FEATUREDHacker News Frontpage· rssEN15:35 · 07·16
→Sentinel: an open-source QA agent that reads your code before it clicks
SimbaStack open-sourced Sentinel under MIT, a QA agent that reads the codebase first, derives business flows on its own, then tests them end-to-end across frontend and backend. They pointed it at their own hotel PMS with only the repo and admin credentials, no test plan. Sentinel read the code, concluded it was a boutique hotel system, and auto-derived nine critical flows including the full reservation lifecycle, group bookings, and night audit. It ran the top two flows twice each and caught three bugs invisible to UI-only checks: a backend NO_AVAILABILITY error on a reservation that already held the room, a calendar showing a room as available when the API said it was booked, and a check-in returning 200 but leaving the guest registration status unchanged. The pipeline: a deterministic grep/find recon pass extracts code structure, Xiaomi's Mimo model derives business flows, Playwright drives the browser, and an api_request tool checks server state. Each flow runs twice by default, findings are unioned, and a 90-call cap bounds each attempt. A final vision pass scores visual hierarchy, spacing, and contrast on visited screens. It currently supports common JS stacks like Next.js, Express, Fastify, and Prisma; other stacks need a recon patch.
#Agent#SimbaStack#Sentinel#Mimo
why featured
Featured · importance 78 · hook + knowledge + resonance
editor take
An MIT-licensed QA agent that reads the codebase first, then tests—caught three backend bugs a UI-only check would miss.
sharp
This one's worth a click because it puts a QA engineer's brain into an agent pipeline: read the codebase, derive nine business flows on its own, run them end-to-end twice, then do a visual pass. They tested it on their own hotel PMS and caught three bugs you'd never find from the UI alone—like a check-in returning 200 while the guest's registration status stayed unchanged.
The pipeline is pragmatic: a deterministic grep/find pass extracts code structure without burning model tokens on blind crawling; Xiaomi's Mimo model turns that digest into prioritized business flows; Playwright drives the browser, and an api_request tool runs fetch inside the page to verify server state. Each flow runs twice by default and findings are unioned, because single-agent runs are flaky—they saw one flow produce zero bugs on one attempt and five on another.
Right now it only supports common JS stacks like Next.js, Express, Fastify, and Prisma; anything else needs a recon patch. The 90-call hard cap per attempt is a real constraint for complex flows. But MIT license, real bugs caught on a real product—that's more signal than most AI testing tool demos. I'd run it on my own project first before judging how general it is.
HKR breakdown
hook ✓knowledge ✓resonance ✓