Fix shared note ownership detection

src/main.jsx

@@ -55,7 +55,14 @@ function noteContent(note) {
 }
 
 function noteOwner(note) {
-  return note?.owner || note?.ownerId || note?.createdBy || note?.userId || "";
+  return principalLabel(note?.owner || note?.ownerId || note?.createdBy || note?.userId);
+}
+
+function principalLabel(value) {
+  if (!value) return "";
+  if (typeof value === "string" || typeof value === "number") return String(value);
+  if (typeof value !== "object") return "";
+  return value.username || value.email || value.id || value._id || value.name || "";
 }
 
 function extractToken(payload) {
@@ -696,10 +703,51 @@ function upsertNote(notes, note) {
 }
 
 function ownsNote(note, currentUser) {
-  const owner = String(noteOwner(note) || "").toLowerCase();
-  const user = String(currentUser || "").toLowerCase();
-  if (!owner || !user) return !note?.sharedWith && !note?.shared;
-  return owner === user || owner.includes(user) || user.includes(owner);
+  if (note?.canEdit === false || note?.readOnly === true) return false;
+  if (typeof note?.owned === "boolean") return note.owned;
+  if (typeof note?.isOwner === "boolean") return note.isOwner;
+
+  const ownerValues = principalValues(note?.owner || note?.ownerId || note?.createdBy || note?.userId);
+  const userValues = principalValues(currentUser);
+  if (ownerValues.length && userValues.length) {
+    return ownerValues.some((owner) => userValues.includes(owner));
+  }
+
+  return !hasSharedAccessMarker(note);
+}
+
+function principalValues(value) {
+  if (!value) return [];
+  if (Array.isArray(value)) return uniqueValues(value.flatMap(principalValues));
+  if (typeof value === "object") {
+    return uniqueValues(
+      ["username", "email", "id", "_id", "name"]
+        .flatMap((key) => principalValues(value[key]))
+        .filter(Boolean),
+    );
+  }
+
+  const normalized = String(value).trim().toLowerCase();
+  if (!normalized) return [];
+  const values = [normalized];
+  const [localPart] = normalized.split("@");
+  if (normalized.includes("@") && localPart) values.push(localPart);
+  return uniqueValues(values);
+}
+
+function uniqueValues(values) {
+  return [...new Set(values)];
+}
+
+function hasSharedAccessMarker(note) {
+  return Boolean(
+    note?.shared === true ||
+      note?.isShared === true ||
+      note?.sharedBy ||
+      note?.sharedFrom ||
+      note?.sharedWith ||
+      String(note?.access || note?.permission || "").toLowerCase().includes("read"),
+  );
 }
 
 createRoot(document.getElementById("root")).render(<App />);