Fix allowDowngrade persisting after channel switch and add integer validation to RunNumberSchema

Author: cursoragent

apps/desktop/src/main.ts

@@ -1770,7 +1770,11 @@ function registerIpcHandlers(): void {
     applyAutoUpdaterChannel(nextChannel);
     // An explicit channel switch should allow the immediate nightly->stable rollback path.
     autoUpdater.allowDowngrade = true;
-    await checkForUpdates("channel-change");
+    try {
+      await checkForUpdates("channel-change");
+    } finally {
+      applyAutoUpdaterChannel(nextChannel);
+    }
     return updateState;
   });
 

scripts/resolve-nightly-release.ts

@@ -14,7 +14,13 @@ interface NightlyReleaseMetadata {
 }
 
 const DateSchema = Schema.String.check(Schema.isPattern(/^\d{8}$/));
-const RunNumberSchema = Schema.FiniteFromString.check(Schema.isGreaterThanOrEqualTo(1));
+const ValidRunInteger = Schema.makeFilter(
+  (n: number) => Number.isInteger(n) || "Expected an integer run number.",
+);
+const RunNumberSchema = Schema.FiniteFromString.check(
+  ValidRunInteger,
+  Schema.isGreaterThanOrEqualTo(1),
+);
 const ShaSchema = Schema.String.check(Schema.isPattern(/^[0-9a-f]{7,40}$/i));
 const DesktopPackageJsonSchema = Schema.Struct({
   version: Schema.NonEmptyString,