--- index.js ---
```javascript
import { pipeline } from 'https://cdn.jsdelivr.net/npm/@xenova/transformers';

// Frontend copy of AVAILABLE_MODELS from constants.py
const AVAILABLE_MODELS = [
  { name: "Moonshot Kimi-K2", id: "moonshotai/Kimi-K2-Instruct" },
  { name: "DeepSeek V3", id: "deepseek-ai/DeepSeek-V3-0324" },
  { name: "DeepSeek R1", id: "deepseek-ai/DeepSeek-R1-0528" },
  { name: "ERNIE-4.5-VL", id: "baidu/ERNIE-4.5-VL-424B-A47B-Base-PT" },
  { name: "MiniMax M1", id: "MiniMaxAI/MiniMax-M1-80k" },
  { name: "Qwen3-235B-A22B", id: "Qwen/Qwen3-235B-A22B" },
  { name: "SmolLM3-3B", id: "HuggingFaceTB/SmolLM3-3B" },
  { name: "GLM-4.1V-9B-Thinking", id: "THUDM/GLM-4.1V-9B-Thinking" },
  { name: "Qwen3-235B-A22B-Instruct-2507", id: "Qwen/Qwen3-235B-A22B-Instruct-2507" },
  { name: "Qwen3-Coder-480B-A35B", id: "Qwen/Qwen3-Coder-480B-A35B-Instruct" }
];

const modelSelect = document.getElementById('modelSelect');
const inputText = document.getElementById('inputText');
const resultSection = document.getElementById('result');
const analyzeButton = document.getElementById('analyzeButton');
let sentimentPipeline;

// Populate dropdown
AVAILABLE_MODELS.forEach(model => {
  const opt = document.createElement('option');
  opt.value = model.id;
  opt.textContent = model.name;
  modelSelect.appendChild(opt);
});

async function initPipeline(modelId) {
  analyzeButton.disabled = true;
  analyzeButton.textContent = 'Loading model...';
  sentimentPipeline = await pipeline('sentiment-analysis', modelId);
  analyzeButton.textContent = 'Analyze Sentiment';
  analyzeButton.disabled = false;
}

// Initialize with first model
initPipeline(modelSelect.value);

// Re-init on change
modelSelect.addEventListener('change', () => {
  initPipeline(modelSelect.value);
  resultSection.textContent = '';
});

// Handle form submission
document.getElementById('analyze-form').addEventListener('submit', async event => {
  event.preventDefault();
  const text = inputText.value.trim();
  if (!text) return;

  analyzeButton.disabled = true;
  analyzeButton.textContent = 'Analyzing...';
  resultSection.textContent = '';

  try {
    const output = await sentimentPipeline(text);
    const { label, score } = output[0];
    resultSection.textContent = `Sentiment: ${label} (Confidence: ${(score*100).toFixed(2)}%)`;
  } catch (err) {
    resultSection.textContent = 'Error analyzing sentiment.';
  }

  analyzeButton.textContent = 'Analyze Sentiment';
  analyzeButton.disabled = false;
});