flow-arch/limitations.html at main · flow-arch-dev/flow-arch · GitHub

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<!doctype html>
<html lang="en">
<head>
  <meta charset="UTF-8" />
  <meta name="viewport" content="width=device-width, initial-scale=1.0" />
  <title>Limitations — Flow-Arch</title>
  <link rel="preconnect" href="https://fonts.googleapis.com">
  <link href="https://fonts.googleapis.com/css2?family=DM+Mono:wght@300;400;500&family=Syne:wght@600;700;800&family=Newsreader:ital,wght@0,300;0,400;1,300&display=swap" rel="stylesheet">
  <style>
    :root {
      --bg:      #0a0a0a;
      --surface: #111;
      --border:  #1e1e1e;
      --accent:  #c8f542;
      --dim:     #8faa2a;
      --text:    #e2e2dc;
      --muted:   #5a5a54;
      --code-bg: #141414;
      --warn:    #e0a86c;
      --fn-mono: 'DM Mono', monospace;
      --fn-disp: 'Syne', sans-serif;
      --fn-body: 'Newsreader', serif;
    }

    *, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
    html { scroll-behavior: smooth; }

    body {
      background: var(--bg);
      color: var(--text);
      font-family: var(--fn-body);
      font-size: 17px;
      line-height: 1.75;
    }

    ::selection { background: var(--accent); color: #000; }

    .wrap {
      display: grid;
      grid-template-columns: 220px 1fr;
      min-height: 100vh;
    }

    /* ── SIDEBAR ── */
    aside {
      position: sticky;
      top: 0;
      height: 100vh;
      overflow-y: auto;
      border-right: 1px solid var(--border);
      padding: 40px 24px;
      background: var(--bg);
    }

    .sidebar-logo {
      font-family: var(--fn-mono);
      font-size: 11px;
      color: var(--accent);
      letter-spacing: 0.15em;
      text-transform: uppercase;
      margin-bottom: 8px;
      display: block;
      text-decoration: none;
    }

    .sidebar-back {
      font-family: var(--fn-mono);
      font-size: 11px;
      color: var(--muted);
      text-decoration: none;
      display: block;
      margin-bottom: 32px;
      transition: color 0.15s;
    }

    .sidebar-back:hover { color: var(--accent); }

    .sidebar-label {
      font-family: var(--fn-mono);
      font-size: 9px;
      letter-spacing: 0.2em;
      color: var(--muted);
      text-transform: uppercase;
      margin-bottom: 10px;
      margin-top: 28px;
    }

    .sidebar-nav {
      list-style: none;
      display: flex;
      flex-direction: column;
      gap: 2px;
    }

    .sidebar-nav a {
      font-family: var(--fn-mono);
      font-size: 12px;
      color: var(--muted);
      text-decoration: none;
      padding: 5px 10px;
      border-radius: 4px;
      display: block;
      transition: all 0.15s;
      line-height: 1.4;
    }

    .sidebar-nav a:hover,
    .sidebar-nav a.active {
      color: var(--accent);
      background: rgba(200,245,66,0.06);
    }

    /* ── MAIN ── */
    main {
      padding: 60px 64px 120px;
      max-width: 780px;
    }

    .breadcrumb {
      font-family: var(--fn-mono);
      font-size: 11px;
      color: var(--muted);
      margin-bottom: 40px;
      display: flex;
      align-items: center;
      gap: 8px;
    }

    .breadcrumb a {
      color: var(--accent);
      text-decoration: none;
    }

    .breadcrumb a:hover { text-decoration: underline; }
    .breadcrumb span { color: var(--muted); }

    /* ── HERO ── */
    .page-hero {
      margin-bottom: 64px;
    }

    .page-eyebrow {
      font-family: var(--fn-mono);
      font-size: 10px;
      letter-spacing: 0.2em;
      color: var(--warn);
      text-transform: uppercase;
      margin-bottom: 16px;
    }

    h1 {
      font-family: var(--fn-disp);
      font-size: clamp(36px, 5vw, 56px);
      font-weight: 800;
      letter-spacing: -0.03em;
      line-height: 1.05;
      margin-bottom: 20px;
    }

    h1 em {
      font-style: italic;
      font-family: var(--fn-body);
      font-weight: 300;
      color: var(--warn);
    }

