Better handling of upgrades, an option to avoid overwriting main and devserver scripts, writing .new.py instead. Error out on unix socket in devserver.

README.md

@@ -1,15 +1,13 @@
 # fastapi-vue-setup
 
-Tool to create or patch FastAPI project with a Vue frontend, with integrated build and development systems. Only building the package needs JS runtime and Vue. Additionally, a devmode setup using Vite dev server with hot auto reloads is available via the scripts/devserver.py script (only intended to be used on the source repo, not included in installed package).
+Tool to create or patch FastAPI project with a Vue frontend, with integrated build and development systems. The Python package will not need any JS runtime because it includes a prebuilt Vue frontend in it. For development (Vite and FastAPI auto reloads) and building the package one of npm, deno or bun is required (node is recommended due to bugs in deno and bun).
 
 ## Features
 
 - **No JavaScript**: Your Python package can be installed and used without any JS runtime
-- **Create new projects** with `uv init` + `create-vue` (interactive)
-- **Patch existing projects** with build hooks and dev server scripts
 - **Integrated build system**: Vue frontend builds into Python package during `uv build`
 - **Development server**: Single command runs Vite + FastAPI with hot-reload
-- **Optimized static serving**: zstd compression, ETag caching, SPA support
+- **Optimized static serving**: Caching, zstd compression and SPA support
 
 ## Installation
 
@@ -28,77 +26,98 @@ uvx fastapi-vue-setup my-app
 
 ## Usage
 
+The script may be used to create an all new project folder or to patch or update an existing project to use this framework. It autodetects the project folder given and performs the appropriate actions.
+
 ### Create a new project
 
 ```sh
-fastapi-vue-setup new my-app
+fastapi-vue-setup my-app
 ```
 
 This will:
 
 1. Run `uv init my-app`
-2. Run `npm create vue@latest frontend` (interactive)
+2. Run `create-vue frontend` (interactive - choose your Vue options)
 3. Patch the project with FastAPI integration
+4. Install dependencies via `uv add`
 
 ### Patch an existing project
 
-```bash
-fastapi-vue-setup patch /path/to/project
+You should have your pyproject.toml at the current working directory, and Vue with its package.json under `frontend/`. If either one is missing, new applications will be initialised. Otherwise we only patch what can be patched without breaking your existing projects.
+
+```sh
+fastapi-vue-setup .
 ```
 
+### CLI Options
+
+```
+fastapi-vue-setup [project-dir] [options]
+
 Options:
-
-- `--module-name NAME`: Python module name (auto-detected from pyproject.toml)
-- `--vite-port PORT`: Vite dev server port (default: 5173)
-- `--backend-port PORT`: Backend API port in dev mode (default: 5174)
-- `--prod-port PORT`: Production server port (default: 8000)
-- `--force`: Overwrite existing files
-- `--dry-run`: Preview changes without modifying files
-
-### Update an existing project
-
-```bash
-fastapi-vue-setup update /path/to/project
+  --module-name NAME    Python module name (auto-detected from pyproject.toml)
+  --dry-run             Preview changes without modifying files
 ```
 
-Same as `patch --force` - overwrites template files with latest versions.
-
 ## Port Configuration
 
-The tool uses three distinct ports:
+In development, you access the Vite dev server at `http://localhost:5173`. Vite proxies `/api/*` requests to FastAPI at port 5180. Ports and hosts of Vite and FastAPI are configurable by `devserver.py` arguments.
 
-| Port | Purpose               | Used by                        |
-| ---- | --------------------- | ------------------------------ |
-| 5173 | Vite dev server (HMR) | `npm run dev` via devserver.py |
-| 5174 | FastAPI in dev mode   | uvicorn via devserver.py       |
-| 8000 | Production server     | `uv run my-app`                |
+In production, FastAPI serves both the API and static files at `http://localhost:5080`. Configurable by `host:port` argument with defaults set in `__main__.py`
 
-In development, you access the app at `http://localhost:5173`. Vite proxies `/api/*` requests to FastAPI at port 5174.
+## Main CLI
 
-In production, FastAPI serves both the API and static files from the same port (8000).
+If your project didn't already have `__main__.py`, we create one that runs the FastAPI app with richer configuration than what the FastAPI CLI offers. Running your module starts it in production mode, and optionally host:port may be given as argument to specify where it listens.
+
+If you are running behind a reverse proxy like [Caddy](https://caddyserver.com/) on localhost, your app will trust the proxy headers it sends. However, if you need to configure another proxy host or IP, set `FORWARDED_ALLOW_IPS` env variable before running the server.
+
+The devserver script depends on this CLI entry for running the backend. You will have to modify the `devserver.py` script if your app has its own incompatible main module. Note that we set FastAPI debug mode and Uvicorn reload when configured via `FASTAPI_VUE_BACKEND_URL` env variable (set by `devserver.py`), while for normal production use these stay disabled. The same variable also controls static files serving (disabled in dev mode).
+
+
+## Vite Plugin Configuration
+
+The `fastapiVue()` plugin in `vite.config.ts` accepts options to customize proxy behavior:
+
+```js
+import fastapiVue from "./vite-plugin-fastapi.js";
+
+export default defineConfig({
+  plugins: [
+    vue(),
+    // Default: proxies only /api
+    fastapiVue(),
+
+    // Or specify custom paths to proxy to backend
+    fastapiVue({ paths: ["/api", "/auth", "/ws"] }),
+  ],
+});
+```
+
+The plugin reads environment `FASTAPI_VUE_BACKEND_URL` (default: `http://localhost:5180`) to determine where to proxy requests. This is set automatically by `devserver.py`.
 
 ## Project Structure
 
-After patching, your project will have:
-
 ```
 my-app/
-├── frontend/                 # Vue.js application
+├── frontend/                 # Vue application
 │   ├── src/
-│   ├── vite.config.ts       # Builds to ../my_app/frontend-build
+│   ├── vite-plugin-fastapi.js
+│   ├── vite.config.js
 │   └── package.json
-├── my_app/                  # Python package
+├── my_app/                   # Python module (files included in sdist)
 │   ├── __init__.py
-│   ├── __main__.py          # CLI entry point
-│   ├── app.py               # FastAPI application
-│   └── frontend-build/      # Built frontend (gitignored)
+│   ├── __main__.py           # CLI entrypoint
+│   ├── app.py                # FastAPI application
+│   └── frontend-build/       # Built frontend (gitignored)
 ├── scripts/
-│   ├── devserver.py         # Development server
-│   └── fastapi-vue/         # Build utilities
-└── pyproject.toml           # Project configuration
+│   ├── devserver.py          # CLI dev server (only in source tree)
+│   └── fastapi-vue/
+│       ├── build-frontend.py
+│       └── util.py
+└── pyproject.toml
 ```
 
-The script finds your existing fastpi app module (even if not named app.py) and other files and patches them with minimal changes to enable the Vue-FastAPI interconnection.
+The project directory tree looks roughly like this after project creation or patching. The script finds your existing app module and other files and patches them with minimal changes to enable the Vue-FastAPI interconnection. New Python and Vue projects are created automatically if none exist.
 
