FastAPI + HTMX：無需建置的全端開發

Browser                FastAPI                Jinja2              HTMX/Alpine
  |                      |                     |                     |
  |--- GET /about ------>|                     |                     |
  |                      |-- render template ->|                     |
  |                      |                     |-- base.html ------->|
  |                      |                     |   + about.html      |
  |                      |<-- full HTML -------|                     |
  |<--- HTML response ---|                     |                     |
  |                                                                  |
  |--- hx-get /search ------------------------------------------------>|
  |                      |<-- HTMX request ----|                     |
  |                      |-- render partial -->|                     |
  |                      |                     |-- _results.html     |
  |                      |<-- HTML fragment ---|                     |
  |<--- HTML fragment ---|                     |                     |
  |--- DOM swap -------------------------------------------------------->|

app/
├── main.py              # FastAPI app, middleware, templates
├── config.py            # Pydantic settings management
├── routes/
│   ├── pages.py         # Page routes (HTML responses)
│   └── api.py           # API routes (JSON/HTML fragment responses)
├── content.py           # Markdown loading, blog post parsing
├── security/
│   ├── headers.py       # CSP, HSTS, security headers middleware
│   ├── csrf.py          # HMAC-signed CSRF tokens
│   ├── rate_limit.py    # 3-tier rate limiting
│   └── logging.py       # Security event logging
├── i18n/
│   ├── config.py        # Supported locales, mappings
│   ├── middleware.py     # URL-based locale detection
│   ├── jinja.py         # Translation functions for templates
│   └── d1_client.py     # Cloudflare D1 translation storage
├── cache_assets.py      # Content-hash asset versioning
└── templates/
    ├── base.html         # Base layout with Alpine.js state
    ├── components/       # Reusable partials (_language_switcher.html, etc.)
    └── pages/            # Page templates (home.html, about.html, etc.)

content/
├── blog/                # Markdown blog posts with YAML frontmatter
└── guides/              # Multi-section guide markdown

static/
├── css/                 # Plain CSS (no preprocessors)
├── js/                  # Vanilla JavaScript (no bundlers)
│   └── vendor/          # Self-hosted HTMX, Alpine.js
└── images/              # Optimized images with WebP srcset

src/
├── components/       # React components (JSX)
├── pages/            # Route handlers (also JSX)
├── api/              # API routes (also in pages/)
├── hooks/            # Custom React hooks
├── context/          # React context providers
├── lib/              # Utility functions
├── styles/           # CSS modules or Tailwind config
└── types/            # TypeScript type definitions

# Plus build configuration
next.config.js
tsconfig.json
postcss.config.js
tailwind.config.js
eslint.config.js
package.json
package-lock.json
node_modules/         # 187+ MB of dependencies

from fastapi import FastAPI
from fastapi.staticfiles import StaticFiles
from fastapi.templating import Jinja2Templates
from starlette.middleware.gzip import GZipMiddleware

app = FastAPI(
    title="Blake Crosley",
    docs_url=None,     # Disable docs in production
    redoc_url=None,
    openapi_url=None,  # Prevent /openapi.json exposure
)

# Middleware order matters: last added = first executed
app.add_middleware(SecurityHeadersMiddleware)
app.add_middleware(GZipMiddleware, minimum_size=500)
app.add_middleware(LocaleMiddleware)
app.add_middleware(RateLimitMiddleware)
app.add_middleware(SecurityLogMiddleware, site_name="blakecrosley.com")

# Static files
app.mount("/static", StaticFiles(directory=STATIC_DIR), name="static")

# Templates
templates = Jinja2Templates(directory=TEMPLATES_DIR)

# routes/pages.py — full HTML responses
from fastapi import APIRouter, Request

router = APIRouter()

@router.get("/about")
async def about(request: Request):
    templates = request.app.state.templates
    return templates.TemplateResponse("pages/about.html", {
        "request": request,
        "page_title": "About — Blake Crosley",
        "page_description": "Designer, developer, dad.",
    })

# routes/api.py — JSON or HTML fragment responses
@router.get("/api/quiz/{quiz_id}/step")
async def quiz_step(request: Request, quiz_id: str, answers: str = ""):
    # Parse answers, compute next question or result
    question = get_next_question(quiz_id, answers)
    templates = request.app.state.templates
    return templates.TemplateResponse("components/_quiz_step.html", {
        "request": request,
        "question": question,
        "answers": answers,
        "step": len(answers.split(",")) if answers else 0,
    })

from fastapi import Depends, Request

def get_templates(request: Request):
    """Get templates from app state."""
    return request.app.state.templates

def get_current_locale(request: Request) -> str:
    """Get locale from middleware-set request state."""
    return getattr(request.state, "locale", "en")

