Open Call agent flags conflicting hackathon data by citing every source it reads

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A developer built Open Call, an AI agent submitted to the DEV × Sanity Challenge, after finding that five major European hackathon listing sites gave contradictory or incomplete information in September 2026. The tool answers questions about free, in-person European hackathons starting after October 2026, and attributes every fact to its source page while flagging outdated or conflicting claims. In one notable finding, the agent surfaced a PDF buried seventeen pages deep revealing that CASSINI's advertised cash prizes of up to €9,000 do not apply to local hackathon participants, contradicting the event's main website. The project uses Next.js, Claude Sonnet, and Sanity Studio, storing each fact alongside its origin and a three-state value — yes, no, or not-stated — to distinguish missing information from a denial. Prerecorded example queries are bundled into the static site so users can explore the agent's reasoning without triggering a live API call.

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