diff --git a/package.json b/package.json
index a856ccf..b577a23 100644
--- a/package.json
+++ b/package.json
@@ -31,7 +31,8 @@
     "lighthouse": "node scripts/lighthouse.mjs",
     "perf-budget": "node scripts/perf-budget.mjs",
     "hue-rotate": "node scripts/hue-rotate.mjs",
-    "validate:all": "npm run validate:brand && npm run typecheck && npm run test && npm run prompt-evals && npm run build && npm run perf-budget"
+    "validate:all": "npm run validate:brand && npm run typecheck && npm run test && npm run prompt-evals && npm run build && npm run perf-budget",
+    "validate": "node scripts/build_validators.mjs dist"
   },
   "dependencies": {
     "@radix-ui/react-accordion": "^1.2.0",
diff --git a/scripts/build_validators.mjs b/scripts/build_validators.mjs
new file mode 100644
index 0000000..33d8b49
--- /dev/null
+++ b/scripts/build_validators.mjs
@@ -0,0 +1,26 @@
+#!/usr/bin/env node
+// build_validators.mjs — orchestrator. Runs every build-gate validator over dist/ and exits
+// non-zero on any error-level finding (blocks deploy). Spec: heymegabyte-claude-skills
+// rules/build-validators-manifest.md. Add validators here as they are implemented.
+import { existsSync } from 'node:fs';
+import { validateLinks } from './validators/validate-links.mjs';
+import { validateRouteMetadata } from './validators/validate-route-metadata.mjs';
+import { validateAssets } from './validators/validate-assets.mjs';
+import { validateSsrHead } from './validators/validate-ssr-head.mjs';
+
+const DIST = process.argv[2] || 'dist';
+if (!existsSync(DIST)) { console.error(`build_validators: ${DIST}/ not found — run the build first`); process.exit(2); }
+
+const VALIDATORS = [validateLinks, validateRouteMetadata, validateAssets, validateSsrHead];
+const findings = VALIDATORS.flatMap((v) => v(DIST));
+const errors = findings.filter((f) => f.level === 'error');
+const warns = findings.filter((f) => f.level === 'warn');
+
+for (const f of warns) console.warn(`⚠ [${f.code}] ${f.route} — ${f.detail}`);
+for (const f of errors) console.error(`✗ [${f.code}] ${f.route} — ${f.detail}`);
+
+if (errors.length) {
+  console.error(`\nbuild_validators: ${errors.length} build-break finding(s) across ${VALIDATORS.length} validators. Fix before deploy.`);
+  process.exit(1);
+}
+console.log(`✓ build_validators: ${VALIDATORS.length} validators passed over ${DIST}/ (${warns.length} warnings).`);
diff --git a/scripts/validators/lib.mjs b/scripts/validators/lib.mjs
new file mode 100644
index 0000000..bf97fe9
--- /dev/null
+++ b/scripts/validators/lib.mjs
@@ -0,0 +1,21 @@
+// Shared helpers for build validators. Pure node, no deps.
+import { readdirSync, readFileSync, statSync, existsSync } from 'node:fs';
+import { join, relative } from 'node:path';
+
+/** Recursively list every .html file under dir. */
+export function htmlFiles(dir) {
+  const out = [];
+  const walk = (d) => {
+    for (const e of readdirSync(d, { withFileTypes: true })) {
+      const p = join(d, e.name);
+      if (e.isDirectory()) walk(p);
+      else if (e.name.endsWith('.html')) out.push(p);
+    }
+  };
+  if (existsSync(dir)) walk(dir);
+  return out;
+}
+
+/** A build-break finding. */
+export const fail = (validator, code, route, detail) => ({ validator, code, route, detail, level: 'error' });
+export const warn = (validator, code, route, detail) => ({ validator, code, route, detail, level: 'warn' });
diff --git a/scripts/validators/validate-assets.mjs b/scripts/validators/validate-assets.mjs
new file mode 100644
index 0000000..da731e6
--- /dev/null
+++ b/scripts/validators/validate-assets.mjs
@@ -0,0 +1,23 @@
+// validate-assets — every local asset ref (src/href to /assets, images, css, js) resolves in dist/. Fail assets.missing.
+import { readFileSync, existsSync, statSync } from 'node:fs';
+import { join } from 'node:path';
+import { htmlFiles, fail } from './lib.mjs';
+
+export function validateAssets(dist) {
+  const out = [];
+  const seen = new Set();
+  for (const f of htmlFiles(dist)) {
+    const html = readFileSync(f, 'utf8');
+    const route = '/' + f.slice(dist.length).replace(/^\/+/, '');
+    for (const m of html.matchAll(/\b(?:src|href)=["'](\/[^"']+\.(?:png|jpe?g|webp|avif|svg|gif|ico|css|js|woff2?|json|webmanifest|xml|txt))["']/gi)) {
+      const ref = m[1].split('?')[0];
+      const key = route + '|' + ref;
+      if (seen.has(key)) continue; seen.add(key);
+      const target = join(dist, ref);
+      if (!(existsSync(target) && statSync(target).isFile())) {
+        out.push(fail('validate-assets', 'assets.missing', route, `asset ref does not resolve: ${ref}`));
+      }
+    }
+  }
+  return out;
+}
diff --git a/scripts/validators/validate-links.mjs b/scripts/validators/validate-links.mjs
new file mode 100644
index 0000000..c37b5d8
--- /dev/null
+++ b/scripts/validators/validate-links.mjs
@@ -0,0 +1,26 @@
+// validate-links — every internal <a href> resolves to a real file in dist/. Fail routes.dead_link.
