diff --git a/test/esm-import-check.test.js b/test/esm-import-check.test.js
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+++ b/test/esm-import-check.test.js
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+// Static ESM import-resolution check for lib/public/.
+//
+// Catches the failure class from lr-8657 / PR #223: a named import that
+// references a symbol that no longer exists in the target module (because it
+// moved, was renamed, or the import path is simply wrong).
+//
+// What is checked:
+//   - Every relative import in lib/public/**/*.js resolves to a file that exists.
+//   - Every named symbol in those imports actually appears as an export in the
+//     target file.
+//
+// What is intentionally NOT checked:
+//   - Bare specifiers (node:*, ws, etc.) — not our code, no local file to check.
+//   - Default imports (import x from '...') — these only consume the default export,
+//     which has no stable name to verify.
+//   - `export * from './bar'` re-export chains — treated as wildcard; any named
+//     import from a file that uses export* is accepted without deep-following, to
+//     avoid false-positives on complex re-export graphs.
+//
+// Run: npm test  (wired into test/*.test.js glob)
+
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import fs from 'node:fs';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const __dirname = path.dirname(fileURLToPath(import.meta.url));
+const PUBLIC_ROOT = path.resolve(__dirname, '../lib/public');
+
+// ---------------------------------------------------------------------------
+// File discovery
+// ---------------------------------------------------------------------------
+
+function collectJsFiles(dir) {
+  const results = [];
+  for (const entry of fs.readdirSync(dir, { withFileTypes: true })) {
+    const full = path.join(dir, entry.name);
+    if (entry.isDirectory()) {
+      results.push(...collectJsFiles(full));
+    } else if (entry.isFile() && entry.name.endsWith('.js')) {
+      results.push(full);
+    }
+  }
+  return results;
+}
+
+// ---------------------------------------------------------------------------
+// Export extraction
+// ---------------------------------------------------------------------------
+
+// Parses all exported names from a file's source text.
+// Returns { names: Set<string>, hasStarReexport: bool }.
+function extractExports(src) {
+  const names = new Set();
+  let hasStarReexport = false;
+
+  // export default ...
+  if (/\bexport\s+default\b/.test(src)) {
+    names.add('default');
+  }
+
+  // export function foo / export async function foo / export class Foo /
+  // export var foo / export let foo / export const foo
+  const declRe = /\bexport\s+(?:async\s+)?(?:function|class|var|let|const)\s+([A-Za-z_$][A-Za-z0-9_$]*)/g;
+  let m;
+  while ((m = declRe.exec(src)) !== null) {
+    names.add(m[1]);
+  }
+
+  // export { foo, bar as baz, ... }        (local re-export, no 'from')
+  // export { foo, bar } from './other'     (named re-export from another module)
+  // In both cases the public exported name is the alias if present, else the original.
+  const braceRe = /\bexport\s*\{([^}]+)\}(?:\s*from\s*['"][^'"]+['"])?/g;
+  while ((m = braceRe.exec(src)) !== null) {
+    const body = m[1];
+    const itemRe = /([A-Za-z_$][A-Za-z0-9_$]*)\s*(?:as\s+([A-Za-z_$][A-Za-z0-9_$]*))?/g;
+    let im;
+    while ((im = itemRe.exec(body)) !== null) {
+      names.add(im[2] || im[1]);
+    }
+  }
+
+  // export * from './bar'  — this file re-exports an unknown set of names.
+  // Record the sentinel; callers skip deep checks against this file to avoid
+  // false-positives on unbounded re-export graphs.
+  if (/\bexport\s+\*\s+from\b/.test(src)) {
+    hasStarReexport = true;
+  }
+
+  return { names, hasStarReexport };
+}
+
+// ---------------------------------------------------------------------------
+// Import extraction
+// ---------------------------------------------------------------------------
+
+// Returns [{ specifier, names[] }] for every static named import of a relative
+// specifier in src.  Bare specifiers (node:*, ws, …) and default-only imports
+// are skipped.
