Make Todo notes use CRDT docs directly

test/crdt-automerge.test.ts

@@ -13,7 +13,7 @@ import {
 
 const type = "camino.CrdtJson";
 
-test("Automerge CRDT fields lift plain values into stored envelopes", () => {
+test("Automerge CRDT fields explicitly create stored envelopes", () => {
   const stored = createAutomergeFieldValue({ title: "draft" }, type);
 
   assert.equal(stored.$caminoCrdtType, type);
@@ -23,6 +23,13 @@ test("Automerge CRDT fields lift plain values into stored envelopes", () => {
   });
 });
 
+test("Automerge CRDT field writes reject plain values", () => {
+  assert.throws(
+    () => encodeAutomergeFieldWrite({ title: "draft" }, type),
+    /CRDT field writes must use an Automerge document/,
+  );
+});
+
 test("Automerge CRDT fields encode rehydrated docs for writes", () => {
   const base = loadAutomergeFieldDoc(
     createAutomergeFieldValue({ title: "draft" }, type),