Adding server-generated properties to transaction in Collection.onInsert etc.

In my onInsert handler, I call a TRPC endpoint which returns the server-generated publicId of the newly created document:

onInsert: async ({ transaction }) => {
  const newDocument = transaction.mutations[0].modified;

  const data = await trpcClient.documents.create.mutate({
    data: newDocument.data,
    multiple: newDocument.data.length > 1,
    templateId: newDocument.templateId,
  });

  // `data.publicId` is available here
};

But when inserting into the collection:

const tx = documentCollection.insert({
  data: documentData,
  multiple: documentData.length > 1,
  templateId: params.templateId,
  publicId: "", // <-- should come from server
  status: "pending",
  createdAt: new Date(),
  updatedAt: new Date(),
  deletedAt: null,
  createdBy: "",
  error: null,
  version: 1,
  key: null,
});

const data = await tx.isPersisted.promise;

// How can I access the `publicId` returned by the server here?

Currently, the transaction doesn’t provide a way to pass back arbitrary data (like publicId) from the TRPC call into the persisted collection record.

Proposed solution:

It would be helpful if the transaction itself exposed a way to attach response metadata from async mutations. For example:
A method like transaction.setResponseData({...})

Start with the Collection.onInsert handler and the transaction.isPersisted.promise flow shown in the issue, then review how the TRPC response is currently handled. Define how transaction.setResponseData could carry server-generated values into the persisted collection record, including when the data becomes available and what completion behavior should mean. Done requires a documented API and coverage for the publicId response case.