deepseek-ai/deepseek-harness · error · Error

seed event at index ${index} has an invalid event envelope

Error message

seed event at index ${index} has an invalid event envelope

What it means

Error "seed event at index ${index} has an invalid event envelope" thrown in deepseek-ai/deepseek-harness.

Source

Thrown at packages/core/session/src/index.ts:229

/** Validate the fixed event envelope after one-pass JSON materialization. */
function assertSessionEventEnvelope(value: Record<string, unknown>, index: number): asserts value is SessionEvent {
  const event = value
  if (event['type'] === 'request/header-delta') {
    throw new Error(`seed event at index ${index} uses unsupported legacy request/header-delta format`)
  }
  for (const key in event) {
    switch (key) {
      case 'type':
      case 'seq':
      case 'time':
      case 'data':
      case 'surfaceOp':
      case 'sourceEventSeqs':
      case 'ignorable':
        break
      default:
        throw new Error(`seed event at index ${index} has an invalid event envelope`)
    }
  }
  const type = event['type']
  const seq = event['seq']
  const time = event['time']
  if (typeof type !== 'string'
    || typeof seq !== 'number' || !Number.isSafeInteger(seq) || seq < 0
    || typeof time !== 'number' || !Number.isSafeInteger(time)
    || event['data'] === undefined
    || (event['ignorable'] !== undefined && event['ignorable'] !== true)) {
    throw new Error(`seed event at index ${index} has an invalid event envelope`)
  }
  switch (type) {
    case 'request/header':
    case 'user/message':
    case 'assistant/message':
    case 'tool/result':
      assertCurrentLlmShape(event, index)

View on GitHub (pinned to b150a551b8)

Solutions

1. Fix the event envelope of the seed event at the reported index.

When it happens

Trigger: Thrown at packages/core/session/src/index.ts:229 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of deepseek-ai/deepseek-harness@b150a551b8 (2026-08-24). Data as JSON: /api/errors/deb90b30d43ebd7e. Report an issue: GitHub.