+function extractNamedImports(src) {
+  const imports = [];
+
+  // Regex matches:  import { ... } from './path'  or  import { ... } from '../path'
+  // The brace body [^}]* is single-line-greedy, which is fine because app.js
+  // uses multi-line imports whose closing } is on its own line — the regex
+  // engine still matches because [^}]* is greedy across newlines.
+  const re = /\bimport\s*\{([^}]*)\}\s*from\s*(['"])(\.\.?\/[^'"]+)\2/g;
+  let m;
+  while ((m = re.exec(src)) !== null) {
+    const body = m[1];
+    const specifier = m[3];
+
+    // Each item in the brace list: "foo" or "foo as localAlias".
+    // We want the original exported name (left side).
+    const itemRe = /([A-Za-z_$][A-Za-z0-9_$]*)\s*(?:as\s+[A-Za-z_$][A-Za-z0-9_$]*)?/g;
+    const names = [];
+    let im;
+    while ((im = itemRe.exec(body)) !== null) {
+      names.push(im[1]);
+    }
+
+    if (names.length > 0) {
+      imports.push({ specifier, names });
+    }
+  }
+
+  return imports;
+}
+
+// ---------------------------------------------------------------------------
+// Export cache — parse each target file at most once
+// ---------------------------------------------------------------------------
+
+const exportCache = new Map();
+
+function getExports(absPath) {
+  if (exportCache.has(absPath)) return exportCache.get(absPath);
+  if (!fs.existsSync(absPath)) {
+    const sentinel = { names: new Set(), hasStarReexport: false, missing: true };
+    exportCache.set(absPath, sentinel);
+    return sentinel;
+  }
+  const src = fs.readFileSync(absPath, 'utf8');
+  const result = extractExports(src);
+  exportCache.set(absPath, result);
+  return result;
+}
+
+// ---------------------------------------------------------------------------
+// Main scan
+// ---------------------------------------------------------------------------
+
+const allFiles = collectJsFiles(PUBLIC_ROOT);
+const violations = [];
+
+for (const file of allFiles) {
+  const src = fs.readFileSync(file, 'utf8');
+  const namedImports = extractNamedImports(src);
+
+  for (const { specifier, names } of namedImports) {
+    const targetPath = path.resolve(path.dirname(file), specifier);
+
+    // Try exact path first, then append .js for extension-less specifiers.
+    const resolved = fs.existsSync(targetPath)
+      ? targetPath
+      : fs.existsSync(targetPath + '.js')
+        ? targetPath + '.js'
+        : null;
+
+    if (!resolved) {
+      violations.push({
+        kind: 'missing-file',
+        importer: path.relative(PUBLIC_ROOT, file),
+        specifier,
+        names,
+      });
+      continue;
+    }
+
+    const { names: exported, hasStarReexport } = getExports(resolved);
+
+    // If the target uses `export * from`, its full export surface is unknown
+    // without recursion. Skip to avoid false-positives.
+    if (hasStarReexport) continue;
+
+    for (const name of names) {
+      if (!exported.has(name)) {
+        violations.push({
+          kind: 'missing-export',
+          importer: path.relative(PUBLIC_ROOT, file),
+          specifier,
+          name,
+          targetFile: path.relative(PUBLIC_ROOT, resolved),
+        });
+      }
+    }
+  }
+}
+
+// ---------------------------------------------------------------------------
+// Test assertion — report all violations in one shot
+// ---------------------------------------------------------------------------
+
+test('ESM named import resolution across lib/public/', () => {
+  if (violations.length === 0) return;
+
+  const lines = violations.map(v => {
+    if (v.kind === 'missing-file') {
+      return `  MISSING FILE  ${v.importer} imports from '${v.specifier}' — file not found`;
+    }
+    return `  MISSING EXPORT  ${v.importer} imports { ${v.name} } from '${v.specifier}' — not exported by ${v.targetFile}`;
+  });
+
+  assert.fail(
+    `${violations.length} broken import(s) found in lib/public/:\n` +
+    lines.join('\n')
+  );
+});