Add myfy frontend build command for production builds (#5)

Author: Copilot

packages/myfy-cli/myfy_cli/commands/frontend.py

@@ -8,6 +8,7 @@
 # Check if frontend module is available
 try:
     from myfy.core.config import load_settings
+    from myfy.frontend import BuildError, build_frontend
     from myfy.frontend.config import FrontendSettings
     from myfy.frontend.scaffold import check_frontend_initialized, scaffold_frontend
 
@@ -18,6 +19,9 @@
 frontend_app = typer.Typer(help="Frontend development commands")
 console = Console()
 
+# Timeout for npm operations (install and build)
+NPM_TIMEOUT = 300  # 5 minutes
+
 
 def _show_missing_module_error() -> None:
     """Display error message when frontend module is not installed."""
@@ -169,3 +173,55 @@ def init(
     except Exception as e:
         console.print(f"[red]✗ Error initializing frontend: {e}[/red]")
         sys.exit(1)
+
+
+@frontend_app.command(name="build")
+def build() -> None:
+    """
+    Build frontend assets for production.
+
+    Runs Vite build to generate optimized, hashed assets with manifest.json
+    for cache busting.
+
+    The build process:
+      - Compiles JavaScript and CSS with Vite
+      - Generates unique hashes for each asset (e.g., main-abc123.js)
+      - Creates manifest.json mapping source files to hashed versions
+      - Outputs to frontend/static/dist/
+
+    Examples:
+      myfy frontend build
+    """
+    # Check if frontend module is installed
+    if not HAS_FRONTEND:
+        _show_missing_module_error()
+        sys.exit(1)
+
+    # Run the build
+    console.print("[cyan]🏗️  Building frontend assets...[/cyan]")
+    console.print("")
+
+    try:
+        output = build_frontend(timeout=NPM_TIMEOUT)
+
+        # Show build output
+        if output:
+            console.print(output)
+
+        # Show success message
+        console.print("")
+        console.print("[green]✨ Build completed successfully![/green]")
+        console.print("")
+        console.print("[bold]Generated files:[/bold]")
+        console.print("  • frontend/static/dist/.vite/manifest.json")
+        console.print("  • frontend/static/dist/js/*.js (with unique hashes)")
+        console.print("  • frontend/static/dist/css/*.css (with unique hashes)")
+        console.print("")
+        console.print("[bold]Next steps:[/bold]")
+        console.print("  1. Set MYFY_FRONTEND_ENVIRONMENT=production")
+        console.print("  2. Deploy your application")
+        console.print("  3. Assets will be served from the manifest")
+
+    except BuildError as e:
+        console.print(f"[red]✗ {e}[/red]")
+        sys.exit(1)

packages/myfy-frontend/myfy/frontend/__init__.py

@@ -5,8 +5,16 @@
 and zero-config setup for rapid development.
 """
 
+from .build import BuildError, build_frontend, ensure_npm_dependencies_installed
 from .module import FrontendModule
 from .templates import render_template
 from .version import __version__
 
-__all__ = ["FrontendModule", "__version__", "render_template"]
+__all__ = [
+    "BuildError",
+    "FrontendModule",
+    "__version__",
+    "build_frontend",
+    "ensure_npm_dependencies_installed",
+    "render_template",
+]

packages/myfy-frontend/myfy/frontend/build.py

@@ -0,0 +1,97 @@
+"""Build logic for frontend assets."""
+
+import subprocess
+from pathlib import Path
+
+
+class BuildError(Exception):
+    """Raised when build fails."""
+
+
+def ensure_npm_dependencies_installed(timeout: int = 300) -> None:
+    """
+    Ensure npm dependencies are installed.
+
+    Args:
+        timeout: Timeout in seconds for npm install
+
+    Raises:
+        BuildError: If npm install fails or times out
+    """
+    node_modules = Path("node_modules")
+    if node_modules.exists():
+        return
+
+    try:
+        subprocess.run(
+            ["npm", "install"],
+            check=True,
+            capture_output=True,
+            text=True,
+            timeout=timeout,
+        )
+    except subprocess.TimeoutExpired as e:
+        raise BuildError(
+            f"npm install timed out after {timeout} seconds. "
+            "Please check your network connection and try again."
+        ) from e
+    except subprocess.CalledProcessError as e:
+        raise BuildError(f"Failed to install dependencies: {e.stderr}") from e
+    except FileNotFoundError as e:
+        raise BuildError("npm not found. Please install Node.js to build the frontend.") from e
+
+
+def build_frontend(timeout: int = 300) -> str:
+    """
+    Build frontend assets for production.
+
+    Runs npm run build to execute Vite build, which:
+    - Compiles JavaScript and CSS with Vite
+    - Generates unique hashes for each asset (e.g., main-abc123.js)
+    - Creates manifest.json mapping source files to hashed versions
+    - Outputs to frontend/static/dist/
+
+    Args:
+        timeout: Timeout in seconds for the build process
+
+    Returns:
+        Build output as string
+
+    Raises:
+        BuildError: If package.json is missing, build fails, or times out
+    """
+    # Check if package.json exists
+    package_json = Path("package.json")
+    if not package_json.exists():
+        raise BuildError(
+            "No package.json found. "
+            "Please run 'myfy frontend init' first to initialize the frontend."
+        )
+
+    # Ensure dependencies are installed
+    ensure_npm_dependencies_installed(timeout=timeout)
+
+    # Run the build
+    try:
+        result = subprocess.run(
+            ["npm", "run", "build"],
+            check=True,
+            capture_output=True,
+            text=True,
+            timeout=timeout,
+        )
+        return result.stdout
+    except subprocess.TimeoutExpired as e:
+        raise BuildError(
+            f"Build timed out after {timeout} seconds. "
+            "The build process is taking too long. Please check for issues."
+        ) from e
+    except subprocess.CalledProcessError as e:
+        error_msg = "Build failed"
+        if e.stderr:
+            error_msg += f": {e.stderr}"
+        if e.stdout:
+            error_msg += f"\n{e.stdout}"
+        raise BuildError(error_msg) from e
+    except FileNotFoundError as e:
+        raise BuildError("npm not found. Please install Node.js to build the frontend.") from e