Implementing the AI Revision Model

Following the generation of critiques based on the constitution, the next logical step in the Constitutional AI (CAI) pipeline is to revise the initial LLM responses to address these critiques. This section details the practical implementation of the component responsible for generating these revisions. Unlike training a model from scratch, this often involves leveraging a powerful existing LLM, guided by carefully constructed prompts, to perform the revision task. The goal is to produce a revised response, $R_{revised}$, that incorporates the feedback from the critique, $C$, making it align more closely with the constitution, $\mathcal{K}$, than the initial response, $R_{initial}$.

Leveraging Large Language Models for Revision

The core idea is to use an LLM's instruction-following capabilities to perform the revision. The "AI Revision Model" in this context usually refers to the process or system orchestrating this revision generation, rather than a distinct, separately trained model architecture (although that is a possible, more resource-intensive approach). Typically, you will use a capable base LLM ($M_{base}$) or potentially an even more powerful model ($M_{prompt}$, perhaps an API-based model if scale or capability demands it) for this task.

The input to this process is the pair ($R_{initial}$, $C$) generated in the previous steps. The output we aim to generate is $R_{revised}$.

Crafting Effective Revision Prompts

The quality of the generated revision heavily depends on the prompt provided to the LLM ($M_{prompt}$). The prompt must clearly instruct the model to modify $R_{initial}$ based specifically on the issues raised in $C$, while ideally preserving the helpful aspects of the original response.

Here are a couple of template structures. Remember that optimal prompt engineering often requires iteration based on the specific LLM and task nuances.

Template 1: Direct Revision Instruction

[INST] You are tasked with revising an AI response based on a critique derived from a constitution.
Original Response:
<response>
{initial_response}
</response>

Critique (identifying constitutional violations):
<critique>
{critique}
</critique>

Based *only* on the critique provided, please revise the original response to address the identified issues and ensure it aligns with the principles mentioned or implied in the critique. Maintain the original response's intent and helpfulness where possible, focusing modifications on resolving the critique. Output *only* the revised response.
[/INST]
Revised Response:

Template 2: Highlighting Specific Principles (if available from critique)

[INST] Original Response:
{initial_response}

Critique (Violated Principles: {list_of_violated_principles}):
{critique}

Revise the original response to fix the issues described in the critique, paying close attention to the violated principles: {list_of_violated_principles}. The revised response should be compliant with the constitution as reflected in the critique.
Output the revised response directly, without preamble.
[/INST]
Revised Response:

Prompt Engineering Considerations:

• Clarity: Be unambiguous about the task: revise based on the critique.
• Constraints: Explicitly instruct the model to output only the revised response to simplify parsing.
• Faithfulness: Encourage preserving the original response's helpfulness unless the critique targets it directly.
• Few-Shot Examples (Advanced): For complex revisions, including 1-3 high-quality examples of (Initial Response, Critique, Revised Response) within the prompt can significantly improve the LLM's performance. This requires curating representative examples.
• Chain-of-Thought (Advanced): You might experiment with prompts asking the LLM to first explain how it will apply the critique and then generate the revision. This intermediate reasoning step can sometimes lead to more thoughtful revisions, although it increases generation cost and complexity.

The Revision Generation Workflow

Automating the generation of revisions involves iterating through your ($R_{initial}$, $C$) pairs and using an LLM to generate $R_{revised}$ for each.

Data flow for generating a single revised response using an LLM prompted with the initial response and its critique.

