The webhook signature verifier used to fall open with a warning log
when META_APP_SECRET was unset — a deliberate soft-rollout choice that
is unsafe for a public template. A forker who forgets the env var
would be running a fully spoofable webhook: anyone knowing the URL
could POST fabricated status updates and drift broadcast counts.
Now:
- `verifyMetaWebhookSignature` returns false when the secret is missing
and logs at error level, so the route responds 401 to every POST
until the operator configures it.
- Docs mark META_APP_SECRET as **required**:
- docs/environment-variables.md lists it under Required, not
Recommended.
- docs/whatsapp-setup.md §6 is now "Signature verification (required)".
- docs/troubleshooting.md updated accordingly.
- .env.local.example lists the var with guidance on where to find it.
Also fixes a pre-existing gitignore bug: `.env*` was swallowing
`.env.local.example`, which meant forkers running
`cp .env.local.example .env.local` from the getting-started guide
hit "no such file". Added a negation for `*.example`.
Upgrade note for existing deploys: set META_APP_SECRET (Meta → App
Settings → Basic → App Secret) before updating, or inbound webhooks
will 401 until it's configured.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
