FetchSandbox MCP - The MCP that proves your AI's integration fixes work
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Your agent's integration fix passes CI. The data is still wrong. FetchSandbox MCP reproduces the real failure on your code, fixes it, and proves the fix held. A receipt, not a vibe. 70+ API sandboxes. One config block in Cursor or Claude Code.
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The 5 seats turning into 15 is the version of this that actually costs money. We hit the same shape at Zeplik, output that parses fine and passes every assertion we wrote, wrong in a way only the end state shows. Green CI on a bad write is worse than a red build because nobody goes back and looks. I'd want to know if the receipt catches partial failures too, 3 of 5 writes landing and the rest silently dropped.
FetchSandbox
@asadmalik901 The Zeplik shape is exactly what this was built around. Green CI on a bad write is worse than red because nobody goes back and looks, the attention's already spent.
Splitting partial failures because the two halves have different answers. Partial webhook delivery is covered today, there's a flaky scenario that drops roughly a third of deliveries on Stripe and a few others, so you can reproduce it and the receipt shows which events landed and which didn't. Three of five writes landing with the rest failing silently is not covered, different shape and I don't have it. Worth being clear you couldn't add it yourself either, failure scenarios ship with each API rather than being something you write per project, so if it's not in the set you're waiting on me. Real limit.
Silent partial writes are probably the nastiest version of this anyway. The run looks like a success with fewer rows and nothing anywhere says which ones were supposed to exist. Adding it, your question is a good argument for it.
@rnagulapalle The waiting-on-you part is the real cost, not the missing scenario. If I hit a shape you don't have, I'm blocked until you ship it, and that's what I'd want to know before wiring this into a gate. Publishing the scenario list per API, with a date on the ones you're adding, turns that into scheduling instead of a gamble. On silent partial writes, the thing that made it expensive for me was the count looking plausible. 3 of 5 rows doesn't read as wrong to anyone glancing at a dashboard.