@router.get("/blog/{slug}")
async def blog_post(
    request: Request,
    slug: str,
    templates=Depends(get_templates),
    locale: str = Depends(get_current_locale),
):
    post = load_post_by_slug(slug)
    if not post:
        raise HTTPException(404, "Post not found")
    return templates.TemplateResponse("pages/blog/post.html", {
        "request": request,
        "post": post,
        "locale": locale,
    })

from pydantic_settings import BaseSettings

class Settings(BaseSettings):
    D1_WORKER_URL: str = ""
    D1_AUTH_SECRET: str = ""
    CLOUDFLARE_ACCOUNT_ID: str = ""
    CLOUDFLARE_API_TOKEN: str = ""
    ANALYTICS_PASSKEY: str = ""

    class Config:
        env_file = ".env"
        env_file_encoding = "utf-8"

settings = Settings()

@app.on_event("startup")
async def startup_load_translations():
    """Load translations from D1 into memory at startup."""
    client = init_d1_client(
        worker_url=settings.D1_WORKER_URL,
        auth_secret=settings.D1_AUTH_SECRET,
    )
    if not client.is_configured:
        logger.warning("i18n: D1 not configured, translations use defaults")
        return
    cache = await load_translations(client)
    logger.info(f"i18n: Loaded {cache.stats['key_count']} keys")

# Sync function — FastAPI runs it in a thread pool
@router.get("/blog/{slug}")
def blog_post(slug: str):
    post = load_post_by_slug(slug)  # CPU-bound Markdown parsing
    return templates.TemplateResponse(...)

<!-- base.html — the skeleton -->
<!DOCTYPE html>
<html lang="{{ lang_attr() }}">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>{{ page_title | default("Blake Crosley") }}</title>
  <meta name="description" content="{{ page_description | default('...') }}">

  <!-- CSS — single file, no preprocessor -->
  <link rel="stylesheet" href="{{ asset('css/styles.css') }}">

  <!-- JSON-LD structured data -->
  <script type="application/ld+json">
  { "@context": "https://schema.org", "@graph": [...] }
  </script>

  {% block head %}{% endblock %}
</head>
<body>
  <header class="header">...</header>

  <main id="main" role="main">
    {% block content %}{% endblock %}
  </main>

  <footer class="footer">...</footer>

  <!-- Scripts deferred for performance -->
  <script defer src="{{ asset('js/vendor/alpine.min.js') }}"></script>
  <script defer src="{{ asset('js/vendor/htmx.min.js') }}"></script>
  <script defer src="{{ asset('js/main.js') }}"></script>

  {% block scripts %}{% endblock %}
</body>
</html>

<!-- pages/about.html — fills the blocks -->
{% extends "base.html" %}

{% block head %}
<script type="application/ld+json">
{ "@type": "AboutPage", "name": "About Blake Crosley", ... }
</script>
{% endblock %}

{% block content %}
<section class="hero">
  <h1>About</h1>
  <p>Designer, developer, dad.</p>
</section>
{% endblock %}

# cache_assets.py
def build_asset_map(static_dir: Path) -> dict[str, str]:
    """Compute MD5 hashes of all static files at startup."""
    asset_map = {}
    for filepath in static_dir.rglob("*"):
        if filepath.is_file():
            rel_path = str(filepath.relative_to(static_dir))
            content_hash = hashlib.md5(filepath.read_bytes()).hexdigest()[:10]
            asset_map[rel_path] = content_hash
    return asset_map

def make_asset_url(asset_map: dict, path: str) -> str:
    """Generate versioned URL: /static/css/styles.css?v=a3f8b2c1d0"""
    clean_path = path.lstrip("/")
    version = asset_map.get(clean_path, "0")
    return f"/static/{clean_path}?v={version}"

<!-- base.html -->
{% include "components/_language_switcher.html" %}

<!-- components/_language_switcher.html -->
{%- set current = current_locale() -%}
{%- set locales = all_locales() -%}

<div class="language-switcher"
     x-data="{ open: false }"
     @click.away="open = false">
  <button @click="open = !open" :aria-expanded="open">
    {{ current_locale_native() }}
  </button>
  <ul class="language-switcher-menu"
      :class="{ 'is-open': open }"
      x-cloak>
    {% for locale in locales %}
    <li>
      <a href="{{ locale_url(request.url.path, locale.code) }}"
         hreflang="{{ locale.code }}">
        {{ locale.native }}
      </a>
    </li>
    {% endfor %}
  </ul>
</div>

