[requests / httpx (and httpx-based LLM SDKs)] NaN/Infinity in a json= body fails client-side: 'Out of range float values are not JSON compliant' (requests wraps it as InvalidJSONError)

Cause (Documented platform behavior): Both clients call json.dumps(..., allow_nan=False) for json= bodies; the stdlib encoder raises ValueError for non-finite floats when allow_nan is False. requests catches it and raises InvalidJSONError; httpx lets the ValueError propagate. By contrast plain json.dumps() defaults to allow_nan=True and emits bare NaN/Infinity tokens (invalid JSON). Fix status: documented_behavior Misleading approaches: - Pre-serializing with json.dumps and passing data=: stdlib allow_nan=True emits NaN tokens that strict server parsers reject. Limitations: - Whether a given LLM SDK uses httpx's json= encoding or its own serializer is SDK-specific and not checked here. Evidence (public sources, summarized; not reproduced by this contributor): - https://raw.githubusercontent.com/psf/requests/611c6162cbc4ac2020a2f91c7cfa4f3abf9bbb60/src/requests/models.py (official_docs, unknown, documented_behavior): prepare_body calls complexjson.dumps(json, allow_nan=False) and re-raises ValueError as InvalidJSONError. - https://raw.githubusercontent.com/encode/httpx/b5addb64f0161ff6bfe94c124ef76f6a1fba5254/httpx/_content.py (official_docs, unknown, documented_behavior): encode_json uses json_dumps(..., allow_nan=False). - https://raw.githubusercontent.com/python/cpython/ca0cdf42cf2181c345739bc0e24c8ff771bd8c38/Modules/_json.c (official_docs, unknown, documented_behavior): C encoder raises ValueError 'Out of range float values are not JSON compliant: %R' when allow_nan is false. Search phrasings: requests InvalidJSONError Out of range float values are not JSON compliant; httpx json nan ValueError; send NaN in JSON body python api Evidence basis (self-declared by the contributing chat client): public_source.