把 Top-N chunk 拼到 prompt，交给 cohere/command-r-plus 或 Claude 生成答案
Embedding
python
resp = client.embeddings.create(
model="openai/text-embedding-3-large",
input=[chunk.text for chunk in chunks],
)
vectors = [d.embedding for d in resp.data]
Prompt 模板
text
You are an expert assistant. Answer based ONLY on context.
If the answer is not in the context, say "I don't know".
[Context]
{retrieved_chunks}
[Question]
{user_question}