fix(kimi): don't send Anthropic thinking to api.kimi.com/coding - #13826
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Kimi's /coding endpoint speaks the Anthropic Messages protocol but has its own thinking semantics: when thinking.enabled is sent, Kimi validates the history and requires every prior assistant tool-call message to carry OpenAI-style reasoning_content. The Anthropic path never populates that field, and convert_messages_to_anthropic strips Anthropic thinking blocks on third-party endpoints — so after one tool-calling turn the next request fails with: HTTP 400: thinking is enabled but reasoning_content is missing in assistant tool call message at index N Kimi on chat_completions handles thinking via extra_body in ChatCompletionsTransport (#13503). On the Anthropic route, drop the parameter entirely and let Kimi drive reasoning server-side. build_anthropic_kwargs now gates the reasoning_config -> thinking block on not _is_kimi_coding_endpoint(base_url). Tests: 8 new parametric tests cover /coding, /coding/v1, /coding/anthropic, /coding/ (trailing slash), explicit disabled, other third-party endpoints still getting thinking (MiniMax), native Anthropic unaffected, and the non-/coding Kimi root route.
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This was referenced Apr 29, 2026
aj-nt
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May 1, 2026
…Research#13826) Kimi's /coding endpoint speaks the Anthropic Messages protocol but has its own thinking semantics: when thinking.enabled is sent, Kimi validates the history and requires every prior assistant tool-call message to carry OpenAI-style reasoning_content. The Anthropic path never populates that field, and convert_messages_to_anthropic strips Anthropic thinking blocks on third-party endpoints — so after one tool-calling turn the next request fails with: HTTP 400: thinking is enabled but reasoning_content is missing in assistant tool call message at index N Kimi on chat_completions handles thinking via extra_body in ChatCompletionsTransport (NousResearch#13503). On the Anthropic route, drop the parameter entirely and let Kimi drive reasoning server-side. build_anthropic_kwargs now gates the reasoning_config -> thinking block on not _is_kimi_coding_endpoint(base_url). Tests: 8 new parametric tests cover /coding, /coding/v1, /coding/anthropic, /coding/ (trailing slash), explicit disabled, other third-party endpoints still getting thinking (MiniMax), native Anthropic unaffected, and the non-/coding Kimi root route.
02356abc
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May 14, 2026
…Research#13826) Kimi's /coding endpoint speaks the Anthropic Messages protocol but has its own thinking semantics: when thinking.enabled is sent, Kimi validates the history and requires every prior assistant tool-call message to carry OpenAI-style reasoning_content. The Anthropic path never populates that field, and convert_messages_to_anthropic strips Anthropic thinking blocks on third-party endpoints — so after one tool-calling turn the next request fails with: HTTP 400: thinking is enabled but reasoning_content is missing in assistant tool call message at index N Kimi on chat_completions handles thinking via extra_body in ChatCompletionsTransport (NousResearch#13503). On the Anthropic route, drop the parameter entirely and let Kimi drive reasoning server-side. build_anthropic_kwargs now gates the reasoning_config -> thinking block on not _is_kimi_coding_endpoint(base_url). Tests: 8 new parametric tests cover /coding, /coding/v1, /coding/anthropic, /coding/ (trailing slash), explicit disabled, other third-party endpoints still getting thinking (MiniMax), native Anthropic unaffected, and the non-/coding Kimi root route.
gweeteve
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Jun 2, 2026
…Research#13826) Kimi's /coding endpoint speaks the Anthropic Messages protocol but has its own thinking semantics: when thinking.enabled is sent, Kimi validates the history and requires every prior assistant tool-call message to carry OpenAI-style reasoning_content. The Anthropic path never populates that field, and convert_messages_to_anthropic strips Anthropic thinking blocks on third-party endpoints — so after one tool-calling turn the next request fails with: HTTP 400: thinking is enabled but reasoning_content is missing in assistant tool call message at index N Kimi on chat_completions handles thinking via extra_body in ChatCompletionsTransport (NousResearch#13503). On the Anthropic route, drop the parameter entirely and let Kimi drive reasoning server-side. build_anthropic_kwargs now gates the reasoning_config -> thinking block on not _is_kimi_coding_endpoint(base_url). Tests: 8 new parametric tests cover /coding, /coding/v1, /coding/anthropic, /coding/ (trailing slash), explicit disabled, other third-party endpoints still getting thinking (MiniMax), native Anthropic unaffected, and the non-/coding Kimi root route.
