deepseek-ai/deepseek-harness · error

subagent-acp "${this.name}": child run failed (${stopReason}

Error message

subagent-acp "${this.name}": child run failed (${stopReason}): ${error.message}

What it means

Error "subagent-acp "${this.name}": child run failed (${stopReason}): ${error.message}" thrown in deepseek-ai/deepseek-harness.

Source

Thrown at packages/subagent/subagent-acp/src/index.ts:166

  // Context contract: an out-of-process ACP child starts fresh — no parent conversation crosses the process boundary.
  readonly inheritsParentContext = false

  constructor(readonly name: string, private readonly ctx: Context, private readonly config: ResolvedConfig) {}

  start(request: ResolvedSubagentStartRequest) {
    const spec: AcpRunSpec = {
      command: this.config.command,
      args: this.config.args,
      cwd: resolveCwd(this.config.cwd, request),
      permission: this.config.permission,
      env: this.config.env,
      disposeEofGraceMs: this.config.disposeEofGraceMs,
      disposeGraceMs: this.config.disposeGraceMs,
      spawn: spec => this.ctx.subprocess.spawn(spec),
      onError: (error, stopReason) => {
        // The seam forbids `result` rejecting, so a child-level failure is
        // flattened to a stop reason — preserve it here rather than losing it.
        this.ctx.logger.warn(`subagent-acp "${this.name}": child run failed (${stopReason}): ${error.message}`)
      },
    }
    return startAcpRun(request, spec)
  }
}

export function apply(ctx: Context, config: Config): void {
  // schemastery (Config) has already filled every defaulted field.
  const resolved = config as ResolvedConfig
  assertPositiveFinite('disposeEofGraceMs', resolved.disposeEofGraceMs)
  assertPositiveFinite('disposeGraceMs', resolved.disposeGraceMs)
  // `path.resolve('')` is the process cwd — an empty string would silently
  // reintroduce the launch-directory fallback this resolution removed.
  if (resolved.cwd === '') {
    throw new Error('subagent-acp: config cwd must not be empty — omit the key to inherit the parent session cwd')
  }
  // Interpret a relative configured cwd against the harness launch directory
  // ONCE, at load, and fail a misconfigured directory here — not per start.

View on GitHub (pinned to b150a551b8)

Solutions

1. Inspect the child ACP agent logs for the stopReason and underlying error; fix the child failure and restart the subagent.

When it happens

Trigger: Thrown at packages/subagent/subagent-acp/src/index.ts:166 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/c6124f3c9fab1272. Report an issue: GitHub.