···233233 * with a `DocSession` whose `ydoc` is the canonical instance for `uri`; the
234234 * first load resolves in the background and updates the ydoc in place.
235235 */
236236-export function acquireDocSession(uri: string): DocSession {
236236+export function acquireDocSession(
237237+ uri: string,
238238+ options?: { initialYdoc?: Y.Doc },
239239+): DocSession {
237240 ensureVisibilityListener();
238241 let entry = ydocRegistry.get(uri);
239242 if (!entry) {
240240- const ydoc = new Y.Doc();
243243+ const ydoc = options?.initialYdoc ?? new Y.Doc();
241244 entry = {
242245 uri,
243246 ydoc,