chore: add nix dev shell, lefthook, and direnv

.envrc

@@ -0,0 +1,3 @@
+# Auto-activate the nix dev shell via direnv
+# Install direnv + nix-direnv for seamless shell activation
+use flake

.gitignore

@@ -29,4 +29,8 @@ npm-debug.log
 *.DS_store
 ./site/_site
 .jekyll-cache
-pnpm-lock.yaml
+pnpm-lock.yaml
+
+# Nix / direnv
+result
+.direnv/

flake.nix

@@ -0,0 +1,58 @@
+{
+  description = "Apache Flagon — behavioral analytics monorepo";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = { self, nixpkgs, flake-utils }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = nixpkgs.legacyPackages.${system};
+      in
+      {
+        devShells.default = pkgs.mkShell {
+          packages = with pkgs; [
+            # Node / TypeScript (UserALE.js)
+            nodejs_24
+            pnpm
+            typescript
+
+            # Python (Distill)
+            python313
+            uv
+
+            # Pre-commit hooks
+            lefthook
+
+            # Protobuf (schema codegen — future use)
+            buf
+
+            # Tools
+            git
+            jq
+            curl
+            nixpkgs-fmt
+          ];
+
+          shellHook = ''
+            echo "🔥 Apache Flagon dev shell"
+            echo "   node:   $(node --version)"
+            echo "   pnpm:   $(pnpm --version)"
+            echo "   tsc:    $(tsc --version)"
+            echo "   python: $(python3 --version)"
+            echo "   buf:    $(buf --version 2>&1 | head -1)"
+            echo ""
+
+            # Install lefthook git hooks on first entry
+            if [ ! -f .git/hooks/pre-commit ] || ! grep -q lefthook .git/hooks/pre-commit 2>/dev/null; then
+              echo "Installing lefthook git hooks..."
+              lefthook install
+            fi
+
+            echo "Run 'pnpm install' in products/userale to get started"
+          '';
+        };
+      });
+}

lefthook.yml

@@ -0,0 +1,41 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+pre-commit:
+  parallel: true
+  commands:
+    nix-fmt:
+      glob: "*.nix"
+      run: nixpkgs-fmt {staged_files}
+    ts-lint:
+      glob: "*.{ts,tsx}"
+      root: "products/userale/"
+      run: pnpm eslint {staged_files}
+    ts-fmt:
+      glob: "*.{ts,tsx,js,jsx,json,css,md}"
+      root: "products/userale/"
+      run: pnpm prettier --check {staged_files}
+
+pre-push:
+  parallel: false
+  commands:
+    userale-build:
+      root: "products/userale/packages/flagon-userale/"
+      run: npx tsup --onSuccess 'tsc --emitDeclarationOnly --declaration'
+    userale-test:
+      root: "products/userale/packages/flagon-userale/"
+      run: npx jest -c ./test/jest.config.ts