    .lead {
      font-size: 18px;
      color: #c0c0ba;
      font-style: italic;
      line-height: 1.6;
      margin-bottom: 28px;
    }

    /* ── SUMMARY TABLE ── */
    .summary-table {
      border: 1px solid var(--border);
      border-radius: 8px;
      overflow: hidden;
      margin: 32px 0 64px;
    }

    .summary-table table {
      width: 100%;
      border-collapse: collapse;
    }

    .summary-table th {
      font-family: var(--fn-mono);
      font-size: 10px;
      letter-spacing: 0.12em;
      text-transform: uppercase;
      color: var(--muted);
      padding: 12px 16px;
      text-align: left;
      border-bottom: 1px solid var(--border);
      background: var(--surface);
    }

    .summary-table td {
      font-family: var(--fn-mono);
      font-size: 12px;
      padding: 12px 16px;
      border-bottom: 1px solid var(--border);
      color: var(--muted);
      vertical-align: middle;
    }

    .summary-table tr:last-child td { border-bottom: none; }
    .summary-table tr:hover td { background: rgba(255,255,255,0.02); }

    .summary-table td:first-child {
      color: var(--warn);
      font-weight: 500;
      white-space: nowrap;
    }

    .summary-table td:nth-child(2) {
      color: var(--text);
    }

    .summary-table td a {
      color: var(--accent);
      text-decoration: none;
    }

    .summary-table td a:hover { text-decoration: underline; }

    /* ── STATUS BADGE ── */
    .badge {
      font-family: var(--fn-mono);
      font-size: 10px;
      letter-spacing: 0.08em;
      padding: 3px 8px;
      border-radius: 100px;
      white-space: nowrap;
    }

    .badge.known      { background: rgba(224,168,108,0.1); color: var(--warn); border: 1px solid rgba(224,168,108,0.3); }
    .badge.exploring  { background: rgba(200,245,66,0.1);  color: var(--accent); border: 1px solid rgba(200,245,66,0.3); }
    .badge.partial    { background: rgba(126,207,207,0.1); color: #7ecfcf; border: 1px solid rgba(126,207,207,0.3); }
    .badge.resolved   { background: rgba(100,180,100,0.1); color: #80c880; border: 1px solid rgba(100,180,100,0.3); }

    .priority { color: var(--muted); font-size: 11px; }
    .priority.high   { color: #cc6666; }
    .priority.medium { color: var(--warn); }
    .priority.low    { color: var(--muted); }

    /* ── LIMITATION SECTIONS ── */
    .limitation {
      padding-top: 64px;
      border-top: 1px solid var(--border);
      margin-bottom: 0;
    }

    .limitation:first-of-type { border-top: none; padding-top: 0; }

    .lim-header {
      display: flex;
      align-items: flex-start;
      justify-content: space-between;
      gap: 16px;
      margin-bottom: 20px;
      flex-wrap: wrap;
    }

    .lim-id {
      font-family: var(--fn-mono);
      font-size: 11px;
      color: var(--warn);
      letter-spacing: 0.1em;
      margin-bottom: 8px;
    }

    h2 {
      font-family: var(--fn-disp);
      font-size: 22px;
      font-weight: 700;
      letter-spacing: -0.02em;
      line-height: 1.2;
    }

    h3 {
      font-family: var(--fn-mono);
      font-size: 11px;
      letter-spacing: 0.12em;
      text-transform: uppercase;
      color: var(--muted);
      margin: 24px 0 10px;
    }

    p { color: #a8a8a2; margin-bottom: 12px; }
    p strong { color: var(--text); font-weight: 400; }
    p:last-child { margin-bottom: 0; }

