Ensure .venv is added to project .gitignore

- Created _ensure_venv_in_gitignore() function to manage project .gitignore
- Automatically creates or updates .gitignore to include .venv when venv is created
- Handles existing .gitignore files gracefully by appending
- Prevents duplication if .venv already exists in .gitignore
- Added 3 new integration tests to verify gitignore handling
- All 40 integration tests pass
- All 14 unit tests for python_env pass

Co-authored-by: ncrmro <8276365+ncrmro@users.noreply.github.com>

Author: Copilot

src/deepwork/cli/install.py

@@ -148,6 +148,42 @@ def _create_tmp_directory(deepwork_dir: Path) -> None:
         )
 
 
+def _ensure_venv_in_gitignore(project_path: Path, venv_path: str) -> None:
+    """
+    Ensure the virtual environment is in the project's .gitignore.
+
+    Creates or updates the project's .gitignore file to include the venv path.
+
+    Args:
+        project_path: Path to project root directory
+        venv_path: Path to virtual environment (e.g., ".venv")
+    """
+    gitignore_path = project_path / ".gitignore"
+    
+    # Read existing .gitignore if it exists
+    if gitignore_path.exists():
+        content = gitignore_path.read_text()
+        lines = content.splitlines()
+    else:
+        content = ""
+        lines = []
+    
+    # Check if venv_path is already in .gitignore (with or without trailing slash)
+    venv_patterns = {venv_path, f"{venv_path}/", f"/{venv_path}", f"/{venv_path}/"}
+    if any(line.strip() in venv_patterns for line in lines):
+        return  # Already present
+    
+    # Add venv to .gitignore
+    if content and not content.endswith("\n"):
+        content += "\n"
+    
+    if content:
+        content += "\n"
+    
+    content += f"# Python virtual environment (added by DeepWork)\n{venv_path}\n"
+    gitignore_path.write_text(content)
+
+
 def _create_rules_directory(project_path: Path) -> bool:
     """
     Create the v2 rules directory structure with example templates.
@@ -400,6 +436,9 @@ def _install_deepwork(platform_name: str | None, project_path: Path, python_mana
             success = env.setup(project_path)
             if success:
                 console.print("  [green]✓[/green] Virtual environment created")
+                # Ensure venv is in project's .gitignore
+                _ensure_venv_in_gitignore(project_path, python_config["venv_path"])
+                console.print("  [green]✓[/green] Added .venv to .gitignore")
             else:
                 console.print("  [yellow]⚠[/yellow] Virtual environment setup returned False")
         except RuntimeError as e:

tests/integration/test_install_python.py

@@ -191,3 +191,77 @@ def test_install_interactive_prompt_skip(self, mock_claude_project: Path) -> Non
         assert config is not None
         assert "python" in config
         assert config["python"]["manager"] == "skip"
+
+    def test_install_creates_gitignore_with_venv(self, mock_claude_project: Path) -> None:
+        """Test that install creates .gitignore with .venv entry."""
+        runner = CliRunner()
+
+        result = runner.invoke(
+            cli,
+            [
+                "install",
+                "--platform", "claude",
+                "--path", str(mock_claude_project),
+                "--python-manager", "uv"
+            ],
+            catch_exceptions=False,
+        )
+
+        # Verify .gitignore was created
+        gitignore_path = mock_claude_project / ".gitignore"
+        assert gitignore_path.exists()
+        
+        # Verify .venv is in .gitignore
+        gitignore_content = gitignore_path.read_text()
+        assert ".venv" in gitignore_content
+
+    def test_install_appends_to_existing_gitignore(self, mock_claude_project: Path) -> None:
+        """Test that install appends .venv to existing .gitignore."""
+        # Create existing .gitignore
+        gitignore_path = mock_claude_project / ".gitignore"
+        original_content = "*.pyc\n__pycache__/\n"
+        gitignore_path.write_text(original_content)
+
+        runner = CliRunner()
+
+        result = runner.invoke(
+            cli,
+            [
+                "install",
+                "--platform", "claude",
+                "--path", str(mock_claude_project),
+                "--python-manager", "uv"
+            ],
+            catch_exceptions=False,
+        )
+
+        # Verify original content is preserved
+        gitignore_content = gitignore_path.read_text()
+        assert "*.pyc" in gitignore_content
+        assert "__pycache__/" in gitignore_content
+        
+        # Verify .venv was added
+        assert ".venv" in gitignore_content
+
+    def test_install_does_not_duplicate_venv_in_gitignore(self, mock_claude_project: Path) -> None:
+        """Test that install doesn't duplicate .venv if already in .gitignore."""
+        # Create .gitignore with .venv already present
+        gitignore_path = mock_claude_project / ".gitignore"
+        gitignore_path.write_text(".venv\n")
+
+        runner = CliRunner()
+
+        result = runner.invoke(
+            cli,
+            [
+                "install",
+                "--platform", "claude",
+                "--path", str(mock_claude_project),
+                "--python-manager", "uv"
+            ],
+            catch_exceptions=False,
+        )
+
+        # Verify .venv appears only once
+        gitignore_content = gitignore_path.read_text()
+        assert gitignore_content.count(".venv") == 1