`tools/tts_tool.py::_xai_requirements` (the provider check text_to_speech_tool
dispatch consults) still resolved xAI credentials OAuth-first, while both TTS
synthesis paths now pass `prefer_api_key=True`. Truthiness is unchanged, but a
configured key no longer routes the availability probe through the OAuth pool
(pool select / refresh) for a bearer the metered `/v1/tts` endpoint rejects.
Docs: the streaming-TTS provider table now states the ordering.
Part of the #113727 salvage of #113728 (@beardthelion); sibling site the PR
missed.
Co-authored-by: beardthelion <beardthelion@users.noreply.github.com>
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