    /* ── CODE BLOCK ── */
    .code-block {
      background: var(--code-bg);
      border: 1px solid var(--border);
      border-radius: 8px;
      overflow: hidden;
      margin: 16px 0;
    }

    .code-header {
      display: flex;
      align-items: center;
      justify-content: space-between;
      padding: 9px 16px;
      border-bottom: 1px solid var(--border);
    }

    .code-title {
      font-family: var(--fn-mono);
      font-size: 10px;
      color: var(--muted);
      letter-spacing: 0.08em;
    }

    .code-lang {
      font-family: var(--fn-mono);
      font-size: 10px;
      color: var(--dim);
    }

    pre {
      padding: 20px;
      overflow-x: auto;
      font-family: var(--fn-mono);
      font-size: 13px;
      line-height: 1.85;
      color: #c0c0b8;
    }

    .k { color: var(--accent); }
    .s { color: #9aba3a; }
    .c { color: #383830; }
    .f { color: #7ecfcf; }
    .n { color: #e0a86c; }
    .bad { color: #cc6666; }
    .ok  { color: #80c880; }

    /* ── CALLOUT ── */
    .callout {
      border-left: 2px solid var(--accent);
      background: rgba(200,245,66,0.04);
      border-radius: 0 6px 6px 0;
      padding: 14px 18px;
      margin: 16px 0;
    }

    .callout.warn {
      border-left-color: var(--warn);
      background: rgba(224,168,108,0.04);
    }

    .callout-label {
      font-family: var(--fn-mono);
      font-size: 10px;
      color: var(--accent);
      letter-spacing: 0.15em;
      text-transform: uppercase;
      margin-bottom: 6px;
    }

    .callout.warn .callout-label { color: var(--warn); }
    .callout p { font-size: 14px; color: #a0a09a; margin: 0; }

    /* ── OPEN QUESTION ── */
    .open-question {
      background: var(--surface);
      border: 1px solid var(--border);
      border-radius: 8px;
      padding: 18px 22px;
      margin: 16px 0;
    }

    .oq-label {
      font-family: var(--fn-mono);
      font-size: 10px;
      color: var(--accent);
      letter-spacing: 0.15em;
      text-transform: uppercase;
      margin-bottom: 8px;
    }

    .oq-text {
      font-size: 15px;
      color: #b0b0aa;
      font-style: italic;
      line-height: 1.6;
    }

    /* ── EXPERIMENT LINK ── */
    .experiment-link {
      display: inline-flex;
      align-items: center;
      gap: 8px;
      font-family: var(--fn-mono);
      font-size: 11px;
      color: var(--muted);
      border: 1px solid var(--border);
      padding: 7px 14px;
      border-radius: 6px;
      text-decoration: none;
      margin-top: 8px;
      transition: all 0.15s;
    }

    .experiment-link:hover {
      color: var(--accent);
      border-color: var(--dim);
    }

    .experiment-link::before { content: '⌗'; margin-right: 2px; }

    /* ── CONTRIBUTE BANNER ── */
    .contribute {
      border: 1px solid var(--border);
      border-radius: 8px;
      padding: 28px;
      margin-top: 72px;
      background: var(--surface);
    }

    .contribute-label {
      font-family: var(--fn-mono);
      font-size: 10px;
      color: var(--accent);
      letter-spacing: 0.15em;
      text-transform: uppercase;
      margin-bottom: 12px;
    }

    .contribute h2 {
      font-size: 20px;
      margin-bottom: 12px;
    }

    .contribute p {
      font-size: 15px;
      margin-bottom: 16px;
    }

    .btn {
      font-family: var(--fn-mono);
      font-size: 12px;
      letter-spacing: 0.08em;
      padding: 10px 20px;
      border-radius: 4px;
      text-decoration: none;
      display: inline-block;
      transition: all 0.2s;
      border: 1px solid var(--border);
      color: var(--muted);
    }

