diff --git a/src/agent.py b/src/agent.py
index 42ff383..d9a61e2 100644
--- a/src/agent.py
+++ b/src/agent.py
@@ -629,9 +629,12 @@ class Executor:
             if not got or start >= int(page.get("total") or 0):
                 return issues
 
-    def search_tolerant(self, keys: List[str], missing: List[str]) -> List[dict]:
+    def search_tolerant(self, keys: List[str], missing: List[str], errors: List[HttpError]) -> List[dict]:
         """key in (...): Jira Server отвечает 400 на несуществующий/недоступный ключ. Чанк делим пополам до
-        одиночного ключа; одиночный с 400 — «не найден» (в missing), не ошибка. Прочие HttpError пробрасываются."""
+        одиночного ключа; одиночный с 400 — «не найден» (в missing), не ошибка. Прочие HttpError пробрасываются.
+        Первый 400 копится в errors: вызывающий пробрасывает его, если не найден НИ ОДИН ключ (неверная конфигурация,
+        а не удалённые задачи).
+        Стоимость: до ~2·m·log2(n) вызовов на m отсутствующих ключей из n — принятое ограничение, рулинг R-7."""
         if not keys:
             return []
         try:
@@ -639,11 +642,13 @@ class Executor:
         except HttpError as e:
             if e.code != 400:
                 raise
+            if not errors:
+                errors.append(e)
             if len(keys) == 1:
                 missing.append(keys[0])
                 return []
             mid = len(keys) // 2
-            return self.search_tolerant(keys[:mid], missing) + self.search_tolerant(keys[mid:], missing)
+            return self.search_tolerant(keys[:mid], missing, errors) + self.search_tolerant(keys[mid:], missing, errors)
 
     def to_state(self, raw: dict) -> dict:
         f = raw.get("fields") or {}
@@ -694,15 +699,18 @@ class Executor:
 
     def do_refresh(self, p: dict, cmd: dict) -> dict:
         missing: List[str] = []
+        errors: List[HttpError] = []
         if p.get("jql"):
             raws = self.search_all(p["jql"])
         else:
-            keys = [k for k in (p.get("keys") or []) if k]
+            keys = list(dict.fromkeys(k for k in (p.get("keys") or []) if k))
             if not keys:
                 return self._out("done", {"issues": 0, "neighbors": 0, "pages": 0})
             raws = []
             for i in range(0, len(keys), 100):
-                raws += self.search_tolerant(keys[i:i + 100], missing)
+                raws += self.search_tolerant(keys[i:i + 100], missing, errors)
+            if not raws and errors:      # ни один ключ не найден: это конфигурация/запрос, а не удалённые задачи
+                raise errors[0]
         fetched = {r["key"] for r in raws}
         known = set(self.hub.known_keys()) if self.hub else set()
         linked = set()
@@ -713,7 +721,7 @@ class Executor:
         absent = sorted(k for k in linked if k not in fetched and k not in known)
         neighbors = []
         for i in range(0, len(absent), 100):
-            neighbors += self.search_tolerant(absent[i:i + 100], missing)
+            neighbors += self.search_tolerant(absent[i:i + 100], missing, errors)
         everything = raws + neighbors
         names = self.sprint_names([r["key"] for r in everything])
         issues, links, seen = [], [], set()
@@ -738,7 +746,7 @@ class Executor:
                             "page": pages, "last_page": i + 100 >= len(issues)})
         result = {"issues": len(raws), "neighbors": len(neighbors), "pages": pages}
         if missing:
-            result["missing"] = sorted(missing)[:50]
+            result["missing"] = list(dict.fromkeys(missing))[:50]
         return self._out("done", result)
 
 
diff --git a/tests/test_refresh.py b/tests/test_refresh.py
index 32729e4..2fe2075 100644
--- a/tests/test_refresh.py
+++ b/tests/test_refresh.py
@@ -93,9 +93,30 @@ class RefreshTest(unittest.TestCase):
         out = self.ex.run({"id": 9, "type": "refresh",
                            "params": {"keys": ["AURORA-1", "AURORA-2", "AURORA-99", "AURORA-3", "AURORA-98"]}})
         self.assertEqual(out["status"], "done")
-        self.assertEqual(out["result"], {"issues": 3, "neighbors": 0, "pages": 1, "missing": ["AURORA-98", "AURORA-99"]})
+        self.assertEqual(out["result"], {"issues": 3, "neighbors": 0, "pages": 1, "missing": ["AURORA-99", "AURORA-98"]})
         self.assertEqual(sorted(i["key"] for i in self.hub.states[0]["issues"]), ["AURORA-1", "AURORA-2", "AURORA-3"])
 
+    def test_all_keys_400_fails(self):
+        out = self.ex.run({"id": 14, "type": "refresh", "params": {"keys": ["X-1", "X-2", "X-3"]}})
+        self.assertEqual(out["status"], "failed")
+        self.assertIn("HTTP 400", out["error"])
+        self.assertEqual(self.hub.states, [])
+
+    def test_bisect_cost_one_missing_of_100(self):
+        for i in range(1, 100):
+            self.fake.add("AURORA-%d" % i)
+        keys = ["AURORA-%d" % i for i in range(1, 101)]      # AURORA-100 отсутствует
+        out = self.ex.run({"id": 15, "type": "refresh", "params": {"keys": keys}})
+        self.assertEqual(out["result"]["missing"], ["AURORA-100"])
+        searches = [r for r in self.fake.requests if r[1] == "/rest/api/2/search"]
+        self.assertLessEqual(len(searches), 2 * 7 + 1)
+
+    def test_missing_deduped_and_truncated(self):
+        self.fake.add("AURORA-1")
+        keys = ["AURORA-1"] + ["GONE-%d" % i for i in range(1, 61)] + ["GONE-1"]
+        out = self.ex.run({"id": 16, "type": "refresh", "params": {"keys": keys}})
+        self.assertEqual(out["result"]["missing"], ["GONE-%d" % i for i in range(1, 51)])
+
     def test_deleted_neighbor(self):
         self.fake.add("AURORA-1")
         self.fake.add("AURORA-2", in_base=False)