feat(chat-media): 修复媒体缓存

frontend/pages/chat/[[username]].vue

@@ -606,16 +606,36 @@ const onGlobalKeyDown = (event) => {
   }
 }
 
+const RESUME_MEDIA_REFRESH_MIN_INTERVAL_MS = 1200
+const RESUME_MEDIA_REFRESH_MIN_HIDDEN_MS = 30 * 1000
+
 let lastResumeMediaRefreshAt = 0
+let lastPageHiddenAt = 0
+
+const hasLoadedConversationMedia = () => {
+  const list = Array.isArray(messages.value) ? messages.value : []
+  return list.some((message) => {
+    return !!(
+      String(message?.imageUrl || '').trim()
+      || String(message?.videoThumbUrl || '').trim()
+      || String(message?.quoteImageUrl || '').trim()
+    )
+  })
+}
 
 const maybeRefreshMediaOnResume = () => {
   if (!process.client) return
   if (!selectedContact.value?.username) return
   if (searchContext.value?.active) return
+  if (!hasLoadedConversationMedia()) return
+
+  const hiddenDuration = lastPageHiddenAt > 0 ? (Date.now() - lastPageHiddenAt) : 0
+  if (hiddenDuration < RESUME_MEDIA_REFRESH_MIN_HIDDEN_MS) return
 
   const now = Date.now()
-  if ((now - lastResumeMediaRefreshAt) < 1200) return
+  if ((now - lastResumeMediaRefreshAt) < RESUME_MEDIA_REFRESH_MIN_INTERVAL_MS) return
   lastResumeMediaRefreshAt = now
+  lastPageHiddenAt = 0
   void refreshCurrentMessageMedia()
 }
 
@@ -624,6 +644,10 @@ const onWindowFocus = () => {
 }
 
 const onVisibilityChange = () => {
+  if (document.visibilityState === 'hidden') {
+    lastPageHiddenAt = Date.now()
+    return
+  }
   if (document.visibilityState !== 'visible') return
   maybeRefreshMediaOnResume()
 }

src/wechat_decrypt_tool/routers/chat_media.py

@@ -12,7 +12,7 @@ from typing import Any, Optional
 from urllib.parse import urlparse
 
 import requests
-from fastapi import APIRouter, HTTPException
+from fastapi import APIRouter, HTTPException, Request
 from fastapi.responses import FileResponse, Response
 from pydantic import BaseModel, Field
 
@@ -67,10 +67,27 @@ logger = get_logger(__name__)
 router = APIRouter(route_class=PathFixRoute)
 
 
-def _build_uncached_media_response(data: bytes, media_type: str) -> Response:
-    resp = Response(content=data, media_type=media_type)
-    resp.headers["Cache-Control"] = "no-store"
-    return resp
+CHAT_MEDIA_BROWSER_CACHE_SECONDS = 24 * 60 * 60
+
+
+def _build_cached_media_response(request: Optional[Request], data: bytes, media_type: str) -> Response:
+    payload = bytes(data or b"")
+    etag = f'"{hashlib.sha1(payload).hexdigest()}"'
+    cache_control = f"private, max-age={CHAT_MEDIA_BROWSER_CACHE_SECONDS}"
+    headers = {
+        "Cache-Control": cache_control,
+        "ETag": etag,
+    }
+
+    try:
+        if_none_match = str(request.headers.get("if-none-match") or "").strip() if request else ""
+    except Exception:
+        if_none_match = ""
+
+    if if_none_match and if_none_match == etag:
+        return Response(status_code=304, headers=headers)
+
+    return Response(content=payload, media_type=media_type, headers=headers)
 
 
 def _image_candidate_variant_rank(path: Path) -> int:
@@ -1363,6 +1380,7 @@ async def download_chat_emoji(req: EmojiDownloadRequest):
 
 @router.get("/api/chat/media/image", summary="获取图片消息资源")
 async def get_chat_image(
+    request: Request,
     md5: Optional[str] = None,
     file_id: Optional[str] = None,
     server_id: Optional[int] = None,
@@ -1502,7 +1520,7 @@ async def get_chat_image(
 
     if not p:
         if cached_path:
-            return _build_uncached_media_response(cached_data, cached_media_type)
+            return _build_cached_media_response(request, cached_data, cached_media_type)
         raise HTTPException(status_code=404, detail="Image not found.")
 
