adding caching to presque gratos

keys.py

@@ -0,0 +1,20 @@
+# keys.py (or inline in your main)
+def xgp_key(item) -> str:
+    # Prefer stable Microsoft Store productId if present; fallback to normalized title.
+    pid = (item.get("productId") or "").strip()
+    if pid:
+        return f"item:xgp:{pid}"
+    title = (item.get("title") or "").strip().lower()
+    return f"item:xgp:title:{title}"
+
+def egs_key(item) -> str:
+    # Use title + start window (your fetcher usually knows the free-week start)
+    title = (item.get("title") or "").strip()
+    start = (item.get("start") or "").strip()  # ISO or YYYY-MM-DD
+    return f"item:egs:{title}|{start}"
+
+def psplus_key(item) -> str:
+    # Use official PS Blog URL + the published month (or your computed date)
+    url = (item.get("url") or "").strip()
+    date = (item.get("date") or "").strip()
+    return f"item:psplus:{url}|{date}"