    .btn:hover { color: var(--accent); border-color: var(--dim); }

    code {
      font-family: var(--fn-mono);
      font-size: 12px;
      background: #1a1a1a;
      border: 1px solid var(--border);
      padding: 1px 6px;
      border-radius: 3px;
      color: var(--accent);
    }

    @keyframes pulse {
      0%, 100% { opacity: 1; }
      50% { opacity: 0.4; }
    }

    @media (max-width: 768px) {
      .wrap { grid-template-columns: 1fr; }
      aside { display: none; }
      main  { padding: 32px 24px 80px; }
    }
  </style>
</head>
<body>

<div class="wrap">

  <!-- ═══ SIDEBAR ═══ -->
  <aside>
    <a href="index.html" class="sidebar-logo">flow-arch/</a>
    <a href="index.html" class="sidebar-back">← back to home</a>

    <p class="sidebar-label">Overview</p>
    <ul class="sidebar-nav">
      <li><a href="#intro">Introduction</a></li>
      <li><a href="#summary">Summary Table</a></li>
    </ul>

    <p class="sidebar-label">Limitations</p>
    <ul class="sidebar-nav">
      <li><a href="#l01">L-01 innerHTML Replacement</a></li>
      <li><a href="#l02">L-02 No Shared State</a></li>
      <li><a href="#l03">L-03 No Async Actions</a></li>
      <li><a href="#l04">L-04 No Enforced Purity</a></li>
      <li><a href="#l05">L-05 No Type Safety</a></li>
      <li><a href="#l06">L-06 No SSR</a></li>
      <li><a href="#l07">L-07 Boilerplate</a></li>
    </ul>

    <p class="sidebar-label">Contribute</p>
    <ul class="sidebar-nav">
      <li><a href="#contribute">Report a limitation</a></li>
    </ul>
  </aside>

  <!-- ═══ MAIN ═══ -->
  <main>

    <!-- BREADCRUMB -->
    <div class="breadcrumb">
      <a href="index.html">flow-arch</a>
      <span>/</span>
      <span>limitations</span>
    </div>

    <!-- HERO -->
    <div id="intro" class="page-hero">
      <p class="page-eyebrow">Honest Documentation</p>
      <h1>Known<br><em>Limitations.</em></h1>
      <p class="lead">
        This is a living record of what Flow-Arch cannot do well — yet.
        Every limitation is an open research question.
        Honesty about constraints is part of the methodology.
      </p>
      <p>
        Each entry describes the problem, explains when it matters,
        shows any current workaround, and frames the open question
        it leaves behind. Limitations resolved through experiments
        will be updated here.
      </p>

      <div class="callout" style="margin-top:24px">
        <div class="callout-label">Philosophy</div>
        <p>
          A limitation honestly documented is more valuable than a feature
          dishonestly promoted. If you find something missing from this list,
          <strong style="color:var(--text)">that is a contribution</strong>.
        </p>
      </div>
    </div>

    <!-- SUMMARY TABLE -->
    <div id="summary">
      <div class="summary-table">
        <table>
          <thead>
            <tr>
              <th>ID</th>
              <th>Limitation</th>
              <th>Status</th>
              <th>Priority</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td><a href="#l01">L-01</a></td>
              <td>Full innerHTML replacement on every render</td>
              <td><span class="badge known">KNOWN</span></td>
              <td><span class="priority high">High</span></td>
            </tr>
            <tr>
              <td><a href="#l02">L-02</a></td>
              <td>No inter-component state management</td>
              <td><span class="badge known">KNOWN</span></td>
              <td><span class="priority high">High</span></td>
            </tr>
            <tr>
              <td><a href="#l03">L-03</a></td>
              <td>No async action handling</td>
              <td><span class="badge known">KNOWN</span></td>
              <td><span class="priority medium">Medium</span></td>
            </tr>
            <tr>
              <td><a href="#l04">L-04</a></td>
              <td>No enforced purity (inherent to JS)</td>
              <td><span class="badge known">KNOWN</span></td>
              <td><span class="priority low">Low</span></td>
            </tr>
            <tr>
              <td><a href="#l05">L-05</a></td>
              <td>String-based view has no type safety</td>
              <td><span class="badge known">KNOWN</span></td>
              <td><span class="priority medium">Medium</span></td>
            </tr>
            <tr>
              <td><a href="#l06">L-06</a></td>
              <td>No SSR implementation yet</td>
              <td><span class="badge known">KNOWN</span></td>
              <td><span class="priority medium">Medium</span></td>
            </tr>
            <tr>
              <td><a href="#l07">L-07</a></td>
              <td>Component boilerplate repetition</td>
              <td><span class="badge known">KNOWN</span></td>
              <td><span class="priority low">Low</span></td>
            </tr>
          </tbody>
        </table>
      </div>
    </div>