waefrebeorn
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Jul 2, 2026
…Research#13826) Kimi's /coding endpoint speaks the Anthropic Messages protocol but has its own thinking semantics: when thinking.enabled is sent, Kimi validates the history and requires every prior assistant tool-call message to carry OpenAI-style reasoning_content. The Anthropic path never populates that field, and convert_messages_to_anthropic strips Anthropic thinking blocks on third-party endpoints — so after one tool-calling turn the next request fails with: HTTP 400: thinking is enabled but reasoning_content is missing in assistant tool call message at index N Kimi on chat_completions handles thinking via extra_body in ChatCompletionsTransport (NousResearch#13503). On the Anthropic route, drop the parameter entirely and let Kimi drive reasoning server-side. build_anthropic_kwargs now gates the reasoning_config -> thinking block on not _is_kimi_coding_endpoint(base_url). Tests: 8 new parametric tests cover /coding, /coding/v1, /coding/anthropic, /coding/ (trailing slash), explicit disabled, other third-party endpoints still getting thinking (MiniMax), native Anthropic unaffected, and the non-/coding Kimi root route.
smasoftware
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Jul 18, 2026
…Research#13826) Kimi's /coding endpoint speaks the Anthropic Messages protocol but has its own thinking semantics: when thinking.enabled is sent, Kimi validates the history and requires every prior assistant tool-call message to carry OpenAI-style reasoning_content. The Anthropic path never populates that field, and convert_messages_to_anthropic strips Anthropic thinking blocks on third-party endpoints — so after one tool-calling turn the next request fails with: HTTP 400: thinking is enabled but reasoning_content is missing in assistant tool call message at index N Kimi on chat_completions handles thinking via extra_body in ChatCompletionsTransport (NousResearch#13503). On the Anthropic route, drop the parameter entirely and let Kimi drive reasoning server-side. build_anthropic_kwargs now gates the reasoning_config -> thinking block on not _is_kimi_coding_endpoint(base_url). Tests: 8 new parametric tests cover /coding, /coding/v1, /coding/anthropic, /coding/ (trailing slash), explicit disabled, other third-party endpoints still getting thinking (MiniMax), native Anthropic unaffected, and the non-/coding Kimi root route.
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Summary
Kimi K2.5 on
kimi-codingno longer 400s after its first tool-calling turn.Root cause
Kimi's
/codingendpoint speaks Anthropic Messages protocol but has its own thinking semantics: whenthinking.enabledis sent it requires every prior assistant tool-call message in the history to carry OpenAI-stylereasoning_content. Hermes' Anthropic path never populates that field, andconvert_messages_to_anthropicstrips Anthropic thinking blocks on third-party endpoints — so the second turn fails with:Kimi on
chat_completionshandles thinking viaextra_bodyinChatCompletionsTransport(#13503). On the Anthropic route, drop the parameter entirely and let Kimi drive reasoning server-side.Changes
agent/anthropic_adapter.pybuild_anthropic_kwargs(): gate thereasoning_config → thinkingblock onnot _is_kimi_coding_endpoint(base_url).tests/agent/test_kimi_coding_anthropic_thinking.py: 8 parametric regression tests.Validation
/coding+ reasoning_configthinkingomitted, request succeeds/anthropic+ reasoning_configthinking.enabledsentthinking.enabledsentthinkingsent8/8 new tests pass. Existing
tests/agent/test_minimax_provider.py+tests/cli/test_fast_command.py+tests/test_ctx_halving_fix.py— all still pass (pre-existing unrelated failure inTestMinimaxSwitchModelCredentialGuard::test_switch_to_minimax_does_not_resolve_anthropic_tokenreproduces on main without this patch).