fix(bulk): CodeQL implicit-concat + a vacuous suggestions-list assertion

CodeQL py/implicit-string-concatenation-in-list (2 findings): the item-5
dynamic-approval suggestions list (middleware.py, previous commit) wrapped
two multi-line string items with no operator between the literals -- the
same shape a missing comma produces. Switched to the explicit "+" already
used elsewhere in this file, plus one more instance in the same list-shape
(the RecursionError fix's suggestions) that CodeQL hadn't flagged yet but
matches the identical pattern.

CodeRabbit: test_custom_suggestions_override_the_defaults asserted a
default suggestion string was absent from response["error"]["suggestions"]
-- but create_error_response only populates the plural "suggestions" key
when more than one suggestion is present, and the test passed exactly one,
so that key was never set regardless of whether the override worked. The
assertion was vacuous: it would pass even if create_connection_error
silently ignored custom suggestions entirely. Fixed by passing two custom
suggestions and asserting the complete list equals them exactly.

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

Author: swissmo

src/ha_mcp/policy/middleware.py

@@ -159,7 +159,7 @@ async def on_call_tool(
                     "evaluate safely against the security policy.",
                     suggestions=[
                         "Reduce the nesting depth of the tool call arguments "
-                        "and retry.",
+                        + "and retry.",
                     ],
                 )
             )
@@ -389,10 +389,10 @@ def _raise_pending_error(
             )
             suggestions = [
                 "Do not tell the user to approve the token above -- it no "
-                "longer exists and there is nothing left to approve.",
+                + "longer exists and there is nothing left to approve.",
                 "Re-call this tool with the same arguments to create a new "
-                "pending request, then have the user approve THAT one "
-                "while the new call is still waiting on it.",
+                + "pending request, then have the user approve THAT one "
+                + "while the new call is still waiting on it.",
             ]
         else:
             message = (

tests/src/unit/test_errors.py

@@ -139,18 +139,28 @@ def test_custom_suggestions_override_the_defaults(self):
         defaults (check HA is running / verify HOMEASSISTANT_URL / check
         network) -- those are actively unhelpful for a non-network cause
         (e.g. a malformed local registry row) that still routes through
-        this same connection-error shape."""
+        this same connection-error shape.
+
+        Two custom suggestions, not one: ``create_error_response`` only
+        sets the plural ``suggestions`` key when there is more than one
+        (a single suggestion is carried solely in the singular
+        ``suggestion`` key), so a one-item list here could never actually
+        populate ``suggestions`` -- checking a default string is absent
+        from a key that is always absent by construction would prove
+        nothing about whether the defaults were really overridden.
+        """
+        custom_suggestions = [
+            "Check Home Assistant's device-registry logs",
+            "Restart Home Assistant if the issue persists",
+        ]
+
         response = create_connection_error(
             "Could not verify against Home Assistant's device registry",
-            suggestions=["Check Home Assistant's device-registry logs"],
+            suggestions=custom_suggestions,
         )
 
-        assert response["error"]["suggestion"] == (
-            "Check Home Assistant's device-registry logs"
-        )
-        assert "Check if Home Assistant is running and accessible" not in (
-            response["error"].get("suggestions", [])
-        )
+        assert response["error"]["suggestion"] == custom_suggestions[0]
+        assert response["error"]["suggestions"] == custom_suggestions
 
     def test_omitted_suggestions_still_yield_the_defaults(self):
         """No ``suggestions`` argument (the overwhelming majority of