 ## Development Workflow
 
@@ -113,12 +132,6 @@ uv build
 uv run my-app
 ```
 
-## Static File Serving
+## Frontend serving
 
-The `Frontend` class provides:
-
-- **Automatic zstd compression** at level 18
-- **Smart caching**: Content-hashed assets get `immutable` cache headers
-- **ETag support**: 304 Not Modified responses for cached content
-- **SPA routing**: Falls back to index.html for client-side routes
-- **Favicon handling**: Automatic /favicon.ico from hashed assets
+Your FastAPI app will use [fastapi-vue](https://git.zi.fi/LeoVasanko/fastapi-vue) to serve the frontend files. Refer to that package's documentation for further configuration.

fastapi_vue_setup.py

@@ -7,12 +7,7 @@ Usage:
 
 Options:
     --module-name NAME      Python module name (auto-detected from pyproject.toml)
-    --vite-port PORT        Vite dev server port (default: 5173)
-    --backend-port PORT     Backend API port in dev mode (default: 5180)
-    --prod-port PORT        Production server port (default: 5080)
     --dry-run               Show what would be done without making changes
-
-Port options update existing files when specified, allowing reconfiguration.
 """
 
 import argparse
@@ -20,26 +15,25 @@ import os
 import re
 import subprocess
 import sys
-import tomllib
 from pathlib import Path
+from textwrap import indent
 
-import tomli_w
-
-# Port configuration (keeping them distinct)
-DEFAULT_VITE_PORT = 5173  # Vite dev server (frontend HMR)
-DEFAULT_BACKEND_PORT = 5180  # FastAPI in dev mode (Vite proxies /api here)
-DEFAULT_PROD_PORT = 5080  # Production server (static files served by FastAPI)
+import tomlkit
 
 # Template directory
 TEMPLATE_DIR = Path(__file__).parent / "template"
 
+# Marker comment indicating file can be auto-upgraded
+# Users should remove this line to prevent automatic updates
+UPGRADE_MARKER = "auto-upgrade@fastapi-vue-setup"
+
 # pyproject.toml additions for patched projects
 PYPROJECT_ADDITIONS = {
     "tool": {
         "hatch": {
             "build": {
-                "packages": ["{{MODULE_NAME}}"],
-                "artifacts": ["{{MODULE_NAME}}/frontend-build"],
+                "packages": ["MODULE_NAME"],
+                "artifacts": ["MODULE_NAME/frontend-build"],
                 "targets": {
                     "sdist": {
                         "hooks": {
@@ -54,6 +48,71 @@ PYPROJECT_ADDITIONS = {
 }
 
 
+# Frontend instantiation block for patching existing apps
+FRONTEND_BLOCK = """
+# Vue Frontend static files
+frontend = Frontend(
+    Path(__file__).with_name("frontend-build"), spa=True, cached=["/assets/"]
+)
+"""
+
+# TypeScript health check script for Vue components
+TS_HEALTH_CHECK_SCRIPT = """\
+import { ref, onMounted } from 'vue'
+
+const backendStatus = ref<'checking' | 'connected' | 'error'>('checking')
+
+onMounted(async () => {
+  try {
+    const res = await fetch('/api/health')
+    backendStatus.value = res.ok ? 'connected' : 'error'
+  } catch {
+    backendStatus.value = 'error'
+  }
+})
+"""
+
+# JavaScript health check script for Vue components
+JS_HEALTH_CHECK_SCRIPT = """\
+import { ref, onMounted } from 'vue'
+
+const backendStatus = ref('checking')
+
+onMounted(async () => {
+  try {
+    const res = await fetch('/api/health')
+    backendStatus.value = res.ok ? 'connected' : 'error'
+  } catch {
+    backendStatus.value = 'error'
+  }
+})
+"""
+
+# Status indicator template for Vue components
+STATUS_SPAN_TEMPLATE = """\
+    <span style="white-space: nowrap">
+      — FastAPI:
+      <span v-if="backendStatus === 'checking'">⏳</span>
+      <span v-else-if="backendStatus === 'connected'">✅</span>
+      <span v-else>❌ not reachable</span>
+    </span>
+"""
+
+# Setup complete message template
+SETUP_COMPLETE_MESSAGE = """
+Next steps:
+
+1. Build for production:
+   CD_CMDuv build
+
+2. Start development server:
+   CD_CMDuv run scripts/devserver.py
+
+3. Run production server:
+   CD_CMDuv run SCRIPT_NAME
+"""
+
+
 # =============================================================================
 # Utility functions
 # =============================================================================
@@ -70,8 +129,7 @@ def find_module_name(project_dir: Path) -> str | None:
     if not pyproject.exists():
         return None
 
-    with open(pyproject, "rb") as f:
-        data = tomllib.load(f)
+    data = tomlkit.parse(pyproject.read_text())
 
     if "project" in data and "name" in data["project"]:
         name = data["project"]["name"]
@@ -123,10 +181,10 @@ def _find_app_in_file(path: Path) -> str | None:
 
 
 def render_template(template: str, **kwargs) -> str:
-    """Simple template rendering with {{KEY}} placeholders."""
+    """Simple template rendering replacing KEY with value."""
     result = template
     for key, value in kwargs.items():
-        result = result.replace(f"{{{{{key}}}}}", str(value))
+        result = result.replace(key, value)
     return result
 
 
@@ -144,31 +202,17 @@ def patch_app_file(
         print(f"❌ Cannot patch {path} - file not found")
         return False
 
-    content = path.read_text()
+    original_content = path.read_text()
     marker = "from fastapi_vue import Frontend"
 
-    if marker in content:
-        print(f"⚠️  Skipping {path} (already patched)")
+    if marker in original_content:
+        print(f"✔️  {path} (already patched)")
         return False
 
-    if dry_run:
-        print(f"[DRY RUN] Would patch {path}")
-        return True
-
     # Find where to insert the import (after other imports)
-    lines = content.split("\n")
+    lines = original_content.split("\n")
     import_line = "from fastapi_vue import Frontend"
 
-    # Frontend instantiation block - use module_name for the frontend-build path
-    frontend_block = """
-# Frontend static file server - configure options here
-frontend = Frontend(
-    Path(__file__).parent / "frontend-build",
-    spa=True,
-    favicon="/assets/favicon",
-    cached=["/assets/"],
-)
-"""
     route_line = f'frontend.route({app_var}, "/")'
 
     # Find last import line and check if pathlib is imported
@@ -184,12 +228,17 @@ frontend = Frontend(
             # Stop at first non-import, non-comment, non-empty line after imports
             break
 
+    # Check if we found imports to insert after
