fix(webapp): an unknown saved theme no longer erases the whole preferences blob

theme and contrast degrade to undefined on their own instead of failing the
blob's validation, which reset favorites, side-menu layout and current
project - permanently after the next preference write.

Author: kathiekiwi

apps/webapp/app/utils/dashboardPreferences.ts

@@ -47,9 +47,11 @@ export type SideMenuPreferences = z.infer<typeof SideMenuPreferences>;
 
 const DashboardPreferences = z.object({
   version: z.literal("1"),
-  theme: ThemePreference.optional(),
+  /* An unknown value (e.g. written by a newer deploy) degrades to undefined
+     instead of failing the whole blob and erasing every other setting */
+  theme: ThemePreference.optional().catch(undefined),
   /** Interface contrast for the System themes, 0-100. */
-  contrast: z.number().int().min(0).max(100).optional(),
+  contrast: z.number().int().min(0).max(100).optional().catch(undefined),
   currentProjectId: z.string().optional(),
   projects: z.record(
     z.string(),

apps/webapp/test/themePreference.test.ts

@@ -36,8 +36,18 @@ describe("DashboardPreferences theme schema", () => {
     expect(result.theme).toBeUndefined();
   });
 
-  it("rejects an invalid theme by falling back to defaults", () => {
-    const result = parseDashboardPreferences({ version: "1", projects: {}, theme: "neon" });
+  it("drops an invalid theme without erasing the rest of the preferences", () => {
+    const result = parseDashboardPreferences({
+      version: "1",
+      projects: {},
+      theme: "neon",
+      contrast: 999,
+      currentProjectId: "proj_123",
+      sideMenu: { isCollapsed: true },
+    });
     expect(result.theme).toBeUndefined();
+    expect(result.contrast).toBeUndefined();
+    expect(result.currentProjectId).toBe("proj_123");
+    expect(result.sideMenu?.isCollapsed).toBe(true);
   });
 });