FactDrop

FactDrop is an AI-powered fact-checking engine designed to make claim verification faster, more accessible, and more scalable. Instead of relying solely on manual fact-checking workflows, FactDrop combines large language models, web intelligence, fact-check databases, and source credibility analysis to automate much of the verification process.

Stack

• Framework: Next.js 16, React 19, TypeScript 6
• AI: Vercel AI SDK, Anthropic, OpenAI, Google, xAI, Vercel AI Gateway, MCP
• API and data: tRPC, TanStack Query, Drizzle ORM, PostgreSQL, Zod
• Auth and UI: Better Auth, Tailwind CSS, Radix UI, Zustand, next-intl
• Search and media: Tavily, Exa, Firecrawl, Parallel, Vercel Blob, Cloudinary
• Editing and visualization: Lexical, CodeMirror, Recharts, ECharts
• Tooling and observability: Ultracite, Playwright, Vitest, Evalite, Langfuse, OpenTelemetry, Pino

Quick Start

pnpm install
cp .env.example .env.local
pnpm check-env
pnpm db:migrate
pnpm dev

Dev server runs at http://localhost:3000.

Dev login shortcut (development only): GET /api/dev-login

Scripts

pnpm dev                  # Start dev server (runs check-env + DB branch resolution first)
pnpm lint                 # Biome via ultracite
pnpm format               # Biome format (auto-fix)
pnpm test:unit            # Vitest only (needs local Postgres)
pnpm test:e2e             # Playwright only (uses .env.local)
pnpm test                 # E2E + unit
pnpm test:types           # Next typegen + full type-check
pnpm build                # Production build (prebuild runs check-env)
pnpm check-env            # Validate required env vars

Configuration

chat.config.ts is the single source of truth for feature switches and model/gateway behavior.

Flow:

chat.config.ts -> lib/config-schema.ts -> lib/config.ts

Use this to configure:

• Gateway selection
• Enabled models and defaults
• Tool toggles (MCP, search, URL fetch, code execution, docs, research)
• Credit and rate-limit behavior

Database Notes

• Schema: lib/db/schema.ts
• Migrations: lib/db/migrations/
• Production migration runner: lib/db/migrate.ts (runs when VERCEL_ENV=production)
• Database connection: set DATABASE_URL to your PostgreSQL instance

Architecture Notes

• Most product routes live under app/workspace/*
• Legacy route aliases redirect to workspace routes via next.config.ts
• lib/db/queries.ts is server-only
• tRPC root router: trpc/routers/_app.ts
• Prefer protectedProcedure for authenticated endpoints
• Lazy prefetch pattern: call prefetchQuery (without await) in Server Components and hydrate on client

Verification Dataflow

flowchart TD
    A([User Query]) --> B{Image attached?}
    B -- Yes --> C[Extract claim from image<br>OCR or describe via vision model]
    B -- No --> D[Split into claims<br>LLM claim-splitter]
    C --> D
    D --> E{Single or multi?}
    E -- Single --> F[Run pipeline once]
    E -- Multi --> G[Run pipeline per sub-claim<br>in parallel via same pipeline]
    F --> H
    G --> H

    subgraph PIPE [Per-claim pipeline]
      H{Bangla?} -- Yes --> I[Translate to English<br>Add English query]
      H -- No --> J[Run in parallel via Promise.all]
      I --> J
      J --> K[Web search<br>Tavily + Exa + Parallel + MCP<br>Concurrent and merged]
      J --> L[Google Fact Check API]
      K --> M{Results empty?}
      M -- Yes --> N[Firecrawl fallback search]
      M -- No --> O[Trust-rank sources<br>SourceCheck MCP: IFFY + IFCN + GDI + internal rules]
      N --> O
      O --> P[LLM final verdict<br>Rating + note]
      L --> P
    end

    P --> Q([Output<br>Rating, note, ranked sources])

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Testing

• Unit tests: pnpm test:unit (Vitest)
• E2E tests: pnpm test:e2e (Playwright projects: chat, reasoning, artifacts, dashboard)
• Types: pnpm test:types

Package Manager

Use pnpm only.

License

Apache-2.0