<!-- components/_macros.html -->
{% macro card(title, description, href, badge=None) %}
<article class="card">
  <a href="{{ href }}" class="card__link">
    {% if badge %}
    <span class="card__badge">{{ badge }}</span>
    {% endif %}
    <h3 class="card__title">{{ title }}</h3>
    {% if description %}
    <p class="card__description">{{ description }}</p>
    {% endif %}
  </a>
</article>
{% endmacro %}

{% macro optimized_image(image_config, loading="lazy") %}
{% if image_config.get("svg") %}
  <img src="{{ image_config.svg }}"
       width="{{ image_config.width }}"
       height="{{ image_config.height }}"
       alt="{{ image_config.alt }}">
{% else %}
  <picture>
    <source type="image/webp"
            srcset="{{ image_config.webp_srcset }}"
            sizes="(max-width: 768px) 100vw, 50vw">
    <img src="{{ image_config.fallback }}"
         width="{{ image_config.width }}"
         height="{{ image_config.height }}"
         alt="{{ image_config.alt }}"
         loading="{{ loading }}">
  </picture>
{% endif %}
{% endmacro %}

{% from "components/_macros.html" import card, optimized_image %}

<section class="projects">
  {% for project in projects %}
    {{ card(
      title=project.title,
      description=project.description,
      href=project.link,
      badge="New" if project.is_new else None
    ) }}
  {% endfor %}
</section>

# In main.py — register globals
templates.env.globals["asset"] = lambda path: make_asset_url(_asset_map, path)
templates.env.globals["csrf_token"] = generate_csrf_token
templates.env.globals["analytics_script"] = analytics.tracking_script

# i18n/jinja.py
def setup_i18n_jinja(env):
    """Register translation functions as Jinja2 globals."""
    env.globals["_"] = get_translation        # _('ui.nav.about')
    env.globals["locale_prefix"] = get_locale_prefix  # '/ja' or ''
    env.globals["current_locale"] = get_current_locale
    env.globals["all_locales"] = get_all_locales
    env.globals["alternate_urls"] = get_alternate_urls
    env.globals["lang_attr"] = get_lang_attr  # 'ja' for HTML lang
    env.globals["og_locale"] = get_og_locale  # 'ja_JP' for og:locale
    env.globals["jsonld_lang"] = get_jsonld_lang  # 'ja-JP' for JSON-LD

<!-- base.html -->
{% block head %}{% endblock %}

<!-- pages/blog/post.html -->
{% block head %}
<script type="application/ld+json">
{
  "@type": "Article",
  "headline": "{{ post.meta.title }}",
  "author": { "@id": "https://blakecrosley.com/#person" },
  "datePublished": "{{ post.meta.date.isoformat() }}",
  "dateModified": "{{ post.meta.updated.isoformat() if post.meta.updated else post.meta.date.isoformat() }}"
}
</script>

{% if post.meta.scripts %}
{% for script in post.meta.scripts %}
<script defer src="{{ asset(script.lstrip('/static/')) }}"></script>
{% endfor %}
{% endif %}

{% if post.meta.styles %}
{% for style in post.meta.styles %}
<link rel="stylesheet" href="{{ asset(style.lstrip('/static/')) }}">
{% endfor %}
{% endif %}
{% endblock %}

import nh3

ALLOWED_TAGS = {"a", "b", "blockquote", "br", "code", "em", "h1", "h2",
                "h3", "h4", "h5", "h6", "hr", "i", "img", "li", "ol",
                "p", "pre", "span", "strong", "table", "td", "th", "tr", "ul"}

def sanitize_html(value: str) -> str:
    """Sanitize HTML to prevent XSS attacks."""
    if not value:
        return ""
    return nh3.clean(
        value,
        tags=ALLOWED_TAGS,
        attributes={"a": {"href", "title"}, "img": {"src", "alt"}},
        link_rel="noopener noreferrer",
    )

templates.env.filters["sanitize"] = sanitize_html

<!-- _quiz_container.html — initial load -->
<div hx-get="/api/quiz/claude-vs-codex/step?answers="
     hx-trigger="load"
     hx-swap="innerHTML"
     id="quiz-wrapper">
  <p>Loading quiz...</p>
</div>

<!-- _quiz_step.html — each question -->
<div class="quiz-step" id="quiz-container">
  <p>Question {{ step }} of {{ total }}</p>
  <h3>{{ question.question }}</h3>
  <div class="quiz-step__options">
    {% for opt in question.options %}
    <button class="quiz-step__btn"
            hx-get="/api/quiz/claude-vs-codex/step?answers={{ answers }},{{ opt.value }}"
            hx-target="#quiz-container"
            hx-swap="outerHTML">
      {{ opt.label }}
    </button>
    {% endfor %}
  </div>
</div>

