fix(x402): share single validated config across Express and Vercel ru…

[DevRushd]

Share one x402 route and asset configuration across runtimes

Problem

Express (server/index.ts) and Vercel (api/search.ts) each independently hardcoded their own x402 payment configuration — network, asset, amount, payTo, timeout, and fee sponsorship. Any future change to one runtime's config could silently drift out of sync, breaking payment consistency across deployments.

Solution

Created a single validated source of truth at src/lib/x402Config.ts that both runtimes consume:

• X402Config interface — typed configuration object with runtime validation
• getX402Config() — memoized function that reads from constants.ts and validates all required fields on first call, throwing descriptive errors for missing/invalid values
• buildPaymentRequiredPayload() — generates a standards-compliant x402-payment-required response body from the shared config (used by Vercel)
• buildExpressRoutes() — mounts the x402 payment middleware on Express routes using the same shared config (used by Express)
• getX402ConfigSnapshot() — exported for snapshot testing

Both server/index.ts and api/search.ts now import from this single module instead of defining config inline.

Files Changed

File	Change
src/lib/x402Config.ts	New — shared config module
src/lib/x402Config.test.ts	New — 25 tests (validation, snapshot comparison, runtime parity)
server/index.ts	Refactored to use buildExpressRoutes() from shared config
api/search.ts	Refactored to use buildPaymentRequiredPayload() from shared config
server/validateQuery.test.ts	Updated env setup for compatibility with new import-time validation

Tests

• 25 new tests in x402Config.test.ts covering:
  • Config validation (missing fields, invalid values, memoization)
  • Snapshot comparison between Express and Vercel payment requirement payloads
  • Runtime parity verification
• All 224 tests pass across 17 test files

Validation

• ✅ TypeScript compilation passes (tsc --noEmit) for server, API, and frontend configs
• ✅ Full test suite passes (224/224)
• ✅ Branch rebased on latest upstream/main — no merge conflicts
• ✅ Express, Vercel, browser, and MCP behavior aligned through shared config
• ✅ x402 settlement semantics preserved

Closes #108

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[vercel]

@DevRushd is attempting to deploy a commit to the Emmanuel's projects Team on Vercel.

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[AbuJulaybeeb]

rebase the whole branch

[AbuJulaybeeb]

resolve conflicts

[DevRushd]

@AbuJulaybeeb I have resolved conflicts and rebase the branch. Kindly review and merge