add preview server

src/zona/cli.py

@@ -1,6 +1,6 @@
 import typer
 from pathlib import Path
-from zona import builder
+from zona import builder, server
 
 app = typer.Typer()
 
@@ -15,6 +15,14 @@ def build(in_dir: str | None = None, out_dir: str | None = None):
     builder.build(Path(in_dir), items)
 
 
+@app.command()
+def serve(dir: Path = Path("public")):
+    if not dir.exists():
+        raise typer.BadParameter(f"Directory {dir} does not exist.")
+    typer.echo(f"Serving files from {dir}")
+    server.serve(dir)
+
+
 @app.command()
 def init():
     # init will populate the current directory with

src/zona/markdown.py

@@ -9,6 +9,7 @@ class ZonaRenderer(HTMLRenderer):
     @override
     def render_link(self, element: Link):
         href = element.dest
+        assert isinstance(href, str)
         if href.endswith(".md") and not href.startswith("http"):
             href = href[:-3] + ".html"
         body: Any = self.render_children(element)

src/zona/server.py

@@ -0,0 +1,13 @@
+from starlette.applications import Starlette
+from starlette.staticfiles import StaticFiles
+import typer
+import uvicorn
+from pathlib import Path
+
+
+def serve(dir: Path, host: str = "localhost", port: int = 8000):
+    app = Starlette()
+    app.mount("/", StaticFiles(directory=dir, html=True), name="zona")
+
+    typer.echo(f"Preview server running at http://{host}:{port}")
+    uvicorn.run(app, host=host, port=port, log_level="warning")