+    if last_import_idx == 0 and not lines[0].strip().startswith(("import ", "from ")):
+        print(f"⚠️  Skipping {path} (no imports found to patch)")
+        return False
+
     # Insert imports after last import, then frontend instantiation
     if not has_pathlib:
         lines.insert(last_import_idx + 1, "from pathlib import Path")
         last_import_idx += 1
     lines.insert(last_import_idx + 1, import_line)
-    lines.insert(last_import_idx + 2, frontend_block)
+    lines.insert(last_import_idx + 2, FRONTEND_BLOCK)
 
     # Append route at end
     lines.append("")
@@ -222,12 +271,21 @@ frontend = Frontend(
         content = content[:insert_pos] + load_code + content[insert_pos:]
         lifespan_patched = True
 
+    # Check if content actually changed
+    if content == original_content:
+        print(f"⚠️  Skipping {path} (no changes needed)")
+        return False
+
+    if dry_run:
+        print(f"[DRY RUN] Would patch {path}")
+        return True
+
     path.write_text(content)
     print(f"✅ Patched {path}")
 
     if not lifespan_patched:
         # Check if they're using deprecated on_event
-        if "@" + app_var + ".on_event" in content or f"@{app_var}.on_event" in content:
+        if f"@{app_var}.on_event" in content:
             print()
             print("⚠️  Your app uses the deprecated @app.on_event decorator.")
             print("   Please migrate to the lifespan pattern and add:")
@@ -246,8 +304,6 @@ frontend = Frontend(
 def patch_vite_config(
     path: Path,
     module_name: str,
-    backend_port: int,
-    vite_port: int,
     dry_run: bool = False,
 ) -> bool:
     """Patch an existing vite.config.js/ts by adding fastapi-vue plugin.
@@ -259,21 +315,17 @@ def patch_vite_config(
         print(f"❌ Cannot patch {path} - file not found")
         return False
 
-    content = path.read_text()
+    original_content = path.read_text()
     marker = "vite-plugin-fastapi"
 
-    if marker in content:
-        print(f"⚠️  Skipping {path} (already patched)")
+    if marker in original_content:
+        print(f"✔️  {path} (already patched)")
         return False
 
-    if dry_run:
-        print(f"[DRY RUN] Would patch {path}")
-        return True
-
     # Add import for the plugin at the top (after other imports)
     import_line = f"import fastapiVue from './{marker}.js'"
 
-    lines = content.split("\n")
+    lines = original_content.split("\n")
     new_lines = []
     import_inserted = False
 
@@ -305,6 +357,18 @@ def patch_vite_config(
     if match:
         insert_pos = match.end()
         content = content[:insert_pos] + "\n    fastapiVue()," + content[insert_pos:]
+    else:
+        print(f"⚠️  Skipping {path} (no plugins array found)")
+        return False
+
+    # Check if content actually changed
+    if content == original_content:
+        print(f"⚠️  Skipping {path} (no changes needed)")
+        return False
+
+    if dry_run:
+        print(f"[DRY RUN] Would patch {path}")
+        return True
 
     path.write_text(content)
     print(f"✅ Patched {path}")
@@ -340,116 +404,116 @@ 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
 
-    content = target_file.read_text()
+    original_content = target_file.read_text()
 
     # Check if already patched
-    if "/api/health" in content:
-        print(f"⚠️  Skipping {target_file} (already patched)")
+    if "/api/health" in original_content:
+        print(f"✔️  {target_file} (already patched)")
+        return False
+
+    content = original_content
+
+    # Detect if TypeScript (has lang="ts" in script tag)
+    is_typescript = 'lang="ts"' in content
+
+    # Build the script content based on JS/TS
+    script_addition = (
+        TS_HEALTH_CHECK_SCRIPT if is_typescript else JS_HEALTH_CHECK_SCRIPT
+    )
+
+    # Insert script addition before </script>
+    script_end_match = re.search(r"</script>", content)
+    if not script_end_match:
+        print(f"⚠️  Skipping {target_file} (no </script> tag found)")
+        return False
+
+    insert_pos = script_end_match.start()
+    content = content[:insert_pos] + script_addition + content[insert_pos:]
+
+    # Insert status inline - find the best place based on file type
+    # For HelloWorld.vue: insert before </h3>
+    # For App.vue (minimal): only patch if it's the default "You did it!" template
+    if "HelloWorld" in str(target_file):
+        # Insert before closing </h3>
+        h3_close = content.find("    </h3>")
+        if h3_close == -1:
+            print(
+                f"⚠️  Skipping {target_file} (no </h3> tag found for status insertion)"
+            )
+            return False
+        before, after = content[:h3_close], content[h3_close:]
+        content = f"{before}{indent(STATUS_SPAN_TEMPLATE, '  ')}{after}"
+    else:
+        # Minimal App.vue - only patch if it contains the default welcome message
+        if "<h1>You did it!</h1>" not in content:
+            print(f"⚠️  Skipping {target_file} (not a default Vue template)")
+            return False
+        # Insert before the </p> tag
+        template_end = content.find("</template>")
+        if template_end == -1:
+            print(f"⚠️  Skipping {target_file} (no </template> tag found)")
+            return False
+        # Find </p> before </template>
+        last_p = content.rfind("</p>", 0, template_end)
+        if last_p == -1:
+            print(f"⚠️  Skipping {target_file} (no </p> tag found for status insertion)")
+            return False
+        before, after = content[:last_p], content[last_p:]
+        content = f"{before}{STATUS_SPAN_TEMPLATE}{after}"
+
+    # Check if content actually changed
+    if content == original_content:
+        print(f"⚠️  Skipping {target_file} (no changes needed)")
         return False
 
     if dry_run:
         print(f"[DRY RUN] Would patch {target_file}")
         return True
 
-    # Detect if TypeScript (has lang="ts" in script tag)
-    is_typescript = 'lang="ts"' in content
-
-    # Build the script content based on JS/TS
-    if is_typescript:
-        script_addition = '''
-import { ref, onMounted } from 'vue'
-
-const backendStatus = ref<'checking' | 'connected' | 'error'>('checking')
-
-onMounted(async () => {
-  try {
-    const res = await fetch('/api/health')
-    backendStatus.value = res.ok ? 'connected' : 'error'
-  } catch {
