Refactor with new fastapi-vue utility module to run the server, used in CLI main and devserver to run the main app. Default ports made part of templating, so that --ports can be easily specified to fastapi-vue-setup to customize (respects earlier choices when no --ports is specified). New overall default ports 3100, 3200.

fastapi-vue/README.md

@@ -0,0 +1,47 @@
+# fastapi-vue
+
+Implements Single-Page-App serving at site root with FastAPI, that the standard StaticFiles module cannot handle. This also caches and zstd compresses the files for lightning-fast operation. This is primarily meant for use with Vue frontend, but technically can host any static files in a similar manner.
+
+## Installation
+
+Script [fastapi-vue-setup](https://git.zi.fi/LeoVasanko/fastapi-vue-setup) should normally be used to convert or create a project with connection between FastAPI and Vue. The target project will depend on this package to serve its static files.
+
+```sh
+uvx fastapi-vue-setup --help
+```
+
+Refer to instructions below for further configuration.
+
+## Usage
+
+```python
+from contextlib import asynccontextmanager
+from fastapi import FastAPI
+from fastapi_vue import Frontend
+
+frontend = Frontend(
+    Path(__file__).with_name("frontend-build"),
+    spa=True,
+    cached=["/assets/"],
+)
+
+@asynccontextmanager
+async def lifespan(app: FastAPI):
+    await frontend.load()
+    yield
+
+app = FastAPI(lifespan=lifespan)
+
+# Add API routes here...
+
+# Final catch-all route for frontend files (keep at end of file)
+frontend.route(app, "/")
+```
+
+## Configuration
+
+- `directory`: Path to static files directory
+- `spa`: Enable SPA mode (serve index.html for unknown routes)
+- `cached`: Path prefixes for immutable cache headers (browser won't check for changes)
+- `favicon`: Path to serve at `/favicon.ico` (e.g., `"/logo.png"` will be served as `image/png`)
+- `zstdlevel`: Compression level (default: 18)

fastapi-vue/fastapi_vue/__init__.py

@@ -0,0 +1,3 @@
+from .staticfiles import Frontend
+
+__all__ = ["Frontend"]

fastapi-vue/fastapi_vue/hostutil.py

@@ -0,0 +1,67 @@
+import contextlib
+import ipaddress
+from urllib.parse import urlparse
+
+
+def parse_endpoint(value: str | None, default_port: int = 0) -> list[dict]:
+    """Parse an endpoint string into uvicorn bind configurations.
+
+    Args:
+        value: Endpoint string to parse
+        default_port: Port to use when not specified
+
+    Returns:
+        List of dicts with uvicorn bind kwargs (host/port or uds).
+
+    Supported forms:
+    - None or empty -> [{host: "localhost", port: default_port}]
+    - port (numeric) -> [{host: "localhost", port: port}]
+    - :port -> [{host: "0.0.0.0", port}, {host: "::", port}] (all interfaces)
+    - host:port -> [{host, port}]
+    - host -> [{host, port: default_port}]
+    - [ipv6]:port -> [{host: ipv6, port}]
+    - ipv6 (unbracketed) -> [{host: ipv6, port: default_port}]
+    - /path or unix:/path -> [{uds: path}]
+    """
+    if not value:
+        return [{"host": "localhost", "port": default_port}]
+
+    # Port only (numeric) -> localhost:port
+    if value.isdigit():
+        return [{"host": "localhost", "port": int(value)}]
+
+    # Leading colon :port -> bind all interfaces (0.0.0.0 + ::)
+    if value.startswith(":") and value != ":":
+        port_part = value[1:]
+        if not port_part.isdigit():
+            raise SystemExit(f"Invalid port in '{value}'")
+        port = int(port_part)
+        return [{"host": "0.0.0.0", "port": port}, {"host": "::", "port": port}]  # noqa: S104
+
+    # UNIX domain socket (unix:/path or just /path)
+    if value.startswith("/"):
+        return [{"uds": value}]
+    if value.startswith("unix:"):
+        uds_path = value[5:] or None
+        if uds_path is None:
+            raise SystemExit("unix: path must not be empty")
+        return [{"uds": uds_path}]
+
+    # Unbracketed IPv6 (cannot safely contain a port) -> detect by multiple colons
+    if value.count(":") > 1 and not value.startswith("["):
+        try:
+            ipaddress.IPv6Address(value)
+        except ValueError as e:
+            raise SystemExit(f"Invalid IPv6 address '{value}': {e}") from e
+        return [{"host": value, "port": default_port}]
+
+    # Use urllib.parse for everything else (host[:port], [ipv6][:port])
+    parsed = urlparse(f"//{value}")  # // prefix lets urlparse treat it as netloc
+    host = parsed.hostname or "localhost"
+    port = parsed.port or default_port
+
+    # Validate IP literals (optional; hostname passes through)
+    with contextlib.suppress(ValueError):
+        ipaddress.ip_address(host)
+
+    return [{"host": host, "port": port}]

fastapi-vue/fastapi_vue/server.py

@@ -0,0 +1,78 @@
+import asyncio
+import logging
+import os
+from contextlib import suppress
+
+import uvicorn
+from uvicorn import Config, Server
+
+from .hostutil import parse_endpoint
+
+logger = logging.getLogger(__name__)
+
+
+def run(
+    app: str,
+    *,
+    listen: str | list[str] | None = None,
+    default_port: int = 8000,
+    reload: bool = False,
+    workers: int | None = None,
+    **uvicorn_config,
+):
+    """Run uvicorn server(s) for the given app.
+
+    Args:
+        app: The ASGI application path (e.g., "myapp.main:app")
+        listen: Endpoint string(s) (see parse_endpoint for formats).
+        default_port: Port to use when not specified in listen args.
+        reload: Enable auto-reload (requires uvicorn.run, single endpoint only).
+        workers: Number of worker processes (requires uvicorn.run, single endpoint only).
+        **uvicorn_config: Additional uvicorn config options (overrides all other settings).
+    """
+    if listen is None:
+        listen = [f"localhost:{default_port}"]
+    elif isinstance(listen, str):
+        listen = [listen]
+    endpoints: list[dict] = []
+    for ep in listen:
+        endpoints.extend(parse_endpoint(ep, default_port))
+
+    conf: dict[str, object] = {"app": app, "reload": reload, "workers": workers}
+    proxy = os.getenv("FORWARDED_ALLOW_IPS", "127.0.0.1,::1")
+    if proxy:
+        conf["proxy_headers"] = True
+        conf["forwarded_allow_ips"] = proxy
+    conf.update(uvicorn_config)
+
+    with suppress(KeyboardInterrupt):
+        if reload or workers:
+            serve_multiprocess(endpoints, **conf)
+        else:
+            asyncio.run(serve(endpoints, **conf))
+
+
+async def serve(endpoints: list[dict], **kwargs) -> None:
+    """Serve the given endpoints in current process/loop. Does not spawn extra processes."""
+    forbidden = {"reload", "workers"} & {k for k, v in kwargs.items() if v}
+    if forbidden:
+        logger.warning(
+            "Options %s have no effect in simple mode (multiple endpoints)",
+            ", ".join(sorted(forbidden)),
+        )
+    await asyncio.gather(*(Server(Config(**kwargs, **ep)).serve() for ep in endpoints))
+
+
+def serve_multiprocess(endpoints: list[dict], **kwargs) -> None:
+    """Serve using uvicorn.run() for reload/workers support. Only first endpoint is used."""
+    if len(endpoints) > 1:
+        eps = [
+            ep["uds"] if "uds" in ep else f"{ep['host']}:{ep['port']}"
+            for ep in endpoints
+        ]
+        logger.warning(
+            "Current mode supports only one endpoint. Listening: %s, skipped: %s",
+            eps[0],
+            " ".join(eps[1:]),
+        )
+    uvicorn.run(**kwargs, **endpoints[0])

