reasoning: {enabled: false} is the only shape the Portal honors, and the
profile refused to send it for every model. Sending nothing means the
upstream default instead, which on a thinking-first route like
deepseek/deepseek-v4-pro (catalog: default_effort high) is thinking ON — so
turning thinking off kept billing reasoning tokens on every turn.
The blanket omission was over-broad. The Portal only rejects a disable on
reasoning-mandatory routes ("Reasoning is mandatory for this model"), which
its catalog flags per model, so that flag now gates the omission. Models the
catalog can't speak to keep the old behavior rather than risk the 400.
extra_body.thinking, DeepSeek's own disable shape, is not forwarded upstream
by the Portal and is not an option here.
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