fix: home tab, layout switch and missing layout fallbacks for looks

src/backend/database/routes/look.ts

@@ -13,6 +13,7 @@ import {
   LAYOUT_SETTING,
   LOOK_ID_PATTERN,
   THEME_SETTING,
+  installedLayoutIds,
   resolveDefaultLook,
   safeLayoutForced,
   unavailableLooks,
@@ -35,7 +36,7 @@ async function adminDefaults() {
  * /user-preferences/look:
  *   get:
  *     summary: Get the layout and theme to show the current user
- *     description: The user's own choice, the admin defaults, the default look of the bundled plugins, whether TERMIX_SAFE_LAYOUT forces the repair view, and installed layout or theme plugins that could not load. The browser resolves the final look from these.
+ *     description: The user's own choice, the admin defaults (a layout no installed plugin brings reads as null), the default look of the bundled plugins, whether TERMIX_SAFE_LAYOUT forces the repair view, and installed layout or theme plugins that could not load. The browser resolves the final look from these.
  *     tags:
  *       - User Preferences
  *     responses:
@@ -101,10 +102,14 @@ router.get("/", authenticateJWT, async (req: Request, res: Response) => {
     const preferences =
       await createCurrentUserPreferenceRepository().findByUserId(userId);
     const { loader } = getPluginRuntime();
+    const installed = installedLayoutIds(loader);
+    const known = (id: string | null | undefined) =>
+      id && installed.has(id) ? id : null;
+    const defaults = await adminDefaults();
     res.json({
-      layoutId: preferences?.layoutId ?? null,
+      layoutId: known(preferences?.layoutId),
       themeId: preferences?.themeId ?? null,
-      defaults: await adminDefaults(),
+      defaults: { ...defaults, layout: known(defaults.layout) },
       defaultLook: resolveDefaultLook(loader),
       safeLayout: safeLayoutForced(),
       unavailable: unavailableLooks(loader),

src/backend/plugins/looks.ts

@@ -14,6 +14,7 @@ export interface DefaultLook {
 
 interface LookLoader {
   get(pluginId: string): Pick<LoadedPlugin, "manifest"> | undefined;
+  list(): Array<Pick<LoadedPlugin, "manifest">>;
   skipped(): SkippedPlugin[];
 }
 
@@ -46,6 +47,24 @@ export function unavailableLooks(loader: LookLoader): SkippedPlugin[] {
     .filter((plugin) => plugin.layouts.length > 0 || plugin.themes.length > 0);
 }
 
+/**
+ * Layout ids some installed plugin brings, whether it runs, is turned off or
+ * failed to load. A choice outside this set was uninstalled, so the next
+ * choice down applies instead of the repair view.
+ */
+export function installedLayoutIds(loader: LookLoader): Set<string> {
+  const ids = new Set<string>();
+  for (const plugin of loader.list()) {
+    for (const layout of plugin.manifest.contributes?.layouts ?? []) {
+      ids.add(layout.id);
+    }
+  }
+  for (const plugin of loader.skipped()) {
+    for (const id of plugin.layouts) ids.add(id);
+  }
+  return ids;
+}
+
 /** TERMIX_SAFE_LAYOUT=1 starts everyone in the layout repair view. */
 export function safeLayoutForced(): boolean {
   const value = process.env.TERMIX_SAFE_LAYOUT?.trim().toLowerCase();

src/backend/tests/database/routes/look.test.ts

@@ -11,6 +11,7 @@ const state = vi.hoisted(() => ({
   audits: [] as unknown[],
   skipped: [] as unknown[],
   defaultLookIds: [] as string[],
+  installed: [] as string[],
 }));
 
 vi.mock("../../../utils/logger.js", () => ({
@@ -69,6 +70,15 @@ vi.mock("../../../plugins/index.js", () => ({
               },
             }
           : undefined,
+      list: () => [
+        {
+          manifest: {
+            contributes: {
+              layouts: state.installed.map((id) => ({ id, label: id })),
+            },
+          },
+        },
+      ],
       skipped: () => state.skipped,
     },
   }),
@@ -90,6 +100,7 @@ beforeEach(async () => {
   state.audits = [];
   state.skipped = [];
   state.defaultLookIds = [];
+  state.installed = [];
   delete process.env.TERMIX_SAFE_LAYOUT;
 
   const app = express();
@@ -133,6 +144,7 @@ describe("GET /user-preferences/look", () => {
 
   it("returns the user's pick, the admin defaults and the default look", async () => {
     state.prefs = { layoutId: "mine", themeId: "nord" };
+    state.installed = ["mine", "admin-layout"];
     state.settings.set("ui.layout", "admin-layout");
     state.settings.set("ui.theme", "gruvbox");
     state.defaultLookIds = ["shipped-look"];
@@ -162,6 +174,31 @@ describe("GET /user-preferences/look", () => {
   });
 });
 
+describe("GET /user-preferences/look with an uninstalled layout", () => {
+  it("drops a choice no installed plugin brings, so the next one applies", async () => {
+    state.prefs = { layoutId: "deleted", themeId: null };
+    state.settings.set("ui.layout", "also-deleted");
+    state.installed = ["kept"];
+    const { body } = await getLook();
+    expect(body.layoutId).toBeNull();
+    expect(body.defaults.layout).toBeNull();
+  });
+
+  it("keeps a choice whose plugin failed to load, for the repair view", async () => {
+    state.prefs = { layoutId: "b", themeId: null };
+    state.skipped = [
+      {
+        id: "broken",
+        version: "1.0.0",
+        layouts: ["b"],
+        themes: [],
+        error: "x",
+      },
+    ];
+    expect((await getLook()).body.layoutId).toBe("b");
+  });
+});
+
 describe("PUT /user-preferences/look/defaults", () => {
   it("is for admins only", async () => {
     const { status } = await putDefaults({ layout: "x" });

src/backend/tests/plugins/looks.test.ts

@@ -6,6 +6,7 @@ vi.mock("../../plugins/bundled-index.js", () => ({
 }));
 
 import {
+  installedLayoutIds,
   resolveDefaultLook,
   safeLayoutForced,
   unavailableLooks,
@@ -23,6 +24,10 @@ function loaderWith(
       plugins[id]
         ? ({ manifest: { contributes: plugins[id] } } as never)
         : undefined,
+    list: () =>
+      Object.values(plugins).map(
+        (contributes) => ({ manifest: { contributes } }) as never,
+      ),
     skipped: () => skipped,
   };
 }
@@ -103,3 +108,14 @@ describe("safeLayoutForced", () => {
     expect(safeLayoutForced()).toBe(false);
   });
 });
+
+describe("installedLayoutIds", () => {
+  it("lists layouts of loaded and skipped plugins", () => {
+    const ids = installedLayoutIds(
+      loaderWith({ a: { layouts: [{ id: "one" }], themes: [{ id: "t" }] } }, [
+        { id: "b", version: null, layouts: ["two"], themes: [], error: "x" },
+      ]),
+    );
+    expect([...ids].sort()).toEqual(["one", "two"]);
+  });
+});