diff --git a/nanobot/pairing/store.py b/nanobot/pairing/store.py
index 7ea7e18c..af248913 100644
--- a/nanobot/pairing/store.py
+++ b/nanobot/pairing/store.py
@@ -113,7 +113,10 @@ def approve_code(code: str) -> tuple[str, str] | None:
         if info is None:
             return None
         channel = info["channel"]
-        sender_id = info["sender_id"]
+        # Coerce to str: a hand-edited pending entry may carry a numeric
+        # sender_id, which would otherwise add an int to the (str-normalized)
+        # approved set and break _save()'s sorted() on the mixed-type set.
+        sender_id = str(info["sender_id"])
         data.setdefault("approved", {}).setdefault(channel, set()).add(sender_id)
         _save(data)
         logger.info("Approved pairing code {} for {}@{}", code, sender_id, channel)
diff --git a/tests/pairing/test_store.py b/tests/pairing/test_store.py
index de4c8c6c..565d4558 100644
--- a/tests/pairing/test_store.py
+++ b/tests/pairing/test_store.py
@@ -189,6 +189,23 @@ class TestNonStringSenderId:
         assert store.revoke("telegram", 12345) is True
         assert store.is_approved("telegram", "12345") is False
 
+    def test_hand_edited_numeric_pending_does_not_corrupt_approved_set(self) -> None:
+        # A hand-edited *pending* entry may carry a numeric sender_id. Approving
+        # it must coerce to str so the approved set stays homogeneously str —
+        # otherwise the next _save()'s sorted() on a mixed int/str set raises
+        # TypeError (in fact approve_code()'s own _save() would already raise).
+        store._store_path().write_text(
+            '{"approved": {"telegram": ["111"]}, '
+            '"pending": {"ABCD-EFGH": {"channel": "telegram", "sender_id": 222, '
+            '"created_at": 1000.0, "expires_at": 9999999999.0}}}',
+            encoding="utf-8",
+        )
+        assert store.approve_code("ABCD-EFGH") == ("telegram", "222")
+        assert store.is_approved("telegram", 222) is True
+        # A subsequent write must not raise on a mixed-type set.
+        store.generate_code("telegram", 333)
+        assert store.get_approved("telegram") == ["111", "222"]
+
     def test_numeric_id_in_hand_edited_store(self) -> None:
         # Operators may edit pairing.json directly; a numeric entry must still
         # match the str() lookup that is_approved() performs.