Please use a private GitHub security advisory. Include the affected route or client, reproduction steps, and likely impact. Do not put credentials, private notes, or an unpatched exploit in a public issue.

• Set a strong AUTH_SECRET and the exact HTTPS AUTH_URL.
• Keep Postgres on a private network. sslmode=require encrypts but does not authenticate the server — acceptable for a same-host database; use sslmode=verify-full (with DATABASE_CA_CERT for a private CA) whenever the database is on another host. DATABASE_TLS_INSECURE=true is only for loopback development with sslmode=no-verify.
• Keep attachment storage private. S3 deployments should enable Block Public Access and grant the application only object read/write/delete permissions under the keep/ prefix.
• Set DEPLOY_KNOWN_HOSTS to a separately verified SSH host-key line. Deployment fails closed when the host key changes.
• A configured ANTHROPIC_KEY sends authenticated note text to Anthropic for titles/summaries; set AI_METADATA_ENABLED=false to keep note text local, and disclose the model use to users when it stays on. Provider and account budgets should also be configured outside the application.
• Back up Postgres and object storage with encryption at rest and tested restore procedures. Restrict production logs and database access to operators who need them.

Keep is not end-to-end encrypted. The server can read note content. Signed-in web clients keep account-scoped offline copies in IndexedDB until explicit sign-out or site-data removal; guest notes remain in localStorage. Native Spotlight integration indexes titles, summaries, and tags, but not note bodies.

Public shares are bearer links. Random links carry 128 bits of entropy; vanity links are public names with a 16-character minimum. Revocation stops page, download, and attachment access immediately.

Releases before the private-upload change wrote attachments with public-read storage permissions and embedded their provider URLs in notes. New uploads are private and use /api/uploads/<id>. Operators upgrading an existing deployment should inventory old keep/ objects, remove public ACLs after deciding how to handle legacy note links, and delete unreferenced public objects.