feat(llm): support semi-automated prompt generation

[LRriver]

Overview

This PR aims to introduce a semi-automated Prompt generation feature #253. This functionality leverages the capabilities of large language models (LLMs), allowing users to generate a highly customized Prompt for knowledge graph extraction by simply providing the original text, a description of the desired scenario, and selecting one example from a few system-provided examples that best matches their scenario. The generated Prompt serves as a reference for users, reducing the difficulty for them to get started.

Main Changes

• New Operator: prompt_generate.py

  • Adds the PromptGenerate operator, which is responsible for constructing the meta-prompt by combining user inputs with a selected few-shot example, invoking the LLM, and returning the generated prompt.

• Built-in Prompt Examples & Configuration:

  • Adds prompt_examples.json, a centralized file to store multiple, high-quality, structured few-shot examples for different domains.
  • Updates prompt_config.py with a new meta-prompt template (generate_extract_prompt_template) designed to guide the LLM in this generation task.

• UI & Workflow Updates:

  • Updates vector_graph_block.py to add a collapsible "Assist in generating graph extraction prompts" section in the “Build RAG Index” tab.
  • This new UI section includes a dropdown for selecting few-shot examples and a dynamic preview area that updates on selection.
  • Fixes a UI "cold start" bug by implementing a demo.load() event to ensure the preview for the default example is displayed on initial page load.

Also refer hugegraph#30 (comment)

Sequence Diagram

sequenceDiagram
    participant User
    participant UI as Gradio UI
    participant PromptGen as PromptGenerate
    participant LLM as LLM后端
    participant Resource as 示例资源

    User->>UI: 选择示例、输入场景与文本，点击生成提示
    UI->>PromptGen: 调用 generate_prompt_for_ui()
    PromptGen->>Resource: 加载 few-shot 示例
    PromptGen->>LLM: 组装元提示，调用 LLM.generate()
    LLM-->>PromptGen: 返回生成的抽取提示
    PromptGen-->>UI: 返回生成的抽取提示
    UI-->>User: 展示生成的抽取提示

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New UI interface features

New interface location

Expected scenario/direction and few-shot

prompt generate by LLM