-    backendStatus.value = 'error'
-  }
-})
-'''
-    else:
-        script_addition = '''
-import { ref, onMounted } from 'vue'
-
-const backendStatus = ref('checking')
-
-onMounted(async () => {
-  try {
-    const res = await fetch('/api/health')
-    backendStatus.value = res.ok ? 'connected' : 'error'
-  } catch {
-    backendStatus.value = 'error'
-  }
-})
-'''
-
-    # Template addition - inline status indicator (no wrapper, fits in existing text)
-    status_span = '''<span class="backend-status">
-      — FastAPI backend:
-      <span v-if="backendStatus === 'checking'">⏳</span>
-      <span v-else-if="backendStatus === 'connected'" class="connected">✓ connected</span>
-      <span v-else class="error">✗ not reachable</span>
-    </span>'''
-
-    style_addition = '''
-.backend-status {
-  white-space: nowrap;
-}
-
-.backend-status .connected {
-  color: hsla(160, 100%, 37%, 1);
-}
-
-.backend-status .error {
-  color: hsla(0, 100%, 50%, 1);
-}
-'''
-
-    # Insert script addition before </script>
-    script_end_match = re.search(r"</script>", content)
-    if script_end_match:
-        insert_pos = script_end_match.start()
-        content = content[:insert_pos] + script_addition + content[insert_pos:]
-
-    # Insert status inline - find the best place based on file type
-    # For HelloWorld.vue: insert before </h3>
-    # For App.vue (minimal): insert before the last </p> in template
-    if "HelloWorld" in str(target_file):
-        # Insert before closing </h3>
-        h3_close = content.find("</h3>")
-        if h3_close != -1:
-            content = content[:h3_close] + "\n      " + status_span + "\n    " + content[h3_close:]
-    else:
-        # Minimal App.vue - insert before the last </p> before </template>
-        template_end = content.find("</template>")
-        if template_end != -1:
-            # Find last </p> before </template>
-            last_p = content.rfind("</p>", 0, template_end)
-            if last_p != -1:
-                content = content[:last_p] + "\n    " + status_span + "\n  " + content[last_p:]
-
-    # Insert style addition before </style>
-    style_end = content.rfind("</style>")
-    if style_end != -1:
-        content = content[:style_end] + style_addition + content[style_end:]
-
     target_file.write_text(content)
     print(f"✅ Patched {target_file}")
     return True
 
 
+# Track .new.py files written during setup (for merge notification)
+_new_files_written: list[tuple[Path, Path]] = []
+
+
 def write_file(
-    path: Path, content: str, overwrite: bool = True, dry_run: bool = False
+    path: Path,
+    content: str,
+    overwrite: bool = True,
+    dry_run: bool = False,
+    executable: bool = False,
+    fallback_path: Path | None = None,
 ) -> bool:
-    """Write content to a file, handling existing files and dry-run."""
+    """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.
+    """
     exists = path.exists()
     if exists and not overwrite:
-        print(f"⚠️  Skipping {path} (exists)")
+        print(f"ℹ️  Skipping {path} (exists)")
         return False
 
+    # Check if content is the same
+    if exists:
+        existing_content = path.read_text()
+        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 and UPGRADE_MARKER not in existing_content:
+            if fallback_path is not None:
+                # Write to fallback path instead
+                return _write_fallback_file(
+                    path, fallback_path, content, dry_run, executable
+                )
+            print(f"ℹ️  Skipping {path} (customized by user)")
+            return False
+
     if dry_run:
         action = "overwrite" if exists else "create"
         print(f"[DRY RUN] Would {action} {path}")
@@ -457,52 +521,107 @@ def write_file(
 
     path.parent.mkdir(parents=True, exist_ok=True)
     path.write_text(content)
+    if executable and sys.platform != "win32":
+        path.chmod(path.stat().st_mode | 0o111)
     action = "Updated" if exists else "Created"
     print(f"✅ {action} {path}")
     return True
 
 
-def merge_pyproject(data: dict, additions: dict, module_name: str) -> dict:
-    """Merge additions into pyproject.toml data."""
-    result = data.copy()
+def _write_fallback_file(
+    original_path: Path,
+    fallback_path: Path,
+    content: str,
+    dry_run: bool,
+    executable: bool,
+) -> bool:
+    """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:
+            print(f"✔️  {fallback_path} (already up to date)")
+            return False
 
+    if dry_run:
+        print(f"[DRY RUN] Would create {fallback_path} (original customized by user)")
+        _new_files_written.append((fallback_path, original_path))
+        return True
+
+    fallback_path.parent.mkdir(parents=True, exist_ok=True)
+    fallback_path.write_text(content)
+    if executable and sys.platform != "win32":
+        fallback_path.chmod(fallback_path.stat().st_mode | 0o111)
+    print(f"✅ Created {fallback_path} (original customized by user)")
+    _new_files_written.append((fallback_path, original_path))
+    return True
+
+
+def merge_pyproject(
+    data: tomlkit.TOMLDocument, additions: dict, module_name: str
+) -> tomlkit.TOMLDocument:
+    """Merge additions into pyproject.toml data, preserving comments and existing values."""
     # Ensure hatchling build system is configured
-    if "build-system" not in result:
-        result["build-system"] = {}
-    result["build-system"]["requires"] = ["hatchling"]
-    result["build-system"]["build-backend"] = "hatchling.build"
+    if "build-system" not in data:
+        data["build-system"] = tomlkit.table()
 
-    # Add dependencies
-    if "project" not in result:
-        result["project"] = {}
-    if "dependencies" not in result["project"]:
-        result["project"]["dependencies"] = []
+    # Add hatchling to requires if not present, preserving existing requires
+    if "requires" not in data["build-system"]:
+        data["build-system"]["requires"] = ["hatchling"]
+    else:
+        requires = list(data["build-system"]["requires"])
+        if not any(r.startswith("hatchling") for r in requires):
+            requires.insert(0, "hatchling")
+            data["build-system"]["requires"] = requires
+
+    if "build-backend" not in data["build-system"]:
