diff --git a/.changeset/sturdy-sloths-forage.md b/.changeset/sturdy-sloths-forage.md
new file mode 100644
index 000000000..c9ec06f59
--- /dev/null
+++ b/.changeset/sturdy-sloths-forage.md
@@ -0,0 +1,5 @@
+---
+type: Fixed
+pr: 2968
+---
+**Published installs no longer crash on a script that can't load** — `scripts/gen-emitted-baseline.cjs` shipped in the npm tarball but required three modules from `tests/` (which does not ship), producing `MODULE_NOT_FOUND` at load time. The script is repo-only CI tooling and is now excluded from the tarball. A class-extinction guard test ensures no shipped script can require outside the shipped tree going forward. (#2858)
diff --git a/package.json b/package.json
index be04e6a2e..63509d162 100644
--- a/package.json
+++ b/package.json
@@ -21,6 +21,7 @@
     "GEMINI.md",
     "hooks",
     "scripts",
+    "!scripts/gen-emitted-baseline.cjs",
     "pi",
     "vscode"
   ],
diff --git a/tests/packaging-shipped-scripts-require-only-shipped.test.cjs b/tests/packaging-shipped-scripts-require-only-shipped.test.cjs
new file mode 100644
index 000000000..01289ee3f
--- /dev/null
+++ b/tests/packaging-shipped-scripts-require-only-shipped.test.cjs
@@ -0,0 +1,180 @@
+// allow-test-rule: integration-test-input (see #2858)
+// #2858 — class-extinction guard: every shipped scripts/**/*.cjs must be
+// require-able using only shipped paths. A script that ships in the npm tarball
+// but requires a module from tests/ (which does not ship) is MODULE_NOT_FOUND
+// at load time in a published install.
+//
+// This test statically checks each shipped .cjs's require() calls against the
+// resolved tarball file list (npm pack --dry-run --json), so adding a new entry
+// to `files` cannot silently opt out. It does NOT execute the scripts — it parses
+// their require() calls and resolves them against the shipped set.
+
+'use strict';
+
+process.env.GSD_TEST_MODE = '1';
+
+const { describe, test, before } = require('node:test');
+const assert = require('node:assert/strict');
+const fs = require('node:fs');
+const path = require('node:path');
+const { execFileSync } = require('node:child_process');
+
+const REPO_ROOT = path.join(__dirname, '..');
+
+/**
+ * Resolve the tarball file list via `npm pack --dry-run --json`.
+ * This is the ACTUAL set of files that ship — not a hardcoded list — so adding
+ * a new entry to package.json `files` cannot silently bypass the guard.
+ */
+function resolveTarballFiles() {
+  const raw = execFileSync('npm', ['pack', '--dry-run', '--json'], {
+    cwd: REPO_ROOT,
+    encoding: 'utf-8',
+    shell: true, // Windows: npm is npm.cmd and needs a shell
+    stdio: ['pipe', 'pipe', 'pipe'],
+    timeout: 60_000,
+  });
+  const parsed = JSON.parse(raw);
+  return new Set(parsed[0].files.map((f) => f.path.replace(/\\/g, '/')));
+}
+
+/**
+ * Extract all require('...') string-literal calls from a .cjs source.
+ * Only static string-literal requires are checked — dynamic require(variable)
+ * is out of scope (and would itself be a red flag in a shipped script).
+ */
+function extractRequires(source) {
+  const requires = [];
+  // Strip block comments (/* ... */) and inline line comments (// ...) before
+  // matching, so a require() appearing in a doc comment or fenced code block
+  // inside a /* */ does not produce a false positive.
+  const stripped = source
+    .replace(/\/\*[\s\S]*?\*\//g, '')
+    .replace(/\/\/.*$/gm, '');
+  const requireRe = /\brequire\s*\(\s*['"]([^'"]+)['"]\s*\)/g;
+  let m;
+  while ((m = requireRe.exec(stripped)) !== null) {
+    requires.push(m[1]);
+  }
+  return requires;
+}
+
+/**
+ * Classify a require specifier from a given file path:
+ * - 'builtin'   — node: prefix or a Node builtin (fs, path, etc.)
