diff --git a/packages/superdoc/package.json b/packages/superdoc/package.json
index 772c54cbec..5b7fdce1ad 100644
--- a/packages/superdoc/package.json
+++ b/packages/superdoc/package.json
@@ -121,7 +121,7 @@
     "word-benchmark-sidecar": "node ../../devtools/word-benchmark-sidecar/server.js",
     "build": "vite build && pnpm run build:cdn",
     "build:dev": "SUPERDOC_SKIP_DTS=1 vite build",
-    "postbuild": "node ./scripts/check-tsconfig-type-surface.cjs && node ./scripts/ensure-types.cjs && node ./scripts/audit-bundle.cjs && node ./scripts/audit-declarations.cjs && node ./scripts/check-export-coverage.cjs",
+    "postbuild": "node ./scripts/check-tsconfig-type-surface.cjs && node ./scripts/ensure-types.cjs && node ./scripts/audit-bundle.cjs && node ./scripts/audit-declarations.cjs && node ./scripts/check-export-coverage.cjs && node ./scripts/report-declaration-reachability.cjs",
     "audit:declarations": "node ./scripts/audit-declarations.cjs",
     "audit:declarations:informational": "node ./scripts/audit-declarations.cjs --informational",
     "check:jsdoc": "node ./scripts/check-jsdoc.cjs",
diff --git a/packages/superdoc/scripts/report-declaration-reachability.cjs b/packages/superdoc/scripts/report-declaration-reachability.cjs
new file mode 100644
index 0000000000..bb73f8937d
--- /dev/null
+++ b/packages/superdoc/scripts/report-declaration-reachability.cjs
@@ -0,0 +1,193 @@
+#!/usr/bin/env node
+/**
+ * SD-2952 step 3: report how many emitted `.d.ts` files in the published
+ * dist are actually reachable from a public consumer's type graph.
+ *
+ * Walks every `exports[*].types` target in `package.json` and follows
+ * relative-import / self-package edges through the emitted `.d.ts`
+ * forest, counting how many files a consumer's TypeScript would
+ * actually parse vs how many are shipped. The output is data for the
+ * SD-2952 trim-emitted-types slice (step 4).
+ *
+ * This script is **instrumentation, not a gate**:
+ *   - It DOES exit 1 on script bugs, missing dist, malformed package
+ *     exports, or unreadable type entry files. "Informational" means
+ *     "metric only," not "broken script ignored."
+ *   - It does NOT exit 1 on a low ratio. There is no threshold yet;
+ *     we are establishing the measurement before deciding what
+ *     unreachable emit is harmless byproduct vs. avoidable noise.
+ *
+ * Walker semantics:
+ *   - Resolves relative `from '../foo.js'` and `import('../foo.js')`
+ *     specifiers to dist `.d.ts` siblings.
+ *   - Resolves self-package `from 'superdoc/<subpath>'` through the
+ *     package's own `exports` map.
+ *   - Ignores external package specifiers (vue, prosemirror-*,
+ *     @tiptap/*, etc.) - those don't live in dist.
+ *   - Ignores private workspace specifiers (`@superdoc/*`); they're
+ *     audited separately by `audit-declarations.cjs` Rule 1, and any
+ *     surviving one in dist is already a build failure.
+ */
+
+const fs = require('node:fs');
+const path = require('node:path');
+
+const packageRoot = path.resolve(__dirname, '..');
+const distRoot = path.join(packageRoot, 'dist');
+
+if (!fs.existsSync(distRoot)) {
+  console.error('[report-declaration-reachability] dist/ not found; run the build first.');
+  process.exit(1);
+}
+
+const packageJsonPath = path.join(packageRoot, 'package.json');
+let packageJson;
+try {
+  packageJson = JSON.parse(fs.readFileSync(packageJsonPath, 'utf8'));
+} catch (err) {
+  console.error(`[report-declaration-reachability] cannot read package.json: ${err.message}`);
+  process.exit(1);
+}
+
+const packageName = packageJson.name;
+const exportsMap = packageJson.exports || {};
+
+// Build a self-package resolver: subpath like `./super-editor` → absolute
+// path of the `types` target in dist. Used when an emitted .d.ts contains
+// `from 'superdoc/super-editor'` (rare but legal).
+const selfPackageTypeMap = new Map();
+for (const [subpath, value] of Object.entries(exportsMap)) {
+  if (typeof value !== 'object' || value === null) continue;
+  if (typeof value.types !== 'string') continue;
+  selfPackageTypeMap.set(subpath, path.resolve(packageRoot, value.types));
+}
+
+// Build the seed set: every typed exports entry, resolved to a dist path.
+const typedExports = [];
+for (const [subpath, value] of Object.entries(exportsMap)) {
+  if (typeof value !== 'object' || value === null) continue;
+  if (typeof value.types !== 'string') continue;
+  const target = path.resolve(packageRoot, value.types);
+  if (!fs.existsSync(target)) {
+    console.error(`[report-declaration-reachability] exports['${subpath}'].types target missing: ${value.types}`);
+    process.exit(1);
+  }
+  typedExports.push({ subpath, target });
+}
+
+if (typedExports.length === 0) {
+  console.error('[report-declaration-reachability] package.json has no typed exports; nothing to walk.');
+  process.exit(1);
+}
+
+// Collect every .d.ts shipped in dist.