+        data["build-system"]["build-backend"] = "hatchling.build"
+
+    # Ensure project table exists
+    if "project" not in data:
+        data["project"] = tomlkit.table()
 
     # Add hatch build config
-    if "tool" not in result:
-        result["tool"] = {}
-    if "hatch" not in result["tool"]:
-        result["tool"]["hatch"] = {}
-    if "build" not in result["tool"]["hatch"]:
-        result["tool"]["hatch"]["build"] = {}
+    if "tool" not in data:
+        data["tool"] = tomlkit.table()
+    if "hatch" not in data["tool"]:
+        data["tool"]["hatch"] = tomlkit.table()
+    if "build" not in data["tool"]["hatch"]:
+        data["tool"]["hatch"]["build"] = tomlkit.table()
 
-    hatch_build = additions["tool"]["hatch"]["build"]
-    result["tool"]["hatch"]["build"]["packages"] = [
-        p.replace("{{MODULE_NAME}}", module_name) for p in hatch_build["packages"]
-    ]
-    result["tool"]["hatch"]["build"]["artifacts"] = [
-        a.replace("{{MODULE_NAME}}", module_name) for a in hatch_build["artifacts"]
-    ]
-    result["tool"]["hatch"]["build"]["only-packages"] = hatch_build["only-packages"]
+    hatch_build = data["tool"]["hatch"]["build"]
+    hatch_additions = additions["tool"]["hatch"]["build"]
 
-    if "targets" not in result["tool"]["hatch"]["build"]:
-        result["tool"]["hatch"]["build"]["targets"] = {}
+    # Set packages if not already set
+    if "packages" not in hatch_build:
+        hatch_build["packages"] = [
+            p.replace("MODULE_NAME", module_name) for p in hatch_additions["packages"]
+        ]
 
-    result["tool"]["hatch"]["build"]["targets"]["sdist"] = hatch_build["targets"][
-        "sdist"
-    ]
+    # Set artifacts if not already set
+    if "artifacts" not in hatch_build:
+        hatch_build["artifacts"] = [
+            a.replace("MODULE_NAME", module_name) for a in hatch_additions["artifacts"]
+        ]
 
-    return result
+    # Set only-packages if not already set
+    if "only-packages" not in hatch_build:
+        hatch_build["only-packages"] = hatch_additions["only-packages"]
+
+    # Add sdist target with custom hook
+    if "targets" not in hatch_build:
+        hatch_build["targets"] = tomlkit.table()
+    if "sdist" not in hatch_build["targets"]:
+        hatch_build["targets"]["sdist"] = tomlkit.table()
+    if "hooks" not in hatch_build["targets"]["sdist"]:
+        hatch_build["targets"]["sdist"]["hooks"] = tomlkit.table()
+    if "custom" not in hatch_build["targets"]["sdist"]["hooks"]:
+        hatch_build["targets"]["sdist"]["hooks"]["custom"] = tomlkit.table()
+    if "path" not in hatch_build["targets"]["sdist"]["hooks"]["custom"]:
+        hatch_build["targets"]["sdist"]["hooks"]["custom"]["path"] = hatch_additions[
+            "targets"
+        ]["sdist"]["hooks"]["custom"]["path"]
+
+    return data
 
 
 # =============================================================================
@@ -573,9 +692,12 @@ def ensure_python_project(project_dir: Path, dry_run: bool = False) -> bool:
 
 
 def ensure_frontend(project_dir: Path, dry_run: bool = False) -> bool:
-    """Ensure frontend directory exists, run create-vue if needed."""
+    """Ensure frontend directory exists with a Vue project, run create-vue if needed."""
     frontend_dir = project_dir / "frontend"
-    if frontend_dir.exists():
+    package_json = frontend_dir / "package.json"
+
+    # Check for package.json, not just directory existence (empty dir shouldn't count)
+    if package_json.exists():
         return True
 
     # Find JS runtime
@@ -632,13 +754,6 @@ def cmd_setup(args: argparse.Namespace) -> int:
     project_dir = project_dir.resolve()
     dry_run = args.dry_run
 
-    # Check if port options were explicitly specified (for updating existing files)
-    ports_specified = (
-        args.vite_port != DEFAULT_VITE_PORT
-        or args.backend_port != DEFAULT_BACKEND_PORT
-        or args.prod_port != DEFAULT_PROD_PORT
-    )
-
     # Create project directory if it doesn't exist
     if not project_dir.exists():
         if dry_run:
@@ -652,12 +767,12 @@ def cmd_setup(args: argparse.Namespace) -> int:
     if dry_run:
         print("\n🏃 DRY RUN MODE - no changes will be made\n")
 
-    # Step 1: Ensure Python project exists
-    if not ensure_python_project(project_dir, dry_run):
+    # Step 1: Ensure frontend exists (do this first so cancellation doesn't leave partial setup)
+    if not ensure_frontend(project_dir, dry_run):
         return 1
 
-    # Step 2: Ensure frontend exists
-    if not ensure_frontend(project_dir, dry_run):
+    # Step 2: Ensure Python project exists
+    if not ensure_python_project(project_dir, dry_run):
         return 1
 
     # Detect module name
@@ -667,24 +782,15 @@ def cmd_setup(args: argparse.Namespace) -> int:
         module_name = project_dir.name.replace("-", "_")
         print(f"📦 Using module name from directory: {module_name}")
 
-    # Ports
-    vite_port = args.vite_port
-    backend_port = args.backend_port
-    prod_port = args.prod_port
-
     # Title for templates
     project_title = module_name.replace("_", " ").title()
 
     print(f"📦 Module: {module_name}")
-    print(f"🔌 Ports: Vite={vite_port}, Backend(dev)={backend_port}, Prod={prod_port}")
 
     # Template variables
     tpl_vars = {
         "MODULE_NAME": module_name,
         "PROJECT_TITLE": project_title,
-        "VITE_PORT": vite_port,
-        "BACKEND_PORT": backend_port,
-        "PROD_PORT": prod_port,
     }
 
     module_dir = project_dir / module_name
@@ -713,19 +819,39 @@ def cmd_setup(args: argparse.Namespace) -> int:
             module_dir.mkdir(parents=True)
 
     # === Install scripts (always update our own scripts) ===
-    script_files = [
+    # util.py and build-frontend.py 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",
         ),
-        (scripts_dir / "devserver.py", "scripts/devserver.py"),
     ]
 
-    for dest_path, template_path in script_files:
+    for dest_path, template_path in internal_script_files:
         template = load_template(template_path)
         content = render_template(template, **tpl_vars)
-        write_file(dest_path, content, overwrite=True, dry_run=dry_run)
+        write_file(
+            dest_path,
+            content,
+            overwrite=True,
+            dry_run=dry_run,
+        )
