deepseek-ai/deepseek-harness · error · ToolOutputError

INVALID_TOOL_OUTPUT

INVALID_TOOL_OUTPUT

Error message

output.${projector} returned non-lossless JSON

What it means

Error "output.${projector} returned non-lossless JSON" thrown in deepseek-ai/deepseek-harness.

Source

Thrown at packages/core/tools/src/index.ts:534

  constructor(toolName: string, violations: string[]) {
    super(`tool "${toolName}" returned invalid output: ${violations.join('; ')}`, 'INVALID_TOOL_OUTPUT')
    this.name = 'ToolOutputError'
    this.violations = violations
  }
}

/** Convert one projector exception into the canonical invalid-output failure. */
function projectionError(toolName: string, projector: 'render' | 'presentationMeta', error: unknown): ToolOutputError {
  return new ToolOutputError(toolName, [`output.${projector} failed: ${errorMessage(error)}`])
}

/** Snapshot one projector result before later durable-result materialization. */
function snapshotProjection<T>(toolName: string, projector: 'render' | 'presentationMeta', candidate: T): T {
  try {
    const detached = snapshotJsonValue(candidate)
    if (detached === undefined) {
      throw new ToolOutputError(toolName, [`output.${projector} returned non-lossless JSON`])
    }
    return detached
  } catch (error: unknown) {
    if (error instanceof ToolOutputError) throw error
    throw projectionError(toolName, projector, error)
  }
}

/** Snapshot one body or policy value into the canonical invalid-output failure class. */
function snapshotToolValue(toolName: string, candidate: unknown): JsonValue {
  try {
    const detached = snapshotJsonValue(candidate)
    if (detached === undefined) throw new ToolOutputError(toolName, ['value is not lossless JSON'])
    return detached as JsonValue
  } catch (error: unknown) {
    if (error instanceof ToolOutputError) throw error
    throw new ToolOutputError(toolName, [`value snapshot failed: ${errorMessage(error)}`])
  }

View on GitHub (pinned to b150a551b8)

When it happens

Trigger: Thrown at packages/core/tools/src/index.ts:534 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/c513977564bcc0c3. Report an issue: GitHub.