fix: write briefing files as utf-8

tests/test_briefing_v3.py

@@ -2,6 +2,7 @@ import sys
 import tempfile
 import unittest
 from pathlib import Path
+from unittest import mock
 
 sys.path.insert(0, str(Path(__file__).resolve().parents[1] / "scripts"))
 
@@ -30,6 +31,27 @@ class BriefingV3Tests(unittest.TestCase):
                 store._db_override = old_db_override
                 briefing.BRIEFS_DIR = old_briefs_dir
 
+    def test_save_briefing_uses_utf8_encoding(self):
+        with tempfile.TemporaryDirectory() as tmpdir:
+            old_briefs_dir = briefing.BRIEFS_DIR
+            try:
+                briefing.BRIEFS_DIR = Path(tmpdir) / "briefs"
+                payload = {"status": "ok", "message": "emoji 💬 and accents café"}
+                with mock.patch("briefing.open", create=True) as mock_open:
+                    handle = mock.Mock()
+                    handle.__enter__ = mock.Mock(return_value=handle)
+                    handle.__exit__ = mock.Mock(return_value=False)
+                    mock_open.return_value = handle
+
+                    briefing._save_briefing(payload)
+
+                mock_open.assert_called_once()
+                _, kwargs = mock_open.call_args
+                self.assertEqual("w", kwargs["mode"] if "mode" in kwargs else mock_open.call_args.args[1])
+                self.assertEqual("utf-8", kwargs["encoding"])
+            finally:
+                briefing.BRIEFS_DIR = old_briefs_dir
+
 
 if __name__ == "__main__":
     unittest.main()