fix(desktop): a failed update-track save keeps offering the current track's updates

apps/desktop/src/updates/DesktopUpdates.test.ts

@@ -932,6 +932,32 @@ describe("DesktopUpdates", () => {
     ).pipe(Effect.provide(Layer.merge(TestClock.layer(), harness.layer)));
   });
 
+  it.effect("keeps the current track's offers when a track switch fails to save", () => {
+    const harness = makeHarness({
+      setUpdateChannelError: new DesktopAppSettings.DesktopSettingsWriteError({
+        operation: "replace-settings-file",
+        path: "desktop-settings.json",
+        cause: new Error("rename failed"),
+      }),
+    });
+
+    return Effect.scoped(
+      Effect.gen(function* () {
+        const updates = yield* DesktopUpdates.DesktopUpdates;
+        yield* updates.configure;
+        const error = yield* updates
+          .setChannel("nightly", { minimumVersion: "1.2.5-nightly.20261028.1" })
+          .pipe(Effect.flip);
+        assert.equal(error._tag, "DesktopUpdateChannelPersistenceError");
+        assert.equal((yield* updates.getState).channel, "latest");
+
+        harness.emit("update-available", { version: "1.2.4" });
+        yield* flushCallbacks;
+        assert.equal((yield* updates.getState).availableVersion, "1.2.4");
+      }),
+    ).pipe(Effect.provide(Layer.merge(TestClock.layer(), harness.layer)));
+  });
+
   it.effect("keeps a saved Stable track across a restart without offering an older release", () => {
     // A Nightly build whose switch to Stable did not finish before the app quit.
     const harness = makeHarness({ appVersion: "1.2.4-nightly.20261027.1", savedChannel: "latest" });

apps/desktop/src/updates/DesktopUpdates.ts

@@ -1229,7 +1229,10 @@ export const make = Effect.gen(function* () {
       }
 
       return yield* Effect.gen(function* () {
-        yield* Ref.set(releaseFloorRef, Option.fromNullishOr(options?.minimumVersion));
+        const previousFloor = yield* Ref.getAndSet(
+          releaseFloorRef,
+          Option.fromNullishOr(options?.minimumVersion),
+        );
         const state = yield* Ref.get(updateStateRef);
         const retained = state.downloadedVersion ?? state.availableVersion;
         // A build from another track re-checks, so retrying a track switch finds an older release.
@@ -1242,13 +1245,12 @@ export const make = Effect.gen(function* () {
           return state;
         }
 
-        yield* desktopSettings
-          .setUpdateChannel(nextChannel)
-          .pipe(
-            Effect.mapError(
-              (cause) => new DesktopUpdateChannelPersistenceError({ channel: nextChannel, cause }),
-            ),
-          );
+        yield* desktopSettings.setUpdateChannel(nextChannel).pipe(
+          Effect.onError(() => Ref.set(releaseFloorRef, previousFloor)),
+          Effect.mapError(
+            (cause) => new DesktopUpdateChannelPersistenceError({ channel: nextChannel, cause }),
+          ),
+        );
 
         const disabledReason = yield* resolveDisabledReason;
         yield* setState(yield* baseUpdateState(nextChannel, disabledReason));