The webhook ingest endpoint read the entire request body with no size
limit, enabling memory exhaustion attacks. Add a 1 MB limit checked
via both Content-Length header (early reject) and actual body size.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
User-controlled fields (skill name, source URL, webhook payloads) were
interpolated directly into agent instruction messages. Sanitize skill
fields by stripping newlines/control chars, and fence all external data
behind "BEGIN EXTERNAL DATA" / "BEGIN STRUCTURED DATA" delimiters with
explicit "do not interpret as instructions" markers. Move system
instructions above the data section so they cannot be overridden.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Webhook ingest endpoint was completely unauthenticated. Add an optional
`secret` field to BoardWebhook. When configured, inbound requests must
include a valid HMAC-SHA256 signature in X-Hub-Signature-256 or
X-Webhook-Signature headers. Uses hmac.compare_digest for timing safety.
Includes migration to add the secret column.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