fastapi-vue/fastapi_vue/staticfiles.py

@@ -0,0 +1,267 @@
+"""FastAPI static file serving with zstd compression and SPA support."""
+
+import logging
+import mimetypes
+import os
+import time
+from base64 import urlsafe_b64encode
+from functools import partial
+from pathlib import Path, PurePath, PurePosixPath
+from wsgiref.handlers import format_date_time
+
+from blake3 import blake3
+from fastapi import FastAPI, Request, Response
+from fastapi.concurrency import run_in_threadpool
+from fastapi.responses import JSONResponse, RedirectResponse
+from starlette.exceptions import HTTPException
+from starlette.routing import Route
+from zstandard import ZstdCompressor
+
+# Dev mode: index files but don't load content, return error responses
+_DEVMODE = os.getenv("FASTAPI_VUE_FRONTEND_URL")
+
+logger = logging.getLogger("uvicorn.error")  # Use FastAPI logging style
+
+
+class Frontend:
+    """Static file server with automatic zstd compression and caching.
+
+    Features:
+    - Automatic zstd compression for compressible files
+    - ETag-based caching with configurable cache headers
+    - SPA (Single Page Application) support
+    - Favicon handling from hashed assets
+    - Dev mode: indexes files but returns error directing to Vite server
+
+    Args:
+        directory: Path to the directory containing static files
+        index: Name of the index file (default: "index.html")
+        spa: Enable SPA mode - serve index.html for unknown routes (default: False)
+        cached: Path prefixes that should have immutable cache headers
+        zstdlevel: Zstd compression level (default: 18)
+        favicon: Path to favicon for automatic /favicon.ico handling
+    """
+
+    def __init__(
+        self,
+        directory: Path | str,
+        *,
+        index: str = "index.html",
+        spa: bool = False,
+        catch_all: bool | None = None,
+        cached: str | list[str] | None = None,
+        zstdlevel: int = 18,
+        favicon: str | None = None,
+    ) -> None:
+        self.www: dict[str, tuple[bytes, bytes | None, dict]] = {}
+        self.base: Path = Path(directory)
+        self.index = index
+        self.spa = spa
+        self._catch_all = spa if catch_all is None else catch_all
+        if cached is None:
+            self.cached_paths = []
+        elif isinstance(cached, str):
+            self.cached_paths = [cached]
+        else:
+            self.cached_paths = cached
+        self.zstdlevel = zstdlevel
+        self.favicon = favicon
+        self.devmode = bool(_DEVMODE)
+        self._app: FastAPI | None = None
+        self._mount_path: str = ""
+        self._ridx: int = 0
+        self._routes: list[Route] = []
+
+    def _index_only(self) -> set[str]:
+        """Index file paths without loading content (for dev mode)."""
+        paths: set[str] = set()
+        if not self.base.exists():
+            return paths
+        queue = [PurePath()]
+        while queue:
+            current = self.base / queue.pop(0)
+            for p in current.iterdir():
+                rel = p.relative_to(self.base)
+                if p.is_dir():
+                    queue.append(rel)
+                    continue
+                name = "/" + rel.as_posix()
+                name = name.removesuffix(self.index)
+                paths.add(name)
+        if self.favicon:
+            p = PurePosixPath(self.favicon)
+            base = str(p.with_suffix(""))
+            ext = p.suffix
+            if any(path.startswith(base) and path.endswith(ext) for path in paths):
+                paths.add("/favicon.ico")
+        return paths
+
+    def _load(self):
+        """Load static files from disk with compression."""
+        www: dict[str, tuple[bytes, bytes | None, dict]] = {}
+        if not self.base.exists():
+            raise ValueError(f"Frontend folder {self.base} not found (try uv build)")
+        paths = [PurePath()]
+        while paths:
+            current = self.base / paths.pop(0)
+            for p in current.iterdir():
+                rel = p.relative_to(self.base)
+                if p.is_dir():
+                    paths.append(rel)
+                    continue
+                # Read file
+                name = "/" + rel.as_posix()
+                mime = mimetypes.guess_type(name)[0] or "application/octet-stream"
+                name = name.removesuffix(self.index)
+                data = p.read_bytes()
+                etag = urlsafe_b64encode(blake3(data).digest(9)).decode()
+                if mime.startswith("text/"):
+                    mime += "; charset=UTF-8"
+                mtime = p.stat().st_mtime
+                cached = any(name.startswith(prefix) for prefix in self.cached_paths)
+                headers = {
+                    "etag": f'"{etag}"',
+                    "last-modified": format_date_time(mtime),
+                    "cache-control": (
+                        "max-age=31536000, immutable" if cached else "no-cache"
+                    ),
+                    "content-type": mime,
+                }
+                zstd = ZstdCompressor(self.zstdlevel).compress(data)
+                if len(zstd) >= len(data):
+                    zstd = None
+                www[name] = data, zstd, headers
+        if self.favicon:
+            p = PurePosixPath(self.favicon)
+            base = str(p.with_suffix(""))
+            ext = p.suffix
+            hashed_path = next(
+                (path for path in www if path.startswith(base) and path.endswith(ext)),
+                None,
+            )
+            if hashed_path:
+                www["/favicon.ico"] = www[hashed_path]
+        if not www:
+            msg = "Frontend files missing, check your installation.\n"
+            www["/"] = (
+                msg.encode(),
+                None,
+                {
+                    "etag": "error",
+                    "content-type": "text/plain",
+                    "cache-control": "no-store",
+                },
+            )
+        return www
+
+    async def load(self, *, log=True):
+        """Load or reload static files from disk.
+
+        In dev mode (FASTAPI_VUE_FRONTEND_URL set), only indexes paths without loading content.
+        """
+        if self.devmode:
+            # Dev mode: just index paths, no content loading
+            self._devmode_paths = await run_in_threadpool(self._index_only)
+            self._register_routes()
+            return
+
+        start = time.perf_counter()
+        self.www = await run_in_threadpool(self._load)
+        self._register_routes()
+        duration = time.perf_counter() - start
+        if not log:
+            return
+        compfiles = [(len(d), len(z)) for d, z, _ in self.www.values() if z]
+        raw = sum(v[0] for v in compfiles)
+        comp = sum(v[1] for v in compfiles)
+        ratio = comp / raw * 100 if raw else 100.0
+        if log and self.www:
+            logger.info(
+                f"{self.base.name}: {len(self.www)} files in {1000 * duration:.1f} ms | "
+                f"zstd {len(compfiles)} files {1e-6 * raw:.2f}->{1e-6 * comp:.2f} MB ({ratio:.0f} %)"
+            )
+
+    def route(self, app: FastAPI, mount_path="/"):
+        """Register frontend routes with a FastAPI app.
+
+        In SPA/catch-all mode, this must only be called only after all other routes.
+
+        The calling position determines routing priority, although in regular mode the
+        routes are actually added only after load() is called.
+
+        Args:
+            app: FastAPI application instance
+            mount_path: Path where the frontend should be mounted (default: "/")
+        """
+        self._app = app
+        self._mount_path = mount_path.rstrip("/")
+        self._ridx = len(app.routes)
+
+        if self._catch_all:
+            # Register catch-all immediately (works without load)
+            path = self._mount_path + "{path:path}"
+            app.api_route(path, methods=["GET", "HEAD"], name="frontend")(self.handle)
+
+    def _register_routes(self):
+        """Register individual routes for each loaded file (non-catch_all mode)."""
+        if self._app is None or self._catch_all:
+            return
+
+        # Remove previously registered routes (for reload support)
+        for route in list(self._routes):
+            if route in self._app.routes:
+                self._app.routes.remove(route)
+        self._routes.clear()
+
+        # Get paths and select handler based on mode (checked once, not per request)
+        paths = self._devmode_paths if self.devmode else self.www.keys()
+        handler = _devmode_respond if self.devmode else self._respond
+        # Insert at the position where route() was called
+        self._app.routes[self._ridx : self._ridx] = self._routes = [
+            Route(
+                self._mount_path + p,
+                endpoint=handler if self.devmode else partial(handler, name=p),
+                methods=["GET", "HEAD"],
+                name=f"frontend{p.replace('/', '_')}",
+            )
+            for p in paths
+        ]
+
+    def _respond(self, request: Request, name: str):
+        """Serve a static file with ETag and compression support."""
+        data, zstd, headers = self.www[name]
+        if request.headers.get("if-none-match") == headers["etag"]:
+            return Response(status_code=304, headers=headers)
+        if zstd and "zstd" in request.headers.get("accept-encoding", ""):
+            return Response(
+                content=zstd, headers={**headers, "content-encoding": "zstd"}
+            )
+        return Response(content=data, headers=headers)
+
+    def handle(self, request: Request, path: str):
+        """SPA catch-all handler with directory redirects and fallback to index."""
+        name = path.removesuffix(self.index)
+        files = self._devmode_paths if self.devmode else self.www
+
+        if name not in files:
+            # Friendly redirect for directories missing trailing slash
+            if name and f"{name}/" in files:
+                return RedirectResponse(request.url.path + "/")
+            # SPA support: serve / for unknown paths if the browser wants HTML
+            if self.spa and "text/html" in request.headers.get("accept", ""):
+                name = "/"
+            # 404 for everything else
+            if name not in files:
+                raise HTTPException(status_code=404)
+
+        return (_devmode_respond if self.devmode else self._respond)(request, name)
+
+
+def _devmode_respond(request: Request, name=""):
+    """Return error response directing to Vite server."""
+    return JSONResponse(
+        status_code=409,
+        content={
+            "detail": f"Frontend assets served by Vite in dev mode. Connect via {_DEVMODE} instead."
+        },
+    )

fastapi-vue/pyproject.toml

@@ -0,0 +1,23 @@
+[project]
+name = "fastapi-vue"
+dynamic = ["version"]
+description = "Serves Vue assets on a FastAPI app. Use fastapi-vue-setup tool to add Vue build to your package."
+readme = "README.md"
+requires-python = ">=3.11"
+dependencies = [
+    "fastapi>=0.115.0",
+    "zstandard>=0.23.0",
+    "blake3>=1.0.8",
+]
+
+[project.urls]
+Homepage = "https://git.zi.fi/LeoVasanko/fastapi-vue"
+Repository = "https://github.com/LeoVasanko/fastapi-vue"
+
+[build-system]
+requires = ["hatchling", "hatch-vcs"]
+build-backend = "hatchling.build"
+
+[tool.hatch.version]
+source = "vcs"
+raw-options.root = ".."

fastapi_vue_setup.py

@@ -7,12 +7,14 @@ Usage:
 
 Options:
     --module-name NAME      Python module name (auto-detected from pyproject.toml)
+    --ports DEFAULT,VITE,DEV  Port configuration (default: 3100,3100,3200)
     --dry-run               Show what would be done without making changes
 """
 
 import argparse
 import os
 import re
+import shutil
 import subprocess
 import sys
 from pathlib import Path
@@ -23,6 +25,10 @@ import tomlkit
 # Template directory
 TEMPLATE_DIR = Path(__file__).parent / "template"
 
+# Default ports: (default, vite, dev)
+# If vite == dev, dev is incremented by 100
+DEFAULT_PORTS = (3100, 3100, 3200)
+
 # Marker comment indicating file can be auto-upgraded
 # Users should remove this line to prevent automatic updates
 UPGRADE_MARKER = "auto-upgrade@fastapi-vue-setup"
@@ -116,9 +122,83 @@ Next steps:
 # =============================================================================
 
 
+def parse_ports(ports_str: str | None) -> tuple[int, int, int]:
+    """Parse comma-separated port string into (default, vite, dev) tuple.
+
+    If dev == vite, dev is incremented by 100 to avoid conflicts.
+    """
+    if not ports_str:
+        return DEFAULT_PORTS
+
+    parts = ports_str.split(",")
+    if len(parts) == 1:
+        default = int(parts[0])
+        vite = default
+        dev = default + 100
+    elif len(parts) == 2:
+        default = int(parts[0])
+        vite = int(parts[1])
+        dev = vite + 100 if vite == default else default + 100
+    elif len(parts) == 3:
+        default = int(parts[0])
+        vite = int(parts[1])
+        dev = int(parts[2])
+    else:
+        raise ValueError(f"Invalid ports format: {ports_str}")
+
+    # Auto-adjust dev if it conflicts with vite
+    if dev == vite:
+        dev = vite + 100
+
+    return default, vite, dev
+
+
+def extract_existing_ports(project_dir: Path) -> tuple[int, int, int] | None:
+    """Extract existing port configuration from project files.
+
+    Returns (default, vite, dev) or None if not found.
+    """
+    module_name = find_module_name(project_dir)
+    if not module_name:
+        return None
+
+    default_port = None
+    vite_port = None
+    dev_port = None
+
+    # Try to extract DEFAULT_PORT from __main__.py
+    main_file = project_dir / module_name / "__main__.py"
+    if main_file.exists():
+        content = main_file.read_text("UTF-8")
+        match = re.search(r"DEFAULT_PORT\s*=\s*(\d+)", content)
+        if match:
+            default_port = int(match.group(1))
+
+    # Try to extract ports from devserver.py
+    devserver_file = project_dir / "scripts" / "devserver.py"
+    if devserver_file.exists():
+        content = devserver_file.read_text("UTF-8")
+        match = re.search(r"DEFAULT_VITE_PORT\s*=\s*(\d+)", content)
+        if match:
+            vite_port = int(match.group(1))
+        match = re.search(r"DEFAULT_DEV_PORT\s*=\s*(\d+)", content)
+        if match:
+            dev_port = int(match.group(1))
+
+    # Return only if we found at least one port
+    if default_port is not None or vite_port is not None or dev_port is not None:
+        return (
+            default_port or DEFAULT_PORTS[0],
+            vite_port or DEFAULT_PORTS[1],
+            dev_port or DEFAULT_PORTS[2],
+        )
+
+    return None
+
+
 def load_template(path: str) -> str:
     """Load a template file from the template directory."""
-    return (TEMPLATE_DIR / path).read_text()
+    return (TEMPLATE_DIR / path).read_text("UTF-8")
 
 
 def find_module_name(project_dir: Path) -> str | None:
@@ -127,7 +207,7 @@ def find_module_name(project_dir: Path) -> str | None:
     if not pyproject.exists():
         return None
 
-    data = tomlkit.parse(pyproject.read_text())
+    data = tomlkit.parse(pyproject.read_text("UTF-8"))
 
     if "project" in data and "name" in data["project"]:
         name = data["project"]["name"]
@@ -176,7 +256,9 @@ def find_fastapi_app(
     return None
 
 
-def _find_app_via_entrypoint(module_dir: Path, project_dir: Path) -> tuple[Path, str] | None:
+def _find_app_via_entrypoint(
+    module_dir: Path, project_dir: Path
+) -> tuple[Path, str] | None:
     """Find FastAPI app by following the CLI entrypoint in pyproject.toml.
 
     If pyproject.toml has a script like `myapp = "myapp.subpkg.__main__:main"`,
@@ -187,7 +269,7 @@ def _find_app_via_entrypoint(module_dir: Path, project_dir: Path) -> tuple[Path,
         return None
 
     try:
-        data = tomlkit.parse(pyproject.read_text())
+        data = tomlkit.parse(pyproject.read_text("UTF-8"))
     except Exception:
         return None
 
@@ -255,7 +337,7 @@ def _find_existing_cli_entrypoint(project_dir: Path, module_name: str) -> str |
         return None
 
     try:
-        data = tomlkit.parse(pyproject.read_text())
+        data = tomlkit.parse(pyproject.read_text("UTF-8"))
     except Exception:
         return None
 
@@ -266,7 +348,7 @@ def _find_existing_cli_entrypoint(project_dir: Path, module_name: str) -> str |
     # Look for any script that references our module
     for script_name, entry in scripts.items():
         if isinstance(entry, str) and entry.startswith(f"{module_name}."):
-            return f"{script_name} = \"{entry}\""
+            return f'{script_name} = "{entry}"'
 
     return None
 
@@ -279,7 +361,7 @@ def _follow_init_reexport(init_file: Path, subpkg_dir: Path) -> tuple[Path, str]
     - from module.subpkg.mainapp import app
     """
     try:
-        content = init_file.read_text()
+        content = init_file.read_text("UTF-8")
     except Exception:
         return None
 
@@ -313,7 +395,7 @@ def _follow_init_reexport(init_file: Path, subpkg_dir: Path) -> tuple[Path, str]
 def _find_app_in_file(path: Path) -> str | None:
     """Find FastAPI app variable name in a file."""
     try:
-        content = path.read_text()
+        content = path.read_text("UTF-8")
     except Exception:
         return None
 
@@ -348,7 +430,7 @@ def patch_app_file(
         print(f"❌ Cannot patch {path} - file not found")
         return False
 
-    original_content = path.read_text()
+    original_content = path.read_text("UTF-8")
     marker = "from fastapi_vue import Frontend"
 
     if marker in original_content:
@@ -415,7 +497,7 @@ def patch_app_file(
         print(f"[DRY RUN] Would patch {path}")
         return True
 
-    path.write_text(content)
+    path.write_text(content, "UTF-8", newline="\n")
     print(f"✅ Patched {path}")
 
     if not lifespan_patched:
@@ -450,7 +532,7 @@ def patch_vite_config(
         print(f"❌ Cannot patch {path} - file not found")
         return False
 
-    original_content = path.read_text()
+    original_content = path.read_text("UTF-8")
     marker = "vite-plugin-fastapi"
 
     if marker in original_content:
@@ -505,7 +587,7 @@ def patch_vite_config(
         print(f"[DRY RUN] Would patch {path}")
         return True
 
-    path.write_text(content)
+    path.write_text(content, "UTF-8", newline="\n")
     print(f"✅ Patched {path}")
     return True
 
@@ -539,7 +621,7 @@ def patch_frontend_health_check(frontend_dir: Path, dry_run: bool = False) -> bo
         print("⚠️  No Vue file found to patch, skipping frontend health check")
         return False
 
-    original_content = target_file.read_text()
+    original_content = target_file.read_text("UTF-8")
 
     # Check if already patched
     if "/api/health" in original_content:
@@ -605,7 +687,7 @@ def patch_frontend_health_check(frontend_dir: Path, dry_run: bool = False) -> bo
         print(f"[DRY RUN] Would patch {target_file}")
         return True
 
-    target_file.write_text(content)
+    target_file.write_text(content, "UTF-8", newline="\n")
     print(f"✅ Patched {target_file}")
     return True
 
@@ -621,11 +703,14 @@ def write_file(
     dry_run: bool = False,
     executable: bool = False,
     fallback_path: Path | None = None,
+    force: bool = False,
 ) -> bool:
     """Write content to a file, handling existing files and dry-run.
 
     If fallback_path is provided and the file exists without the upgrade marker,
     the content will be written to fallback_path instead of being skipped.
+
+    If force=True, always overwrite without checking for upgrade marker.
     """
     exists = path.exists()
     if exists and not overwrite:
@@ -634,13 +719,13 @@ def write_file(
 
     # Check if content is the same
     if exists:
-        existing_content = path.read_text()
+        existing_content = path.read_text("UTF-8")
         if existing_content == content:
             print(f"✔️  {path} (already up to date)")
             return False
 
-        # If overwrite requested but file doesn't have upgrade marker
+        # If overwrite requested but file doesn't have upgrade marker (unless force)
-        if overwrite and UPGRADE_MARKER not in existing_content:
+        if overwrite and not force and UPGRADE_MARKER not in existing_content:
             if fallback_path is not None:
                 # Write to fallback path instead
                 return _write_fallback_file(
@@ -655,7 +740,7 @@ def write_file(
         return True
 
     path.parent.mkdir(parents=True, exist_ok=True)
-    path.write_text(content)
+    path.write_text(content, "UTF-8", newline="\n")
     if executable and sys.platform != "win32":
         path.chmod(path.stat().st_mode | 0o111)
     action = "Updated" if exists else "Created"
@@ -673,7 +758,7 @@ def _write_fallback_file(
     """Write content to a fallback .new.py file when original can't be overwritten."""
     # Check if fallback already has same content
     if fallback_path.exists():
-        if fallback_path.read_text() == content:
+        if fallback_path.read_text("UTF-8") == content:
             print(f"✔️  {fallback_path} (already up to date)")
             return False
 
@@ -683,7 +768,7 @@ def _write_fallback_file(
         return True
 
     fallback_path.parent.mkdir(parents=True, exist_ok=True)
-    fallback_path.write_text(content)
+    fallback_path.write_text(content, "UTF-8", newline="\n")
     if executable and sys.platform != "win32":
         fallback_path.chmod(fallback_path.stat().st_mode | 0o111)
     print(f"✅ Created {fallback_path} (original customized by user)")
@@ -720,6 +805,7 @@ def merge_pyproject(
         req = data["project"]["requires-python"]
         # Parse minimum version from strings like ">=3.10" or ">=3.9,<4"
         import re
+
         match = re.search(r">=\s*(\d+)\.(\d+)", req)
         if match:
             major, minor = int(match.group(1)), int(match.group(2))
@@ -783,8 +869,6 @@ def find_js_runtime() -> tuple[str, str] | None:
     Returns (tool_path, tool_name) where tool_name is "deno", "npm", or "bun".
     Returns None if no runtime is found.
     """
-    import shutil
-
     options = ["deno", "npm", "bun"]
 
     # Check for JS_RUNTIME environment variable
@@ -891,6 +975,9 @@ def cmd_setup(args: argparse.Namespace) -> int:
     - Patching existing projects with integration files
     - Updating already-patched projects
     """
+    # Clear any existing virtual environment to avoid uv using the wrong one (warning)
+    os.environ.pop("VIRTUAL_ENV", None)
+
     project_path = Path(args.project_dir)
 
     # Handle both "." and "/path/to/project"
@@ -935,10 +1022,31 @@ def cmd_setup(args: argparse.Namespace) -> int:
 
     print(f"📦 Module: {module_name}")
 
+    # Determine port configuration
+    # Priority: --ports argument > existing project values > defaults
+    if args.ports:
+        default_port, vite_port, dev_port = parse_ports(args.ports)
+        ports_note = "(--ports)"
+    else:
+        existing_ports = extract_existing_ports(project_dir)
+        if existing_ports:
+            default_port, vite_port, dev_port = existing_ports
+            ports_note = "(kept for upgrade)"
+        else:
+            default_port, vite_port, dev_port = DEFAULT_PORTS
+            ports_note = "(--ports to override)"
+
+    print(
+        f"📡 Ports: default={default_port}, vite={vite_port}, dev={dev_port} {ports_note}"
+    )
+
     # Template variables
     tpl_vars = {
         "MODULE_NAME": module_name,
         "PROJECT_TITLE": project_title,
+        "TEMPLATE_DEFAULT_PORT": str(default_port),
+        "TEMPLATE_VITE_PORT": str(vite_port),
+        "TEMPLATE_DEV_PORT": str(dev_port),
     }
 
     module_dir = project_dir / module_name
@@ -946,7 +1054,9 @@ def cmd_setup(args: argparse.Namespace) -> int:
     fastapi_vue_scripts = scripts_dir / "fastapi-vue"
 
     # Find existing FastAPI app
-    app_info = find_fastapi_app(module_dir, project_dir) if module_dir.exists() else None
+    app_info = (
+        find_fastapi_app(module_dir, project_dir) if module_dir.exists() else None
+    )
 
     if app_info:
         app_file, app_var = app_info
@@ -962,29 +1072,36 @@ def cmd_setup(args: argparse.Namespace) -> int:
 
     # Create directories
     if not dry_run:
-        fastapi_vue_scripts.mkdir(parents=True, exist_ok=True)
         if not module_dir.exists():
             module_dir.mkdir(parents=True)
+        fastapi_vue_scripts.mkdir(parents=True, exist_ok=True)
 
     # === Install scripts (always update our own scripts) ===
-    # util.py and build-frontend.py are internal and always overwritten
+    # Scripts in fastapi-vue folder are internal and always overwritten
     # devserver.py can be customized, so use fallback if needed
-    internal_script_files = [
-        (fastapi_vue_scripts / "util.py", "scripts/fastapi-vue/util.py"),
-        (
-            fastapi_vue_scripts / "build-frontend.py",
-            "scripts/fastapi-vue/build-frontend.py",
-        ),
-    ]
 
-    for dest_path, template_path in internal_script_files:
+    # Remove obsolete util.py if present
-        template = load_template(template_path)
+    obsolete_util = fastapi_vue_scripts / "util.py"
+    if obsolete_util.exists():
+        if dry_run:
+            print(f"[DRY RUN] Would remove obsolete {obsolete_util}")
+        else:
+            obsolete_util.unlink()
+            print(f"🗑️  Removed obsolete {obsolete_util}")
+
+    # Copy all files from the template's fastapi-vue folder
+    template_fastapi_vue_dir = TEMPLATE_DIR / "scripts" / "fastapi-vue"
+    for template_file in template_fastapi_vue_dir.iterdir():
+        if template_file.is_file():
+            dest_path = fastapi_vue_scripts / template_file.name
+            template = template_file.read_text("UTF-8")
             content = render_template(template, **tpl_vars)
             write_file(
                 dest_path,
                 content,
                 overwrite=True,
                 dry_run=dry_run,
+                force=True,  # Internal files, always overwrite
             )
 
     # devserver.py - use fallback if customized by user
@@ -1021,20 +1138,16 @@ def cmd_setup(args: argparse.Namespace) -> int:
         write_file(app_file_path, content, overwrite=False, dry_run=dry_run)
 
     # === Handle __main__.py ===
-    # Skip if project already has a CLI entrypoint in pyproject.toml
-    existing_cli = _find_existing_cli_entrypoint(project_dir, module_name)
-    if existing_cli:
-        print(f"ℹ️  Using existing CLI entrypoint: {existing_cli}")
-    else:
     main_file = module_dir / "__main__.py"
     main_fallback = module_dir / "__main__.new.py"
     template = load_template("backend/__main__.py")
     main_content = render_template(template, **tpl_vars)
 
-        # Use write_file with fallback - it handles all cases:
+    # Check if project already has a CLI entrypoint in pyproject.toml
-        # - File doesn't exist: create it
+    existing_cli = _find_existing_cli_entrypoint(project_dir, module_name)
-        # - File exists with marker: update it
+
-        # - File exists without marker: write to fallback
+    if main_file.exists():
+        # File exists: update if it has the auto-upgrade marker, otherwise use fallback
         write_file(
             main_file,
             main_content,
@@ -1042,6 +1155,15 @@ def cmd_setup(args: argparse.Namespace) -> int:
             dry_run=dry_run,
             fallback_path=main_fallback,
         )
+    elif not existing_cli:
+        # No file and no existing entrypoint: create new __main__.py
+        write_file(
+            main_file,
+            main_content,
+            overwrite=False,
+            dry_run=dry_run,
+        )
+    # else: no file but has existing entrypoint - don't create (user has custom CLI setup)
 
     # === Update vite.config.js/ts ===
     frontend_dir = project_dir / "frontend"
@@ -1070,7 +1192,7 @@ def cmd_setup(args: argparse.Namespace) -> int:
     # === Update pyproject.toml ===
     pyproject_path = project_dir / "pyproject.toml"
     if pyproject_path.exists():
-        old_content = pyproject_path.read_text()
+        old_content = pyproject_path.read_text("UTF-8")
         data = tomlkit.parse(old_content)
 
         updated = merge_pyproject(data, PYPROJECT_ADDITIONS, module_name)
@@ -1089,30 +1211,9 @@ def cmd_setup(args: argparse.Namespace) -> int:
         elif dry_run:
             print(f"[DRY RUN] Would update {pyproject_path}")
         else:
-            pyproject_path.write_text(new_content)
+            pyproject_path.write_text(new_content, "UTF-8", newline="\n")
             print(f"✅ Updated {pyproject_path}")
 
-    # === Add dependencies using uv ===
-    if dry_run:
-        print("[DRY RUN] Would run: uv add -U 'fastapi[standard]' fastapi-vue")
-        print("[DRY RUN] Would run: uv add -U --group dev httpx")
-    else:
-        print("📦 Adding dependencies...")
-        result = subprocess.run(
-            ["uv", "add", "-U", "fastapi[standard]", "fastapi-vue"],
-            cwd=project_dir,
-            check=False,
-        )
-        if result.returncode != 0:
-            print("⚠️  Failed to add main dependencies")
-        result = subprocess.run(
-            ["uv", "add", "-U", "--group", "dev", "httpx"],
-            cwd=project_dir,
-            check=False,
-        )
-        if result.returncode != 0:
-            print("⚠️  Failed to add dev dependencies")
-
     # === Update .gitignore ===
     gitignore_path = project_dir / ".gitignore"
     gitignore_entry = f"/{module_name}/frontend-build"
@@ -1125,14 +1226,39 @@ def cmd_setup(args: argparse.Namespace) -> int:
         else:
             nl = b"\r\n" if b"\r\n" in gitignore_content else b"\n"
             suffix = b"" if gitignore_content.endswith(nl) else nl
-            gitignore_path.write_bytes(gitignore_content + suffix + gitignore_entry.encode() + nl)
+            gitignore_path.write_bytes(
+                gitignore_content + suffix + gitignore_entry.encode() + nl
+            )
             print(f"✅ Added {gitignore_entry} to .gitignore")
     elif dry_run:
         print(f"[DRY RUN] Would create .gitignore with {gitignore_entry}")
     else:
-        gitignore_path.write_text(f"{gitignore_entry}\n")
+        gitignore_path.write_text(f"{gitignore_entry}\n", "UTF-8", newline="\n")
         print("✅ Created .gitignore")
 
+    # === Add dependencies using uv ===
+    uv_add_main = [
+        "uv",
+        "add",
+        "-q",
+        "-U",
+        "--no-sync",
+        "fastapi[standard]",
+        "fastapi-vue",
+    ]
+    uv_add_dev = ["uv", "add", "-q", "-U", "--group", "dev", "httpx"]
+    if dry_run:
+        print(f"[DRY RUN] Would run: {' '.join(uv_add_main)}")
+        print(f"[DRY RUN] Would run: {' '.join(uv_add_dev)}")
+    else:
+        print("📦 Adding dependencies...")
+        result = subprocess.run(uv_add_main, cwd=project_dir, check=False)
+        if result.returncode != 0:
+            print("⚠️  Failed to add main dependencies")
+        result = subprocess.run(uv_add_dev, cwd=project_dir, check=False)
+        if result.returncode != 0:
+            print("⚠️  Failed to add dev dependencies")
+
     print()
     print("=" * 60)
     print("✅ Setup complete!")
@@ -1197,6 +1323,7 @@ Examples:
   fastapi-vue-setup my-new-project     Create a new project from scratch
   fastapi-vue-setup .                  Set up integration in current directory
   fastapi-vue-setup . --dry-run        Preview what would be done
+  fastapi-vue-setup . --ports 8000,5173,8080  Custom ports (default,vite,dev)
 """,
     )
     parser.add_argument(
@@ -1206,6 +1333,11 @@ Examples:
         help="Project directory (use . for current directory)",
     )
     parser.add_argument("--module-name", help="Python module name (auto-detected)")
+    parser.add_argument(
+        "--ports",
+        metavar="DEFAULT,VITE,DEV",
+        help="Port configuration as comma-separated values (default: 3100,3100,3200)",
+    )
     parser.add_argument(
         "--dry-run", action="store_true", help="Show what would be done"
     )

scripts/release.py

@@ -0,0 +1,35 @@
+#!/usr/bin/env -S uv run
+"""Build and release both fastapi-vue and fastapi-vue-setup packages."""
+
+import shutil
+import subprocess
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parent.parent
+DIST = ROOT / "dist"
+FASTAPI_VUE = ROOT / "fastapi-vue"
+
+
+def main():
+    # Clear the dist directory
+    if DIST.exists():
+        shutil.rmtree(DIST)
+    DIST.mkdir()
+
+    # Build fastapi-vue (subdirectory) to root dist
+    subprocess.run(
+        ["uv", "build", "--out-dir", str(DIST)],
+        cwd=FASTAPI_VUE,
+        check=True,
+    )
+
+    # Build fastapi-vue-setup (root)
+    subprocess.run(
+        ["uv", "build", "--out-dir", str(DIST)],
+        cwd=ROOT,
+        check=True,
+    )
+
+
+if __name__ == "__main__":
+    main()

template/backend/__main__.py

@@ -1,54 +1,25 @@
 # auto-upgrade@fastapi-vue-setup - remove this if you modify this file
 import argparse
-import asyncio
-import os
 
-import uvicorn
+from fastapi_vue import server
-from fastapi_vue.hostutil import parse_endpoint
-from uvicorn import Config, Server
 
-from .APP_MODULE import APP_VAR
+DEFAULT_PORT = TEMPLATE_DEFAULT_PORT
-
-DEFAULT_PORT = 5080
-
-
-def run_server(endpoints: list[dict], *, proxy="", devmode=False):
-    conf: dict[str, object] = {"app": "MODULE_NAME.APP_MODULE:APP_VAR"}
-    if proxy:
-        conf["proxy_headers"] = True
-        conf["forwarded_allow_ips"] = proxy
-    if devmode:
-        conf["reload"] = True
-        conf["reload_dirs"] = ["MODULE_NAME"]
-        APP_VAR.debug = True
-
-    if len(endpoints) > 1:
-        # Run separate servers for multiple endpoints
-        async def serve_all():
-            async with asyncio.TaskGroup() as tg:
-                for ep in endpoints:
-                    tg.create_task(Server(Config(**conf, **ep)).serve())
-
-        asyncio.run(serve_all())
-    else:
-        uvicorn.run(**conf, **endpoints[0])
 
 
 def main():
     parser = argparse.ArgumentParser(description="Run the MODULE_NAME server.")
     parser.add_argument(
-        "endpoint",
+        "-l",
-        nargs="?",
+        "--listen",
-        help=(
+        action="append",
-            f"Endpoint (default: localhost:{DEFAULT_PORT}). "
+        help=(f"Endpoint (default: localhost:{DEFAULT_PORT})."),
-            "Forms: host:port | :port | [ipv6]:port | ip | host | unix:/path.sock"
-        ),
     )
     args = parser.parse_args()
-    proxy = os.getenv("FORWARDED_ALLOW_IPS", "127.0.0.1,::1")
+    server.run(
-    devmode = bool(os.getenv("FASTAPI_VUE_FRONTEND_URL"))
+        "MODULE_NAME.APP_MODULE:APP_VAR",
-    endpoints = parse_endpoint(args.endpoint, DEFAULT_PORT)
+        listen=args.listen,
-    run_server(endpoints, proxy=proxy, devmode=devmode)
+        default_port=DEFAULT_PORT,
+    )
 
 
 if __name__ == "__main__":

template/scripts/devserver.py

@@ -1,276 +1,91 @@
 #!/usr/bin/env -S uv run
 # auto-upgrade@fastapi-vue-setup - remove this if you modify this file
-"""Run Vite development server for frontend and FastAPI backend with auto-reload.
+"""Run Vite development server for frontend and FastAPI backend with auto-reload."""
-
-Usage:
-    uv run scripts/devserver.py [host:port] [--backend host:port]
-
-The optional host:port argument sets where the Vite frontend listens.
-Supported forms: host[:port], :port (all interfaces), or just port.
-The --backend option sets where the FastAPI backend listens (default: localhost:5180).
-
-Environment:
-    JS_RUNTIME          Path or name of JS runtime to use (deno, npm/node or bun).
-    FASTAPI_VUE_FRONTEND_URL    Set by this script for the backend to know where Vite is.
-"""
 
 import argparse
 import asyncio
 import contextlib
 import os
+import sys
 from pathlib import Path
-from sys import stderr
 
-import httpx
+from fastapi_vue import server
-from fastapi_vue.hostutil import parse_endpoint
 
-exec((Path(__file__).parent / "fastapi-vue/util.py").read_text("UTF-8"))  # noqa: S102
+# Import util.py from scripts/fastapi-vue (not a package, so we adjust sys.path)
+sys.path.insert(0, str(Path(__file__).with_name("fastapi-vue")))
+from devutil import (  # type: ignore
+    ProcessGroup,
+    check_ports_free,
+    logger,
+    ready,
+    setup_fastapi,
+    setup_vite,
+)
 
-DEFAULT_VITE_PORT = 5173
+DEFAULT_VITE_PORT = TEMPLATE_VITE_PORT
-DEFAULT_BACKEND_PORT = 5180
+DEFAULT_DEV_PORT = TEMPLATE_DEV_PORT
-FRONTEND_PATH = Path(__file__).parent.parent / "frontend"
-
-EPILOG = """
-  scripts/devserver.py                       # Default ports on localhost
-  scripts/devserver.py 3000                  # Vite on localhost:3000
-  scripts/devserver.py :3000 --backend 8000  # *:3000, localhost:8000
-"""
-
-BUN_BUG = """\
-┃ ⚠️  Bun cannot correctly proxy API requests to the backend.
-┃ Bug report: https://github.com/oven-sh/bun/issues/9882
-┃
-┃ Consider using deno or npm instead for development.
-"""
 
