Fix flake8 spacing for json_safe invalid-utf8 test

.github/workflows/ci.yml

@@ -14,6 +14,25 @@ permissions:
   contents: read
 
 jobs:
+  changes:
+    runs-on: ubuntu-latest
+    outputs:
+      e2e: ${{ steps.filter.outputs.e2e }}
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      - name: Detect changes for E2E
+        id: filter
+        uses: dorny/paths-filter@v3
+        with:
+          filters: |
+            e2e:
+              - 'frontend/**'
+              - 'frontend/cypress/**'
+              - 'frontend/package.json'
+              - 'frontend/package-lock.json'
+              - '.github/workflows/ci.yml'
+
   check:
     runs-on: ubuntu-latest
 
@@ -190,7 +209,8 @@ jobs:
 
   e2e:
     runs-on: ubuntu-latest
-    needs: [check]
+    needs: [check, changes]
+    if: needs.changes.outputs.e2e == 'true'
 
     steps:
       - name: Checkout

backend/tests/test_error_handling.py

@@ -219,6 +219,13 @@ def test_json_safe_handles_binary_inputs() -> None:
     assert _json_safe(memoryview(b"world")) == "world"
 
 
+def test_json_safe_replaces_invalid_utf8_bytes() -> None:
+    # Invalid UTF-8 should be replaced with U+FFFD, not crash error handling.
+    assert _json_safe(b"\xff") == "\ufffd"
+    assert _json_safe(bytearray(b"\xff")) == "\ufffd"
+    assert _json_safe(memoryview(b"\xff")) == "\ufffd"
+
+
 def test_json_safe_falls_back_to_string_for_unknown_objects() -> None:
     class Weird:
         def __str__(self) -> str: