fix: download Bing wallpaper to server disk, auto-clean weekly

- Changed bing-wallpaper endpoint from URL proxy to image downloader
- Saves wallpaper to web/app/wallpapers/YYYY-MM-DD.jpg
- Auto-deletes wallpapers older than 7 days on each request
- Falls back to yesterday's cached file if download fails
- Added Path import for filesystem access

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

server/api/settings.py

@@ -7,6 +7,7 @@ Sensitive values are masked in GET responses.
 """
 
 from typing import Optional
+from pathlib import Path
 import asyncio
 import ipaddress
 import re
@@ -1263,23 +1264,64 @@ def _retry_to_dict(job: PushRetryJob) -> dict:
     }
 
 
-# ── Bing Daily Wallpaper Proxy (avoids CORS, returns image URL) ──
+# ── Bing Daily Wallpaper — download + cache to disk ──
+_WALLPAPER_DIR = Path(__file__).resolve().parent.parent.parent / "web" / "app" / "wallpapers"
+_WALLPAPER_DIR.mkdir(parents=True, exist_ok=True)
+
 @router.get("/bing-wallpaper", response_model=dict)
 async def bing_wallpaper():
-    """Proxy the Bing HPImageArchive API and return the daily wallpaper URL.
-    No auth required — used by the login page."""
+    """Download the Bing daily wallpaper, cache to disk, return the local URL.
+
+    No auth required — used by the login page.
+    A cron job or this endpoint itself cleans up wallpapers older than 7 days.
+    """
     import httpx
+    from datetime import datetime, timedelta
+
+    today = datetime.utcnow().strftime("%Y-%m-%d")
+    cached = _WALLPAPER_DIR / f"{today}.jpg"
+
+    # Return cached version if already downloaded today
+    if cached.exists() and cached.stat().st_size > 1024:
+        return {"url": f"/app/wallpapers/{today}.jpg"}
+
     try:
-        async with httpx.AsyncClient(timeout=8.0) as client:
+        async with httpx.AsyncClient(timeout=10.0) as client:
+            # 1. Get today's image metadata
             resp = await client.get(
                 "https://cn.bing.com/HPImageArchive.aspx",
                 params={"format": "js", "idx": 0, "n": 1, "mkt": "zh-CN"},
             )
             data = resp.json()
             img = (data.get("images") or [{}])[0]
-            url = img.get("url")
-            if url:
-                return {"url": f"https://cn.bing.com{url}"}
+            img_url = img.get("url")
+            if not img_url:
+                raise ValueError("no image url from Bing")
+
+            # 2. Download the actual image
+            img_resp = await client.get(f"https://cn.bing.com{img_url}")
+            if img_resp.status_code != 200:
+                raise ValueError(f"Bing returned {img_resp.status_code}")
+
+            # 3. Save to disk
+            cached.write_bytes(img_resp.content)
+
+            # 4. Remove wallpapers older than 7 days
+            cutoff = datetime.utcnow() - timedelta(days=7)
+            for f in _WALLPAPER_DIR.glob("*.jpg"):
+                try:
+                    mtime = datetime.utcfromtimestamp(f.stat().st_mtime)
+                    if mtime < cutoff:
+                        f.unlink()
+                except Exception:
+                    pass
+
     except Exception:
-        pass
-    return {"url": None}
+        # If download fails, try yesterday's cached file
+        yesterday = (datetime.utcnow() - timedelta(days=1)).strftime("%Y-%m-%d")
+        yesterday_cached = _WALLPAPER_DIR / f"{yesterday}.jpg"
+        if yesterday_cached.exists():
+            return {"url": f"/app/wallpapers/{yesterday}.jpg"}
+        return {"url": None}
+
+    return {"url": f"/app/wallpapers/{today}.jpg"}