diff --git a/docs/hugo.yaml b/docs/hugo.yaml
index 7074dd8..c9d7fd7 100644
--- a/docs/hugo.yaml
+++ b/docs/hugo.yaml
@@ -57,6 +57,10 @@ params:
   # Site metadata
   description: "actsense is an open-source workflow security auditor. It maps every dependency a CI workflow runs and explains what each one exposes. GitHub Actions is supported today."
   author: "actsense"
+
+  # Social preview (og:image, twitter:image). Source: scripts/og/og.html
+  images:
+    - "og.png"
   
   # Navbar
   navbar:
diff --git a/docs/scripts/og/og.html b/docs/scripts/og/og.html
new file mode 100644
index 0000000..44b330b
--- /dev/null
+++ b/docs/scripts/og/og.html
@@ -0,0 +1,137 @@
+<!DOCTYPE html>
+<!-- Source for static/og.png (1200x630). Render with scripts/og/render.py. -->
+<html lang="en">
+<head>
+<meta charset="utf-8">
+<title>actsense OG image</title>
+<link href="https://fonts.googleapis.com/css2?family=Google+Sans:wght@400..700&family=Google+Sans+Code:wght@400..600&family=Stack+Sans+Notch:wght@200..700&display=block" rel="stylesheet">
+<style>
+  * { box-sizing: border-box; margin: 0; padding: 0; }
+  html, body { width: 1200px; height: 630px; overflow: hidden; }
+  body {
+    position: relative;
+    background: #0c0e12;
+    color: #f3f4f6;
+    font-family: "Google Sans", system-ui, sans-serif;
+  }
+
+  /* Same letter field as the homepage hero, frozen on one frame. */
+  canvas {
+    position: absolute;
+    inset: 0;
+    width: 1200px;
+    height: 630px;
+  }
+
+  /* Same horizon band as the homepage, tilted across the lower right. */
+  .horizon {
+    position: absolute;
+    left: -10%;
+    right: -10%;
+    top: 300px;
+    height: 460px;
+    transform: skewY(-7deg);
+    background: linear-gradient(180deg,
+      transparent 0%,
+      rgba(13, 59, 110, 0.55) 22%,
+      rgba(20, 78, 140, 0.9) 36%,
+      #e8491d 54%,
+      #ff7a2e 62%,
+      #ffd29a 70%,
+      rgba(255, 236, 214, 0.9) 74%,
+      transparent 92%);
+    -webkit-mask-image: linear-gradient(90deg, rgba(0, 0, 0, 0.12) 0%, rgba(0, 0, 0, 0.5) 45%, #000 80%);
+  }
+  .horizon::after {
+    content: '';
+    position: absolute;
+    inset: 0;
+    opacity: 0.75;
+    mix-blend-mode: soft-light;
+    -webkit-mask-image: linear-gradient(180deg, transparent 12%, #000 36%, #000 72%, transparent 90%);
+    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='220' height='220'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.8' numOctaves='3' stitchTiles='stitch'/%3E%3CfeColorMatrix type='saturate' values='0'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
+  }
+
+  .content {
+    position: absolute;
+    left: 88px;
+    top: 92px;
+    width: 760px;
+  }
+  .eyebrow {
+    display: inline-block;
+    padding: 8px 18px;
+    font-size: 21px;
+    font-weight: 500;
+    color: #d1d5db;
+    background: #111318;
+    border: 1px solid #262a33;
+    border-radius: 999px;
+    box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.04);
+  }
+  h1 {
+    margin-top: 26px;
+    font-family: "Stack Sans Notch", sans-serif;
+    font-size: 150px;
+    font-weight: 650;
+    line-height: 1;
+    letter-spacing: -0.03em;
+  }
+  .lede {
+    margin-top: 26px;
+    font-size: 30px;
+    line-height: 1.4;
+    color: #9ca3af;
+    text-wrap: balance;
+  }
+  .url {
+    position: absolute;
+    left: 88px;
+    bottom: 64px;
+    font-family: "Google Sans Code", ui-monospace, monospace;
+    font-size: 24px;
+    font-weight: 500;
+    color: #f3f4f6;
+    letter-spacing: 0.01em;
+  }
+</style>
+</head>
+<body>
+  <canvas width="2400" height="1260"></canvas>
+  <div class="horizon"></div>
+  <div class="content">
+    <span class="eyebrow">Open-source Workflow Security Auditor</span>
+    <h1>actsense</h1>
+    <p class="lede">See every dependency your CI workflows run, at the version they run, and what each one exposes.</p>
+  </div>
+  <div class="url">actsense.dev</div>
+
+<script>
+  // Mirrors static/hero-letters.js (dark theme), with the quiet zone moved
+  // behind the left-aligned text block.
+  document.fonts.ready.then(function () {
+    const canvas = document.querySelector('canvas');
+    const ctx = canvas.getContext('2d');
+    const W = 1200, H = 630, STEP = 22, CHARS = 'ACTSENSE';
+    const t = 5200;
+    ctx.scale(2, 2);
+    ctx.font = '12px "Google Sans Code", ui-monospace, monospace';
+    ctx.textAlign = 'center';
+    ctx.textBaseline = 'middle';
+    const cx = 420, cy = 250;
+    for (let y = STEP / 2, row = 0; y < H; y += STEP, row++) {
+      for (let x = STEP / 2, col = 0; x < W; x += STEP, col++) {
+        const wave = Math.sin(x / 140 - t / 1400) * Math.cos(y / 90 + t / 2100);
+        const light = Math.max(0, wave) * 0.34 + 0.035;
+        const away = Math.min(1, Math.hypot((x - cx) / 560, (y - cy) / 300));
+        const alpha = light * away;
+        if (alpha < 0.012) continue;
+        ctx.fillStyle = 'rgba(245, 245, 244,' + alpha.toFixed(3) + ')';
+        ctx.fillText(CHARS[(row + col) % CHARS.length], x, y);
+      }
+    }
+    document.body.dataset.ready = '1';
+  });
+</script>
+</body>
+</html>
diff --git a/docs/scripts/og/render.py b/docs/scripts/og/render.py
new file mode 100644
index 0000000..7715b71
--- /dev/null
+++ b/docs/scripts/og/render.py
@@ -0,0 +1,28 @@
+"""Render og.html to static/og.png at 1200x630.
+
+    python3 docs/scripts/og/render.py
+
+Needs Playwright (`pip install playwright && playwright install chromium`)
+and network access for Google Fonts.
+"""
+from pathlib import Path
+
+from playwright.sync_api import sync_playwright
+
+HERE = Path(__file__).resolve().parent
+OUT = HERE.parent.parent / "static" / "og.png"
+
+
+def main() -> None:
+    with sync_playwright() as p:
+        browser = p.chromium.launch()
+        page = browser.new_page(viewport={"width": 1200, "height": 630})
+        page.goto((HERE / "og.html").as_uri())
+        page.wait_for_selector("body[data-ready='1']")
+        page.screenshot(path=str(OUT))
+        browser.close()
+    print(f"wrote {OUT}")
+
+
+if __name__ == "__main__":
+    main()
diff --git a/docs/static/og.png b/docs/static/og.png
new file mode 100644
index 0000000..0a5ae9b
Binary files /dev/null and b/docs/static/og.png differ