feat: prose completion api

src/prose/graph/prose_continue_node.py

@@ -0,0 +1,31 @@
+# Copyright (c) 2025 Bytedance Ltd. and/or its affiliates
+# SPDX-License-Identifier: MIT
+
+import logging
+
+from langchain.schema import HumanMessage, SystemMessage
+
+from src.config.agents import AGENT_LLM_MAP
+from src.llms.llm import get_llm_by_type
+from src.prose.graph.state import ProseState
+
+logger = logging.getLogger(__name__)
+
+
+def prose_continue_node(state: ProseState):
+    logger.info("Generating prose continue content...")
+    model = get_llm_by_type(AGENT_LLM_MAP["prose_writer"])
+    prose_content = model.invoke(
+        [
+            SystemMessage(
+                content="""
+You are an AI writing assistant that continues existing text based on context from prior text.
+- Give more weight/priority to the later characters than the beginning ones.
+- Limit your response to no more than 200 characters, but make sure to construct complete sentences.
+- Use Markdown formatting when appropriate
+"""
+            ),
+            HumanMessage(content=state["content"]),
+        ],
+    )
+    return {"output": prose_content.content}