deepseek-ai/deepseek-harness · error · PresetMountError

agent-presets: preset "${presetId}" failed to mount: ${prese

Error message

agent-presets: preset "${presetId}" failed to mount: ${preset.broken}

What it means

Error "agent-presets: preset "${presetId}" failed to mount: ${preset.broken}" thrown in deepseek-ai/deepseek-harness.

Source

Thrown at packages/preset/agent-presets/src/index.ts:236

      throw new UnknownPresetError(wanted, presets.map(preset => preset.id))
    }
    return found
  }

  /**
   * Resolve one preset that is about to compose an agent, refusing a broken
   * one with its discovery-reported reason. Failing here rather than inside
   * the loader keeps the answer the same for every unloadable shape — ghost
   * directory, unparsable YAML, rowless list — and spends no mount attempt
   * on a composition discovery already read as unusable.
   * @param id - the preset id, or `undefined` for {@link defaultId}.
   * @returns the resolved, mountable preset.
   * @throws when the preset is unknown or discovery reports it broken.
   */
  private async resolveMountable(id?: string): Promise<AgentPreset> {
    const preset = await this.resolve(id)
    if (preset.broken !== undefined) {
      throw new PresetMountError(preset.id, preset.broken)
    }
    return preset
  }

  /**
   * Standing mounts by preset id, single-flight so two agents racing the
   * first use of one preset share one composition. A settled failure is
   * removed so a later session retries a preset whose file has been fixed; a
   * settled success serves until the composition FILE visibly changes — each
   * generation records its file stamp, and a stale stamp starts the next
   * generation for sessions created afterwards. Sessions already joined keep
   * the generation they run on; a superseded one is never disposed while the
   * process lives (reclaimed only by whole-tree teardown), so editing files
   * is bounded by how often compositions change, not by session count.
   */
  private readonly standing = new Map<string, Promise<StandingMount>>()

  /**

View on GitHub (pinned to b150a551b8)

Solutions

1. Fix the preset per the recorded breakage detail, then mount again.

When it happens

Trigger: Thrown at packages/preset/agent-presets/src/index.ts:236 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/f690f9f5364c635f. Report an issue: GitHub.