Generation parameters and logprobs

export API_ROOT_URL='https://gateway.example.com'
export API_KEY='YOUR_API_KEY'
export API_MODEL='YOUR_LOGPROBS_MODEL_ID'
node examples/logprobs.mjs

import { requestJSON } from './http-client.mjs';

try {
  const model = process.env.API_MODEL;
  if (!model?.trim()) throw new Error('Set model.');
  const result = await requestJSON('/v1/chat/completions', {
    model, messages: [{ role: 'user', content: 'Reply with the word hello.' }],
    temperature: 0, seed: 0, frequency_penalty: 0, presence_penalty: 0,
    logprobs: true, top_logprobs: 2,
  });
  const choice = result.choices?.[0];
  const message = choice?.message;
  if (!Array.isArray(result.choices) || result.choices.length !== 1 || choice?.index !== 0
    || choice.finish_reason !== 'stop' || message?.role !== 'assistant'
    || message.refusal != null || message.tool_calls != null || message.function_call != null
    || typeof message.content !== 'string' || !message.content.trim()) throw new Error('Incomplete text.');
  const tokens = choice.logprobs?.content;
  if (!Array.isArray(tokens) || !tokens.length) throw new Error('Missing logprobs.');
  const observations = [];
  for (const token of tokens) {
    if (!Array.isArray(token?.top_logprobs)) throw new Error('Missing alternatives.');
    for (const value of [token, ...token.top_logprobs]) {
      if (typeof value?.token !== 'string' || typeof value.logprob !== 'number'
        || !Number.isFinite(value.logprob) || value.logprob > 0
        || (value.bytes != null && (!Array.isArray(value.bytes)
          || value.bytes.some((byte) => !Number.isInteger(byte) || byte < 0 || byte > 255)))) {
        throw new Error('Invalid token metadata.');
      }
    }
    observations.push({ token: token.token, logprob: token.logprob,
      top_logprobs: token.top_logprobs.map(({ token, logprob }) => ({ token, logprob })) });
  }
  console.log(JSON.stringify({ text: message.content, tokens: observations }));
} catch {
  console.error('Logprobs example failed. Check model support, retained metadata, and completion status. No automatic retry.');
  process.exitCode = 1;
}