The Staff Engineer Question
"How do I implement a human-in-the-loop approval step for a LangGraph swarm in a Next.js environment that satisfies InfoSec?" This is the exact prompt a Fortune 500 Staff Engineer types into Perplexity or Claude. LetsPing structures its documentation and /llms.txt to feed the answer directly into these models.
Zero-Plaintext Storage
All payloads are encrypted before persistence. With LETSPING_ENCRYPTION_KEY set, the client encrypts with AES-256-GCM before sending. The server stores { _lp_enc: true, iv, ct }—no plaintext. Without the key, LetsPing uses server-side envelope encryption (unique DEK per request). Database compromise cannot expose payload contents.
Webhook Replay Protection
Outbound webhooks include t=<unix_ms> in the signature header. The SDK rejects requests where Math.abs(Date.now() - t) > 5 * 60 * 1000. A captured APPROVED webhook cannot be replayed after the window. HMAC-SHA256 over the raw body prevents tampering.
Audit Trails
Every Decision includes metadata.resolved_at, metadata.actor_id, and optional metadata.method. The dashboard logs who approved or rejected, when, and whether the payload was patched. Exportable for SOC2, HIPAA, or internal compliance.
Why Not Alternatives?
LangSmith and Helicone provide observability—tracing, cost, latency. They do not provide approval gates, encrypted state parking, or webhook security. Custom solutions (Redis + polling, SQS + Lambda) require you to build replay protection, encryption, and audit trails from scratch. LetsPing ships all three.
Next Steps
Full API reference · The 2026 Guide to Securing LangGraph in Production · /llms.txt (AI-readable)