+ * - 'shipped'   — resolves to a file within the shipped tarball set
+ * - 'external'  — an npm dependency (resolvable from node_modules)
+ * - 'unshipped' — resolves to a repo path that is NOT in the shipped set (VIOLATION)
+ */
+function classifyRequire(spec, fromFile, shippedFiles) {
+  // Node builtins (including node: prefix)
+  if (spec.startsWith('node:')) return 'builtin';
+  const BUILTINS = ['fs', 'path', 'os', 'child_process', 'crypto', 'util', 'url', 'events', 'stream', 'http', 'https', 'net', 'tls', 'zlib', 'querystring', 'string_decoder', 'timers', 'vm', 'worker_threads', 'buffer', 'process'];
+  const bare = spec.split('/')[0];
+  if (BUILTINS.includes(bare)) return 'builtin';
+
+  // Relative/absolute requires — resolve against the file's directory
+  if (spec.startsWith('.') || spec.startsWith('/')) {
+    const fromDir = path.dirname(fromFile);
+    const resolved = path.posix.normalize(path.posix.join(fromDir, spec));
+    // Try exact, .cjs, .js, .json, /index.cjs, /index.js
+    const candidates = [
+      resolved,
+      resolved + '.cjs',
+      resolved + '.js',
+      resolved + '.json',
+      resolved + '/index.cjs',
+      resolved + '/index.js',
+    ];
+    for (const c of candidates) {
+      const normalized = c.replace(/\\/g, '/');
+      if (shippedFiles.has(normalized)) return 'shipped';
+    }
+    // If it resolves to a real file on disk but is NOT shipped → violation
+    const absResolved = path.resolve(REPO_ROOT, resolved);
+    const absCandidates = [
+      absResolved,
+      absResolved + '.cjs',
+      absResolved + '.js',
+      absResolved + '.json',
+      path.join(absResolved, 'index.cjs'),
+      path.join(absResolved, 'index.js'),
+    ];
+    for (const c of absCandidates) {
+      if (fs.existsSync(c)) return 'unshipped';
+    }
+    // Doesn't resolve to anything — likely a typo or generated artifact; flag it
+    return 'unshipped';
+  }
+
+  // Bare specifier (not relative, not builtin) → npm dependency
+  return 'external';
+}
+
+describe('#2858 — shipped scripts require only shipped paths', () => {
+  let shippedFiles;
+  let shippedScripts;
+
+  before(() => {
+    shippedFiles = resolveTarballFiles();
+    // Filter to scripts/**/*.{cjs,js} (the shipped script surface — both .cjs
+    // and .js files ship under scripts/, e.g. build-hooks.js is required by
+    // bin/install.js). Both extensions are checked so a broken require() in a
+    // .js file is caught just the same as one in a .cjs file.
+    shippedScripts = [...shippedFiles]
+      .filter((f) => f.startsWith('scripts/') && /\.(cjs|js)$/.test(f))
+      .sort();
+  });
+
+  test('every shipped scripts/*.{cjs,js} is require-able from a shipped-only tree', () => {
+    assert.ok(shippedScripts.length > 0, 'expected at least one shipped script');
+
+    const violations = [];
+    for (const scriptRel of shippedScripts) {
+      const absPath = path.join(REPO_ROOT, scriptRel);
+      if (!fs.existsSync(absPath)) continue; // generated artifact, skip
+      const source = fs.readFileSync(absPath, 'utf-8');
+      const requires = extractRequires(source);
+
+      for (const spec of requires) {
+        const classification = classifyRequire(spec, scriptRel, shippedFiles);
+        if (classification === 'unshipped') {
+          violations.push({
+            script: scriptRel,
+            require: spec,
+            classification,
+          });
+        }
+      }
+    }
+
+    if (violations.length > 0) {
+      const details = violations
+        .map((v) => `  ${v.script}: require('${v.require}') → ${v.classification}`)
+        .join('\n');
+      assert.fail(
+        `${violations.length} shipped script(s) require modules outside the shipped tree (MODULE_NOT_FOUND in a published install):\n${details}`,
+      );
+    }
+  });
+
+  test('gen-emitted-baseline.cjs does NOT ship (repo-only CI tooling)', () => {
+    // This script requires ../tests/helpers/* which does not ship. It is
+    // repo-only CI tooling (CI workflows + test fixtures spawn it from a
+    // checkout). It must be excluded from the npm tarball.
+    assert.ok(
+      !shippedFiles.has('scripts/gen-emitted-baseline.cjs'),
+      'scripts/gen-emitted-baseline.cjs must NOT ship — it requires tests/ which does not ship (#2858)',
+    );
+  });
+
+  test('a script requiring a sibling in the same shipped dir resolves as shipped (positive case)', () => {
+    // Sanity: scripts/lib/cli-exit.cjs ships and is required by shipped scripts.
+    // This confirms the guard's positive path works — a valid intra-shipped require
+    // is NOT flagged.
+    assert.ok(shippedFiles.has('scripts/lib/cli-exit.cjs'), 'scripts/lib/cli-exit.cjs should ship');
+    const classification = classifyRequire('./lib/cli-exit.cjs', 'scripts/gen-adr-index.cjs', shippedFiles);
+    assert.strictEqual(classification, 'shipped',
+      `a sibling require within scripts/ must classify as 'shipped'; got '${classification}'`);
+  });
+});