 
-def resolve_frontend_tools(
+async def run_devserver(frontend: str, backend: str) -> None:
-    vite_port: int, all_ifaces: bool
+    reporoot = Path(__file__).parent.parent
-) -> tuple[list[str], list[str], str]:
+    front = reporoot / "frontend"
-    """Resolve frontend install and dev commands.
+    if not (front / "package.json").exists():
-
+        logger.warning("Frontend source not found at %s", front)
-    Returns (install_cmd, dev_cmd, tool_name).
-    Raises SystemExit if tools are not available.
-    """
-    if not (FRONTEND_PATH / "package.json").exists():
-        stderr.write(f"┃ ⚠️  Frontend source not found at {FRONTEND_PATH}\n")
         raise SystemExit(1)
 
-    result = find_js_runtime()  # noqa # type: ignore
+    viteurl, npm_install, vite = setup_vite(frontend, DEFAULT_VITE_PORT)
-    if result is None:
+    backurl, module, backend_config = setup_fastapi(
-        if not os.environ.get("JS_RUNTIME"):
+        backend, "MODULE_NAME.APP_MODULE:APP_VAR", DEFAULT_DEV_PORT
-            stderr.write("┃ ⚠️  deno, npm or bun needed to run the frontend server.\n")
-        raise SystemExit(1)
-
-    tool, name = result
-
-    install_args = {
-        "deno": ("install", "--quiet", "--allow-scripts=npm:vue-demi"),
-        "npm": ("install", "--silent"),
-        "bun": ("install", "--silent"),
-    }
-    dev_args = {
-        "deno": ("run", "dev", "--"),
-        "npm": ("--silent", "run", "dev", "--"),
-        "bun": ("run", "dev", "--"),
-    }
-
-    install_cmd = [tool, *install_args[name]]
-    dev_cmd = [
-        tool,
-        *dev_args[name],
-        "--clearScreen=false",
-        f"--port={vite_port}",
-    ]
-
-    if all_ifaces:
-        dev_cmd.append("--host")
-
-    if name == "bun":
-        stderr.write(BUN_BUG)
-
-    return install_cmd, dev_cmd, name
-
-
-async def wait_for_backend(host: str, port: int):
-    """Wait for the backend to be ready by polling the health endpoint."""
-    max_attempts = 50
-    url = f"http://{host}:{port}"
-
-    async with httpx.AsyncClient() as client:
-        for attempt in range(max_attempts):
-            try:
-                await client.get(url, timeout=1.0)
-                stderr.write("✓ Backend ready!\n")
-                return True
-            except httpx.RequestError:
-                if attempt == max_attempts - 1:
-                    stderr.write("┃ ⚠️  Backend didn't start in time\n")
-                    return False
-                await asyncio.sleep(0.1)
-    return False
-
-
-async def _terminate_process(proc: asyncio.subprocess.Process, name: str) -> None:
-    """Gracefully terminate a subprocess."""
-    if proc.returncode is not None:
-        return
-    try:
-        proc.terminate()
-    except ProcessLookupError:
-        return
-    try:
-        await asyncio.wait_for(proc.wait(), timeout=2)
-    except TimeoutError:
-        try:
-            proc.kill()
-        except ProcessLookupError:
-            return
-        await proc.wait()
-
-
-async def run_devserver(
-    vite_port: int,
-    all_ifaces: bool,
-    backend_host: str,
-    backend_port: int,
-) -> None:
-    """Run the development server with install, backend, and frontend."""
-    install_cmd, dev_cmd, tool_name = resolve_frontend_tools(vite_port, all_ifaces)
-
-    # Tell the backend where the Vite dev server is
-    os.environ["FASTAPI_VUE_FRONTEND_URL"] = f"http://localhost:{vite_port}"
-    # Tell Vite where the backend is (for proxying /api requests)
-    os.environ["FASTAPI_VUE_BACKEND_URL"] = f"http://{backend_host}:{backend_port}"
-
-    backend_cmd = [
-        "uvicorn",
-        "MODULE_NAME.app:app",
-        "--host",
-        backend_host,
-        "--port",
-        str(backend_port),
-        "--reload",
-    ]
-
-    cwd = str(Path(__file__).parent.parent)
-    frontend_cwd = str(FRONTEND_PATH)
-
-    backend_proc: asyncio.subprocess.Process | None = None
-    install_proc: asyncio.subprocess.Process | None = None
-    frontend_proc: asyncio.subprocess.Process | None = None
-
-    try:
-        # Start install (concurrent with backend)
-        stderr.write(f">>> {tool_name} {' '.join(install_cmd[1:])}\n")
-        install_proc = await asyncio.create_subprocess_exec(
-            *install_cmd, cwd=frontend_cwd
     )
 
-        await asyncio.sleep(0.1)
+    # Tell the everyone where the frontend and backend are (vite proxy, etc)
+    os.environ["FASTAPI_VUE_FRONTEND_URL"] = viteurl
+    os.environ["FASTAPI_VUE_BACKEND_URL"] = backurl
 
-        # Start backend (concurrent with install)
+    async with ProcessGroup() as pg:
-        stderr.write(f">>> {' '.join(backend_cmd)}\n")
+        npm_i = await pg.spawn(*npm_install, cwd=front)
-        backend_proc = await asyncio.create_subprocess_exec(*backend_cmd, cwd=cwd)
+        await check_ports_free(viteurl, backurl)
 
-        # Wait for install to complete and backend to be ready
+        # Run backend in a thread (server.run is blocking)
-        install_task = asyncio.create_task(install_proc.wait(), name="install")
+        loop = asyncio.get_event_loop()
-        backend_ready_task = asyncio.create_task(
+        loop.run_in_executor(None, lambda: server.run(module, **backend_config))
-            wait_for_backend(backend_host, backend_port), name="backend_ready"
-        )
 
-        done, pending = await asyncio.wait(
+        # Wait for both install and backend to be ready
-            {install_task, backend_ready_task},
+        await pg.wait(npm_i, ready(backurl, path="/api/health?from=devserver.py"))
-            return_when=asyncio.FIRST_COMPLETED,
-        )
 
-        for task in done:
+        # Start Vite dev server (ProcessGroup waits for any exit, then terminates others)
-            if task.get_name() == "install":
+        await pg.spawn(*vite, cwd=front)
-                if task.result() != 0:
-                    stderr.write("┃ ⚠️  Install failed\n")
-                    raise SystemExit(1)
-            elif task.get_name() == "backend_ready" and not task.result():
-                raise SystemExit(1)
-
-        if pending:
-            done2, _ = await asyncio.wait(pending)
-            for task in done2:
-                if task.get_name() == "install":
-                    if task.result() != 0:
-                        stderr.write("┃ ⚠️  Install failed\n")
-                        raise SystemExit(1)
-                elif task.get_name() == "backend_ready" and not task.result():
-                    raise SystemExit(1)
-
-        install_proc = None
-
-        # Start Vite dev server
-        stderr.write(f">>> {tool_name} {' '.join(dev_cmd[1:])}\n")
-        frontend_proc = await asyncio.create_subprocess_exec(*dev_cmd, cwd=frontend_cwd)
-
-        # Wait for either process to exit
-        done, pending = await asyncio.wait(
-            {
-                asyncio.create_task(backend_proc.wait(), name="backend"),
-                asyncio.create_task(frontend_proc.wait(), name="frontend"),
-            },
-            return_when=asyncio.FIRST_COMPLETED,
-        )
-        for t in done:
-            t.result()
-        for t in pending:
-            t.cancel()
-
-    except asyncio.CancelledError:
-        stderr.write("\n✓ Shutting down...\n")
-    finally:
-        if frontend_proc is not None:
-            await _terminate_process(frontend_proc, "frontend")
-        if install_proc is not None:
-            await _terminate_process(install_proc, "install")
-        if backend_proc is not None:
-            await _terminate_process(backend_proc, "backend")
 
 
 def main():
     parser = argparse.ArgumentParser(
         description="Run Vite and FastAPI development servers",
         formatter_class=argparse.RawDescriptionHelpFormatter,
-        epilog=EPILOG,
+        epilog=HELP_EPILOG,
     )
     parser.add_argument(
         "frontend",
         nargs="?",
         metavar="host:port",
-        help="Vite frontend endpoint (default: localhost:5173)",
+        help=f"Vite frontend endpoint (default: localhost:{DEFAULT_VITE_PORT})",
     )
     parser.add_argument(
         "--backend",
         metavar="host:port",
-        help="FastAPI backend endpoint (default: localhost:5180)",
+        help=f"FastAPI backend endpoint (default: localhost:{DEFAULT_DEV_PORT})",
     )
     args = parser.parse_args()
-
-    # parse_endpoint returns list of dicts with host/port or uds keys
-    # Multiple entries means bind all interfaces (IPv4 + IPv6)
-    vite_endpoints = parse_endpoint(args.frontend, DEFAULT_VITE_PORT)
-    backend_endpoints = parse_endpoint(args.backend, DEFAULT_BACKEND_PORT)
-
-    # Vite doesn't support unix sockets
-    if "uds" in vite_endpoints[0]:
-        stderr.write("┃ ⚠️  Unix sockets not supported for frontend\n")
-        raise SystemExit(1)
-    if "uds" in backend_endpoints[0]:
-        stderr.write("┃ ⚠️  Unix sockets not supported for backend\n")
-        raise SystemExit(1)
-
-    vite_port = vite_endpoints[0]["port"]
-    all_ifaces = len(vite_endpoints) > 1
-    backend_host = backend_endpoints[0]["host"]
-    backend_port = backend_endpoints[0]["port"]
-
     with contextlib.suppress(KeyboardInterrupt):
-        asyncio.run(run_devserver(vite_port, all_ifaces, backend_host, backend_port))
+        asyncio.run(run_devserver(args.frontend, args.backend))
+
+
+HELP_EPILOG = """
+  scripts/devserver.py                       # Default ports on localhost
+  scripts/devserver.py 3000                  # Vite on localhost:3000
+  scripts/devserver.py :3000 --backend 8000  # *:3000, localhost:8000
+
+  JS_RUNTIME environment variable can be used to select the JS runtime
+"""
 
 
 if __name__ == "__main__":

template/scripts/fastapi-vue/build-frontend.py

@@ -1,34 +1,15 @@
 """Hatch build hook for building Vue frontend during package build."""
 
