RelayKit sent some Claude effort levels that the target model does not
accept. A request with an effort but no thinking reached Opus 4.5 with
max or xhigh. Sonnet 4.5, Haiku 4.5 and other models without effort
support received an effort anyway. When a model-name suffix or modifier
turned thinking off, the client's output_config.effort stayed in the
request unchecked. Opus 5 and Haiku 5.5 then got disabled thinking at
xhigh or max, and Sonnet 5.5 got between_tools at those levels. The API
rejects these combinations with a 400.

Known Claude models now get the nearest effort level they accept, and no
effort when they accept none. Effort works without thinking, so a
thinking-off request keeps the client's effort within those limits. On
Opus 5, Haiku 5.5 and Sonnet 5.5 it is capped at high. Fable, Mythos
and Mythos Preview are now marked as taking effort. These models cannot
turn thinking off, so a thinking-off request runs them at low effort,
as Opus 5.5 already does. The new reasoning.ClaudeEffort returns the
effort a model accepts for a requested level. Native requests without a
suffix or modifier still pass through unchanged, and models RelayKit
does not know keep the effort they were sent.

Claude Haiku 5.5 joins the capability table: adaptive thinking only, on
by default, all five effort levels, and medium as the default effort.
Converted requests no longer send it manual thinking with budget_tokens,
which it rejects. They also drop temperature, top_p and top_k, which it
accepts only at their defaults.

Gemini 2.5 Pro takes thinking budgets up to 32768, but xhigh and max
were rendered as 24576. They now get the model's largest budget: 32768
on 2.5 Pro, and 24576 on 2.5 Flash and Flash-Lite as before. high stays
at 24576, as in Google's OpenAI-compatible mapping.