A deployment carrying reasoning_effort in its litellm_params on the
/v1/messages passthrough mapped the effort to a legacy thinking block
whose budget_tokens was forwarded as is, so any request whose max_tokens
sat at or below that budget was rejected upstream with a 400. The mapped
budget now runs through the same cap the adaptive-to-legacy branch and
the chat path already use: it is clamped to max_tokens - 1, and dropped
with a warning when even the minimum budget cannot fit.
The cap helper becomes public since three call sites outside
AnthropicConfig use it.
The supported_endpoints passthrough had no way to keep ttl for an upstream
that honors it, so the deployment now opts in with
model_info.cache_control_ttl: true, injected into the config the same way
the providers.json constraint is for JSON providers
Rewrite the sanitizer without recursion (the code-quality gate rejects new
recursive functions) and only touch cache_control where the Messages API
defines it: the request, system blocks, tools, message content blocks, and
tool_result content. Application data such as tool_use.input and tool
input_schema is left untouched even when it contains a cache_control key
* feat(messages): passthrough /v1/messages to native endpoints via supported_endpoints
The unified /v1/messages proxy endpoint always translated inbound Anthropic
requests down to /v1/chat/completions (or the Responses API for openai) when the
deployment's provider lacked a native Anthropic-messages config, dropping
Anthropic-only features like cache_control and thinking. Some customers run
OpenAI-compatible servers (self-hosted vLLM, DeepSeek's Anthropic endpoint, etc.)
that also natively expose /v1/messages and want the raw Anthropic payload
forwarded untranslated, while keeping provider openai so /v1/chat/completions to
the same deployment stays native.
Opt in per deployment via model_info.supported_endpoints containing
/v1/messages. When present, the gate routes to a generic, provider-agnostic
OpenAILikeAnthropicMessagesConfig that POSTs the Anthropic payload to
{api_base}/v1/messages with Bearer auth, instead of translating. Default
behavior is unchanged. Generalizes and supersedes the hosted_vllm-only,
env-var-toggled PR #28745.
* fix(messages): preserve standard-cased caller headers in native passthrough
The OpenAI-like Anthropic passthrough config only checked for lowercase header
names before injecting Bearer auth, anthropic-version, and content-type
defaults. A caller sending standard-cased Authorization, Anthropic-Version, or
Content-Type was treated as missing those headers, so LiteLLM added duplicate
lowercase variants and overwrote the caller's credential/version at the HTTP
layer. Header presence is now checked case-insensitively and the merge no longer
mutates the caller dict.
Also moves the feature docs out of the main repo (docs live in litellm-docs).
* fix(openai_like/messages): delegate to parent transform and inject anthropic-beta headers
The passthrough config bypassed the parent transform and skipped header beta injection. Both gaps cause native /v1/messages features (context management, advisor tool, fast mode, structured outputs, reasoning_effort, advisor stripping) to silently degrade on opted-in deployments. Reuse the parent's pipeline and call _update_headers_with_anthropic_beta after merging defaults
* fix: normalize anthropic-beta header key case before beta injection
* style: collapse anthropic-beta header normalization to single line
ruff format --check requires the comprehension on one line (it fits within
the 120 char limit); fixes the lint job failure on the bugbot autofix commit
* fix(messages): forward anthropic-beta to native passthrough upstream
The shared anthropic_messages HTTP handler ran update_headers_with_filtered_beta
with the deployment's custom_llm_provider after validate. For the native
/v1/messages passthrough that provider is openai, which has no beta-header
mapping, so every anthropic-beta value (caller-supplied or feature-derived for
speed/context_management/etc.) was stripped to empty before the upstream
request, breaking beta passthrough to the Anthropic-compatible endpoint.
Beta filtering only makes sense on cross-provider translation paths where the
upstream cannot understand Anthropic betas. Gate it on a new
should_filter_anthropic_beta_headers() that defaults to True (bedrock, vertex_ai,
native anthropic unchanged) and is overridden to False by
OpenAILikeAnthropicMessagesConfig, whose upstream is a native Anthropic endpoint,
so betas pass through verbatim.
* chore: remove accidentally committed local QA logs and config
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Co-authored-by: Cursor Agent <cursoragent@cursor.com>
