Fix desktop settings legacy override

packages/desktop/src/settings/desktop-settings.test.ts

@@ -94,6 +94,58 @@ describe("desktop-settings", () => {
     expect(files).toEqual(["desktop-settings.json"]);
   });
 
+  it("does not let stale legacy renderer settings override an explicit desktop patch", async () => {
+    const userDataPath = await createTempUserDataDir();
+    directories.add(userDataPath);
+    const store = createDesktopSettingsStore({ userDataPath });
+
+    const patched = await store.patch({
+      daemon: {
+        manageBuiltInDaemon: false,
+      },
+    });
+    const migrated = await store.migrateLegacyRendererSettings({
+      manageBuiltInDaemon: true,
+      releaseChannel: "beta",
+    });
+    const persisted = JSON.parse(await readFile(settingsFilePath(userDataPath), "utf8")) as {
+      migrations: { legacyRendererSettingsImported: boolean };
+      settings: DesktopSettings;
+    };
+
+    expect(patched.daemon.manageBuiltInDaemon).toBe(false);
+    expect(migrated.daemon.manageBuiltInDaemon).toBe(false);
+    expect(migrated.releaseChannel).toBe("stable");
+    expect(persisted.migrations.legacyRendererSettingsImported).toBe(true);
+    expect(persisted.settings.daemon.manageBuiltInDaemon).toBe(false);
+  });
+
+  it("does not rewrite existing settings while reading them", async () => {
+    const userDataPath = await createTempUserDataDir();
+    directories.add(userDataPath);
+    const raw = JSON.stringify({
+      version: 1,
+      settings: {
+        releaseChannel: "stable",
+        daemon: {
+          manageBuiltInDaemon: false,
+          keepRunningAfterQuit: true,
+        },
+      },
+      migrations: {
+        legacyRendererSettingsImported: false,
+      },
+    });
+    await writeFile(settingsFilePath(userDataPath), raw);
+    const store = createDesktopSettingsStore({ userDataPath });
+
+    const settings = await store.get();
+    const persisted = await readFile(settingsFilePath(userDataPath), "utf8");
+
+    expect(settings.daemon.manageBuiltInDaemon).toBe(false);
+    expect(persisted).toBe(raw);
+  });
+
   it("migrates desktop-owned values from legacy renderer settings once", async () => {
     const userDataPath = await createTempUserDataDir();
     directories.add(userDataPath);

packages/desktop/src/settings/desktop-settings.ts

@@ -1,4 +1,4 @@
-import { access, mkdir, readFile, rename, writeFile } from "node:fs/promises";
+import { mkdir, readFile, rename, writeFile } from "node:fs/promises";
 import path from "node:path";
 
 import type { AppReleaseChannel } from "../features/auto-updater.js";
@@ -58,10 +58,17 @@ function coerceBoolean(value: unknown): boolean | null {
   return typeof value === "boolean" ? value : null;
 }
 
+function isNodeError(error: unknown): error is NodeJS.ErrnoException {
+  return error instanceof Error;
+}
+
 function buildDefaultDocument(): PersistedDesktopSettingsDocument {
   return {
     version: 1,
-    settings: DEFAULT_DESKTOP_SETTINGS,
+    settings: {
+      releaseChannel: DEFAULT_DESKTOP_SETTINGS.releaseChannel,
+      daemon: { ...DEFAULT_DESKTOP_SETTINGS.daemon },
+    },
     migrations: {
       legacyRendererSettingsImported: false,
     },
@@ -159,6 +166,10 @@ function mergeDesktopSettings(
   };
 }
 
+function hasLegacyRendererOwnedPatch(patch: DesktopSettingsPatch): boolean {
+  return patch.releaseChannel !== undefined || patch.daemon?.manageBuiltInDaemon !== undefined;
+}
+
 function coerceDocument(input: unknown): PersistedDesktopSettingsDocument {
   if (!isRecord(input)) {
     return buildDefaultDocument();
@@ -201,19 +212,31 @@ export function createDesktopSettingsStore({
       return cachedDocument;
     }
 
+    let raw: string;
     try {
-      await access(filePath);
-    } catch {
+      raw = await readFile(filePath, "utf8");
+    } catch (error) {
+      if (!isNodeError(error) || error.code !== "ENOENT") {
+        throw error;
+      }
       const document = buildDefaultDocument();
       await persistDocument(document);
       return document;
     }
+    const document = coerceDocument(JSON.parse(raw));
+    cachedDocument = document;
+    return document;
+  }
 
+  async function loadWritableDocument(): Promise<PersistedDesktopSettingsDocument> {
+    const document = await loadDocument();
+    await persistDocument(document);
+    return document;
+  }
+
+  async function initializeLegacyRendererMigration(): Promise<PersistedDesktopSettingsDocument> {
     try {
-      const raw = await readFile(filePath, "utf8");
-      const document = coerceDocument(JSON.parse(raw));
-      await persistDocument(document);
-      return document;
+      return await loadDocument();
     } catch {
       const document = buildDefaultDocument();
       await persistDocument(document);
@@ -228,17 +251,24 @@ export function createDesktopSettingsStore({
     },
 
     async patch(patch: unknown): Promise<DesktopSettings> {
-      const current = await loadDocument();
-      const next = mergeDesktopSettings(current.settings, coerceDesktopSettingsPatch(patch));
+      const current = await loadWritableDocument();
+      const coercedPatch = coerceDesktopSettingsPatch(patch);
+      const next = mergeDesktopSettings(current.settings, coercedPatch);
       await persistDocument({
         ...current,
         settings: next,
+        migrations: {
+          ...current.migrations,
+          legacyRendererSettingsImported:
+            current.migrations.legacyRendererSettingsImported ||
+            hasLegacyRendererOwnedPatch(coercedPatch),
+        },
       });
       return next;
     },
 
     async migrateLegacyRendererSettings(legacySettings: unknown): Promise<DesktopSettings> {
-      const current = await loadDocument();
+      const current = await initializeLegacyRendererMigration();
       if (current.migrations.legacyRendererSettingsImported) {
         return current.settings;
       }