ADR-003: Runtime cryptography and ACME dependencies

• Status: accepted

Context

AES-GCM payloads, Secure Notepad ECDH, X.509 handling, self-signed certificates, and built-in HTTP-01 issuance are runtime features. Treating their libraries as optional would make installed behavior depend on an extra chosen outside the runtime contract.

Decision

Declare cryptography, acme, and josepy as runtime dependencies. cryptography provides AES-GCM, ECDH, X.509 parsing, and certificate helpers. acme and josepy provide HTTP-01 issuance.

Do not substitute weaker crypto when an operation is unavailable or fails. The affected request or startup path fails closed.

Consequences

• A normal source installation includes the libraries required by documented crypto and ACME features.
• Import paths that do not need ACME avoid eager ACME initialization.
• Dependency updates require compatibility and security testing across all supported Python versions.