deepseek-ai/deepseek-harness · error · Error

tool/result surface replacement may change only content

Error message

tool/result surface replacement may change only content

What it means

Error "tool/result surface replacement may change only content" thrown in deepseek-ai/deepseek-harness.

Source

Thrown at packages/core/session/src/surface.ts:315

  for (const originalSeq of shadowedSeqs) {
    const original = events[originalSeq - baseSeq]
    if (original?.type !== 'tool/result') {
      throw new Error('tool/result surface replacement must target a current tool/result')
    }
    const originalRest = { ...original.data } as Record<string, unknown>
    const replacementRest = { ...event.data } as Record<string, unknown>
    const originalResult = original.data.message.content[0]
    const replacementResult = event.data.message.content[0]
    originalRest['message'] = {
      ...original.data.message,
      content: [{ ...originalResult, content: null }],
    }
    replacementRest['message'] = {
      ...event.data.message,
      content: [{ ...replacementResult, content: null }],
    }
    if (!isDeepEqualJson(originalRest, replacementRest)) {
      throw new Error('tool/result surface replacement may change only content')
    }
  }
}

/** Validate one event at its replay boundary and prepare its atomic fold transition. */
function planSurfaceEvent(
  state: SurfaceFoldState,
  event: SessionEvent,
  expectedSeq: number,
  events: readonly SessionEvent[],
  baseSeq: number,
): SurfacePlan | undefined {
  if (event.seq !== expectedSeq) {
    throw new Error(`session event seq ${event.seq} is not contiguous; expected ${expectedSeq}`)
  }
  const surfaceOp = surfaceOpOf(event)
  if (surfaceOp === undefined) return
  if (surfaceOp === 'append') {

View on GitHub (pinned to b150a551b8)

When it happens

Trigger: Thrown at packages/core/session/src/surface.ts:315 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/d510bb042dae441e. Report an issue: GitHub.