+function findDtsFiles(dir, acc = []) {
+  for (const entry of fs.readdirSync(dir, { withFileTypes: true })) {
+    const full = path.join(dir, entry.name);
+    if (entry.isDirectory()) findDtsFiles(full, acc);
+    else if (entry.name.endsWith('.d.ts')) acc.push(full);
+  }
+  return acc;
+}
+const allDtsFiles = findDtsFiles(distRoot);
+const allDtsSet = new Set(allDtsFiles);
+
+// Match `from '...'` (top-level imports + re-exports) and `import('...')`
+// (type-position dynamic imports). Both contribute edges.
+const SPECIFIER_RE = /(?:from\s+|import\(\s*)['"]([^'"]+)['"]/g;
+
+// Per-extension fallbacks the resolver tries when a relative specifier
+// has no extension. TypeScript itself accepts a wider set; keep these
+// minimal because the dist files we emit are all `.d.ts` (or directories
+// containing `index.d.ts`).
+function resolveRelative(spec, fromFile) {
+  const base = path.resolve(path.dirname(fromFile), spec);
+  // Spec already points at .d.ts? unusual but support it.
+  if (base.endsWith('.d.ts') && fs.existsSync(base)) return base;
+  // `.js` specifier → swap to `.d.ts`.
+  if (base.endsWith('.js')) {
+    const cand = base.slice(0, -3) + '.d.ts';
+    if (fs.existsSync(cand)) return cand;
+  }
+  // `.ts` specifier (rare in emitted dist after ensure-types) → `.d.ts`.
+  if (base.endsWith('.ts')) {
+    const cand = base.slice(0, -3) + '.d.ts';
+    if (fs.existsSync(cand)) return cand;
+  }
+  // Bare directory → look for `<dir>/index.d.ts`.
+  const indexCand = path.join(base, 'index.d.ts');
+  if (fs.existsSync(indexCand)) return indexCand;
+  // Plain `<base>.d.ts`.
+  const dtsCand = `${base}.d.ts`;
+  if (fs.existsSync(dtsCand)) return dtsCand;
+  return null;
+}
+
+function resolveSelfPackage(spec) {
+  // spec like `superdoc` or `superdoc/super-editor`.
+  if (!spec.startsWith(packageName)) return null;
+  const remainder = spec.slice(packageName.length);
+  const subpath = remainder === '' ? '.' : `.${remainder}`;
+  return selfPackageTypeMap.get(subpath) || null;
+}
+
+function resolveSpecifier(spec, fromFile) {
+  if (spec.startsWith('.')) return resolveRelative(spec, fromFile);
+  if (spec.startsWith(packageName)) return resolveSelfPackage(spec);
+  // External package or private workspace specifier — not in dist tree.
+  return null;
+}
+
+// BFS walk.
+const visited = new Set();
+const queue = typedExports.map((e) => e.target);
+for (const start of queue) visited.add(start);
+
+while (queue.length > 0) {
+  const file = queue.shift();
+  let content;
+  try {
+    content = fs.readFileSync(file, 'utf8');
+  } catch (err) {
+    console.error(`[report-declaration-reachability] cannot read ${file}: ${err.message}`);
+    process.exit(1);
+  }
+  for (const match of content.matchAll(SPECIFIER_RE)) {
+    const resolved = resolveSpecifier(match[1], file);
+    if (!resolved) continue;
+    if (visited.has(resolved)) continue;
+    visited.add(resolved);
+    queue.push(resolved);
+  }
+}
+
+const reachableInDist = [...visited].filter((f) => allDtsSet.has(f));
+const total = allDtsFiles.length;
+const reachable = reachableInDist.length;
+const pct = total === 0 ? 0 : ((reachable / total) * 100).toFixed(1);
+
+// Bucket reachable + total by top-level dist directory for the trim slice.
+function bucket(file) {
+  const rel = path.relative(distRoot, file).split(path.sep);
+  return rel[0] || '<root>';
+}
+const totalsByBucket = new Map();
+const reachableByBucket = new Map();
+for (const f of allDtsFiles) totalsByBucket.set(bucket(f), (totalsByBucket.get(bucket(f)) || 0) + 1);
+for (const f of reachableInDist) reachableByBucket.set(bucket(f), (reachableByBucket.get(bucket(f)) || 0) + 1);
+
+console.log('[report-declaration-reachability] SD-2952 step 3: declaration reachability');
+console.log('='.repeat(72));
+console.log(`Reachable declarations: ${reachable} / ${total} (${pct}%) from ${typedExports.length} typed exports`);
+console.log();
+console.log('Per top-level dist bucket (reachable / total):');
+const buckets = [...new Set([...totalsByBucket.keys(), ...reachableByBucket.keys()])].sort();
+for (const b of buckets) {
+  const r = reachableByBucket.get(b) || 0;
+  const t = totalsByBucket.get(b) || 0;
+  const bp = t === 0 ? '0.0' : ((r / t) * 100).toFixed(1);
+  console.log(`  ${b.padEnd(20)} ${String(r).padStart(5)} / ${String(t).padStart(5)} (${bp}%)`);
+}
+console.log();
+console.log('Note: instrumentation only. The ratio is not a CI gate (SD-2952 step 3).');
+console.log('      Use the bucket breakdown to inform SD-2952 step 4 (trim unreachable emit).');