feat: cross-OS profile sync

src/lib/backend-errors.ts

@@ -155,6 +155,7 @@ export type BackendErrorCode =
   | "REMOTE_HOURS_EXHAUSTED"
   | "PROFILE_RUNNING_REMOTELY"
   | "PROFILE_REMOTE_SYNC_PENDING"
+  | "PROFILE_DATA_NOT_DOWNLOADED"
   | "PROFILE_LOCKED_BY_MEMBER"
   | "PROFILE_LOCKED_ELSEWHERE"
   | "PROFILE_LOCK_UNAVAILABLE"
@@ -670,6 +671,8 @@ export function translateBackendError(t: TFunction, err: unknown): string {
       return t("backendErrors.profileRunningRemotely");
     case "PROFILE_REMOTE_SYNC_PENDING":
       return t("backendErrors.profileRemoteSyncPending");
+    case "PROFILE_DATA_NOT_DOWNLOADED":
+      return t("backendErrors.profileDataNotDownloaded");
     case "PROFILE_LOCKED_BY_MEMBER":
       return t("backendErrors.profileLockedByMember", {
         email: parsed.params?.email ?? "",

src/lib/browser-utils.ts

@@ -90,10 +90,29 @@ export function getProfileIcon(profile: {
   return getBrowserIcon(profile.browser);
 }
 
+/**
+ * The OS a fingerprint without an explicit `os` was generated for: the machine
+ * that created the profile. Mirrors `BrowserProfile::native_os`, without its
+ * fallback to this computer, so callers can tell "unknown" apart.
+ */
+export function getProfileNativeOs(profile: {
+  host_os?: string;
+}): "macos" | "windows" | "linux" | undefined {
+  const os = profile.host_os;
+  return os === "macos" || os === "windows" || os === "linux" ? os : undefined;
+}
+
+/**
+ * Whether a profile cannot run on this computer because a browser bound to
+ * its OS created it elsewhere. Mirrors `BrowserProfile::is_cross_os`: a
+ * Wayfern profile runs on every OS, so it is never cross-OS.
+ */
 export function isCrossOsProfile(profile: {
+  browser: string;
   host_os?: string;
   wayfern_config?: { os?: string };
 }): boolean {
+  if (profile.browser === "wayfern") return false;
   const profileOs = profile.host_os || profile.wayfern_config?.os;
   if (!profileOs) return false;
   return profileOs !== getCurrentOS();