Convert to Nix flake-only setup with direnv support, CI integration, and hook CLI command

.envrc

@@ -0,0 +1 @@
+use flake

.github/workflows/validate.yml

@@ -18,23 +18,27 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
-      - name: Install uv
-        uses: astral-sh/setup-uv@v4
-        with:
-          version: "latest"
+      - name: Install Nix
+        uses: cachix/install-nix-action@v31
 
-      - name: Set up Python
-        uses: actions/setup-python@v5
-        with:
-          python-version: "3.11"
+      - name: Setup Nix development environment
+        uses: nicknovitski/nix-develop@v1
 
-      - name: Install dependencies
+      - name: Install Python dependencies
         run: uv sync --extra dev
 
       - name: Check formatting (ruff)
         run: |
-          uv run ruff format --check src/ tests/
-          uv run ruff check src/ tests/
+          ruff format --check src/ tests/
+          ruff check src/ tests/
 
       - name: Run tests
-        run: uv run pytest tests/ -v
+        run: pytest tests/ -v
+
+      - name: Build deepwork package
+        run: nix build
+
+      - name: Verify package output
+        run: |
+          ls -la result/bin/deepwork
+          ./result/bin/deepwork --version

.gitignore

@@ -66,6 +66,9 @@ dmypy.json
 *~
 .DS_Store
 
+# direnv
+.direnv/
+
 # Jupyter Notebook
 .ipynb_checkpoints
 

AGENTS.md

@@ -83,4 +83,22 @@ deepwork/
     ├── deepwork_jobs/              # ← Installed copy, NOT source of truth
     ├── deepwork_rules/             # ← Installed copy, NOT source of truth
     └── [bespoke_job]/              # ← Source of truth for bespoke only
+
+## Development Environment
+
+This project uses **Nix Flakes** to provide a reproducible development environment.
+
+### Using the Environment
+
+- **With direnv (Recommended)**: Just `cd` into the directory. The `.envrc` will automatically load the flake environment.
+- **Without direnv**: Run `nix develop` to enter the shell.
+- **Building**: Run `nix build` to build the package.
+
+**Note**: The flake is configured to automatically allow unfree packages (required for the BSL 1.1 license), so you do not need to set `NIXPKGS_ALLOW_UNFREE=1`.
+
+The environment includes:
+- Python 3.11
+- uv (package manager)
+- All dev dependencies (pytest, ruff, mypy, etc.)
+
 ```