    <!-- ── L-01 ── -->
    <div id="l01" class="limitation">
      <div class="lim-header">
        <div>
          <div class="lim-id">L-01</div>
          <h2>Full innerHTML Replacement<br>on Every Render</h2>
        </div>
        <span class="badge known">KNOWN</span>
      </div>

      <h3>What happens</h3>
      <p>
        Every time state changes, the entire Shadow DOM is destroyed and rebuilt from scratch.
      </p>

      <div class="code-block">
        <div class="code-header">
          <span class="code-title">the current pattern</span>
          <span class="code-lang">JS</span>
        </div>
        <pre><span class="f">render</span>() {
  <span class="c">// Every render — full replacement</span>
  <span class="c">// Old nodes destroyed. New nodes created.</span>
  <span class="k">this</span>.shadowRoot.innerHTML = <span class="f">view</span>(<span class="k">this</span>.state)
}</pre>
      </div>

      <h3>Why it is a problem</h3>
      <p>The browser must destroy all existing nodes, parse the new HTML string, create all new nodes, recalculate styles, re-layout, and repaint — even when only one value changed.</p>

      <div class="code-block">
        <div class="code-header">
          <span class="code-title">concrete consequences</span>
          <span class="code-lang">JS</span>
        </div>
        <pre><span class="c">// 1. Input loses focus on every render</span>
<span class="bad">// &lt;input&gt; is destroyed and recreated — cursor position lost</span>

<span class="c">// 2. CSS transitions reset</span>
<span class="bad">// transition: opacity 0.3s — resets every render because
// the element is a brand new node each time</span>

<span class="c">// 3. Expensive for large lists</span>
<span class="bad">// 100 todo items = 100 nodes destroyed + 100 recreated
// on every single keystroke or tick</span></pre>
      </div>

      <h3>When it does not matter</h3>
      <p>Simple components updated on user click (counter, toggle, timer). DOM trees with fewer than ~20 nodes. No <code>&lt;input&gt;</code> elements inside the component.</p>

      <div class="open-question">
        <div class="oq-label">Open Question</div>
        <p class="oq-text">
          Can we build a minimal DOM diff algorithm in pure vanilla JS,
          without dependencies, that still fits the Flow-Arch pure function philosophy?
          What is the minimum viable diffing strategy?
        </p>
      </div>

      <a class="experiment-link" href="#">experiments/dom-diff/ — not started yet</a>
    </div>


    <!-- ── L-02 ── -->
    <div id="l02" class="limitation">
      <div class="lim-header">
        <div>
          <div class="lim-id">L-02</div>
          <h2>No Inter-Component<br>State Management</h2>
        </div>
        <span class="badge known">KNOWN</span>
      </div>

      <h3>What happens</h3>
      <p>
        Each Web Component manages its own private state.
        There is no shared store or global state layer.
        Two sibling components cannot share data directly.
      </p>

      <h3>Current workaround</h3>
      <p>Use <code>CustomEvent</code> to bubble data up, and attributes to pass data down. It works but becomes verbose for complex trees.</p>

