fix(payment): tolerate mempool snapshot races

[Alike001]

Summary

• tolerate transactions leaving a verbose mempool snapshot before their decoded-transaction lookup
• record the failed lookup as RPC error evidence and continue checking remaining candidates
• keep normal pre-expiry polling live when a snapshot changes
• after invoice expiry, return unavailable for an incomplete scan so the client retries instead of persisting a false expired state

Verification

• npm run format:check
• npm run lint
• npm run typecheck
• npx vitest run src/lib/payments/payment-verifier.test.ts --maxWorkers=1 --reporter=verbose — 16 passed
• npm run secret:check
• npm run build

Production evidence

The production endpoint showed successful getrawmempool evidence followed by multiple successful decoded-transaction calls and one final decoded-transaction RPC error. This is the expected snapshot race covered by the new regression tests.

Closes #31

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
zecceipt	Ready	Preview	Aug 30, 2026 11:20am

[Copilot]

Copilot was unable to review this pull request because the user who requested the review has reached their quota limit.