deepseek-ai/deepseek-harness · error

subagent "${activation.childId}" best-effort final session f

Error message

subagent "${activation.childId}" best-effort final session flush failed; the persisted state may be unavailable or stale on resume: ${errorChain(error)}

What it means

Error "subagent "${activation.childId}" best-effort final session flush failed; the persisted state may be unavailable or stale on resume: ${errorChain(error)}" thrown in deepseek-ai/deepseek-harness.

Source

Thrown at packages/subagent/subagent/src/continuation.ts:1524

      this.ctx.logger.warn(
        `subagent "${activation.childId}" settlement notice was not delivered to its parent: `
        + errorChain(error),
      )
    }
  }

  /**
   * Request a best-effort final session flush after the child is quiescent.
   * Listener failure is logged because flush participation cannot identify a
   * particular persistence backend, and teardown must still release ownership.
   * @param activation - the Activation whose final events should be flushed.
   */
  private async flushFinalState(activation: Activation): Promise<void> {
    const child = activation.handle.agent
    try {
      await child.ctx.sessions.flush(child.session)
    } catch (error: unknown) {
      this.ctx.logger.warn(
        `subagent "${activation.childId}" best-effort final session flush failed; `
        + `the persisted state may be unavailable or stale on resume: ${errorChain(error)}`,
      )
    }
  }

  /** Resolve the persistence service continuable children require, or fail loud. */
  private requirePersistence(): SessionPersistence {
    const persistence = this.ctx.get('sessionPersistence')
    if (persistence === undefined) {
      throw new SubagentError(
        'continuable subagents require session persistence (load a dsh-session-persistence backend)',
        'PERSISTENCE_UNAVAILABLE',
      )
    }
    return persistence
  }
}

View on GitHub (pinned to b150a551b8)

Solutions

1. Verify session persistence storage is writable; on resume expect stale state and re-run the flush or the child task.

When it happens

Trigger: Thrown at packages/subagent/subagent/src/continuation.ts:1524 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/e1d3604564662c87. Report an issue: GitHub.