+
+    # devserver.py - use fallback if customized by user
+    devserver_path = scripts_dir / "devserver.py"
+    devserver_fallback = scripts_dir / "devserver.new.py"
+    template = load_template("scripts/devserver.py")
+    content = render_template(template, **tpl_vars)
+    write_file(
+        devserver_path,
+        content,
+        overwrite=True,
+        dry_run=dry_run,
+        executable=True,
+        fallback_path=devserver_fallback,
+    )
 
     # === Handle app module ===
     if app_file:
@@ -748,12 +874,21 @@ def cmd_setup(args: argparse.Namespace) -> int:
 
     # === Handle __main__.py ===
     main_file = module_dir / "__main__.py"
-    if not main_file.exists() or ports_specified:
-        template = load_template("backend/__main__.py")
-        content = render_template(template, **tpl_vars)
-        write_file(main_file, content, overwrite=True, dry_run=dry_run)
-    else:
-        print(f"⚠️  Skipping {main_file} (exists, use --prod-port to update)")
+    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:
+    # - File doesn't exist: create it
+    # - File exists with marker: update it
+    # - File exists without marker: write to fallback
+    write_file(
+        main_file,
+        main_content,
+        overwrite=True,
+        dry_run=dry_run,
+        fallback_path=main_fallback,
+    )
 
     # === Update vite.config.js/ts ===
     frontend_dir = project_dir / "frontend"
@@ -769,13 +904,9 @@ def cmd_setup(args: argparse.Namespace) -> int:
         vite_config_js = frontend_dir / "vite.config.js"
 
         if vite_config_ts.exists():
-            patch_vite_config(
-                vite_config_ts, module_name, backend_port, vite_port, dry_run
-            )
+            patch_vite_config(vite_config_ts, module_name, dry_run)
         elif vite_config_js.exists():
-            patch_vite_config(
-                vite_config_js, module_name, backend_port, vite_port, dry_run
-            )
+            patch_vite_config(vite_config_js, module_name, dry_run)
         else:
             print("⚠️  No vite.config.ts or vite.config.js found in frontend/")
             print("   Run create-vue first to generate a Vite config to patch.")
@@ -786,39 +917,43 @@ def cmd_setup(args: argparse.Namespace) -> int:
     # === Update pyproject.toml ===
     pyproject_path = project_dir / "pyproject.toml"
     if pyproject_path.exists():
-        with open(pyproject_path, "rb") as f:
-            data = tomllib.load(f)
+        old_content = pyproject_path.read_text()
+        data = tomlkit.parse(old_content)
 
         updated = merge_pyproject(data, PYPROJECT_ADDITIONS, module_name)
 
-        # Add script entry pointing to the app we found/created
-        if "scripts" not in updated["project"]:
-            updated["project"]["scripts"] = {}
-        script_name = module_name.replace("_", "-")
-        updated["project"]["scripts"][script_name] = f"{module_name}.__main__:main"
+        # Only add script entry if project doesn't already have scripts
+        if "scripts" not in updated["project"] or not updated["project"]["scripts"]:
+            updated["project"]["scripts"] = tomlkit.table()
+            script_name = module_name.replace("_", "-")
+            updated["project"]["scripts"][script_name] = f"{module_name}.__main__:main"
 
-        if dry_run:
+        # Check if content actually changed
+        new_content = tomlkit.dumps(updated)
+
+        if new_content == old_content:
+            print(f"✔️  {pyproject_path} (already up to date)")
+        elif dry_run:
             print(f"[DRY RUN] Would update {pyproject_path}")
         else:
-            with open(pyproject_path, "wb") as f:
-                tomli_w.dump(updated, f)
+            pyproject_path.write_text(new_content)
             print(f"✅ Updated {pyproject_path}")
 
     # === Add dependencies using uv ===
     if dry_run:
-        print("[DRY RUN] Would run: uv add 'fastapi[standard]' fastapi-vue")
-        print("[DRY RUN] Would run: uv add --group dev httpx")
+        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", "fastapi[standard]", "fastapi-vue"],
+            ["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", "--group", "dev", "httpx"],
+            ["uv", "add", "-U", "--group", "dev", "httpx"],
             cwd=project_dir,
             check=False,
         )
@@ -854,18 +989,23 @@ def cmd_setup(args: argparse.Namespace) -> int:
     cd_cmd = "" if project_dir == Path.cwd() else f"cd {project_dir}\n   "
     script_name = module_name.replace("_", "-")
 
-    print(f"""
-Next steps:
+    message = SETUP_COMPLETE_MESSAGE.replace("CD_CMD", cd_cmd).replace(
+        "SCRIPT_NAME", script_name
+    )
+    print(message)
 
-1. Build for production:
-   {cd_cmd}uv build
-
-2. Start development server:
-   {cd_cmd}uv run scripts/devserver.py
-
-3. Run production server:
-   {cd_cmd}uv run {script_name}
-""")
+    # Show merge note if any .new.py files were written
+    if _new_files_written:
+        print()
+        print(
+            "⚠️  Note: Some files could not be auto-upgraded because you customized them."
+        )
+        print("   Please manually merge the following files:")
+        for new_file, original_file in _new_files_written:
+            print(f"     • {new_file.name} → {original_file.name}")
+        print()
+        # Clear the list for potential subsequent runs
+        _new_files_written.clear()
 
     return 0
 
@@ -904,60 +1044,24 @@ 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 . --vite-port 3000 Update port configuration
 """,
     )
     parser.add_argument(
         "project_dir",
         nargs="?",
         default=None,
-        help="Project directory (default: current directory)",
+        help="Project directory (use . for current directory)",
     )
     parser.add_argument("--module-name", help="Python module name (auto-detected)")
-    parser.add_argument(
-        "--vite-port",
-        type=int,
-        default=DEFAULT_VITE_PORT,
-        help=f"Vite dev server port (default: {DEFAULT_VITE_PORT})",
-    )
-    parser.add_argument(
-        "--backend-port",
-        type=int,
-        default=DEFAULT_BACKEND_PORT,
-        help=f"Backend API port in dev mode (default: {DEFAULT_BACKEND_PORT})",
-    )
-    parser.add_argument(
