diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 8a9131140..5e28c91fd 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -16,7 +16,7 @@ concurrency:
   cancel-in-progress: true
 
 jobs:
-  # Static lint: no source-grep tests in the test suite.
+  # Static lint: test-suite and PR-check contracts.
   # Runs once (not per matrix node version) since it is a file-content check.
   lint-tests:
     runs-on: ubuntu-latest
@@ -33,6 +33,9 @@ jobs:
       - name: Lint — command contract (ADR-0002)
         shell: bash
         run: node scripts/lint-command-contract.cjs
+      - name: Lint — PR checks use projectDir
+        shell: bash
+        run: node scripts/lint-pr-check-project-dir.cjs
 
   test:
     runs-on: ${{ matrix.os }}
diff --git a/package.json b/package.json
index 1f64997f3..0a6ac5075 100644
--- a/package.json
+++ b/package.json
@@ -71,6 +71,7 @@
     "lint:descriptions": "node scripts/lint-descriptions.cjs",
     "lint:skill-deps": "node scripts/lint-skill-deps.cjs",
     "lint:tests": "node scripts/lint-no-source-grep.cjs",
+    "lint:pr-checks": "node scripts/lint-pr-check-project-dir.cjs",
     "lint:changeset": "node scripts/changeset/lint.cjs",
     "changeset": "node scripts/changeset/new.cjs",
     "changelog:render": "node scripts/changeset/cli.cjs render",
diff --git a/scripts/lint-pr-check-project-dir.cjs b/scripts/lint-pr-check-project-dir.cjs
new file mode 100644
index 000000000..a3fd1a237
--- /dev/null
+++ b/scripts/lint-pr-check-project-dir.cjs
@@ -0,0 +1,98 @@
+#!/usr/bin/env node
+'use strict';
+
+const fs = require('fs');
+const path = require('path');
+
+const ROOT = path.join(__dirname, '..');
+
+const DEFAULT_RELATIVE_FILES = [
+  '.github/workflows/test.yml',
+  '.github/workflows/pr-template-format.yml',
+  '.github/workflows/changeset-required.yml',
+  'scripts/lint-no-source-grep.cjs',
+  'scripts/lint-command-contract.cjs',
+  'scripts/lint-skill-deps.cjs',
+  'scripts/lint-descriptions.cjs',
+  'scripts/lint-shell-command-projection-drift.cjs',
+  'scripts/pr-template-policy.cjs',
+  'scripts/changeset/lint.cjs',
+];
+
+function defaultFiles(rootDir = ROOT) {
+  return DEFAULT_RELATIVE_FILES
+    .map((file) => path.join(rootDir, file))
+    .filter((file) => fs.existsSync(file));
+}
+
+function findForbiddenCwd(content, file = '<inline>') {
+  const findings = [];
+  const lines = content.split(/\r?\n/);
+
+  lines.forEach((line, index) => {
+    const pattern = /\bcwd\b/g;
+    let match;
+    while ((match = pattern.exec(line)) !== null) {
+      findings.push({
+        file,
+        line: index + 1,
+        column: match.index + 1,
+        source: line.trim(),
+      });
+    }
+  });
+
+  return findings;
+}
+
+function checkFiles(files, { rootDir = ROOT } = {}) {
+  const findings = [];
+  for (const file of files) {
+    const content = fs.readFileSync(file, 'utf8');
+    const rel = path.relative(rootDir, file);
+    findings.push(...findForbiddenCwd(content, rel));
+  }
+  return findings;
+}
+
+function formatFindings(findings) {
+  const lines = [
+    `ERROR lint-pr-check-project-dir: ${findings.length} forbidden cwd reference(s) found`,
+    '',
+    'PR checkers must use projectDir for project roots; cwd is forbidden in this layer.',
+    '',
+  ];
+
+  for (const finding of findings) {
+    lines.push(`  ${finding.file}:${finding.line}:${finding.column}`);
+    lines.push(`    ${finding.source}`);
+  }
+
+  return `${lines.join('\n')}\n`;
+}
+
+function main(argv = process.argv.slice(2)) {
+  const files = argv.length > 0 ? argv.map((file) => path.resolve(file)) : defaultFiles();
+  const findings = checkFiles(files);
+
+  if (findings.length === 0) {
+    console.log(`ok lint-pr-check-project-dir: ${files.length} PR check files checked`);
+    return 0;
+  }
+
+  process.stderr.write(formatFindings(findings));
+  return 1;
+}
+
+if (require.main === module) {
+  process.exit(main());
+}
+
+module.exports = {
+  DEFAULT_RELATIVE_FILES,
+  checkFiles,
+  defaultFiles,
+  findForbiddenCwd,
+  formatFindings,
+  main,
+};
diff --git a/tests/feat-3251-command-aliases-manifest-coverage.test.cjs b/tests/feat-3251-command-aliases-manifest-coverage.test.cjs
index 9904b2080..1003b0fc4 100644
--- a/tests/feat-3251-command-aliases-manifest-coverage.test.cjs
+++ b/tests/feat-3251-command-aliases-manifest-coverage.test.cjs
@@ -137,9 +137,9 @@ function createProject() {
   return dir;
 }
 