Here's a Python snippet illustrating the automation:

import logging # Use logging for better tracking

# Configure logging
logging.basicConfig(level=logging.INFO, format='%(asctime)s - %(levelname)s - %(message)s')

# Assume llm_service is a pre-configured client for an LLM API or local model
# critique_data is a list of dictionaries: [{'initial_response': str, 'critique': str, 'metadata': {...}}]

REVISION_PROMPT_TEMPLATE = """
[INST] Original Response:
<response>
{initial_response}
</response>

Critique:
<critique>
{critique}
</critique>

Revise the original response to specifically address the issues raised in the critique, ensuring alignment with constitutional principles reflected in the critique. Preserve helpfulness where appropriate. Output only the revised response.
[/INST]
Revised Response:
"""

def generate_revisions(critique_data, llm_service, prompt_template):
    """Generates revisions for a list of critiques."""
    revised_data = []
    for i, item in enumerate(critique_data):
        prompt = prompt_template.format(
            initial_response=item['initial_response'],
            critique=item['critique']
        )
        try:
            # Example parameters, adjust based on the LLM provider/model
            response = llm_service.generate(
                prompt=prompt,
                max_new_tokens=len(item['initial_response']) + 512, # Heuristic max length
                temperature=0.4, # Lower temperature for more focused revisions
                stop_sequences=["[INST]", "\n\nHuman:", "\n\nAssistant:"] # Prevent run-on generation
            )
            revised_text = response.strip() # Basic cleaning

            if not revised_text:
                 logging.warning(f"Empty revision generated for item {i}. Skipping.")
                 continue

            item['revised_response'] = revised_text
            revised_data.append(item)
            if (i + 1) % 100 == 0: # Log progress periodically
                 logging.info(f"Generated revisions for {i+1}/{len(critique_data)} items.")

        except Exception as e:
            logging.error(f"Error processing item {i}: {e}", exc_info=True)
            # Implement retry logic or skip problematic items as needed

    return revised_data

# Example usage:
# Assuming critique_outputs contains the data from the critiquer step
# revised_dataset = generate_revisions(critique_outputs, my_llm_client, REVISION_PROMPT_TEMPLATE)
# logging.info(f"Successfully generated {len(revised_dataset)} revisions.")

# The revised_dataset now contains triplets (or more info if metadata kept)
# suitable for building the SFT dataset in the next step.

Quality Control and Iteration

The revision generated by $M_{prompt}$ is not guaranteed to be perfect. Common failure modes include:

• Incomplete Revision: The revision fails to address all points in the critique.
• Introduction of New Issues: The revision fixes the original problem but introduces new constitutional violations or factual errors.
• Loss of Helpfulness: The revision becomes overly cautious or stilted, losing the original response's value.
• Over-Correction: The revision modifies parts of the response not targeted by the critique.

Strategies for mitigation include:

1. Prompt Refinement: Iteratively improving the revision prompt based on observed failure patterns.
2. Model Selection: Using the most capable LLM available ($M_{prompt}$) for the revision task.
3. Filtering: Implementing automated checks. For instance, you could use the AI Critiquer Model again to score $R_{revised}$ against the constitution. Revisions that still receive poor scores or score worse than $R_{initial}$ on some dimensions might be discarded or flagged for review.
4. Iterative Revision: For critical applications, implementing a loop where $R_{revised}$ is critiqued again, and a second revision attempt is made. This adds significant computational cost.

Advanced Approaches

• Specialized Revision Model: While often relying on prompting a general LLM, you could fine-tune a separate model specifically for the revision task. This requires a high-quality dataset of ($R_{initial}$, $C$, $R_{target}$) examples, where $R_{target}$ is a human-verified or demonstrably superior revision. This is resource-intensive but can yield a more efficient and specialized revision component.
• Maintaining Consistency: Ensuring the revision model doesn't drastically alter the persona or core function of the original response requires careful prompting and potentially specific constraints during fine-tuning if a specialized model is trained.

Preparing for Fine-Tuning

The output of this revision generation process is a dataset containing tuples, at minimum ($R_{initial}$, $C$, $R_{revised}$). This dataset is the foundation for the next critical step in the CAI supervised learning phase: constructing the final dataset and fine-tuning the target LLM ($M_{SFT}$) to internalize the constitutional principles, as detailed in the subsequent section. The quality of the revisions generated here directly impacts the effectiveness of that final fine-tuning stage.