Contracts & Validation

Agent contracts define expected input/output types and SLA limits. AgentVM validates at runtime.

Defining a Contract

const agent = new Agent({
  name: 'summarizer',
  contract: {
    input: { type: 'string' },
    output: {
      type: 'object',
      properties: {
        summary: { type: 'string' },
        wordCount: { type: 'number' },
      },
      required: ['summary'],
    },
    maxLatency: 5000, // warn if > 5 seconds
  },
  handler: async (ctx) => ({
    summary: 'Short version...',
    wordCount: 42,
  }),
});

What Gets Validated

• Input — Checked before the handler runs. Throws ContractValidationError on mismatch.
• Output — Checked after the handler returns. Throws ContractValidationError on mismatch.
• Latency — If execution exceeds maxLatency, the kernel emits a contract:sla:latency event.

Catching Validation Errors

import { ContractValidationError } from '@llmhut/agentvm';

try {
  await kernel.execute(proc.id, { task: 'test', input: 42 });
} catch (e) {
  if (e instanceof ContractValidationError) {
    console.log(e.agentName);   // 'summarizer'
    console.log(e.phase);       // 'input'
    console.log(e.violations);  // ['input is number, expected string']
  }
}

Supported Types

string, number, boolean, object (with properties and required), array (with items). Nested validation is recursive.