<!-- Pagination link -->
<a href="/writing?page=2&category=Engineering"
   hx-get="/writing?page=2&category=Engineering"
   hx-target="#writing-content"
   hx-swap="innerHTML"
   hx-replace-url="true"
   hx-indicator="#writing-loading"
   aria-label="Go to page 2">
  2
</a>

<input type="search" name="q"
       hx-get="/api/search"
       hx-trigger="keyup changed delay:300ms"
       hx-target="#results"
       hx-indicator="#search-spinner" />
<div id="results"></div>

@router.get("/api/search")
async def search(request: Request, q: str = ""):
    results = search_content(q)
    return templates.TemplateResponse("components/_search_results.html", {
        "request": request,
        "results": results,
        "query": q,
    })

<!-- Server returns multiple elements in one response -->
<!-- Primary target: swapped normally via hx-target -->
<div id="cart-items">
  <ul>
    <li>Widget A — $29.99</li>
    <li>Widget B — $14.99</li>
  </ul>
</div>

<!-- OOB target: swapped independently via hx-swap-oob -->
<span id="cart-count" hx-swap-oob="true">2 items</span>
<span id="cart-total" hx-swap-oob="true">$44.98</span>

<nav hx-boost="true">
  <a href="/about">About</a>
  <a href="/writing">Writing</a>
  <a href="/guides">Guides</a>
</nav>

@router.get("/writing")
async def writing(request: Request, page: int = 1, category: str = None):
    posts = load_all_posts(page=page, category=category)
    context = {"request": request, "posts": posts, "current_page": page}

    # HTMX request: return only the post list fragment
    if request.headers.get("HX-Request"):
        return templates.TemplateResponse(
            "pages/writing/_post_list.html", context
        )

    # Normal request: return the full page
    return templates.TemplateResponse("pages/writing/index.html", context)

<a href="/writing?page=2"
   hx-get="/writing?page=2"
   hx-target="#writing-content"
   hx-swap="innerHTML">
  Next Page
</a>

<button hx-post="/api/contact"
        hx-target="#form-result"
        hx-indicator="#submit-spinner">
  <span id="submit-spinner" class="htmx-indicator">Sending...</span>
  <span>Send Message</span>
</button>

.htmx-indicator {
  display: none;
}
.htmx-request .htmx-indicator,
.htmx-request.htmx-indicator {
  display: inline;
}

<div x-data="{ navOpen: false, langOpen: false }"
     @keydown.escape.window="navOpen = false; langOpen = false">

  <!-- Mobile hamburger button -->
  <button @click="navOpen = !navOpen; langOpen = false"
          :aria-expanded="navOpen"
          :class="navOpen ? 'nav__toggle is-open' : 'nav__toggle'"
          aria-label="Toggle navigation">
    <span class="nav__toggle-icon">
      <span class="nav__toggle-bar"></span>
      <span class="nav__toggle-bar"></span>
      <span class="nav__toggle-bar"></span>
    </span>
  </button>

  <!-- Mobile menu panel -->
  <div class="mobile-menu" x-show="navOpen" x-cloak>
    <nav class="mobile-menu__nav">
      <a href="/about" @click="navOpen = false">About</a>
      <a href="/#work" @click="navOpen = false">Work</a>
      <a href="/writing" @click="navOpen = false">Writing</a>
    </nav>
  </div>
</div>

<div x-data="{ open: false }"
     @click.away="open = false"
     @keydown.escape.window="open = false">

  <button @click="open = !open"
          :aria-expanded="open"
          aria-haspopup="listbox">
    English
    <svg :class="{ 'rotated': open }">...</svg>
  </button>

  <ul :class="{ 'is-open': open }"
      :aria-hidden="!open"
      role="listbox"
      x-cloak>
    <li role="option">
      <a href="/ja/about">日本語</a>
    </li>
    <!-- more languages -->
  </ul>
</div>

<!-- base.html — no CDN, no external requests -->
<script defer src="{{ asset('js/vendor/alpine.min.js') }}"></script>
<script defer src="{{ asset('js/vendor/htmx.min.js') }}"></script>

<div class="container">
  <div class="row">
    <div class="col-12 col-md-8">
      <article>Main content</article>
    </div>
    <div class="col-12 col-md-4">
      <aside>Sidebar</aside>
    </div>
  </div>
</div>