      <div class="code-block">
        <div class="code-header">
          <span class="code-title">manual event bus pattern</span>
          <span class="code-lang">JS</span>
        </div>
        <pre><span class="c">// Child → Parent: dispatch a custom event</span>
<span class="k">this</span>.<span class="f">dispatchEvent</span>(<span class="k">new</span> CustomEvent(<span class="s">"state-changed"</span>, {
  bubbles: <span class="k">true</span>,
  detail: { count: <span class="k">this</span>.state.count }
}))

<span class="c">// Parent → Child: set attribute</span>
childEl.<span class="f">setAttribute</span>(<span class="s">"count"</span>, newCount)

<span class="c">// This works. But with 5+ components it becomes
// very hard to trace where data comes from.</span></pre>
      </div>

      <div class="open-question">
        <div class="oq-label">Open Question</div>
        <p class="oq-text">
          Can a global store be designed as a pure function system,
          consistent with Flow-Arch's philosophy, without introducing
          a framework or complex observer pattern?
        </p>
      </div>

      <a class="experiment-link" href="#">experiments/global-store/ — not started yet</a>
    </div>


    <!-- ── L-03 ── -->
    <div id="l03" class="limitation">
      <div class="lim-header">
        <div>
          <div class="lim-id">L-03</div>
          <h2>No Async Action Handling</h2>
        </div>
        <span class="badge known">KNOWN</span>
      </div>

      <h3>What happens</h3>
      <p>
        Reducers are synchronous pure functions.
        There is no built-in mechanism for async operations like <code>fetch</code>.
      </p>

      <div class="code-block">
        <div class="code-header">
          <span class="code-title">async is not allowed in reducers</span>
          <span class="code-lang">JS</span>
        </div>
        <pre><span class="c">// ✗ This breaks the pure function contract</span>
<span class="k">const</span> <span class="f">reducer</span> = <span class="k">async</span> (state, action) => {
  <span class="k">const</span> data = <span class="k">await</span> <span class="f">fetch</span>(<span class="s">"/api/data"</span>)  <span class="bad">// ✗ side effect</span>
  <span class="k">return</span> { ...state, data }
}

<span class="c">// ✓ Current workaround: async in the component shell</span>
<span class="k">async</span> <span class="f">connectedCallback</span>() {
  <span class="k">this</span>.<span class="f">dispatch</span>({ type: <span class="s">"LOADING"</span> })

  <span class="k">const</span> res  = <span class="k">await</span> <span class="f">fetch</span>(<span class="s">"/api/data"</span>)
  <span class="k">const</span> data = <span class="k">await</span> res.<span class="f">json</span>()

  <span class="c">// Then dispatch synchronously with the result</span>
  <span class="k">this</span>.<span class="f">dispatch</span>({ type: <span class="s">"DATA_LOADED"</span>, payload: data })
}</pre>
      </div>

      <div class="callout warn">
        <div class="callout-label">Trade-off</div>
        <p>
          Keeping reducers synchronous is not a bug — it is a deliberate choice.
          Async reducers make testing harder and blur the boundary between
          pure logic and side effects. The workaround above keeps the
          separation intact, but has no standard pattern yet.
        </p>
      </div>

      <div class="open-question">
        <div class="oq-label">Open Question</div>
        <p class="oq-text">
          What is the Flow-Arch equivalent of Redux-Thunk?
          Can a lightweight effect system be designed without middleware complexity,
          keeping reducers pure and async logic explicit?
        </p>
      </div>

      <a class="experiment-link" href="#">experiments/async-actions/ — not started yet</a>
    </div>


    <!-- ── L-04 ── -->
    <div id="l04" class="limitation">
      <div class="lim-header">
        <div>
          <div class="lim-id">L-04</div>
          <h2>No Enforced Purity</h2>
        </div>
        <span class="badge known">KNOWN</span>
      </div>

      <h3>What happens</h3>
      <p>
        Unlike Haskell or Elm, JavaScript cannot enforce that reducers
        and view functions are truly pure. Side effects can be written
        inside them with no warning from the language.
      </p>

