Shared-token auth was off on prod (no MAPPA_API_TOKEN) — anyone with network
access could call /admin/purge_secrets and all mutations. Token generated,
stored in pass mappa/full-env, wired into stack env + agent MCP configs
(~/.claude.json). Redeployed via Portainer (stack 27). Verify: /inbox without
token → 401, with token → 200.