src/model_loader.py

import torch
from transformers import AutoModelForCausalLM, AutoTokenizer

# Define the model path (adjust as needed)
MODEL_PATH = "model_files"  # Your fine-tuned model path

# System prompt for guiding model behavior
DEFAULT_PROMPT = """<|system|>
You are a compassionate listener. Respond with:
- Short, natural sentences
- Occasional empathetic sounds ("Oh...", "I see")
- Open-ended questions when appropriate
- Validation before advice
- Clear crisis handoff when needed
Examples of good responses:
1. "That sounds really overwhelming. Can you tell me more about what's been happening?"
2. "I'm hearing a lot of pain in what you're sharing. Have you talked to anyone about this?"
3. "This seems really important. Let's focus on how you're feeling right now."
</s>"""

def load_model():
    """
    Loads the fine-tuned model and tokenizer with optimizations for memory and performance.
    Returns:
        model: The loaded Hugging Face model.
        tokenizer: The corresponding tokenizer.
        device: The device (CPU/GPU) the model is loaded on.
    """
    print(f"🔍 Loading model from: {MODEL_PATH}")

    # 1. Load Tokenizer
    tokenizer = AutoTokenizer.from_pretrained(
        MODEL_PATH,
        cache_dir="./cache",  # Cache directory for faster reloads
        use_fast=True,        # Use the fast tokenizer for better performance
        padding_side="left"   # Ensure padding is consistent for generation
    )

    # 2. Load Model with Memory Optimization
    model = AutoModelForCausalLM.from_pretrained(
        MODEL_PATH,
        cache_dir="./cache",
        trust_remote_code=True,  # Allow custom model code
        torch_dtype=torch.float16 if torch.cuda.is_available() else torch.float32,  # Use FP16 on GPU
        device_map="auto",       # Automatically map model to available devices
        load_in_4bit=True if torch.cuda.is_available() else False  # Quantize to 4-bit on GPU
    )

    # 3. Set Device
    device = "cuda" if torch.cuda.is_available() else "cpu"
    model.to(device)

    print("✅ Model successfully loaded.")
    return model, tokenizer, device

# Test the loader
if __name__ == "__main__":
    model, tokenizer, device = load_model()
    print("Model and tokenizer successfully loaded.")