-function runGsdTools(args, cwd) {
+function runGsdTools(args, projectDir) {
   return spawnSync(process.execPath, [GSD_TOOLS, ...args], {
-    cwd,
+    cwd: projectDir,
     encoding: 'utf8',
   });
 }
diff --git a/tests/lint-pr-check-project-dir.test.cjs b/tests/lint-pr-check-project-dir.test.cjs
new file mode 100644
index 000000000..cae74d40e
--- /dev/null
+++ b/tests/lint-pr-check-project-dir.test.cjs
@@ -0,0 +1,121 @@
+'use strict';
+
+const { describe, test } = require('node:test');
+const assert = require('node:assert/strict');
+const fs = require('fs');
+const os = require('os');
+const path = require('path');
+const { spawnSync } = require('child_process');
+
+const ROOT = path.join(__dirname, '..');
+const LINT_SCRIPT = path.join(ROOT, 'scripts', 'lint-pr-check-project-dir.cjs');
+
+const {
+  checkFiles,
+  defaultFiles,
+  findForbiddenCwd,
+  formatFindings,
+} = require(LINT_SCRIPT);
+
+function createFixtureDir() {
+  return fs.mkdtempSync(path.join(os.tmpdir(), 'gsd-pr-check-lint-'));
+}
+
+function runLint(args = []) {
+  return spawnSync(process.execPath, [LINT_SCRIPT, ...args], { encoding: 'utf8' });
+}
+
+describe('lint-pr-check-project-dir', () => {
+  test('flags cwd parameters and shorthand properties', () => {
+    const findings = findForbiddenCwd(
+      [
+        'function runCheck(args, cwd) {',
+        '  return spawnSync(process.execPath, args, { cwd });',
+        '}',
+      ].join('\n'),
+      'fixture.cjs',
+    );
+
+    assert.deepEqual(
+      findings.map((finding) => [finding.line, finding.column]),
+      [
+        [1, 25],
+        [2, 46],
+      ],
+    );
+  });
+
+  test('flags cwd option keys even when the value is projectDir', () => {
+    const findings = findForbiddenCwd(
+      [
+        'function runCheck(args, projectDir) {',
+        '  return spawnSync(process.execPath, args, { cwd: projectDir });',
+        '}',
+      ].join('\n'),
+      'fixture.cjs',
+    );
+
+    assert.deepEqual(findings, [
+      {
+        file: 'fixture.cjs',
+        line: 2,
+        column: 46,
+        source: 'return spawnSync(process.execPath, args, { cwd: projectDir });',
+      },
+    ]);
+  });
+
+  test('allows projectDir project-root naming without cwd references', () => {
+    const findings = findForbiddenCwd(
+      [
+        'function checkProject(args, projectDir) {',
+        '  return runProjectCheck(args, projectDir);',
+        '}',
+      ].join('\n'),
+      'fixture.cjs',
+    );
+
+    assert.deepEqual(findings, []);
+  });
+
+  test('formats diagnostics with file, line, and source', () => {
+    const output = formatFindings([
+      {
+        file: 'scripts/example.cjs',
+        line: 12,
+        column: 7,
+        source: 'const cwd = projectDir;',
+      },
+    ]);
+
+    assert.match(output, /ERROR lint-pr-check-project-dir: 1 forbidden cwd reference/);
+    assert.match(output, /scripts\/example\.cjs:12:7/);
+    assert.match(output, /const cwd = projectDir;/);
+    assert.match(output, /projectDir/);
+  });
+
+  test('checks the real PR-check files without violations', () => {
+    const files = defaultFiles(ROOT);
+    assert.ok(files.length > 0, 'expected default PR-check files');
+    assert.deepEqual(checkFiles(files, { rootDir: ROOT }), []);
+  });
+
+  test('CLI exits non-zero when a passed file contains cwd', () => {
+    const dir = createFixtureDir();
+    try {
+      const file = path.join(dir, 'bad-check.cjs');
+      fs.writeFileSync(file, 'const cwd = process.env.PROJECT_DIR;\n');
+
+      const result = runLint([file]);
+
+      assert.notStrictEqual(result.status, 0);
+    } finally {
+      fs.rmSync(dir, { recursive: true, force: true });
+    }
+  });
+
+  test('script parses without syntax errors', () => {
+    const result = spawnSync(process.execPath, ['--check', LINT_SCRIPT], { encoding: 'utf8' });
+    assert.strictEqual(result.status, 0, result.stderr);
+  });
+});