+import { readFileSync, existsSync, statSync } from 'node:fs';
+import { join } from 'node:path';
+import { htmlFiles, fail } from './lib.mjs';
+
+export function validateLinks(dist) {
+  const out = [];
+  const files = htmlFiles(dist);
+  for (const f of files) {
+    const html = readFileSync(f, 'utf8');
+    const route = '/' + f.slice(dist.length).replace(/^\/+/, '');
+    for (const m of html.matchAll(/<a\b[^>]*\bhref=["']([^"'#]+)["']/gi)) {
+      let href = m[1].trim();
+      if (/^(https?:|mailto:|tel:|data:|\/\/)/i.test(href)) continue; // external/scheme
+      if (href.startsWith('#') || href === '') continue;
+      const clean = href.split('?')[0].split('#')[0];
+      // resolve relative to dist root (absolute) — template uses absolute internal links
+      let target = clean.startsWith('/') ? join(dist, clean) : join(f, '..', clean);
+      const candidates = [target, target + '.html', join(target, 'index.html')];
+      if (!candidates.some((c) => existsSync(c) && statSync(c).isFile())) {
+        out.push(fail('validate-links', 'routes.dead_link', route, `unresolved internal href: ${href}`));
+      }
+    }
+  }
+  return out;
+}
diff --git a/scripts/validators/validate-route-metadata.mjs b/scripts/validators/validate-route-metadata.mjs
new file mode 100644
index 0000000..ada07e5
--- /dev/null
+++ b/scripts/validators/validate-route-metadata.mjs
@@ -0,0 +1,17 @@
+// validate-route-metadata — every HTML page has a non-empty <title> + meta description. Fail meta.missing.
+import { readFileSync } from 'node:fs';
+import { htmlFiles, fail } from './lib.mjs';
+
+export function validateRouteMetadata(dist) {
+  const out = [];
+  for (const f of htmlFiles(dist)) {
+    const html = readFileSync(f, 'utf8');
+    const route = '/' + f.slice(dist.length).replace(/^\/+/, '');
+    if (/\b(404|500|offline)\.html$/.test(f)) continue; // utility pages exempt from meta-desc
+    const title = (html.match(/<title>([^<]*)<\/title>/i) || [])[1]?.trim();
+    const desc = (html.match(/<meta[^>]+name=["']description["'][^>]*content=["']([^"']*)["']/i) || [])[1]?.trim();
+    if (!title) out.push(fail('validate-route-metadata', 'meta.no_title', route, 'missing/empty <title>'));
+    if (!desc) out.push(fail('validate-route-metadata', 'meta.no_description', route, 'missing/empty meta description'));
+  }
+  return out;
+}
diff --git a/scripts/validators/validate-ssr-head.mjs b/scripts/validators/validate-ssr-head.mjs
new file mode 100644
index 0000000..24ee9d4
--- /dev/null
+++ b/scripts/validators/validate-ssr-head.mjs
@@ -0,0 +1,38 @@
+// validate-ssr-head — detect the SEO-collapse anti-pattern: a multi-route SPA that serves
+// every route from one index.html (SPA fallback) with NO per-route server head — no
+// prerendered route HTML AND no edge HTMLRewriter. Crawlers then read the homepage head on
+// every URL → site collapses to one indexable URL. Fail seo.client_only_head. (checklist #3)
+import { readFileSync, existsSync, readdirSync, statSync } from 'node:fs';
+import { join } from 'node:path';
+import { htmlFiles, fail } from './lib.mjs';
+
+export function validateSsrHead(dist, root = '.') {
+  // 1. How many routes does the site claim? (sitemap <loc> count)
+  let routeCount = 0;
+  const sm = join(dist, 'sitemap.xml');
+  if (existsSync(sm)) routeCount = (readFileSync(sm, 'utf8').match(/<loc>/g) || []).length;
+
+  // 2. How many prerendered route HTML files exist (excluding utility shells)?
+  const UTIL = /(?:^|\/)(?:404|500|offline|index)\.html$/;
+  const prerendered = htmlFiles(dist).filter((f) => !UTIL.test(f)).length;
+
+  // 3. SPA catch-all fallback present? (_redirects /* → /index.html)
+  const redir = join(dist, '_redirects');
+  const spaFallback = existsSync(redir) && /\/\*\s+\/index\.html\s+200/.test(readFileSync(redir, 'utf8'));
+
+  // 4. Any edge worker that rewrites the per-route <head>?
+  const fnDirs = ['functions', 'src/worker', 'workers'].map((d) => join(root, d)).filter(existsSync);
+  const grepDir = (d) => readdirSync(d, { withFileTypes: true }).some((e) => {
+    const p = join(d, e.name);
+    if (e.isDirectory()) return grepDir(p);
+    return /\.(ts|js|mjs)$/.test(e.name) && /HTMLRewriter|getMeta\(|rewrite.*<title|on\(['"]title/.test(readFileSync(p, 'utf8'));
+  });
+  const edgeRewriter = fnDirs.some(grepDir);
+
+  // Verdict: multi-route + SPA-fallback + no prerender + no edge rewrite = client-only head.
+  if (routeCount > 1 && spaFallback && prerendered === 0 && !edgeRewriter) {
+    return [fail('validate-ssr-head', 'seo.client_only_head', '/*',
+      `${routeCount} routes (sitemap) all serve one index.html (SPA fallback) with NO per-route server head — no prerendered route HTML, no edge HTMLRewriter. Crawlers read the homepage head on every URL → SEO collapse. Add SSG prerender (vite-ssg) OR a Worker HTMLRewriter keyed on getMeta(pathname).`)];
+  }
+  return [];
+}