src/methods/prompt_base.py

"""M0 — PromptBase: Prompt-only baseline with no activation intervention."""

from typing import Optional

import numpy as np

from src.methods.base import SteeringMethod


class PromptBase(SteeringMethod):
    """Append style keyword + definition to the prompt; no steering vector.

    This is the baseline that all steering methods should beat.
    """

    @property
    def name(self) -> str:
        return "PromptBase"

    @property
    def method_id(self) -> str:
        return "M0"

    @property
    def is_training_free(self) -> bool:
        return True

    def extract_vector(
        self,
        h_pos: np.ndarray,
        h_neg: np.ndarray,
        **kwargs,
    ) -> Optional[np.ndarray]:
        """PromptBase has no steering vector — returns None."""
        return None

    @staticmethod
    def build_prompt(base_prompt: str, style: str, style_definition: str) -> str:
        """Build a style-conditioned prompt.

        Args:
            base_prompt: The base captioning prompt
            style: Style name (e.g., "poetic")
            style_definition: Style definition from styles.yaml

        Returns:
            Prompt with style instruction appended
        """
        return (
            f"{base_prompt}\n"
            f"Please describe this image in a {style} style. "
            f"{style}: {style_definition}"
        )