create-workflow failed: the workflow-builder sub-agent never

Error message

create-workflow failed: the workflow-builder sub-agent never called save-workflow. No workflow was persisted.${otherErrors}

Sub-agent summary:
${summary}

What it means

If the workflow-builder sub-agent finished its turn without ever invoking save-workflow, create-workflow throws this error stating no workflow was persisted. It guards against the sub-agent hallucinating success while nothing was saved.

Source

Thrown at mastracode/sdk/src/tools/workflows/create-workflow.ts:114

    // If save-workflow errored, surface that error explicitly — do NOT return
    // the sub-agent's summary as if things were fine.
    const saveErrors = toolErrors.filter(e => e.toolName === 'save-workflow');
    if (saveErrors.length > 0 && !saveSucceeded) {
      throw new Error(
        `create-workflow failed: save-workflow threw ${saveErrors.length} error(s):\n- ${saveErrors
          .map(e => e.error)
          .join('\n- ')}\n\nSub-agent summary (unreliable, save did not succeed):\n${summary}`,
      );
    }

    // If save-workflow was never called, the sub-agent gave up (or hallucinated
    // success). Fail loudly so the caller doesn't think a workflow exists.
    if (!saveAttempted) {
      const otherErrors = toolErrors.length
        ? `\n\nOther sub-agent tool errors:\n- ${toolErrors.map(e => `${e.toolName}: ${e.error}`).join('\n- ')}`
        : '';
      throw new Error(
        `create-workflow failed: the workflow-builder sub-agent never called save-workflow. No workflow was persisted.${otherErrors}\n\nSub-agent summary:\n${summary}`,
      );
    }

    // Save was attempted but never returned ok (no tool-result with { ok: true, id }).
    if (!saveSucceeded) {
      const otherErrors = toolErrors.length
        ? `\n\nSub-agent tool errors:\n- ${toolErrors.map(e => `${e.toolName}: ${e.error}`).join('\n- ')}`
        : '';
      throw new Error(
        `create-workflow failed: save-workflow was called but did not return { ok: true }.${otherErrors}\n\nSub-agent summary:\n${summary}`,
      );
    }

    return { summary, workflowId };
  },
});

View on GitHub (pinned to 75dd419e61)

Solutions

Re-run the request; instruct the agent to explicitly call save-workflow before finishing.
Check toolErrors appended in the message for other sub-agent failures that derailed the flow.
Ensure the sub-agent has access to the save-workflow tool and a capable model.

Defensive patterns

Strategy: try-catch

Try / catch

try { const res = await createWorkflowTool.execute({ request }, { mastra }); } catch (e) { if (e.message.includes('never called save-workflow')) { /* retry with explicit instruction to call save-workflow */ } else throw e; }

Prevention

Instruct users/prompts to require an explicit save-workflow call before finishing.
Use a capable model for the builder sub-agent so it follows the tool-call protocol.
Verify the sub-agent has save-workflow in its tool allowlist.

When it happens

Trigger: saveAttempted === false after the sub-agent stream completes — the model answered with a summary but never called the save-workflow tool.

Common situations: Model decided to explain the workflow instead of saving; weak prompt so the agent skipped the save step; model lacking permission/routing to call save-workflow.

Related errors

AI-assisted analysis of mastra-ai/mastra@75dd419e61 (2026-08-30). Data as JSON: /api/errors/aeb06cb759cadf37. Report an issue: GitHub.