/* Custom design tokens — no Sass, no Tailwind */
:root {
  --color-bg-dark:        #000000;
  --color-text-primary:   #ffffff;
  --color-text-secondary: rgba(255, 255, 255, 0.65);
  --color-text-tertiary:  rgba(255, 255, 255, 0.40);
  --spacing-sm:           1rem;
  --spacing-md:           1.5rem;
  --spacing-lg:           2rem;
  --gutter:               48px;
  --font-size-lg:         1.25rem;
}

/* Responsive override — the browser reads this at runtime */
@media (max-width: 768px) {
  :root {
    --gutter: var(--spacing-md);  /* 48px → 24px on mobile */
  }
}

/* Override Bootstrap's default body styles */
body {
  background: var(--color-bg-dark);
  color: var(--color-text-primary);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", system-ui, sans-serif;
}

<!-- Bootstrap utility for one-off spacing -->
<div class="mt-4 mb-3 px-2">One-off layout</div>

<!-- Component class for repeated patterns -->
<article class="writing__item">
  <h3 class="writing__item-title">Post Title</h3>
  <p class="writing__item-description">Description</p>
</article>

/* Component CSS — BEM naming, reusable */
.writing__item {
  padding: var(--spacing-md);
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
  transition: background 0.15s ease;
}
.writing__item:hover {
  background: rgba(255, 255, 255, 0.03);
}
.writing__item-title {
  font-size: var(--font-size-lg);
  margin-bottom: 0.5rem;
}

# i18n/config.py
SUPPORTED_LOCALES = [
    "en", "zh-Hans", "zh-Hant", "fr", "de", "ja", "ko", "pl", "pt-BR", "es"
]
DEFAULT_LOCALE = "en"

# i18n/middleware.py
class LocaleMiddleware(BaseHTTPMiddleware):
    async def dispatch(self, request, call_next):
        path = request.url.path
        # Check if path starts with a supported locale
        for locale in SUPPORTED_LOCALES:
            if path.startswith(f"/{locale}/") or path == f"/{locale}":
                request.state.locale = locale
                # Strip locale prefix for route matching
                request.scope["path"] = path[len(f"/{locale}"):]
                break
        else:
            request.state.locale = DEFAULT_LOCALE

        response = await call_next(request)
        return response

<!-- Template usage -->
<h3>{{ _('ui.footer.navigate') | default('Navigate') }}</h3>
<a href="{{ locale_prefix() }}/about">
  {{ _('ui.nav.about') | default('About') }}
</a>

<!-- Generated in base.html -->
{% for alt in alternate_urls(request.url.path) %}
<link rel="alternate" hreflang="{{ alt.hreflang }}" href="{{ alt.url }}">
{% endfor %}

<link rel="alternate" hreflang="en" href="https://blakecrosley.com/about">
<link rel="alternate" hreflang="ja" href="https://blakecrosley.com/ja/about">
<link rel="alternate" hreflang="zh-Hans" href="https://blakecrosley.com/zh-Hans/about">
<!-- ... all 10 locales -->
<link rel="alternate" hreflang="x-default" href="https://blakecrosley.com/about">

@app.on_event("startup")
async def startup_load_translations():
    client = init_d1_client(worker_url=settings.D1_WORKER_URL,
                            auth_secret=settings.D1_AUTH_SECRET)
    cache = await load_translations(client)
    logger.info(f"i18n: Loaded {cache.stats['key_count']} keys")

@app.get("/health/i18n")
async def health_i18n():
    cache = get_translation_cache()
    result = {
        "status": "healthy",
        "cache_loaded": cache.is_loaded,
        "locales": {},
        "alerts": [],
    }

    # Check coverage for each locale
    for locale in SUPPORTED_LOCALES:
        coverage = await calculate_coverage(locale, en_count)
        result["locales"][locale] = {"coverage": round(coverage, 2)}

        if coverage < 99.5:
            result["alerts"].append(
                f"{locale}: {coverage:.1f}% coverage (threshold: 99.5%)"
            )
            result["status"] = "warning"

    return result

# In route handler
translated = get_blog_translation(post.meta.slug, locale)
return templates.TemplateResponse("pages/blog/post.html", {
    "request": request,
    "post": post,
    "translated_title": translated.title if translated else post.meta.title,
    "translated_description": translated.description if translated else post.meta.description,
})

<!-- In template -->
<h1>{{ translated_title }}</h1>
<p class="post__description">{{ translated_description }}</p>
<!-- Body content falls back to English if translation unavailable -->
{{ post.html | sanitize | safe }}

