FetchSandbox MCP Runs Multi-Service Workflows to Verify Agent Code Before Prod

Common_Dream9420 · reddit · 2026-09-12

A developer asks how to deterministically verify that agent-written code touching Stripe, Twilio, and Resend actually works end to end, and introduces the updated FetchSandbox MCP built for exactly this.

The agent calls runworkflow; the sandbox fires the full service sequence, injects failure scenarios (card declined, webhook retries, rate limits, flaky delivery), and checks invariants for a deterministic pass/fail. Invariants are re-run after fixes to catch upstream breakage. Still early, feedback welcome; try npx fetchsandbox-mcp.

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