.
+const extensions = [
+  StarterKit,
+  UniqueID.configure({ types: ["heading", "paragraph"] }),
+];
+
+const para = (id: string | undefined, text: string) => ({
+  type: "paragraph",
+  ...(id !== undefined ? { attrs: { id } } : {}),
+  content: [{ type: "text", text }],
+});
+
+const ids = (doc: any): (string | undefined)[] =>
+  (doc.content ?? []).map((n: any) => n.attrs?.id);
+
+describe("addUniqueIdsToDoc", () => {
+  it("fills ids on nodes that are missing one", () => {
+    const doc = { type: "doc", content: [para(undefined, "a"), para(undefined, "b")] };
+    const out = addUniqueIdsToDoc(doc, extensions);
+    const [a, b] = ids(out);
+    expect(a).toBeTruthy();
+    expect(b).toBeTruthy();
+    expect(a).not.toBe(b);
+  });
+
+  it("deduplicates two nodes that share the same id (#206 editor-pm-7)", () => {
+    // A copy/paste or bulk-JSON duplicate keeps the original id on both nodes.
+    const doc = {
+      type: "doc",
+      content: [para("dup", "first"), para("dup", "second")],
+    };
+    const out = addUniqueIdsToDoc(doc, extensions);
+    const [first, second] = ids(out);
+    // The first occurrence keeps the id (stable anchor); the duplicate is
+    // reassigned a fresh one so MCP addressing can't hit the wrong/both nodes.
+    expect(first).toBe("dup");
+    expect(second).toBeTruthy();
+    expect(second).not.toBe("dup");
+  });
+
+  it("leaves already-unique ids untouched", () => {
+    const doc = {
+      type: "doc",
+      content: [para("x1", "first"), para("x2", "second")],
+    };
+    const out = addUniqueIdsToDoc(doc, extensions);
+    expect(ids(out)).toEqual(["x1", "x2"]);
+  });
+});

packages/editor-ext/src/lib/unique-id/unique-id.util.ts

@@ -59,18 +59,44 @@ export function addUniqueIdsToDoc(
   ]);
   const contentNode = Node.fromJSON(schema, doc);
 
-  // Find nodes that don't have a unique ID
-  const nodesWithoutId = findChildren(contentNode, (node) => {
-    return !node.attrs[attributeName] && types.includes(node.type.name);
+  // All nodes of the configured types, in document order, so that the FIRST
+  // occurrence of any given id keeps it and later duplicates get reassigned.
+  const idNodes = findChildren(contentNode, (node) => {
+    return types.includes(node.type.name);
   });
 
-  // Edit the document to add unique IDs to the nodes that don't have a unique ID
+  // `transclusionSource` ids are cross-reference keys (a transclusionReference /
+  // the page_transclusions table resolves a source by this id), so rewriting one
+  // would orphan its references. We only fill a MISSING id for those, never
+  // reassign an existing one; plain block anchors (heading/paragraph) are safe to
+  // dedupe.
+  const NO_REASSIGN = new Set(["transclusionSource"]);
+
+  // Edit the document to (a) add ids where missing and (b) dedupe collisions. A
+  // duplicate id otherwise lets copy/paste/import produce two nodes sharing an
+  // id, so MCP addressed edits (patch_node / delete_node "before/after id") hit
+  // the wrong node or both (#206 editor-pm-7). This previously only filled
+  // missing ids and never deduplicated existing ones.
+  const seenIds = new Set<string>();
   let tr = EditorState.create({
     doc: contentNode,
   }).tr;
   // eslint-disable-next-line no-restricted-syntax
-  for (const { node, pos } of nodesWithoutId) {
-    tr = tr.setNodeAttribute(pos, attributeName, generateID({ node, pos }));
+  for (const { node, pos } of idNodes) {
+    const currentId = node.attrs[attributeName];
+    const isDuplicate = currentId != null && seenIds.has(currentId);
+    const needsNewId =
+      currentId == null || (isDuplicate && !NO_REASSIGN.has(node.type.name));
+
+    if (needsNewId) {
+      // setNodeAttribute only changes attributes (no size change), so positions
+      // from the original node stay valid across the whole loop.
+      const newId = generateID({ node, pos });
+      tr = tr.setNodeAttribute(pos, attributeName, newId);
+      seenIds.add(newId);
+    } else if (currentId != null) {
+      seenIds.add(currentId);
+    }
   }
 
   // Return the updated document