feat: migrate to flake-parts + devenv, replace attic with nix-bindings

.envrc

@@ -1,3 +1 @@
-source .env
-# Tell direnv to load the 'default' from your flake.nix
-use flake .#default
+use devenv

.gitignore

@@ -7,13 +7,16 @@ Cargo.lock
 .idea/
 .vscode/
 
-#Config
+# Config
 loft.toml
 attic/
 
-#env
+# Env / Direnv / Nix
 .direnv
+.devenv/
+.devenv.flake.nix
 .env
 result
 .loft_scan_complete
 .loft_cache.db
+.pre-commit-config.yaml

AGENTS.md

@@ -0,0 +1,72 @@
+# Agent Working Guide — Loft
+
+## Environment
+
+This project uses **devenv** for both builds and the development environment. Everything is defined in `devenv.nix` — `flake.nix` just wires outputs.
+
+## Available Commands
+
+| Command                         | Description          |
+| ------------------------------- | -------------------- |
+| `devenv shell -- cargo build`   | Build                 |
+| `devenv shell -- cargo test`    | Run tests             |
+| `devenv shell -- cargo fmt`     | Format code           |
+| `devenv shell -- cargo clippy`  | Lint                  |
+| `devenv test`                   | Run test suite        |
+| `nix flake check`               | Run all checks        |
+| `nix build`                     | Full sandboxed build  |
+| `cache-test`                    | Test cache workflow   |
+
+## Checks
+
+| Check          | Command                                        |
+| -------------- | ---------------------------------------------- |
+| Formatting     | `treefmt --fail-on-change`                     |
+| Clippy         | `nix build .#checks.<system>.clippy`           |
+| Unit tests     | `nix build .#checks.<system>.unit-tests`       |
+| Integration    | `nix build .#checks.<system>.integration`      |
+
+## NixOS Module
+
+The flake exports `nixosModules.loft` — a NixOS module for running loft as a systemd service. Enable it with:
+
+```nix
+{
+  imports = [ inputs.loft.nixosModules.loft ];
+  services.loft = {
+    enable = true;
+    s3 = {
+      bucket = "my-cache";
+      endpoint = "https://s3.example.com";
+      accessKeyFile = "/run/secrets/s3-access-key";
+      secretKeyFile = "/run/secrets/s3-secret-key";
+    };
+  };
+}
+```
+
+## Architecture
+
+Store operations use **nix C API** where available (`nix-bindings` vendored crate) and **CLI** for operations the C API doesn't expose yet:
+
+| Operation | Backend | Reason |
+|-----------|---------|--------|
+| `Store::open`, `store_dir`, `real_path` | C API (`nix-bindings`) | Available in `nix_api_store.h` |
+| `StorePath::parse`, `hash_part` | C API (`nix-bindings`) | Available in `nix_api_store.h` |
+| `query_path_info` | CLI (`nix path-info --json`) | Not in C API — requires C++ internals |
+| `nar_from_path` | CLI (`nix nar dump-path`) | Not in C API — requires C++ internals |
+| `compute_fs_closure` | CLI (`nix-store --query`) | Not in C API at nix 2.31 |
+
+**TODO**: Revisit when [nix C API](https://github.com/NixOS/nix/issues) expands to cover path info queries and NAR streaming. Tracked in `src/nix_store.rs`.
+
+## Adding a Dependency
+
+1. `devenv shell -- cargo add <crate>`
+2. Build and test: `devenv shell -- cargo build && devenv shell -- cargo test`
+3. For sys crates, add system libs to `buildInputs` in `flake.nix`
+
+## Adding a Dependency
+
+1. `devenv shell -- cargo add <crate>`
+2. Build and test: `devenv shell -- cargo build && devenv shell -- cargo test`
+3. For sys crates, add system libs to `buildInputs` in `crane.nix`