PR #7202 added empty-assistant filtering in `_query` so strict
providers (Moonshot, etc.) wouldn't 400 on history with blank
assistant entries. The streaming sibling `_query_stream` was
never updated, so DeepSeek Reasoner — which returns reasoning only
during tool calls, leaving serialized content as `""` — blew up with
`Invalid assistant message: content or tool_calls must be set` on
the next turn.
Hoisted the filter into a `_sanitize_assistant_messages` helper and
called it from both paths. Also widened the empty check to cover
`content == []`, which the original filter missed and which shows up
with providers that emit content as a list of parts.
* fix: filter empty assistant messages to prevent 400 error on strict APIs
Some OpenAI-compatible APIs (e.g., Moonshot) reject requests with
empty content in assistant messages when no tool_calls are present.
This fix cleans up the messages payload before sending to avoid
'message at position X must not be empty' errors.
Closes related issue with fallback provider behavior.
* test(openai): add tests for empty assistant message filtering
* refactor(openai): simplify empty assistant message filtering logic
* style: format code
---------
Co-authored-by: RC-CHN <1051989940@qq.com>
