Tool selection and parallel controls

export API_ROOT_URL='https://gateway.example.com'
export API_KEY='YOUR_API_KEY'
export API_MODEL='YOUR_MODEL_ID'
export API_TOOL_POLICY='forced'
node examples/tool-policy.mjs

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

try {
  const model = process.env.API_MODEL;
  const policy = process.env.API_TOOL_POLICY || 'forced';
  if (!model?.trim() || !['auto', 'required', 'forced', 'none'].includes(policy)) throw new Error('Invalid configuration.');
  const tools = [{ type: 'function', function: {
    name: 'get_stock', description: 'Read stock from the local demonstration catalog.', strict: true,
    parameters: { type: 'object', properties: { sku: { type: 'string', enum: ['NOTEBOOK'] } },
      required: ['sku'], additionalProperties: false },
  } }];
  const messages = [{ role: 'user', content: 'How many NOTEBOOK items are available? Use get_stock if permitted; otherwise say the stock is unknown.' }];
  let completed = false;
  let callCount = 0;
  for (let round = 0; round < 2; round++) {
    const toolChoice = round === 1 ? 'none' : policy === 'forced'
      ? { type: 'function', function: { name: 'get_stock' } } : policy;
    const result = await requestJSON('/v1/chat/completions', {
      model, messages, tools, tool_choice: toolChoice, parallel_tool_calls: false,
    });
    const choice = result.choices?.[0];
    const message = choice?.message;
    if (!Array.isArray(result.choices) || result.choices.length !== 1 || choice?.index !== 0
      || message?.role !== 'assistant' || message.refusal != null || message.function_call != null) {
      throw new Error('Invalid assistant result.');
    }
    const calls = message.tool_calls ?? [];
    if (!Array.isArray(calls) || calls.length > 1) throw new Error('Expected at most one call.');
    if (!calls.length) {
      if ((round === 0 && ['required', 'forced'].includes(policy)) || choice.finish_reason !== 'stop'
        || typeof message.content !== 'string' || !message.content.trim()) throw new Error('Missing final answer or required call.');
      console.log(JSON.stringify({ answer: message.content, tool_calls: callCount }));
      completed = true;
      break;
    }
    if (round !== 0 || policy === 'none' || choice.finish_reason !== 'tool_calls') throw new Error('Tool policy violated.');
    const call = calls[0];
    if (call?.type !== 'function' || typeof call.id !== 'string' || !call.id.trim()
      || call.function?.name !== 'get_stock' || typeof call.function.arguments !== 'string'
      || call.function.arguments.length > 4096) throw new Error('Invalid tool call.');
    const args = JSON.parse(call.function.arguments);
    if (!args || Array.isArray(args) || Object.keys(args).length !== 1 || args.sku !== 'NOTEBOOK') {
      throw new Error('Invalid catalog arguments.');
    }
    // Only this read-only fixture is executable. Preserve the original assistant message for replay.
    messages.push(message, { role: 'tool', tool_call_id: call.id, content: JSON.stringify({ sku: args.sku, available: 8 }) });
    callCount++;
  }
  if (!completed) throw new Error('No final answer within the example budget.');
} catch {
  console.error('Tool policy example failed. Check model support, call policy, arguments, and completion. No automatic retry.');
  process.exitCode = 1;
}