      <div class="code-block">
        <div class="code-header">
          <span class="code-title">JS cannot stop this</span>
          <span class="code-lang">JS</span>
        </div>
        <pre><span class="c">// This compiles and runs fine — JS does not care</span>
<span class="k">const</span> <span class="f">reducer</span> = (state, action) => {
  console.<span class="f">log</span>(<span class="s">"side effect"</span>)        <span class="bad">// ✗ impure</span>
  localStorage.<span class="f">setItem</span>(<span class="s">"x"</span>, <span class="s">"y"</span>)  <span class="bad">// ✗ impure</span>
  <span class="k">return</span> { ...state }               <span class="ok">// ✓ pure return</span>
}

<span class="c">// Compare: Haskell makes this impossible at compile time</span>
<span class="c">// IO actions must be declared in the type signature</span>
<span class="c">// pure :: Int -> Int          ← enforced pure</span>
<span class="c">// impure :: Int -> IO Int     ← enforced impure</span></pre>
      </div>

      <h3>Honest assessment</h3>
      <p>
        This limitation is <strong>inherent to JavaScript</strong>.
        It cannot be fully solved without a type system or compiler.
        Flow-Arch accepts this and relies on discipline, documentation, and code review.
      </p>

      <div class="callout">
        <div class="callout-label">What helps</div>
        <p>
          ESLint rule <code>no-param-reassign</code> catches mutation.
          TypeScript <code>readonly</code> reduces mutation risk.
          Neither fully solves the problem — they reduce it.
        </p>
      </div>
    </div>


    <!-- ── L-05 ── -->
    <div id="l05" class="limitation">
      <div class="lim-header">
        <div>
          <div class="lim-id">L-05</div>
          <h2>String-Based View Has<br>No Type Safety</h2>
        </div>
        <span class="badge known">KNOWN</span>
      </div>

      <h3>What happens</h3>
      <p>
        The <code>view</code> function returns an HTML string via a template literal.
        Typos in HTML structure fail silently. Typos in state properties
        cause runtime errors. There is no autocomplete, no validation.
      </p>

      <div class="code-block">
        <div class="code-header">
          <span class="code-title">silent failure modes</span>
          <span class="code-lang">JS</span>
        </div>
        <pre><span class="k">const</span> <span class="f">view</span> = (state) => <span class="s">`
  &lt;div class="contaner"&gt;       </span><span class="bad">← typo: silent failure</span><span class="s">
    &lt;p&gt;${state.usr.name}&lt;/p&gt;  </span><span class="bad">← typo: runtime TypeError</span><span class="s">
    &lt;p&gt;${state.userInput}&lt;/p&gt; </span><span class="bad">← XSS if not sanitized</span><span class="s">
  &lt;/div&gt;
`</span>

<span class="c">// Minimum protection: sanitize user input</span>
<span class="k">const</span> <span class="f">escape</span> = (str) =>
  String(str)
    .<span class="f">replace</span>(/&amp;/g, <span class="s">"&amp;amp;"</span>)
    .<span class="f">replace</span>(/&lt;/g, <span class="s">"&amp;lt;"</span>)
    .<span class="f">replace</span>(/&gt;/g, <span class="s">"&amp;gt;"</span>)

<span class="c">// Always escape before interpolating user data</span>
<span class="k">const</span> <span class="f">view</span> = (state) => <span class="s">`
  &lt;p&gt;${<span class="f">escape</span>(state.userInput)}&lt;/p&gt;
`</span></pre>
      </div>

      <div class="open-question">
        <div class="oq-label">Open Question</div>
        <p class="oq-text">
          Could a lightweight tagged template literal function provide
          automatic sanitization and basic validation,
          without abandoning the pure function view pattern?
          This could become part of <code>flow-core.js</code>.
        </p>
      </div>
    </div>


    <!-- ── L-06 ── -->
    <div id="l06" class="limitation">
      <div class="lim-header">
        <div>
          <div class="lim-id">L-06</div>
          <h2>No SSR Implementation Yet</h2>
        </div>
        <span class="badge known">KNOWN</span>
      </div>

