* fix(openai): send chat completions through client.post so the SDK's per-message param transform stops holding the event loop
create() walks every message, content part and tool of the request through
openai._utils._transform before posting, 91 ms at 300k tokens and ~300 ms at
1M tokens on the event loop, and returns the same dict for the plain dicts
litellm builds. client.post is what create() calls after that walk, same
request, headers, retries, raw response and stream objects, so the chat
helpers now call it directly through the helper embeddings already used
* fix(openai): type the chat client.post result as LegacyAPIResponse so the type gate sees .headers and .parse
* fix(openai): assert the chat client.post result is a LegacyAPIResponse instead of casting it
* test(openai): stub client.post with a LegacyAPIResponse spec in the empty-response and no-leak tests
* test(core-utils): stub client.post with a LegacyAPIResponse spec in the agentic loop leak test
* test: every client.post stub on the OpenAI chat path returns a LegacyAPIResponse-spec'd mock
---------
Co-authored-by: devin-ai-integration[bot] <158243242+devin-ai-integration[bot]@users.noreply.github.com>
e8550c1454