     candidates.extend(_iter_media_source_candidates(p))
@@ -1562,7 +1580,7 @@ async def get_chat_image(
     logger.info(
         f"chat_image: md5={md5} file_id={file_id} chosen={chosen} media_type={media_type} bytes={len(data)}"
     )
-    return _build_uncached_media_response(data, media_type)
+    return _build_cached_media_response(request, data, media_type)
 
 
 @router.get("/api/chat/media/emoji", summary="获取表情消息资源")

tests/test_chat_media_image_cache_upgrade.py

@@ -18,6 +18,10 @@ sys.path.insert(0, str(ROOT / "src"))
 
 
 class TestChatMediaImageCacheUpgrade(unittest.TestCase):
+    def assert_cacheable_chat_image_response(self, resp) -> None:
+        self.assertEqual(resp.headers.get("cache-control"), "private, max-age=86400")
+        self.assertTrue(str(resp.headers.get("etag") or "").strip())
+
     def _seed_contact_db(self, path: Path, *, account: str, username: str) -> None:
         conn = sqlite3.connect(str(path))
         try:
@@ -147,7 +151,7 @@ class TestChatMediaImageCacheUpgrade(unittest.TestCase):
                 )
                 self.assertEqual(resp.status_code, 200)
                 self.assertEqual(resp.content, live_original)
-                self.assertEqual(resp.headers.get("cache-control"), "no-store")
+                self.assert_cacheable_chat_image_response(resp)
                 self.assertEqual(cache_path.read_bytes(), live_original)
             finally:
                 try:
@@ -192,7 +196,7 @@ class TestChatMediaImageCacheUpgrade(unittest.TestCase):
                 )
                 self.assertEqual(resp.status_code, 200)
                 self.assertEqual(resp.content, cached_original)
-                self.assertEqual(resp.headers.get("cache-control"), "no-store")
+                self.assert_cacheable_chat_image_response(resp)
                 self.assertEqual(cache_path.read_bytes(), cached_original)
             finally:
                 try:
@@ -205,6 +209,59 @@ class TestChatMediaImageCacheUpgrade(unittest.TestCase):
                 else:
                     os.environ["WECHAT_TOOL_DATA_DIR"] = prev_data
 
+    def test_chat_image_supports_etag_revalidation(self):
+        with TemporaryDirectory() as td:
+            root = Path(td)
+            account = "wxid_test"
+            username = "wxid_friend"
+            md5 = "cccccccccccccccccccccccccccccccc"
+
+            account_dir = root / "output" / "databases" / account
+            wxid_dir = root / "wxid_source"
+            account_dir.mkdir(parents=True, exist_ok=True)
+            wxid_dir.mkdir(parents=True, exist_ok=True)
+
+            self._seed_contact_db(account_dir / "contact.db", account=account, username=username)
+            self._seed_session_db(account_dir / "session.db", username=username)
+            self._seed_source_info(account_dir, wxid_dir=wxid_dir)
+
+            cached_original = b"\xff\xd8\xff\xe0" + (b"\x22" * 64) + b"\xff\xd9"
+            self._seed_cached_resource(account_dir, md5=md5, payload=cached_original)
+
+            prev_data = os.environ.get("WECHAT_TOOL_DATA_DIR")
+            client = None
+            try:
+                os.environ["WECHAT_TOOL_DATA_DIR"] = str(root)
+                client = self._build_client()
+                first = client.get(
+                    "/api/chat/media/image",
+                    params={"account": account, "md5": md5, "username": username},
+                )
+                self.assertEqual(first.status_code, 200)
+                self.assertEqual(first.content, cached_original)
+                self.assert_cacheable_chat_image_response(first)
+
+                etag = str(first.headers.get("etag") or "").strip()
+                second = client.get(
+                    "/api/chat/media/image",
+                    params={"account": account, "md5": md5, "username": username},
+                    headers={"If-None-Match": etag},
+                )
+                self.assertEqual(second.status_code, 304)
+                self.assertEqual(second.content, b"")
+                self.assertEqual(second.headers.get("etag"), etag)
+                self.assertEqual(second.headers.get("cache-control"), "private, max-age=86400")
+            finally:
+                try:
+                    client.close()
+                except Exception:
+                    pass
+                logging.shutdown()
+                if prev_data is None:
+                    os.environ.pop("WECHAT_TOOL_DATA_DIR", None)
+                else:
+                    os.environ["WECHAT_TOOL_DATA_DIR"] = prev_data
+
 
 if __name__ == "__main__":
     unittest.main()