feat: add Nix CI workflow and configuration files

.github/workflows/ci.yml

@@ -0,0 +1,35 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  test:
+    name: Test (${{ matrix.os }})
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macos-latest, windows-latest]
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+      - uses: Swatinem/rust-cache@v2
+
+      - name: Test
+        run: cargo test --release
+
+      - name: Clippy
+        run: cargo clippy --release -- -D warnings
+
+  fmt:
+    name: Format Check
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+
+      - name: Format
+        run: cargo fmt -- --check

.gitignore

@@ -11,3 +11,9 @@
 node_modules/
 package-lock.json
 yarn.lock
+
+# Nix development
+result
+result-*
+.dirlocals
+.envrc

.nix/README.md

@@ -0,0 +1,20 @@
+# Nix Configuration Files
+
+This directory contains supplementary Nix configurations for advanced use cases.
+
+## Files
+
+- `shell.nix` - (Optional) Legacy shell.nix for compatibility
+- `default.nix` - (Optional) Legacy default.nix for compatibility
+
+## Using flake.nix (Recommended)
+
+Use the modern flake.nix at the root instead:
+
+```bash
+nix develop              # Enter dev shell
+nix build                # Build package
+nix build .#docker       # Build Docker image
+```
+
+See [docs/NIX.md](../docs/NIX.md) for full documentation.

.nix/default.nix

@@ -0,0 +1,5 @@
+# Legacy Nix support (for non-flake setups)
+# This file allows `nix-build` to work without flakes
+# Usage: nix-build .nix/
+
+(import <nixpkgs> {}).callPackage ./package.nix { }

.nix/shell.nix

@@ -0,0 +1,24 @@
+# Legacy shell.nix for non-flake Nix users
+# Usage: nix-shell .nix/shell.nix
+
+let
+  nixpkgs = import <nixpkgs> { };
+in
+
+nixpkgs.mkShell {
+  buildInputs = with nixpkgs; [
+    rustup
+    pkg-config
+    openssl
+    cargo-watch
+    cargo-edit
+    cargo-outdated
+  ];
+
+  shellHook = ''
+    echo "🧙 Langsmith dev environment (legacy nix-shell)"
+    echo "Run: cargo build, cargo test, cargo run -- --help"
+    echo ""
+    echo "⚠️  Note: Flakes are recommended. Use 'nix develop' instead."
+  '';
+}

flake.nix

@@ -0,0 +1,90 @@
+{
+  description = "Langsmith - Automatic i18n extraction and translation CLI";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+    rust-overlay.url = "github:oxalica/rust-overlay";
+    pre-commit-hooks.url = "github:cachix/pre-commit-hooks.nix";
+  };
+
+  outputs = { self, nixpkgs, flake-utils, rust-overlay, pre-commit-hooks }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        overlays = [ (import rust-overlay) ];
+        pkgs = import nixpkgs {
+          inherit system overlays;
+        };
+
+        rustToolchain = pkgs.rust-bin.stable.latest.default.override {
+          extensions = [ "rust-src" "rust-analyzer" ];
+        };
+
+        version = "0.1.0";
+
+      in
+      {
+        # Development shell with all tools
+        devShells.default = pkgs.mkShell {
+          buildInputs = with pkgs; [
+            rustToolchain
+            cargo-watch
+            cargo-edit
+            cargo-outdated
+            cargo-deny
+            cargo-audit
+            pkg-config
+            openssl
+            pre-commit
+            git
+          ];
+
+          shellHook = ''
+            echo "🧙 Langsmith dev environment loaded (Nix)"
+            echo "Run: cargo build, cargo test, cargo run -- --help"
+          '';
+        };
+
+        # Production build (for current system)
+        packages.default = pkgs.rustPlatform.buildRustPackage {
+          name = "langsmith";
+          inherit version;
+          src = ./.;
+          cargoLock.lockFile = ./Cargo.lock;
+
+          buildInputs = with pkgs; [
+            pkg-config
+            openssl
+          ];
+
+          meta = with pkgs.lib; {
+            description = "Automatic i18n extraction and translation CLI";
+            homepage = "https://github.com/chahinebenlahcen/langsmith";
+            license = licenses.mit;
+            maintainers = [];
+            mainProgram = "langsmith";
+          };
+        };
+
+        # Docker image
+        packages.docker = pkgs.dockerTools.buildLayeredImage {
+          name = "langsmith";
+          tag = version;
+          contents = [ self.packages.${system}.default pkgs.cacert ];
+          config = {
+            Cmd = [ "${self.packages.${system}.default}/bin/langsmith" ];
+            Env = [ "SSL_CERT_FILE=${pkgs.cacert}/etc/ssl/certs/ca-bundle.crt" ];
+          };
+        };
+
+        # CLI app
+        apps.default = {
+          type = "app";
+          program = "${self.packages.${system}.default}/bin/langsmith";
+        };
+
+        # Quality checks (disabled in flake check, available in nix develop)
+        checks = { };
+      }
+    );
+}