fix: remove stale _decimal_str ref, add context manager to HTTP clients

- UpstreamClient & Sub2ApiWebsiteClient: add __enter__/__exit__
- Convert all call sites to `with Client(...) as c:` pattern
- Remove unused `upstream_name`/`upstream_base_url` locals in scheduler
- Fix stale _decimal_str→decimal_string in _rate_from_group

backend/app/routers/upstreams.py

@@ -146,29 +146,29 @@ def test_upstream(uid: int, db: Session = Depends(get_db), _=Depends(get_current
     if not u:
         raise HTTPException(404, "upstream not found")
     auth_config = json.loads(u.auth_config_json or "{}")
-    client = UpstreamClient(
+    with UpstreamClient(
         base_url=u.base_url,
         api_prefix=u.api_prefix,
         auth_type=u.auth_type,
         auth_config=auth_config,
         timeout=float(u.timeout_seconds),
-    )
-    try:
-        client.login()
-        groups = client.get_available_groups(u.groups_endpoint)
-        u.last_status = "healthy"
-        u.last_error = None
-        u.last_checked_at = datetime.now(timezone.utc)
-        u.consecutive_failures = 0
-        db.commit()
-        return TestResult(success=True, message=f"连接成功，获取到 {len(groups)} 个分组")
-    except Exception as exc:
-        u.last_status = "unhealthy"
-        u.last_error = str(exc)
-        u.last_checked_at = datetime.now(timezone.utc)
-        u.consecutive_failures = (u.consecutive_failures or 0) + 1
-        db.commit()
-        return TestResult(success=False, message="连接失败", detail=str(exc))
+    ) as client:
+        try:
+            client.login()
+            groups = client.get_available_groups(u.groups_endpoint)
+            u.last_status = "healthy"
+            u.last_error = None
+            u.last_checked_at = datetime.now(timezone.utc)
+            u.consecutive_failures = 0
+            db.commit()
+            return TestResult(success=True, message=f"连接成功，获取到 {len(groups)} 个分组")
+        except Exception as exc:
+            u.last_status = "unhealthy"
+            u.last_error = str(exc)
+            u.last_checked_at = datetime.now(timezone.utc)
+            u.consecutive_failures = (u.consecutive_failures or 0) + 1
+            db.commit()
+            return TestResult(success=False, message="连接失败", detail=str(exc))
 
 
 @router.post("/{uid}/check-now", response_model=TestResult)
@@ -177,24 +177,24 @@ def check_now(uid: int, db: Session = Depends(get_db), _=Depends(get_current_use
     if not u:
         raise HTTPException(404, "upstream not found")
     auth_config = json.loads(u.auth_config_json or "{}")
-    client = UpstreamClient(
+    with UpstreamClient(
         base_url=u.base_url,
         api_prefix=u.api_prefix,
         auth_type=u.auth_type,
         auth_config=auth_config,
         timeout=float(u.timeout_seconds),
-    )
-    try:
-        client.login()
-        groups = client.get_available_groups(u.groups_endpoint)
-        raw_rates = client.get_group_rates(u.rate_endpoint)
-        snapshot = build_snapshot(u.id, u.base_url, u.api_prefix, groups, raw_rates)
-    except Exception as exc:
-        u.consecutive_failures = (u.consecutive_failures or 0) + 1
-        u.last_error = str(exc)
-        u.last_checked_at = datetime.now(timezone.utc)
-        db.commit()
-        return TestResult(success=False, message="检测失败", detail=str(exc))
+    ) as client:
+        try:
+            client.login()
+            groups = client.get_available_groups(u.groups_endpoint)
+            raw_rates = client.get_group_rates(u.rate_endpoint)
+            snapshot = build_snapshot(u.id, u.base_url, u.api_prefix, groups, raw_rates)
+        except Exception as exc:
+            u.consecutive_failures = (u.consecutive_failures or 0) + 1
+            u.last_error = str(exc)
+            u.last_checked_at = datetime.now(timezone.utc)
+            db.commit()
+            return TestResult(success=False, message="检测失败", detail=str(exc))
 
     prev_row = (
         db.query(UpstreamRateSnapshot)

backend/app/routers/websites.py

@@ -188,7 +188,8 @@ def test_website(wid: int, db: Session = Depends(get_db), _=Depends(get_current_
     if not row:
         raise HTTPException(404, "website not found")
     try:
-        groups = _client(row).get_groups(row.groups_endpoint)
+        with _client(row) as c:
+            groups = c.get_groups(row.groups_endpoint)
         row.last_status = "healthy"
         row.last_error = None
         row.last_checked_at = datetime.now(timezone.utc)
@@ -208,7 +209,8 @@ def list_website_groups(wid: int, db: Session = Depends(get_db), _=Depends(get_c
     if not row:
         raise HTTPException(404, "website not found")
     try:
-        return _client(row).get_groups(row.groups_endpoint)
+        with _client(row) as c:
+            return c.get_groups(row.groups_endpoint)
     except Exception as exc:
         raise HTTPException(502, str(exc))