{{ translated.title if translated else post.meta.title }}

# i18n/data.py
def translate_projects(projects: list, locale: str) -> list:
    """Return projects with translated titles and descriptions."""
    if locale == "en":
        return projects
    translated = []
    for project in projects:
        t = get_translation(f"project.{project['slug']}.title", locale)
        d = get_translation(f"project.{project['slug']}.description", locale)
        translated.append({
            **project,
            "title": t or project["title"],
            "description": d or project["description"],
        })
    return translated

@app.get("/sitemap.xml")
async def sitemap():
    for page in static_pages:
        for locale in SUPPORTED_LOCALES:
            # Each URL entry includes alternates for all locales
            locale_path = f"/{locale}{path}" if locale != "en" else path
            xml_parts.append(f"<loc>{base_url}{locale_path}</loc>")
            # Add xhtml:link alternates
            for alt_locale in SUPPORTED_LOCALES:
                alt_path = f"/{alt_locale}{path}" if alt_locale != "en" else path
                hreflang = LOCALE_TO_HREFLANG[alt_locale]
                xml_parts.append(
                    f'<xhtml:link rel="alternate" hreflang="{hreflang}" '
                    f'href="{base_url}{alt_path}"/>'
                )

from sqlalchemy.ext.asyncio import create_async_engine, AsyncSession
from sqlalchemy.orm import sessionmaker, DeclarativeBase

engine = create_async_engine("sqlite+aiosqlite:///./data.db")
async_session = sessionmaker(engine, class_=AsyncSession, expire_on_commit=False)

class Base(DeclarativeBase):
    pass

from fastapi import Depends
from sqlalchemy.ext.asyncio import AsyncSession

async def get_db() -> AsyncGenerator[AsyncSession, None]:
    async with async_session() as session:
        try:
            yield session
            await session.commit()
        except Exception:
            await session.rollback()
            raise

@router.get("/users/{user_id}")
async def get_user(user_id: int, db: AsyncSession = Depends(get_db)):
    result = await db.execute(select(User).where(User.id == user_id))
    user = result.scalar_one_or_none()
    if not user:
        raise HTTPException(404, "User not found")
    return templates.TemplateResponse("pages/user.html", {
        "request": request, "user": user
    })

from pydantic import BaseModel, EmailStr

class ContactForm(BaseModel):
    name: str
    email: EmailStr
    message: str

@router.post("/contact")
async def submit_contact(form: ContactForm):
    # form.name, form.email, form.message are validated
    await send_email(form)
    return templates.TemplateResponse("components/_contact_success.html", {
        "request": request
    })

# Generate a migration from model changes
alembic revision --autogenerate -m "add user preferences table"

# Apply migrations
alembic upgrade head

# Roll back one migration
alembic downgrade -1

# alembic/versions/001_add_user_preferences.py
def upgrade():
    op.create_table(
        "user_preferences",
        sa.Column("id", sa.Integer, primary_key=True),
        sa.Column("user_id", sa.Integer, sa.ForeignKey("users.id")),
        sa.Column("locale", sa.String(10), default="en"),
        sa.Column("theme", sa.String(20), default="dark"),
    )

def downgrade():
    op.drop_table("user_preferences")

class D1Client:
    """HTTP client for Cloudflare D1 via Worker proxy."""

    def __init__(self, worker_url: str, auth_secret: str):
        self.worker_url = worker_url
        self.auth_secret = auth_secret

    async def fetch_all(self, sql: str, params: list = None) -> list[dict]:
        async with httpx.AsyncClient() as client:
            response = await client.post(
                f"{self.worker_url}/query",
                json={"sql": sql, "params": params or []},
                headers={"Authorization": f"Bearer {self.auth_secret}"},
            )
            return response.json()["results"]

class SecurityHeadersMiddleware(BaseHTTPMiddleware):
    CSP_DIRECTIVES = {
        "default-src": "'self'",
        "script-src": "'self' 'unsafe-inline' 'unsafe-eval'",
        "style-src": "'self' 'unsafe-inline'",
        "img-src": "'self' data: https:",
        "connect-src": "'self'",
        "frame-ancestors": "'self'",
        "base-uri": "'self'",
        "form-action": "'self'",
        "upgrade-insecure-requests": "",
    }

    async def dispatch(self, request, call_next):
        response = await call_next(request)
        response.headers["X-Content-Type-Options"] = "nosniff"
        response.headers["X-Frame-Options"] = "SAMEORIGIN"
        response.headers["Referrer-Policy"] = "strict-origin-when-cross-origin"
        response.headers["Strict-Transport-Security"] = (
            "max-age=31536000; includeSubDomains"
        )
        response.headers["Cross-Origin-Opener-Policy"] = "same-origin"
        response.headers["Content-Security-Policy"] = self.csp
        response.headers["Permissions-Policy"] = self.PERMISSIONS_POLICY
        return response

if request.headers.get("HX-Request"):
    existing_vary = response.headers.get("Vary", "")
    if "HX-Request" not in existing_vary:
        parts = [v.strip() for v in existing_vary.split(",") if v.strip()]
        parts.append("HX-Request")
        response.headers["Vary"] = ", ".join(parts)

