fix: expire frontend caches

src/api.test.ts

@@ -51,6 +51,47 @@ describe("api helpers", () => {
     await expect(getJSON("/api/fail")).rejects.toThrow("boom");
   });
 
+  it("cleans expired JSON cache entries", async () => {
+    vi.useFakeTimers();
+    try {
+      vi.setSystemTime(new Date("2026-05-31T00:00:00Z"));
+      const { getJSON, readJSONCache } = await loadApi();
+      const fetchMock = vi.fn().mockResolvedValue(jsonResponse({ items: [1] }));
+      vi.stubGlobal("fetch", fetchMock);
+
+      await getJSON("/api/posts");
+      expect(readJSONCache("/api/posts")).toEqual({ items: [1] });
+
+      vi.setSystemTime(new Date("2026-05-31T00:05:01Z"));
+      expect(readJSONCache("/api/posts")).toBeNull();
+      expect(window.localStorage.length).toBe(0);
+    } finally {
+      vi.useRealTimers();
+    }
+  });
+
+  it("prunes old JSON cache entries beyond the entry limit", async () => {
+    vi.useFakeTimers();
+    try {
+      const { getJSON, readJSONCache } = await loadApi();
+      const fetchMock = vi.fn((url: string) =>
+        Promise.resolve(jsonResponse({ url })),
+      );
+      vi.stubGlobal("fetch", fetchMock);
+
+      for (let index = 0; index < 81; index += 1) {
+        vi.setSystemTime(new Date(2026, 4, 31, 0, 0, index));
+        await getJSON(`/api/cache-${index}`);
+      }
+
+      expect(readJSONCache("/api/cache-0")).toBeNull();
+      expect(readJSONCache("/api/cache-80")).toEqual({ url: "/api/cache-80" });
+      expect(window.localStorage.length).toBe(80);
+    } finally {
+      vi.useRealTimers();
+    }
+  });
+
   it("posts JSON with optional bearer token", async () => {
     const { postJSON } = await loadApi();
     const fetchMock = vi.fn().mockResolvedValue(jsonResponse({ id: 1 }));