fix(xss): dati query in x-data passano da tojson_attr, non interpolazione JS (#10)

select_recipe.html e recipe_list.html interpolavano recipe/lot/serial/search
dentro un letterale JS con apici singoli: un valore con `'` chiudeva la
stringa e iniettava chiavi nell'oggetto x-data (CSP con unsafe-eval).
Anche recipe_list.html:222 (toLocaleDateString) aveva lo stesso schema su
current_language. Fix: |tojson_attr ovunque.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/frontend/flask_app/tests/test_measure.py

@@ -32,6 +32,69 @@ class TestSelectRecipe:
         assert resp.status_code == 302
         assert "/auth/login" in resp.headers["Location"]
 
+    def test_select_recipe_query_params_do_not_break_out_of_x_data(
+        self, logged_in_client, mock_api_client, monkeypatch
+    ):
+        """#10: recipe/lot query params are JSON-encoded inside x-data.
+
+        A raw ``'{{ auto_lot }}'`` interpolation lets a value containing a
+        single quote close the JS string literal and inject new keys into
+        the Alpine ``x-data`` object (reflected XSS, CSP has unsafe-eval).
+        The fix is ``|tojson_attr``: the payload must survive only as the
+        *content* of a single quoted JSON string token, never as JS syntax
+        that opens a new object key (``lot_number:`` must directly follow).
+        """
+        import re
+        from html.parser import HTMLParser
+
+        monkeypatch.setenv("STATION_CODE", "ST-TEST")
+        import config
+        import importlib
+        importlib.reload(config)
+        import blueprints.measure
+        importlib.reload(blueprints.measure)
+
+        mock_api_client.get_station_recipes.return_value = []
+
+        payload = "',x:alert(document.domain),y:'"
+        resp = logged_in_client.get("/measure/select", query_string={"recipe": payload})
+        assert resp.status_code == 200
+        html = resp.get_data(as_text=True)
+
+        captured = {}
+
+        class _P(HTMLParser):
+            def handle_starttag(self, tag, attrs):
+                d = dict(attrs)
+                if d.get("x-data") and "search:" in d["x-data"]:
+                    captured["x_data"] = d["x-data"]
+
+        _P().feed(html)
+        assert "x_data" in captured
+        m = re.search(r'search:\s*"([^"]*)"\s*,\s*lot_number:', captured["x_data"])
+        assert m, f"search is not a single quoted JSON token: {captured['x_data']!r}"
+        assert m.group(1).replace("\\u0027", "'") == payload
+
+    def test_select_recipe_lot_with_apostrophe_stays_valid_json_string(
+        self, logged_in_client, mock_api_client, monkeypatch
+    ):
+        """#10: a lot number like ``L'23`` must not break the page."""
+        monkeypatch.setenv("STATION_CODE", "ST-TEST")
+        import config
+        import importlib
+        importlib.reload(config)
+        import blueprints.measure
+        importlib.reload(blueprints.measure)
+
+        mock_api_client.get_station_recipes.return_value = []
+
+        resp = logged_in_client.get("/measure/select", query_string={"lot": "L'23"})
+        assert resp.status_code == 200
+        # Raw HTML (pre-entity-decoding): the value is a JSON string whose
+        # delimiting quotes are the HTML entity, and the apostrophe is the
+        # JS unicode escape - never a bare ``'`` that could end the token.
+        assert "lot_number: "L\\u002723"" in resp.get_data(as_text=True)
+
 
 class TestTaskList:
     """GET /measure/tasks/<recipe_id> tests."""