WeixinConfig lacked a streaming field, so channels.weixin.streaming was
silently dropped by pydantic and supports_streaming stayed False, forcing the
non-streaming Messages API. Some upstream Anthropic relays drop tool_use
id/name/input on the non-stream path (but handle SSE fine), breaking WeChat
tool calls.
Two parts:
1. Add a streaming field (default True) so WeChat routes LLM calls through the
streaming API. WeChat iLink has no native incremental delivery, so this is
user-invisible — it only changes how the LLM is called.
2. WeChat send_delta previously dropped content, and the manager bypasses send
for the _streamed final answer, so a streamed reply never reached the user.
send_delta now buffers content deltas and flushes the full reply in one shot
at _stream_end (also stopping the typing indicator via send).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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