-        "--prod-port",
-        type=int,
-        default=DEFAULT_PROD_PORT,
-        help=f"Production server port (default: {DEFAULT_PROD_PORT})",
-    )
     parser.add_argument(
         "--dry-run", action="store_true", help="Show what would be done"
     )
 
     args = parser.parse_args()
 
-    # Handle default project directory with safety check
     if args.project_dir is None:
-        cwd = Path.cwd()
-        if not is_uninitialized_folder(cwd) and not is_already_patched(cwd):
-            print(
-                "⚠️  Current directory contains an existing project that hasn't been patched yet."
-            )
-            print()
-            print(
-                "   If you want to set up FastAPI+Vue integration in the current directory, run:"
-            )
-            print("       fastapi-vue-setup .")
-            print()
-            print("   Or specify a new project directory:")
-            print("       fastapi-vue-setup my-new-project")
-            print()
-            print("   Python project will be at root, while Vue lives in frontend/.")
-            print()
-            return 1
-        args.project_dir = "."
+        parser.print_help()
+        return 0
 
     return cmd_setup(args)
 

pyproject.toml

@@ -9,7 +9,7 @@ description = "Tool to create or patch FastAPI+Vue projects with integrated buil
 readme = "README.md"
 requires-python = ">=3.11"
 dependencies = [
-    "tomli-w>=1.0.0",
+    "tomlkit>=0.12.0",
 ]
 
 [project.urls]

template/backend/__init__.py

@@ -1,3 +0,0 @@
-"""{{PROJECT_TITLE}} package."""
-
-__version__ = "0.1.0"

template/backend/__main__.py

@@ -1,31 +1,54 @@
-"""Entry point for the application."""
+# auto-upgrade@fastapi-vue-setup - remove this if you modify this file
+import argparse
+import asyncio
+import os
 
-import sys
+import uvicorn
+from fastapi_vue.hostutil import parse_endpoint
+from uvicorn import Config, Server
+
+from .APP_MODULE import APP_VAR
+
+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():
-    """Run the FastAPI application using uvicorn."""
-    import uvicorn
-
-    if len(sys.argv) > 1:
-        endpoint = sys.argv[1]
-        if ":" in endpoint:
-            host, port = endpoint.rsplit(":", 1)
-            host = host or "localhost"
-            port = int(port)
-        else:
-            host = "localhost"
-            port = int(endpoint)
-    else:
-        host = "localhost"
-        port = {{PROD_PORT}}
-
-    uvicorn.run(
-        "{{MODULE_NAME}}.app:app",
-        host=host,
-        port=port,
-        log_level="info",
+    parser = argparse.ArgumentParser(description="Run the MODULE_NAME server.")
+    parser.add_argument(
+        "endpoint",
+        nargs="?",
+        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")
+    devmode = bool(os.getenv("FASTAPI_VUE_FRONTEND_URL"))
+    endpoints = parse_endpoint(args.endpoint, DEFAULT_PORT)
+    run_server(endpoints, proxy=proxy, devmode=devmode)
 
 
 if __name__ == "__main__":

template/backend/app.py

@@ -1,17 +1,12 @@
-"""Main FastAPI application."""
-
 from contextlib import asynccontextmanager
 from pathlib import Path
 
 from fastapi import FastAPI
 from fastapi_vue import Frontend
 
-# Frontend static file server - configure options here
+# Vue Frontend static files
 frontend = Frontend(
-    Path(__file__).parent / "frontend-build",
-    spa=True,
-    favicon="/assets/favicon",
-    cached=["/assets/"],
+    Path(__file__).with_name("frontend-build"), spa=True, cached=["/assets/"]
 )
 
 
@@ -22,19 +17,17 @@ async def lifespan(app: FastAPI):
     yield
 
 
-app = FastAPI(title="{{PROJECT_TITLE}}", lifespan=lifespan)
+app = FastAPI(title="PROJECT_TITLE", lifespan=lifespan)
 
 
+# Add API routes here...
+
+
+# Health check endpoint for the Vue demo app to verify the backend is running
 @app.get("/api/health")
 async def health_check():
-    """Health check endpoint for the dev server."""
     return {"status": "ok"}
 
 
-# Add your API routes here
-# @app.get("/api/example")
-# async def example():
-#     return {"message": "Hello World"}
-
-
+# Final catch-all route for frontend files (keep at end of file)
 frontend.route(app, "/")

template/frontend/vite-plugin-fastapi.js

@@ -6,34 +6,30 @@
  * - Builds to the Python module's frontend-build directory
  *
  * Environment variables (with defaults):
- *   VITE_PORT=5173        - Vite dev server port
- *   VITE_BACKEND_URL=http://localhost:5180 - Backend API URL for proxying
+ *   FASTAPI_VUE_BACKEND_URL=http://localhost:5180 - Backend API URL for proxying
  */
 
-const backendUrl =
-  process.env.VITE_BACKEND_URL || "http://localhost:{{BACKEND_PORT}}";
-const vitePort = parseInt(process.env.VITE_PORT || "{{VITE_PORT}}");
+const backendUrl = process.env.FASTAPI_VUE_BACKEND_URL || "http://localhost:5180"
+
+export default function fastapiVue({ paths = ["/api"] } = {}) {
+  // Build proxy configuration for each path
+  const proxy = {}
+  for (const path of paths) {
+    proxy[path] = {
+      target: backendUrl,
+      changeOrigin: false,
+      ws: true,
+    }
+  }
 
-export default function fastapiVue() {
   return {
     name: "fastapi-vite",
     config: () => ({
-      server: {
-        host: "localhost",
-        port: vitePort,
-        strictPort: true,
-        proxy: {
-          "/api": {
-            target: backendUrl,
-            changeOrigin: false,
-            ws: true,
-          },
-        },
-      },
+      server: { proxy },
       build: {
-        outDir: "../{{MODULE_NAME}}/frontend-build",
+        outDir: "../MODULE_NAME/frontend-build",
         emptyOutDir: true,
       },
     }),
-  };
+  }
 }

template/scripts/devserver.py

@@ -1,36 +1,41 @@
 #!/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.
 
 Usage:
-    uv run scripts/devserver.py [host:port]
+    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.
-Backend always listens on localhost:{{BACKEND_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 ipaddress
 import os
-import sys
 from pathlib import Path
 from sys import stderr
-from urllib.parse import urlparse
 
 import httpx
+from fastapi_vue.hostutil import parse_endpoint
 
 exec((Path(__file__).parent / "fastapi-vue/util.py").read_text("UTF-8"))  # noqa: S102
 
-DEFAULT_HOST = "localhost"
-DEFAULT_VITE_PORT = {{VITE_PORT}}
