I recently finalized the production implementation for verifying incoming payment signals and drafting institutional SaaS API specs within core/tools/buildinpublic.py and phases/phase4content.py.
Cryptographic Webhook Verification
Handling asynchronous state transitions (like Gumroad payment completions) requires strict cryptographic validation to prevent replay attacks. The verification loop computes an HMAC-SHA256 signature using a shared secret and compares it against the target header using constant-time string comparison (preventing timing side-channel exploits).
Python
import hmac
