* fix(transformation): merge consecutive system and developer messages for non-OpenAI providers and Responses API
* fix(base_utils): keep later cache_control and billing metadata boundaries when merging system messages
* perf(base_utils): fold consecutive system messages in a single linear pass
The tuple accumulator passed to reduce copied the whole prefix on every step,
making map_developer_role_to_system_role O(n^2) in the number of messages.
Message count is not bounded by default, so a caller could tie up a proxy
worker with thousands of small messages before any provider call. Use a list
and merge into its last element in place instead.
* fix(base_utils): hoist later developer messages into the leading system message for non-OpenAI providers
A developer message that arrives after the first user turn (Codex CLI's
per-turn permissions item, a re-injected instruction after compaction, a
mid-conversation policy update) was translated to a system message in
place, and system-first chat templates such as Fireworks' qwen3.8 reject
any system message that is not at the beginning with 400. The fold that
merges consecutive system messages never saw it because a user turn sat
in between.
Move every developer message that follows the leading system block to
the end of that block before the fold, so it merges into the single
leading system message; client-authored mid-conversation system messages
stay where the client put them.
* fix(openai): hoist later developer messages into one leading system message on OpenAI-compatible backends
Developer role translation moves onto the provider config. OpenAI's own endpoint,
Azure OpenAI, and the o-series keep their current behavior. Every other config
inheriting OpenAIGPTConfig (Fireworks, DeepSeek, Together, vLLM, Groq, openai/
with a custom api_base) hoists developer messages that arrive after the leading
system block into that block and folds the block into a single system message,
which is what system-first chat templates require. Providers with their own
message format are untouched.
Messages carrying cache_control or Anthropic billing metadata fold as their own
text blocks, so breakpoints and provider-side stripping survive the merge. The
Responses bridge goes back to prepending instructions as a separate system
message and lets the hoist fold it.
* refactor(base_utils): fold each run of system messages in one pass
The pairwise fold recopied the accumulated system text or block list on every
merge, so a request carrying many consecutive system or developer messages cost
quadratic time in preprocessing. Group consecutive system messages once and
build the merged message from the whole run: plain strings join with a blank
line, and any cached, billing, or block content keeps one text block per
message. The name of the last named message in the run survives, as before.
* fix(base_utils): keep a closing developer message in place and hoist for OpenAIConfig backends
A developer message that closes the conversation stays where the client put it, translated
to system in place, so the request never ends on the assistant's turn. OpenAIConfig and its
subclasses (Azure AI Foundry, GitHub Copilot, ChatGPT, RAGFlow) now share the OpenAI-compatible
hoist, litellm_proxy passes developer messages through to the downstream proxy, and the Anthropic
billing header literals use the shared constant
* fix(base_utils): keep a closing developer message in place only after an assistant turn
A developer message that closes the conversation after a user or tool message hoists like
any other, so the request shape the ticket reports keeps working on system-first templates;
only a closing run that follows an assistant turn stays in place
* refactor(openai): reuse is_openai_backed_api_base for the hosted endpoint check
* test(base_utils): cover an empty system message inside a block-content run
Codecov flagged the empty-string branch of _text_blocks as the one line the
PR left uncovered. The existing empty-string test only hits the plain-text
join; this one forces the block path by merging an empty system message with
a developer message that carries list content.
* fix(openai): hoist developer messages for litellm_proxy and harden the system fold
- drop the LiteLLMProxyChatConfig passthrough so litellm_proxy/ hoists later developer messages like every other OpenAI-compatible endpoint, whichever backend or LiteLLM version sits downstream
- a system message with null or missing content inside a folded run is dropped instead of raising KeyError('content')
- a message-level cache_control on a list-content member lands on its last block so the breakpoint survives the fold
* fix(litellm_proxy): keep the AllMessageValues import the transform signatures still name
* fix(fireworks_ai): hoist developer items after the first turn on the native Responses path
The native Fireworks Responses path landed on staging mapping developer input items to
system in place, so a developer item after the first input item still hit the same
"System message must be at the beginning" 400 on system-first chat templates. The
ordering rules now live in one shared helper over item roles, and the native path
reorders through it before mapping, keeping a closing developer item after an assistant
turn in place exactly like the chat path does
* fix(transformation): carry the developer-message hoist onto main 963333d654
Resolves the main merge for this branch: the tests move to tests/unit, every translate_developer_role_to_system_role override takes and returns a Sequence, Azure OpenAI keeps the in-place mapping, and the system content reads tolerate a missing key
* fix(transformation): join a lone plain text block as text when hoisting developer messages
The Responses bridge turns every developer item into a one-block list, so the hoisted run merged the
instructions string and that block as a block list, and Databricks could no longer collapse it into the
single system string it sends today. A lone text block with no extra keys now joins the run as text,
while multi-block, cached, and billing-header content keep the block path
* fix(transformation): hoist later developer messages only for models that reject mid-conversation system messages
Runs of consecutive system messages still fold into one, which keeps the cached prefix stable. A developer message after the first turn moves into the leading system message only when the model declares supports_mid_conversation_system false, or when it is a Fireworks model with no declaration, matching the native Fireworks Responses route. Every other backend keeps it in place as before, so their prompt cache prefix is unchanged. Malformed system content passes through unmerged so the provider returns its own 400.
* fix(responses): fold later developer items into instructions on hosted_vllm for system-first models
Moves the Responses developer fold shared by Fireworks into one module and applies it to hosted_vllm native Responses when the model declares supports_mid_conversation_system false. Renames the run-merging helper so it no longer shares a name with the Databricks one, and returns tuples from the block helpers.
* fix(llms): place developer messages only for models declared system-first
Models without a supports_mid_conversation_system declaration now keep the
in-place developer-to-system translation they had before, so their cached
prompt prefix does not change. Hoisting and folding run only when the
deployment's model_info or the cost map declares the flag false, with the
deployment value read first.
A developer message that closes the conversation after an assistant turn is
sent as a user message on those models instead of being hoisted, merged list
content keeps a blank-line separator before each later part, and the cost map
declares the flag false for fireworks_ai qwen3p8-max
* fix(proxy): keep a closing developer message's cache mark when it is sent as a user turn
* test: type the developer-hoist tests and fake HTTP with respx
* fix: count non-string roles as turns, keep the Fireworks fold for twins, and copy closing developer content
A message whose role is a list or dict now counts as a conversation turn instead of raising a 500.
Fireworks native Responses skips the developer-item fold only when the deployment's own model_info
declares supports_mid_conversation_system true, since the router registers every deployment's flag
under its shared backend key. A hoisted developer message keeps only role, content, name, and
cache_control, a closing developer message's content is deep-copied so the caller's list is left
alone, and a hosted_vllm developer item with no content is forwarded unchanged.
The Fireworks in-place test now declares true on the deployment itself, because a cost-map true can
no longer be told apart from another deployment's registration.
---------
Co-authored-by: sowmy narayanan <sowmysuresh86@gmail.com>
Co-authored-by: mateo-berri <277851410+mateo-berri@users.noreply.github.com>
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