Architecture decisions

The accepted records that define Quirl's extension language, layering, protocols, process boundaries, and release scope.

Architecture decision records capture decisions that should not drift while implementation moves quickly. Read them as constraints on the current design, not as a general roadmap.

The sequence begins with Lua as the sole extension language and crate layering, then follows the runtime, contract, plugin, protocol, process, testing, release, interactive-surface, theme, external-history, and preview-gallery decisions through the runtime-layering, shared-execution, and typed-Lua-runner decisions in ADR 0018. ADR 0014 remains proposed: it describes an external-history boundary, not Atuin support.