      <h3>What happens</h3>
      <p>
        Flow-Arch components are defined and rendered entirely in the browser.
        The page is blank until JavaScript runs. Search engines may not
        see component content.
      </p>

      <h3>The platform solution already exists</h3>
      <p>
        Declarative Shadow DOM allows Shadow DOM to be rendered as plain HTML
        by the server — no JavaScript required. Flow-Arch does not use this yet.
      </p>

      <div class="code-block">
        <div class="code-header">
          <span class="code-title">declarative shadow dom — server renders this</span>
          <span class="code-lang">HTML</span>
        </div>
        <pre><span class="c">&lt;!-- Rendered by server. Works without any JavaScript. --&gt;</span>
&lt;<span class="f">flow-counter</span>&gt;
  &lt;template shadowrootmode=<span class="s">"open"</span>&gt;
    &lt;style&gt;.count { color: #c8f542; }&lt;/style&gt;
    &lt;div class=<span class="s">"count"</span>&gt;0&lt;/div&gt;
    &lt;button&gt;+&lt;/button&gt;
  &lt;/template&gt;
&lt;/<span class="f">flow-counter</span>&gt;

<span class="c">&lt;!-- When JS loads, the component hydrates in place --&gt;</span>
<span class="c">&lt;!-- No flash of unstyled content --&gt;</span></pre>
      </div>

      <div class="open-question">
        <div class="oq-label">Open Question</div>
        <p class="oq-text">
          How does Flow-Arch's State → View → Reducer loop integrate
          with server-side rendering and hydration?
          Can the pure <code>view()</code> function generate both
          the server HTML and the client render from the same code?
        </p>
      </div>

      <a class="experiment-link" href="#">experiments/ssr/ — not started yet</a>
    </div>


    <!-- ── L-07 ── -->
    <div id="l07" class="limitation">
      <div class="lim-header">
        <div>
          <div class="lim-id">L-07</div>
          <h2>Component Boilerplate Repetition</h2>
        </div>
        <span class="badge known">KNOWN</span>
      </div>

      <h3>What happens</h3>
      <p>
        Every Flow-Arch component repeats the same structural boilerplate.
        The unique logic of each component is buried inside identical scaffolding.
      </p>

      <div class="code-block">
        <div class="code-header">
          <span class="code-title">repeated in every component</span>
          <span class="code-lang">JS</span>
        </div>
        <pre><span class="c">// This exact structure appears in every component</span>
<span class="k">class</span> <span class="f">AnyComponent</span> <span class="k">extends</span> HTMLElement {
  <span class="f">constructor</span>() {
    <span class="k">super</span>()
    <span class="k">this</span>.<span class="f">attachShadow</span>({ mode: <span class="s">"open"</span> })
    <span class="k">this</span>.state = <span class="f">createInitialState</span>()
    <span class="k">this</span>.dispatch = (action) => {
      <span class="k">this</span>.state = <span class="f">reducer</span>(<span class="k">this</span>.state, action)
      <span class="k">this</span>.<span class="f">render</span>()
    }
  }
  <span class="f">connectedCallback</span>() { <span class="k">this</span>.<span class="f">render</span>() }
  <span class="f">render</span>() { <span class="k">this</span>.shadowRoot.innerHTML = <span class="f">view</span>(<span class="k">this</span>.state) }
}

<span class="c">// Proposed: a factory that removes the boilerplate</span>
<span class="k">const</span> FlowCounter = <span class="f">createFlowComponent</span>(reducer, view)
customElements.<span class="f">define</span>(<span class="s">"flow-counter"</span>, FlowCounter)
<span class="c">// This is one of the most promising paths to flow-core.js</span></pre>
      </div>

      <div class="open-question">
        <div class="oq-label">Open Question</div>
        <p class="oq-text">
          A <code>createFlowComponent(reducer, view)</code> factory function
          could eliminate the boilerplate entirely.
          This would be the first step toward a real <code>flow-core.js</code>.
          What should its API look like?
        </p>
      </div>
    </div>