-import subprocess
+import sys
 from pathlib import Path
-from sys import stderr
 
 from hatchling.builders.hooks.plugin.interface import BuildHookInterface  # type: ignore
 
-exec(Path(__file__).with_name("util.py").read_text("UTF-8"))  # noqa: S102
+sys.path.insert(0, str(Path(__file__).parent))
-
+from buildutil import build
-
-def run(cmd, **kwargs):
-    """Run a command and display it."""
-    display_cmd = [Path(cmd[0]).name, *cmd[1:]]
-    stderr.write(f"### {' '.join(display_cmd)}\n")
-    subprocess.run(cmd, check=True, **kwargs)
 
 
 class CustomBuildHook(BuildHookInterface):
-    """Build hook that compiles Vue frontend before packaging."""
-
     def initialize(self, version, build_data):
         super().initialize(version, build_data)
-        stderr.write(">>> Building the frontend\n")
+        build("frontend")
-
-        install_cmd, build_cmd = find_build_tool()  # noqa # type: ignore
-
-        try:
-            run(install_cmd, cwd="frontend")
-            stderr.write("\n")
-            run(build_cmd, cwd="frontend")
-        except Exception as e:
-            stderr.write(f"Error occurred while building frontend: {e}\n")
-            raise

template/scripts/fastapi-vue/buildutil.py

@@ -0,0 +1,191 @@
+"""Utilities used at build time and in devserver script. No dependencies."""
+
+import logging
+import os
+import re
+import shutil
+import subprocess
+from pathlib import Path
+
+
+class _PrefixFormatter(logging.Formatter):
+    """Formatter that adds prefix based on log level."""
+
+    def format(self, record: logging.LogRecord) -> str:
+        if record.levelno >= logging.WARNING:
+            return f"⚠️  {record.getMessage()}"
+        return record.getMessage()
+
+
+_handler = logging.StreamHandler()
+_handler.setFormatter(_PrefixFormatter())
+logger = logging.getLogger("fastapi-vue")
+logger.addHandler(_handler)
+logger.setLevel(logging.INFO)
+
+
+def _check_node_version(node_path: str) -> None:
+    """Check if Node.js version is >= 20.
+
+    Raises RuntimeError if version is too old or cannot be determined.
+    """
+    try:
+        result = subprocess.run(
+            [node_path, "--version"], capture_output=True, text=True, check=True
+        )
+        version_str = result.stdout.strip()
+        # Parse version like "v20.10.0" or "v18.17.1"
+        match = re.match(r"v(\d+)", version_str)
+        if match:
+            major_version = int(match.group(1))
+            if major_version >= 20:
+                return
+            raise RuntimeError(
+                f"Node.js {version_str} found, but v20+ required (install with nvm)"
+            )
+    except (subprocess.CalledProcessError, FileNotFoundError, ValueError):
+        pass
+    raise RuntimeError("Could not determine Node.js version")
+
+
+def find_js_runtime() -> tuple[str, str]:
+    """Find a JavaScript runtime from JS_RUNTIME env or auto-detect.
+
+    Returns (tool_path, tool_name) where tool_name is "deno", "npm", or "bun".
+    Raises JSRuntimeError if no suitable runtime is found.
+    """
+    options = ["npm", "deno", "bun"]
+    node_version_error: RuntimeError | None = None
+
+    # Check for JS_RUNTIME environment variable
+    if js_runtime_env := os.environ.get("JS_RUNTIME"):
+        js_runtime = js_runtime_env
+        js_path = Path(js_runtime)
+        runtime_name = js_path.name
+        # Map node to npm
+        if runtime_name == "node":
+            runtime_name = "npm"
+            js_runtime = str(js_path.parent / "npm") if js_path.parent.name else "npm"
+        for option in options:
+            if option == runtime_name or runtime_name.startswith(option):
+                tool = shutil.which(js_runtime)
+                if tool is None:
+                    raise RuntimeError(
+                        f"JS_RUNTIME={js_runtime_env}: {option} not found"
+                    )
+                # Check Node.js version if using npm
+                if option == "npm":
+                    node_path = shutil.which("node", path=str(Path(tool).parent))
+                    if node_path is None:
+                        raise RuntimeError(
+                            f"JS_RUNTIME={js_runtime_env}: node not found"
+                        )
+                    _check_node_version(node_path)  # Raises on failure
+                return tool, option
+        raise RuntimeError(f"JS_RUNTIME={js_runtime_env} not recognized")
+
+    # Auto-detect
+    for option in options:
+        if tool := shutil.which(option):
+            # Check Node.js version if using npm
+            if option == "npm":
+                node_path = shutil.which("node", path=str(Path(tool).parent))
+                if node_path is None:
+                    continue
+                try:
+                    _check_node_version(node_path)
+                except RuntimeError as e:
+                    node_version_error = e
+                    continue  # Try next runtime
+            return tool, option
+
+    # No runtime found - provide helpful error
+    if node_version_error:
+        raise node_version_error
+    raise RuntimeError("Node.js (v20+), Deno or Bun is required but none was found")
+
+
+def find_build_tool():
+    """Find JavaScript runtime and construct install/build commands.
+
+    Returns (install_cmd, build_cmd) tuples of command lists.
+    Raises RuntimeError if no runtime is found.
+    """
+    install = {
+        "deno": ("install", "--allow-scripts=npm:vue-demi"),
+        "npm": ("install",),
+        "bun": ("--bun", "install"),
+    }
+    # Run vite directly for deno to avoid npm-run-all2/run-p issues
+    build = {
+        "deno": ("run", "-A", "npm:vite", "build"),
+        "npm": ("run", "build"),
+        "bun": ("--bun", "run", "build"),
+    }
+
+    tool, name = find_js_runtime()
+    return [tool, *install[name]], [tool, *build[name]]
+
+
+def find_dev_tool() -> list[str]:
+    """Find JavaScript runtime and construct dev command.
+
+    Returns dev_cmd (without vite-specific args).
+    Raises RuntimeError if no runtime is found.
+    """
+    dev_args = {
+        "deno": ("run", "dev", "--"),
+        "npm": ("--silent", "run", "dev", "--"),
+        "bun": ("run", "dev", "--"),
+    }
+
+    tool, name = find_js_runtime()
+
+    if name == "bun":
+        logger.warning(
+            "Bun has a bug in WS proxying (https://github.com/oven-sh/bun/issues/9882). Consider using npm instead."
+        )
+
+    return [tool, *dev_args[name]]
+
+
+def find_install_tool() -> list[str]:
+    """Find JavaScript runtime and construct install command.
+
+    Returns install_cmd.
+    Raises RuntimeError if no runtime is found.
+    """
+    install_args = {
+        "deno": ("install", "--quiet", "--allow-scripts=npm:vue-demi"),
+        "npm": ("install", "--silent"),
+        "bun": ("install", "--silent"),
+    }
+
+    tool, name = find_js_runtime()
+    return [tool, *install_args[name]]
+
+
+def build(folder: str = "frontend") -> None:
+    """Build the frontend in the specified folder.
+
+    Raises SystemExit(1) on failure.
+    """
+    logger.info(">>> Building %s", folder)
+
+    try:
+        install_cmd, build_cmd = find_build_tool()
+    except RuntimeError as e:
+        logger.warning(e)
+        raise SystemExit(1)
+
+    def run(cmd):
+        display_cmd = [Path(cmd[0]).name, *cmd[1:]]
+        logger.info("### %s", " ".join(display_cmd))
+        subprocess.run(cmd, check=True, cwd=folder)
+
+    try:
+        run(install_cmd)
+        logger.info("")
+        run(build_cmd)
+    except subprocess.CalledProcessError:
+        raise SystemExit(1)

