deepseek-ai/deepseek-harness · error · Error

sourceEventSeqs must not be empty except on assistant/messag

Error message

sourceEventSeqs must not be empty except on assistant/message

What it means

Error "sourceEventSeqs must not be empty except on assistant/message" thrown in deepseek-ai/deepseek-harness.

Source

Thrown at packages/core/session/src/surface.ts:222

  if (!isReplaceOp(op)) {
    throw new Error(`session event "${event.type}" carries an invalid replace surfaceOp`)
  }
  return op
}

/** Validate cited source-event seqs against prior log entries and the replacement range. */
function assertProvenance(
  event: SessionEvent,
  shadowedSeqs: readonly number[],
): void {
  const raw = (event as SessionEvent & { sourceEventSeqs?: unknown }).sourceEventSeqs
  const sources = new Set<number>()
  if (raw !== undefined) {
    if (!Array.isArray(raw)) {
      throw new Error(`sourceEventSeqs on event at seq ${event.seq} must be an array when present`)
    }
    if (raw.length === 0 && event.type !== 'assistant/message') {
      throw new Error('sourceEventSeqs must not be empty except on assistant/message')
    }
    let nonEarlierSource: number | undefined
    for (const source of raw) {
      if (!isEventSeq(source)) {
        throw new Error(`session event "${event.type}" sourceEventSeqs must densely contain non-negative safe integers`)
      }
      sources.add(source)
      if (nonEarlierSource === undefined && source >= event.seq) nonEarlierSource = source
    }
    if (sources.size !== raw.length) {
      throw new Error('sourceEventSeqs must not contain duplicates')
    }
    if (nonEarlierSource !== undefined) {
      throw new Error(`sourceEventSeqs must reference earlier events: ${nonEarlierSource} >= current seq ${event.seq}`)
    }
  }
  const missing = shadowedSeqs.filter(seq => !sources.has(seq))
  if (missing.length > 0) {

View on GitHub (pinned to b150a551b8)

When it happens

Trigger: Thrown at packages/core/session/src/surface.ts:222 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/f5f72b46bbb537fc. Report an issue: GitHub.