# csrf.py
def generate_csrf_token() -> str:
    """Token format: timestamp:random:HMAC-SHA256-signature"""
    timestamp = str(int(time.time()))
    random_value = secrets.token_hex(16)
    payload = f"{timestamp}:{random_value}"
    signature = hmac.new(
        CSRF_SECRET.encode(), payload.encode(), hashlib.sha256
    ).hexdigest()
    return f"{payload}:{signature}"

def validate_csrf_token(token: str) -> bool:
    """Verify signature and check expiration (1 hour)."""
    timestamp, random_value, signature = token.split(":")
    if int(time.time()) - int(timestamp) > 3600:
        return False
    expected = hmac.new(
        CSRF_SECRET.encode(),
        f"{timestamp}:{random_value}".encode(),
        hashlib.sha256
    ).hexdigest()
    return hmac.compare_digest(expected, signature)

<form hx-post="/contact" hx-target="#form-result">
  <input type="hidden" name="csrf_token" value="{{ csrf_token() }}">
  <!-- form fields -->
</form>

templates.env.filters["sanitize"] = sanitize_html
# In templates: {{ content | sanitize }}

from pydantic import BaseModel, Field, EmailStr

class ContactRequest(BaseModel):
    name: str = Field(..., min_length=1, max_length=100)
    email: EmailStr
    message: str = Field(..., min_length=10, max_length=5000)

<!-- Critical CSS inlined for instant first paint -->
<style>{% include "components/_critical.css" %}</style>

<!-- Full CSS loads async — doesn't block render -->
<link rel="stylesheet" href="/static/css/styles.css"
      media="print" onload="this.media='all'">
<noscript>
  <link rel="stylesheet" href="/static/css/styles.css">
</noscript>

app.add_middleware(GZipMiddleware, minimum_size=500)

# In security headers middleware
if request.url.path.startswith("/static/"):
    if os.environ.get("RAILWAY_ENVIRONMENT"):
        response.headers["Cache-Control"] = "public, max-age=31536000, immutable"

<script defer src="{{ asset('js/vendor/alpine.min.js') }}"></script>
<script defer src="{{ asset('js/vendor/htmx.min.js') }}"></script>
<script defer src="{{ asset('js/main.js') }}"></script>

OPTIMIZED_IMAGES = {
    "vision-sprint": {
        "webp_srcset": (
            "/static/images/optimized/vision-sprint-400w.webp 400w, "
            "/static/images/optimized/vision-sprint-800w.webp 800w, "
            "/static/images/optimized/vision-sprint-1200w.webp 1200w"
        ),
        "fallback": "/static/images/optimized/vision-sprint-fallback.jpg",
        "width": 1200,
        "height": 1045,
    },
}

<picture>
  <source type="image/webp"
          srcset="{{ image.webp_srcset }}"
          sizes="(max-width: 768px) 100vw, 50vw">
  <img src="{{ image.fallback }}"
       width="{{ image.width }}"
       height="{{ image.height }}"
       alt="{{ image.alt }}"
       loading="lazy">
</picture>

# In main.py
app.state.preload_links = [
    f'<{make_asset_url(_asset_map, "css/styles.css")}>; rel=preload; as=style',
]

# In security headers middleware
if "text/html" in content_type:
    preload_links = getattr(request.app.state, "preload_links", [])
    if preload_links:
        response.headers["Link"] = ", ".join(preload_links)

# railway.toml
[build]
builder = "nixpacks"

[deploy]
startCommand = "uvicorn app.main:app --host 0.0.0.0 --port ${PORT:-8000}"
healthcheckPath = "/health"
healthcheckTimeout = 300
restartPolicyType = "ON_FAILURE"
restartPolicyMaxRetries = 10

@app.get("/health")
async def health():
    return {"status": "healthy"}

git push origin main
  → Railway detects push
  → Nixpacks installs Python + requirements.txt (cached)
  → uvicorn starts
  → Health check passes
  → Traffic routes to new deployment
  → ~40 seconds total

web: uvicorn app.main:app --host 0.0.0.0 --port ${PORT:-8000}

uvicorn app.main:app \
  --host 0.0.0.0 \
  --port ${PORT:-8000} \
  --workers 4 \
  --loop uvloop \
  --http httptools

uvicorn app.main:app --reload --port 8000

FROM python:3.11-slim

WORKDIR /app
COPY requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt

COPY . .

