fix(bedrock): clamp top_p >= 0.95 for adaptive thinking, not just legacy budget#3472
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fix(bedrock): clamp top_p >= 0.95 for adaptive thinking, not just legacy budget#3472resrever wants to merge 1 commit into
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…acy budget Anthropic-on-Bedrock enforces the top_p >= 0.95-or-unset constraint for both thinking.enabled (legacy budget) and thinking.adaptive modes. The previous code only applied the clamp for emits_legacy_thinking, leaving top_p unconstrained for Opus 4.6 / Sonnet 4.6 in adaptive mode. The direct Anthropic and Vertex AI paths were already correct (ReasoningTransform strips top_p to None whenever is_reasoning_supported()). Opus 4.7/4.8 on Bedrock were also fine (ModelSpecificReasoning strips top_p before conversion). The only broken combo was AdaptiveFriendly models (Opus 4.6, Sonnet 4.6) on Bedrock where top_p was passed through untouched alongside thinking.adaptive. Fix: change the adjusted_top_p guard from emits_legacy_thinking to reasoning_on. Update the test that previously asserted adaptive thinking left top_p untouched.
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What
ModelSpecificReasoningnormalizesreasoningper model family before the Bedrock conversion runs. Previously thetop_p >= 0.95clamp inConverseStreamInput::from_domainfired only when the legacythinking.enabled(budget) shape was being emitted. This change applies the clamp whenever any thinking shape is active (reasoning_on), coveringthinking.adaptive(Opus 4.6 / Sonnet 4.6) as well.The only broken combo was AdaptiveFriendly models (Opus 4.6, Sonnet 4.6) on Bedrock, where
top_pwas passed through untouched alongsidethinking.adaptive. Opus 4.7 / 4.8 are unaffected (ModelSpecificReasoningstripstop_ptoNonefor them before conversion), and the direct Anthropic / Vertex paths were already correct.Why
Anthropic-on-Bedrock rejects
top_p < 0.95for adaptive thinking, not just the legacy budget shape. Confirmed against the live endpoint — without this fix, an adaptive-thinking request withtop_p < 0.95returns:With the fix applied, the request succeeds (no error).
Test
test_from_domain_context_adaptive_thinking_does_not_clamp_top_p->..._clamps_top_pand inverted the assertion (top_p >= 0.95). This reverses the earlier assumption that adaptive thinking should leavetop_puntouched.cargo test -p forge_repopasses.