fix(client): keep tools when anthropic tool_choice is none - #16535

Related to #6662 (tool_choice: none support for Anthropic, delivered for the playground in #15683). No separate issue was filed for this client-side gap.

Summary

to_chat_messages_and_kwargs dropped the entire tools list from the replayed request when a stored Anthropic prompt had tool_choice: none, so a request captured with tools but tool use disabled replayed without any tools.

Why

_ToolKwargsConversion.to_anthropic in packages/phoenix-client/src/phoenix/client/helpers/sdk/anthropic/messages.py:513-514 returned an empty dict as soon as the stored tool choice was "none":

if "tool_choice" in obj:
    if obj["tool_choice"]["type"] == "none":
        return {}

ans["tools"] was already set at that point, so the early return discarded it along with the tool choice. _ToolChoiceConversion.to_anthropic (same file, lines 560-561) already maps "none" to {"type": "none"}, and _ToolChoiceConversion.from_anthropic (lines 612-613) already accepts it, so the early return bypassed existing handling on one side of a round trip that otherwise works. The server-side playground sends tool_choice: none together with the tools for the same stored prompt (src/phoenix/server/api/helpers/playground_clients.py:2253-2254 and :2276-2278), so capture and replay must round-trip both.

Changes

• Removed the early return {} in _ToolKwargsConversion.to_anthropic so the existing _ToolChoiceConversion.to_anthropic mapping emits {"type": "none"} while tools is kept.
• Added a tool_choice: {"type": "none"} case to the TestToolKwargs round-trip parametrization.
• Added TestToolKwargs.test_tool_choice_none_keeps_tools, which captures a request with tools and tool_choice: none via create_prompt_version_from_anthropic and asserts to_chat_messages_and_kwargs returns both.

Testing

On the unpatched tree the two new tests fail (to_anthropic returns {}; kwargs.get("tools") is None). With the fix, from packages/phoenix-client/:

$ pytest --disable-socket tests/canary/sdk/anthropic
27 passed
$ pyright -p src/phoenix/client/helpers/sdk/pyrightconfig.json src/phoenix/client/helpers/sdk/anthropic
0 errors, 0 warnings, 0 informations
$ pyright -p tests/canary/sdk/pyrightconfig.json tests/canary/sdk/anthropic
0 errors, 0 warnings, 0 informations
$ mypy --strict --follow-untyped-imports src/phoenix/client/helpers/sdk/anthropic/messages.py
Success: no issues found in 1 source file
$ mypy --strict --follow-untyped-imports tests/canary/sdk/anthropic/test_messages.py
Success: no issues found in 1 source file
$ ruff format --check src/phoenix/client/helpers/sdk/anthropic/messages.py tests/canary/sdk/anthropic/test_messages.py
2 files already formatted
$ ruff check src/phoenix/client/helpers/sdk/anthropic/messages.py tests/canary/sdk/anthropic/test_messages.py
All checks passed!
$ pytest --disable-socket tests/client
744 passed, 7 failed, 1 xfailed, 103 errors — identical to unpatched main (pre-existing executor/rate-limiter/pytest-plugin failures on this machine, unrelated to this change)

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