EXPOSE 8000
CMD ["uvicorn", "app.main:app", "--host", "0.0.0.0", "--port", "8000"]

# Cache headers for HTML pages (set in security middleware)
response.headers["Cache-Control"] = (
    "public, max-age=300, s-maxage=3600, "
    "stale-while-revalidate=86400"
)

# Development
source venv/bin/activate
uvicorn app.main:app --reload --port 8000

# Production
uvicorn app.main:app --host 0.0.0.0 --port ${PORT:-8000}

# Testing
python -m pytest -v --cov=app

# Database migrations
alembic upgrade head
alembic revision --autogenerate -m "description"

hx-get="/url"                     <!-- GET request -->
hx-post="/url"                    <!-- POST request -->
hx-target="#element"              <!-- Where to put response -->
hx-swap="innerHTML"               <!-- How to insert (innerHTML, outerHTML, beforeend) -->
hx-trigger="click"                <!-- What triggers request -->
hx-trigger="keyup changed delay:300ms"  <!-- Debounced input -->
hx-trigger="load"                 <!-- Fire on element load -->
hx-indicator="#spinner"           <!-- Show during request -->
hx-push-url="true"                <!-- Update browser URL -->
hx-replace-url="true"             <!-- Replace URL (no history) -->

x-data="{ open: false }"         <!-- Component scope + state -->
x-show="open"                    <!-- Toggle visibility -->
x-cloak                          <!-- Hide until Alpine inits -->
@click="open = !open"            <!-- Event handler -->
@click.away="open = false"       <!-- Outside click -->
@keydown.escape="open = false"   <!-- Keyboard event -->
:class="{ 'active': open }"      <!-- Dynamic class -->
:aria-expanded="open"            <!-- Dynamic attribute -->
x-text="count"                   <!-- Dynamic text content -->
x-init="fetchData()"             <!-- Run on init -->

:root {
  --color-bg:     #000000;
  --color-text:   #ffffff;
  --spacing-sm:   1rem;
  --spacing-md:   1.5rem;
  --font-size-lg: 1.25rem;
}
@media (max-width: 768px) {
  :root { --gutter: 24px; }
}

Content-Security-Policy: default-src 'self'; script-src 'self' 'unsafe-eval'
Strict-Transport-Security: max-age=31536000; includeSubDomains
X-Content-Type-Options: nosniff
X-Frame-Options: SAMEORIGIN
Referrer-Policy: strict-origin-when-cross-origin
Cross-Origin-Opener-Policy: same-origin
Permissions-Policy: camera=(), microphone=(), geolocation=()

[ ] FastAPI app with Jinja2Templates
[ ] Security headers middleware (CSP, HSTS, X-Frame-Options)
[ ] CSRF token generation and validation
[ ] GZip middleware (minimum_size=500)
[ ] Content-hash asset versioning (cache busting)
[ ] HTMX self-hosted in /static/js/vendor/
[ ] Alpine.js self-hosted in /static/js/vendor/
[ ] CSS custom properties for design tokens
[ ] Health check endpoint (/health)
[ ] Error handlers (404, 500)
[ ] robots.txt, sitemap.xml, llms.txt
[ ] JSON-LD structured data in base template
[ ] Hreflang tags for i18n (if multi-language)
[ ] HTML sanitization filter (nh3)
[ ] Rate limiting middleware
[ ] Deferred script loading

<form hx-post="/contact" hx-target="#form-container" hx-swap="outerHTML">
  <input type="email" name="email" required>
  <button type="submit">Send</button>
</form>

@router.post("/contact")
async def contact(request: Request, email: str = Form(...)):
    if not validate_email(email):
        return templates.TemplateResponse("components/_contact_form.html", {
            "request": request,
            "error": "Please enter a valid email address",
            "email": email,  # Preserve input
        })
    await send_email(email)
    return templates.TemplateResponse("components/_contact_success.html", {
        "request": request
    })

from fastapi import WebSocket

@app.websocket("/ws/notifications")
async def websocket_endpoint(websocket: WebSocket):
    await websocket.accept()
    while True:
        data = await get_notification()
        await websocket.send_text(render_notification_html(data))

<div hx-ws="connect:/ws/notifications">
  <div id="notifications" hx-ws="send"></div>
</div>