deepseek-ai/deepseek-harness · error · SessionForkError

INVALID_BOUNDARY

INVALID_BOUNDARY

Error message

fork boundary for session "${session.id}" must be a non-negative safe integer, got ${String(boundary)}

What it means

Error "fork boundary for session "${session.id}" must be a non-negative safe integer, got ${String(boundary)}" thrown in deepseek-ai/deepseek-harness.

Source

Thrown at packages/core/session/src/index.ts:1108

        ...liveSource.header.cwd !== undefined ? { cwd: liveSource.header.cwd } : {},
        parentSession: liveSource.id,
        seedLength: seed.length,
      },
    })
  }

  private _forkSeed(session: Session, requestedBoundary: number | undefined): SessionEvent[] {
    const events = session.events
    const lastEvent = events.at(-1)
    let boundary: number
    if (requestedBoundary !== undefined) {
      boundary = requestedBoundary
    } else {
      if (lastEvent === undefined) return []
      boundary = lastEvent.seq
    }
    if (!Number.isSafeInteger(boundary) || boundary < 0) {
      throw new SessionForkError(
        `fork boundary for session "${session.id}" must be a non-negative safe integer, got ${String(boundary)}`,
        'INVALID_BOUNDARY',
      )
    }
    if (boundary >= events.length) {
      const lastSeq = events.at(-1)?.seq
      throw new SessionForkError(
        `fork boundary ${boundary} does not exist in session "${session.id}" (last seq: ${lastSeq ?? 'none'})`,
        'INVALID_BOUNDARY',
      )
    }

    const boundaryEvent = events[boundary]
    if (boundaryEvent === undefined || boundaryEvent.seq !== boundary) {
      throw new SessionForkError(
        `fork boundary ${boundary} does not match a contiguous event seq in session "${session.id}"`,
        'INVALID_BOUNDARY',
      )

View on GitHub (pinned to b150a551b8)

When it happens

Trigger: Thrown at packages/core/session/src/index.ts:1108 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/e26ccb3808b2379a. Report an issue: GitHub.