deepseek-ai/deepseek-harness · error · Error

session event "${event.type}" carries an invalid replace sur

Error message

session event "${event.type}" carries an invalid replace surfaceOp

What it means

Error "session event "${event.type}" carries an invalid replace surfaceOp" thrown in deepseek-ai/deepseek-harness.

Source

Thrown at packages/core/session/src/surface.ts:205

  if (!isSurfaceEligibleType(event.type)) {
    if (raw.surfaceOp !== undefined) {
      throw new Error(`session event "${event.type}" is not surface-eligible and cannot carry surfaceOp`)
    }
    if (raw.sourceEventSeqs !== undefined) {
      throw new Error(`session event "${event.type}" is not surface-eligible and cannot carry sourceEventSeqs`)
    }
    return
  }
  const op = raw.surfaceOp
  if (op === undefined) {
    throw new Error(`session event "${event.type}" is surface-eligible and requires a surfaceOp marker`)
  }
  if (op === 'append') return op
  if (op === null || typeof op !== 'object' || Array.isArray(op)) {
    throw new Error(`session event "${event.type}" carries an invalid surfaceOp`)
  }
  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')
    }

View on GitHub (pinned to b150a551b8)

When it happens

Trigger: Thrown at packages/core/session/src/surface.ts:205 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/cd4a6ed248b6f130. Report an issue: GitHub.