Add Redis scan_keys iterator API.

Provide a SCAN-based key iterator for Redis adapters so callers can enumerate large keyspaces without relying on blocking KEYS lookups.

Co-authored-by: Cursor <[email protected]>

tests/integration/redis_adapter_test.py

@@ -254,5 +254,34 @@ def test_should_raise_connection_error_on_list_keys_when_not_connected(
         adapter.list_keys("some_pattern")
 
 
+def test_should_scan_keys(
+    redis_adapter: RedisAdapter,
+) -> None:
+    """Test scanning keys matching a pattern returns correct keys."""
+    redis_adapter.set("key1", {"a": 1})
+    redis_adapter.set("key2", {"b": 2})
+    keys = set(redis_adapter.scan_keys("key*"))
+    assert keys == {"key1", "key2"}
+
+
+def test_should_raise_value_error_on_invalid_scan_keys_pattern(
+    redis_adapter: RedisAdapter,
+) -> None:
+    """Test that the RedisAdapter raises ValueError when scanning keys with an invalid pattern."""
+    invalid_patterns = ["", 123, None]
+    for pattern in invalid_patterns:
+        with pytest.raises(ValueError):
+            list(redis_adapter.scan_keys(pattern))  # type: ignore[arg-type]
+
+
+def test_should_raise_connection_error_on_scan_keys_when_not_connected(
+    redis_config: RedisConfig,
+) -> None:
+    """Test that the RedisAdapter raises ConnectionError when scanning keys while not connected."""
+    adapter = RedisAdapter(config=redis_config)
+    with pytest.raises(ConnectionError):
+        list(adapter.scan_keys("some_pattern"))
+
+
 if __name__ == "__main__":
     pytest.main(["-s", "-v", __file__])