fix: one-time migration from courses table to localStorage on first open

Author: LeafCreeper

frontend/js/app.js

@@ -622,16 +622,29 @@ document.addEventListener("alpine:init", () => {
       this.subsSelMiddle = [];
       this.subsSelRight = [];
       this.subsError = "";
-      // Load current subscription from localStorage (last-saved secret state).
-      // The ``courses`` table is NOT a valid fallback — it holds every course
-      // that has ever been processed, not just the currently subscribed ones.
+      // Load subscription from localStorage (cached secret state).
       this.subscribedIds = [];
       try {
         var cached = JSON.parse(
           localStorage.getItem(_LS + "lastSubscribed") || "null"
         );
         if (Array.isArray(cached)) this.subscribedIds = cached.map(String);
       } catch {}
+      // One-time migration: if the cache is empty, seed it from the courses
+      // table so the user doesn't start with an empty left column.  Save
+      // immediately so future loads read from localStorage without the DB
+      // fallback (the courses table grows over time and isn't the secret).
+      if (!this.subscribedIds.length) {
+        this.subscribedIds = ICS.db.getSubscribedCourseIds().map(String);
+        if (this.subscribedIds.length) {
+          try {
+            localStorage.setItem(
+              _LS + "lastSubscribed",
+              JSON.stringify(this.subscribedIds),
+            );
+          } catch {}
+        }
+      }
       this.rebuildSubsFiltered();
       this.navigate("subscriptions");
     },