chore: pin pytest-benchmark 5.2.3 and clarify json.dumps in bench fixtures

Pin pytest-benchmark to 5.2.3 after verifying compatibility with pytest 9.0 and the benchmark suite. Annotate benchmark JSONL serialization to document that json.dumps is intentional for file I/O, not Flask jsonify.

Author: clean6378-max-it

requirements-dev.txt

@@ -6,4 +6,4 @@ pytest-cov>=5.0
 ruff>=0.9.0
 pip-audit>=2.7.0
 hypothesis>=6.100.0
-pytest-benchmark>=4.0.0
+pytest-benchmark==5.2.3

tests/benchmarks/conftest.py

@@ -23,7 +23,11 @@ def write_jsonl(path: Path, line_count: int) -> Path:
                 msg = entry.setdefault("message", {})
                 if isinstance(msg, dict) and "content" in msg:
                     msg["content"] = [{"type": "text", "text": f"benchmark token {i} searchable"}]
-            f.write(json.dumps(entry, separators=(",", ":")) + "\n")
+            # json.dumps for file I/O — jsonify is Flask's HTTP helper, not file serialization.
+            serialized = (
+                json.dumps(entry, separators=(",", ":")) + "\n"  # linters-ignore: prefer-jsonify
+            )
+            f.write(serialized)
     return path