devenv 2.0: A Fresh Interface to Nix

devenv 2.0 is a major release that significantly improves the Nix developer experience. Key highlights include a live terminal UI with structured progress, native shell reloading that rebuilds in the background without freezing your prompt, and a built-in Rust process manager replacing process-compose with dependency ordering, restart policies, readiness probes, and socket activation. Performance is dramatically improved via a C FFI backend using nix-bindings-rust, replacing multiple Nix CLI spawns with direct evaluator calls and an incremental per-attribute evaluation cache. New polyrepo support lets you reference outputs from other devenv projects, and a --from flag enables out-of-tree configurations. For coding agents, automatic port allocation prevents port conflicts, and SecretSpec integration provides declarative secrets management that prevents silent credential leakage. An MCP server exposes package and option search, and most language modules now include LSP support out of the box.