template/scripts/fastapi-vue/devutil.py

@@ -0,0 +1,183 @@
+"""Utilities meant for devserver script, used only in source repository with dev deps."""
+
+import asyncio
+import subprocess
+from collections.abc import Coroutine
+from contextlib import suppress
+from pathlib import Path
+from typing import Any
+
+import httpx
+from buildutil import find_dev_tool, find_install_tool, logger
+from fastapi_vue.hostutil import parse_endpoint
+
+
+class ProcessGroup:
+    """Manage async subprocesses with automatic cleanup, like TaskGroup for processes."""
+
+    def __init__(self):
+        self._procs: list[asyncio.subprocess.Process] = []
+        self._cmds: dict[int, str] = {}  # pid -> command name
+
+    async def spawn(
+        self, *cmd: str, cwd: str | None = None
+    ) -> asyncio.subprocess.Process:
+        """Spawn a subprocess and track it."""
+        cmd_name = Path(cmd[0]).name
+        logger.info(">>> %s", " ".join([cmd_name, *cmd[1:]]))
+        proc = await asyncio.create_subprocess_exec(*cmd, cwd=cwd)
+        self._procs.append(proc)
+        self._cmds[proc.pid] = cmd_name
+        return proc
+
+    async def wait(
+        self, *waitables: "asyncio.subprocess.Process | Coroutine[Any, Any, Any]"
+    ) -> None:
+        """Wait for processes/coroutines to complete, raise SystemExit on failure."""
+
+        async def wait_proc(proc: asyncio.subprocess.Process) -> None:
+            returncode = await proc.wait()
+            if returncode != 0:
+                cmd_name = self._cmds.get(proc.pid, "unknown")
+                raise subprocess.CalledProcessError(returncode, cmd_name)
+
+        tasks = [
+            wait_proc(w) if isinstance(w, asyncio.subprocess.Process) else w
+            for w in waitables
+        ]
+        try:
+            await asyncio.gather(*tasks)
+        except subprocess.CalledProcessError as e:
+            logger.warning("%s failed with exit status %d", e.cmd, e.returncode)
+            raise SystemExit(1) from None
+
+    async def __aenter__(self):
+        return self
+
+    async def __aexit__(self, exc_type, *_):
+        """Wait for one process to exit, terminate others, then wait for all."""
+        await self._cleanup(immediate=exc_type is not None)
+
+    async def _cleanup(self, immediate: bool = False):
+        running = [p for p in self._procs if p.returncode is None]
+        if not running:
+            return
+
+        if not immediate:
+            # Wait for any one process to exit
+            with suppress(asyncio.CancelledError):
+                await asyncio.wait(
+                    [asyncio.create_task(p.wait()) for p in running],
+                    return_when=asyncio.FIRST_COMPLETED,
+                )
+
+        # Terminate remaining processes
+        for p in self._procs:
+            if p.returncode is None:
+                with suppress(ProcessLookupError):
+                    p.terminate()
+
+        # Wait for all to finish (with overall timeout), shielded from cancellation
+        still_running = [p for p in self._procs if p.returncode is None]
+        if still_running:
+            with suppress(asyncio.CancelledError):
+                try:
+                    await asyncio.shield(
+                        asyncio.wait_for(
+                            asyncio.gather(*[p.wait() for p in still_running]),
+                            timeout=10,
+                        )
+                    )
+                except TimeoutError:
+                    for p in self._procs:
+                        if p.returncode is None:
+                            with suppress(ProcessLookupError):
+                                p.kill()
+                            await p.wait()
+
+
+async def check_ports_free(*urls: str) -> None:
+    """Verify URLs are not responding (ports are free). Raise SystemExit if any respond."""
+
+    async def check(client: httpx.AsyncClient, url: str) -> None:
+        with suppress(httpx.RequestError):
+            res = await client.get(url, timeout=0.1)
+            server = res.headers.get("server", "server")
+            logger.warning("Conflicting %s already running at %s", server, url)
+            raise SystemExit(1)
+
+    async with httpx.AsyncClient() as client:
+        await asyncio.gather(*[check(client, url) for url in urls])
+
+
+async def ready(url: str, path: str = "") -> None:
+    """Wait for the server to be ready by polling an endpoint.
+
+    Raises SystemExit(1) if server doesn't start in time.
+    """
+    max_attempts = 50
+    full_url = f"{url}{path}"
+
+    async with httpx.AsyncClient() as client:
+        for attempt in range(max_attempts):
+            try:
+                await client.get(full_url, timeout=1.0)
+                logger.info("✓ Backend ready!")
+                return
+            except httpx.RequestError:
+                if attempt == max_attempts - 1:
+                    logger.warning("Backend didn't start in time")
+                    raise SystemExit(1)
+                await asyncio.sleep(0.1)
+
+
+def setup_vite(
+    endpoint: str, default_port: int = 5173
+) -> tuple[str, list[str], list[str]]:
+    """Parse frontend endpoint and build commands.
+
+    Returns (url, install_cmd, dev_cmd).
+    Raises SystemExit(1) on invalid config.
+    """
+    endpoints = parse_endpoint(endpoint, default_port)
+
+    if "uds" in endpoints[0]:
+        logger.warning("Unix sockets not supported with vite devserver")
+        raise SystemExit(1)
+
+    port = endpoints[0]["port"]
+    host = endpoints[0]["host"]
+
+    install_cmd = find_install_tool()
+    dev_cmd = find_dev_tool()
+    if host != "localhost":
+        dev_cmd.append("--host" if len(endpoints) > 1 else f"--host={host}")
+    dev_cmd.append(f"--port={port}")
+
+    return f"http://{host}:{port}", install_cmd, dev_cmd
+
+
+def setup_fastapi(
+    endpoint: str, module: str, default_port: int = 8000
+) -> tuple[str, str, dict]:
+    """Parse backend endpoint and build server.run() config.
+
+    Returns (url, module, config_dict).
+    Raises SystemExit(1) on invalid config.
+    """
+    endpoints = parse_endpoint(endpoint, default_port)
+
+    if "uds" in endpoints[0]:
+        logger.warning("Unix sockets not supported with vite devserver")
+        raise SystemExit(1)
+
+    host = endpoints[0]["host"]
+    port = endpoints[0]["port"]
+
+    config = {
+        "listen": f"{host}:{port}",
+        "reload": True,
+        "reload_dirs": [module.split(".")[0]],  # Don't reload on frontend changes
+        "forwarded_allow_ips": "*",
+    }
+    return f"http://{host}:{port}", module, config

template/scripts/fastapi-vue/util.py

@@ -1,87 +0,0 @@
-"""Shared utilities for build and dev scripts."""
-
-import os
-import shutil
-from pathlib import Path
-from sys import stderr
-
-
-def find_js_runtime() -> tuple[str, str] | None:
-    """Find a JavaScript runtime from JS_RUNTIME env or auto-detect.
-
-    Returns (tool_path, tool_name) where tool_name is "deno", "npm", or "bun".
-    Returns None if no runtime is found.
-    """
-    options = ["deno", "npm", "bun"]
-
-    # Check for JS_RUNTIME environment variable
-    if js_runtime_env := os.environ.get("JS_RUNTIME"):
-        js_runtime = js_runtime_env
-        js_path = Path(js_runtime)
-        runtime_name = js_path.name
-        # Map node to npm
-        if runtime_name == "node":
-            runtime_name = "npm"
-            js_runtime = str(js_path.parent / "npm") if js_path.parent.name else "npm"
-        for option in options:
-            if option == runtime_name or runtime_name.startswith(option):
-                tool = shutil.which(js_runtime)
-                if tool is None:
-                    stderr.write(f"┃ ⚠️  JS_RUNTIME={js_runtime_env} not found\n")
-                    return None
-                return tool, option
-        stderr.write(f"┃ ⚠️  JS_RUNTIME={js_runtime_env} not recognized\n")
-        return None
-
-    # Auto-detect
-    for option in options:
-        if tool := shutil.which(option):
-            return tool, option
-    return None
-
-
-def find_build_tool():
-    """Find JavaScript runtime and construct install/build commands.
-
-    Returns (install_cmd, build_cmd) tuples of command lists.
-    Raises RuntimeError if no runtime is found.
-    """
-    install = {
-        "deno": ("install", "--allow-scripts=npm:vue-demi"),
-        "npm": ("install",),
-        "bun": ("--bun", "install"),
-    }
-    # Run vite directly for deno to avoid npm-run-all2/run-p issues
-    build = {
-        "deno": ("run", "-A", "npm:vite", "build"),
-        "npm": ("run", "build"),
-        "bun": ("--bun", "run", "build"),
-    }
-
-    result = find_js_runtime()
-    if result is None:
-        raise RuntimeError(
-            "Deno, npm or Bun is required for building but none was found"
-        )
-
-    tool, name = result
-    return [tool, *install[name]], [tool, *build[name]]
-
-
-def find_dev_tool():
-    """Find JavaScript runtime and construct dev command.
-
-    Returns (dev_cmd, tool_name) or (None, None) if not found.
-    """
-    dev_args = {
-        "deno": ("run", "dev", "--"),
-        "npm": ("--silent", "run", "dev", "--"),
-        "bun": ("run", "dev", "--"),
-    }
-
-    result = find_js_runtime()
-    if result is None:
-        return None, None
-
-    tool, name = result
-    return [tool, *dev_args[name]], name