Reproduce provider signatures locally
Webhook verification fails when teams hash pretty-printed JSON instead of the raw body bytes the sender signed. Generating HMAC on the exact string you received isolates whether the bug is secret rotation, encoding, or middleware order.
Canonical message bytes
Some APIs concatenate timestamp, method, and path before hashing. Read the vendor doc for delimiter rules and whether Base64 or hex encoding is expected in the final header value.
Key rotation checklist
When secrets roll, update both the dashboard configuration and your worker environment. A matching HMAC here confirms the new secret before you redeploy verification middleware.