-BACKEND_PORT = {{BACKEND_PORT}}
+DEFAULT_VITE_PORT = 5173
+DEFAULT_BACKEND_PORT = 5180
 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
@@ -39,43 +44,8 @@ BUN_BUG = """\
 """
 
 
-def parse_endpoint(value: str | None) -> tuple[str | None, int, bool]:
-    """Parse an endpoint for Vite (no unix socket support).
-
-    Returns (host, port, all_ifaces).
-    """
-    if not value:
-        return DEFAULT_HOST, DEFAULT_VITE_PORT, False
-
-    # Port only (numeric) -> localhost:port
-    if value.isdigit():
-        return DEFAULT_HOST, int(value), False
-
-    # Leading colon :port -> bind all interfaces
-    if value.startswith(":") and value != ":":
-        port_part = value[1:]
-        if not port_part.isdigit():
-            raise SystemExit(f"Invalid port in '{value}'")
-        return None, int(port_part), True
-
-    # Unbracketed IPv6 (cannot safely contain a port)
-    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 value, DEFAULT_VITE_PORT, False
-
-    # Use urllib.parse for everything else
-    parsed = urlparse(f"//{value}")
-    host = parsed.hostname or DEFAULT_HOST
-    port = parsed.port or DEFAULT_VITE_PORT
-
-    return host, port, False
-
-
 def resolve_frontend_tools(
-    vite_host: str | None, vite_port: int, all_ifaces: bool
+    vite_port: int, all_ifaces: bool
 ) -> tuple[list[str], list[str], str]:
     """Resolve frontend install and dev commands.
 
@@ -86,7 +56,7 @@ def resolve_frontend_tools(
         stderr.write(f"┃ ⚠️  Frontend source not found at {FRONTEND_PATH}\n")
         raise SystemExit(1)
 
-    result = find_js_runtime()
+    result = find_js_runtime()  # noqa # type: ignore
     if result is None:
         if not os.environ.get("JS_RUNTIME"):
             stderr.write("┃ ⚠️  deno, npm or bun needed to run the frontend server.\n")
@@ -106,12 +76,15 @@ def resolve_frontend_tools(
     }
 
     install_cmd = [tool, *install_args[name]]
-    dev_cmd = [tool, *dev_args[name], "--port", str(vite_port)]
+    dev_cmd = [
+        tool,
+        *dev_args[name],
+        "--clearScreen=false",
+        f"--port={vite_port}",
+    ]
 
     if all_ifaces:
         dev_cmd.append("--host")
-    elif vite_host:
-        dev_cmd.extend(["--host", vite_host])
 
     if name == "bun":
         stderr.write(BUN_BUG)
@@ -119,13 +92,15 @@ def resolve_frontend_tools(
     return install_cmd, dev_cmd, name
 
 
-async def wait_for_backend():
+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(f"http://localhost:{BACKEND_PORT}", timeout=1.0)
+                await client.get(url, timeout=1.0)
                 stderr.write("✓ Backend ready!\n")
                 return True
             except httpx.RequestError:
@@ -155,19 +130,29 @@ async def _terminate_process(proc: asyncio.subprocess.Process, name: str) -> Non
 
 
 async def run_devserver(
-    vite_host: str | None, vite_port: int, all_ifaces: bool
+    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_host, vite_port, all_ifaces
-    )
+    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://{vite_host or 'localhost'}:{vite_port}"
-    )
+    os.environ["FASTAPI_VUE_FRONTEND_URL"] = f"http://localhost:{vite_port}"
     # Tell Vite where the backend is (for proxying /api requests)
-    os.environ["VITE_BACKEND_URL"] = f"http://localhost:{BACKEND_PORT}"
+    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)
 
@@ -185,22 +170,13 @@ async def run_devserver(
         await asyncio.sleep(0.1)
 
         # Start backend (concurrent with install)
-        backend_cmd = [
-            "uvicorn",
-            "{{MODULE_NAME}}.app:app",
-            "--host",
-            "localhost",
-            "--port",
-            str(BACKEND_PORT),
-            "--reload",
-        ]
         stderr.write(f">>> {' '.join(backend_cmd)}\n")
         backend_proc = await asyncio.create_subprocess_exec(*backend_cmd, cwd=cwd)
 
         # Wait for install to complete and backend to be ready
         install_task = asyncio.create_task(install_proc.wait(), name="install")
         backend_ready_task = asyncio.create_task(
-            wait_for_backend(), name="backend_ready"
+            wait_for_backend(backend_host, backend_port), name="backend_ready"
         )
 
         done, pending = await asyncio.wait(
@@ -257,11 +233,44 @@ async def run_devserver(
 
 
 def main():
-    hostport = sys.argv[1] if len(sys.argv) > 1 else None
-    vite_host, vite_port, all_ifaces = parse_endpoint(hostport)
+    parser = argparse.ArgumentParser(
+        description="Run Vite and FastAPI development servers",
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+        epilog=EPILOG,
+    )
+    parser.add_argument(
+        "frontend",
+        nargs="?",
+        metavar="host:port",
+        help="Vite frontend endpoint (default: localhost:5173)",
+    )
+    parser.add_argument(
+        "--backend",
+        metavar="host:port",
+        help="FastAPI backend endpoint (default: localhost:5180)",
+    )
+    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_host, vite_port, all_ifaces))
+        asyncio.run(run_devserver(vite_port, all_ifaces, backend_host, backend_port))
 
 
 if __name__ == "__main__":

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

@@ -4,7 +4,7 @@ import subprocess
 from pathlib import Path
 from sys import stderr
 
-from hatchling.builders.hooks.plugin.interface import BuildHookInterface
+from hatchling.builders.hooks.plugin.interface import BuildHookInterface  # type: ignore
 
 exec(Path(__file__).with_name("util.py").read_text("UTF-8"))  # noqa: S102
 
@@ -23,7 +23,7 @@ class CustomBuildHook(BuildHookInterface):
         super().initialize(version, build_data)
         stderr.write(">>> Building the frontend\n")
 
-        install_cmd, build_cmd = find_build_tool()
+        install_cmd, build_cmd = find_build_tool()  # noqa # type: ignore
 
         try:
             run(install_cmd, cwd="frontend")

template/scripts/fastapi-vue/util.py

@@ -51,8 +51,9 @@ def find_build_tool():
         "npm": ("install",),
         "bun": ("--bun", "install"),
     }
+    # Run vite directly for deno to avoid npm-run-all2/run-p issues
     build = {
-        "deno": ("task", "build"),
+        "deno": ("run", "-A", "npm:vite", "build"),
         "npm": ("run", "build"),
         "bun": ("--bun", "run", "build"),
     }