feat: add Nix flake for reproducible builds

.gitignore

@@ -48,4 +48,7 @@ TODO.md
 .claude/settings.local.json
 .claude/doc/
 temp/
-templates/
+templates/
+# Nix build output
+result
+result-*

README.md

@@ -43,6 +43,33 @@ kilm status
 
 > **[Complete Installation Guide](https://kilm.aristovnik.me/guides/installation/)** - Multiple installation methods, verification steps, and troubleshooting.
 
+## Nix
+
+Run without installing:
+
+```bash
+nix run github:barisgit/KiLM -- --version
+```
+
+Build, or drop into a dev shell:
+
+```bash
+nix build github:barisgit/KiLM   # ./result/bin/kilm
+nix develop                      # dev shell with pytest + ruff
+```
+
+Add to a NixOS / home-manager config via the overlay:
+
+```nix
+{
+  inputs.kilm.url = "github:barisgit/KiLM";
+
+  # in your config:
+  nixpkgs.overlays = [ inputs.kilm.overlays.default ];
+  environment.systemPackages = [ pkgs.kilm ];  # or home.packages
+}
+```
+
 ## Documentation
 
 **[Complete Documentation](https://kilm.aristovnik.me)**

flake.nix

@@ -0,0 +1,46 @@
+{
+  # Pin nixpkgs, select dep versions, wire overlay, expose outputs.
+  # NO build logic here — that lives in pkgs/kilm.nix.
+  description = "Flake for kilm (KiCad Library Manager)";
+
+  inputs = {
+    nixpkgs.url = "https://github.com/NixOS/nixpkgs/archive/567a49d1913ce81ac6e9582e3553dd90a955875f.tar.gz";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = { self, nixpkgs, flake-utils }:
+    let
+      out = system:
+        let
+          pkgs = nixpkgs.legacyPackages.${system};
+          applied = self.overlays.default pkgs pkgs;
+        in {
+          packages.kilm = applied.kilm;
+          packages.default = applied.kilm;
+
+          # `nix run github:barisgit/KiLM` and `nix run .#kilm`.
+          apps.kilm = flake-utils.lib.mkApp { drv = applied.kilm; };
+          apps.default = flake-utils.lib.mkApp { drv = applied.kilm; };
+
+          devShells.default = pkgs.mkShell {
+            inputsFrom = [ applied.kilm ];
+            packages = with pkgs.python3Packages; [ pytest ruff ];
+          };
+        };
+    in
+      flake-utils.lib.eachDefaultSystem out // {
+        overlays.default = final: prev:
+          let
+            python3Packages = prev.python3Packages;
+          in {
+            kilm =
+              (prev.callPackage ./pkgs/kilm.nix {
+                inherit python3Packages;
+                inherit (prev) git;
+              }).overrideAttrs (old: {
+                # Local in-tree source.
+                src = self;
+              });
+          };
+      };
+}

pkgs/kilm.nix

@@ -0,0 +1,46 @@
+{
+  # Build logic for kilm (KiCad Library Manager). buildPythonPackage, hatchling backend.
+  # Invoked via callPackage; `src` is overridden by the flake overlay.
+  python3Packages,
+  git,
+}:
+
+python3Packages.buildPythonPackage {
+  pname = "kilm";
+  version = "0.5.5";
+  pyproject = true;
+
+  src = null; # flake overrides via overrideAttrs
+
+  build-system = with python3Packages; [ hatchling ];
+
+  # `pathlib` is declared in pyproject but is stdlib; the PyPI backport is a
+  # no-op and absent from nixpkgs, so drop the requirement.
+  pythonRemoveDeps = [ "pathlib" ];
+
+  # Runtime deps from pyproject. `pathlib` dep dropped: stdlib since py3, the PyPI
+  # backport is a no-op on a modern interpreter.
+  dependencies = with python3Packages; [
+    click
+    typer
+    rich
+    packaging
+    pyyaml
+    pathspec
+    jinja2
+    questionary
+    requests
+  ];
+
+  nativeCheckInputs = [ git ] ++ (with python3Packages; [ pytest-cov pytestCheckHook ]);
+
+  # Tests shell out to `git` and write into HOME; give them a writable one.
+  preCheck = ''
+    export HOME=$TMPDIR
+  '';
+
+  meta = {
+    description = "Command-line tool for managing KiCad libraries across projects and workstations";
+    mainProgram = "kilm";
+  };
+}