deepseek-ai/deepseek-harness · error · SdkProtocolError

assistant/message event carried malformed content: ${JSON.st

Error message

assistant/message event carried malformed content: ${JSON.stringify(value)}

What it means

Error "assistant/message event carried malformed content: ${JSON.stringify(value)}" thrown in deepseek-ai/deepseek-harness.

Source

Thrown at packages/sdk/client/src/api.ts:218

 * @returns the content blocks to send.
 */
export function normalizeInput(input: string | ContentBlock[]): ContentBlock[] {
  return typeof input === 'string' ? [{ type: 'text', text: input }] : input
}

/** Validate the fields in a wire `session.event` envelope before returning the typed result. */
function validatedSessionEvent(value: unknown): SessionEvent {
  if (!isRecord(value) || typeof value.type !== 'string') {
    throw new SdkProtocolError(`session.event carried no event envelope: ${JSON.stringify(value)}`)
  }
  // The one variant this module reads into (finalResponse) must carry
  // kind-tagged content blocks; other variants pass through under their
  // envelope shape.
  if (value.type === 'assistant/message') {
    const message = isRecord(value.data) ? value.data.message : undefined
    const content = isRecord(message) ? message.content : undefined
    if (!Array.isArray(content) || !content.every(block => isRecord(block) && typeof block.type === 'string')) {
      throw new SdkProtocolError(`assistant/message event carried malformed content: ${JSON.stringify(value)}`)
    }
  }
  return value as unknown as SessionEvent
}

/** Whether a raw session event is the durable enqueue receipt for `messageId`. */
function isInboxReceipt(value: unknown, messageId: string): boolean {
  if (!isRecord(value) || value.type !== 'agent/inbox/spliced' || !isRecord(value.data)) return false
  const inserted = value.data.inserted
  return Array.isArray(inserted) && inserted.some(message => isRecord(message) && message.id === messageId)
}

/**
 * Extract the concatenated text of the last assistant message.
 * @param events - the activity interval's `session.event` payloads in wire order.
 * @returns the final response text, or `''` when no assistant message exists.
 */
export function finalResponse(events: SessionEvent[]): string {

View on GitHub (pinned to b150a551b8)

Solutions

1. Check the server emits well-formed assistant/message content blocks; align SDK and server versions.

When it happens

Trigger: Thrown at packages/sdk/client/src/api.ts:218 when the library encounters an invalid state.

Common situations: See trigger scenarios.

Understand the failure class

• Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

AI-assisted analysis of deepseek-ai/deepseek-harness@b150a551b8 (2026-08-24). Data as JSON: /api/errors/d354910c6254fa85. Report an issue: GitHub.