Integration rehearsal for agent workflows
Connect your running app through FetchSandbox MCP. Checks run against isolated test versions of your APIs and return a receipt: passed, failed, or could not verify.
Requires a FetchSandbox account, app setup, and supported integrations. The walkthrough below is illustrative.
Your running app connects to FetchSandbox and receives the test request.
Why teams rehearse before they ship
Bring one workflow. Agree on the rules. Configure supported checks against isolated provider twins and inspect the stored side effects. Custom cases are scoped together.
An approval request went out for one amount. Before it came back, the amount was edited or the request was canceled. Your workflow holds a pending approval that may no longer apply.
Define what your workflow should do: cancel the pending approval, re-request at the new amount, or stop. Verify it follows that rule.
Two stakeholders both submit instructions. One approves, one denies, or both approve for different amounts. Your workflow has to decide which one counts.
Agree which stakeholder's instruction takes priority and under what conditions. Verify the workflow applies that rule when both arrive.
Your workflow got no confirmation and retried. The provider had already processed the first request. The action may have run twice.
Verify a retry after a lost response does not duplicate the action. Configure the twin to model an accepted-but-silent scenario.
The same event arrived out of order, or two triggers fired at the same time. What your workflow did depends on how it handles ordering and concurrency.
Define the expected rule and inspect stored results after the run. Actual handler overlap requires scoping before it can be measured.
Custom cases require scoping before they can be configured and measured. Cross-worker crash recovery was not verified in the November 8 run.
Real measured evidence
One recorded run of a native n8n lead workflow across HubSpot, Gmail, Google Calendar, and Slack. Isolated provider twins only. Not a qualification of native SaaS or OAuth flows.
Passed
Could not verify
70 Provider-state checks passed
Isolated twins only. This run does not qualify native SaaS integrations or OAuth flows, and overall verification was incomplete.
How it works
Point FetchSandbox to your running app. Local apps use an outbound tunnel. Cloud apps require an authenticated trigger and app setup. Not all tools connect automatically.
Describe what your workflow should do at key steps. Configure supported provider twins to model the integrations you want to test.
FetchSandbox drives configured failure scenarios against your app. Results come back as passed, failed, or could not verify. Setup failures may not produce a receipt.
Get started
No live provider keys needed for isolated twin rehearsals. FetchSandbox account and authentication required.
A step-by-step article covering a duplicate charge refund workflow: app setup, approval gate, repeated-trigger check, and isolated twin evidence from October 2026.
Read the walkthroughEnterprise pilot
FetchSandbox is running a small pilot for teams with more complex integration needs: background workers, queues, and requirements scoping across services. Not a generally available tier.
Talk to us about the pilotSupported paths require a workflow trigger, authentication, app setup, and configured checks. Not all tools connect automatically. Check the docs for supported setups.
No live provider keys are needed for isolated twin rehearsals. A FetchSandbox account is required.
A receipt records what each check returned: passed, failed, or could not verify. Checks that did not run are not counted as passed.
An outbound connection that lets FetchSandbox reach a local or private app. The tunnel handles transport. App setup and expected behavior declarations are still required.