diff --git a/scripts/security_audit.py b/scripts/security_audit.py
index f77909a..c8c9f7d 100644
--- a/scripts/security_audit.py
+++ b/scripts/security_audit.py
@@ -459,8 +459,8 @@ def main(argv: list[str] | None = None) -> int:
     if not dirs and PLUGINS.is_dir():
         add(findings, "BLOCKER", "plugins", "no plugin directories found")
     for plugin_dir in dirs:
-        if not plugin_dir.is_dir() or not plugin_dir.is_relative_to(PLUGINS):
-            add(findings, "BLOCKER", str(plugin_dir), "plugin path must be a directory below plugins/")
+        if not plugin_dir.is_dir():
+            add(findings, "BLOCKER", str(plugin_dir), "plugin path must be a directory")
             continue
         plugin_findings, _ = audit_plugin(plugin_dir)
         findings.extend(plugin_findings)
@@ -469,8 +469,8 @@ def main(argv: list[str] | None = None) -> int:
 
     blockers = [finding for finding in findings if finding.severity == "BLOCKER"]
     reviews = [finding for finding in findings if finding.severity == "REVIEW"]
-    if not PLUGINS.is_dir():
-        print("Source audit skipped: this repository keeps packages only; every package in packages/ is audited directly.")
+    if not dirs and not PLUGINS.is_dir():
+        print("Source audit skipped: no source directories supplied and this repository keeps packages only.")
     print(f"Security audit: {len(dirs)} plugin source(s), {len(blockers)} blocker(s), {len(reviews)} manual-review signal(s)")
     for finding in findings:
         print(finding.render())
diff --git a/tests/test_external_source_audit.py b/tests/test_external_source_audit.py
new file mode 100644
index 0000000..823273f
--- /dev/null
+++ b/tests/test_external_source_audit.py
@@ -0,0 +1,77 @@
+"""Explicit source directories can belong to a separate plugin repository."""
+import contextlib
+import importlib.util
+import io
+import json
+import sys
+import tempfile
+import unittest
+from pathlib import Path
+from unittest.mock import patch
+
+spec = importlib.util.spec_from_file_location(
+    "external_source_audit", Path(__file__).resolve().parents[1] / "scripts" / "security_audit.py",
+)
+audit = importlib.util.module_from_spec(spec)
+sys.modules[spec.name] = audit
+spec.loader.exec_module(audit)
+
+
+class ExternalSourceAuditTests(unittest.TestCase):
+    def setUp(self):
+        self.tmp = tempfile.TemporaryDirectory()
+        self.addCleanup(self.tmp.cleanup)
+        self.root = Path(self.tmp.name)
+        self.repo = self.root / "distribution"
+        self.repo.mkdir()
+        self.plugin = self.root / "sample.plugin"
+        self.plugin.mkdir()
+        (self.plugin / "main.js").write_text("module.exports = {};\n", encoding="utf-8")
+        (self.plugin / "manifest.json").write_text(json.dumps({
+            "schemaVersion": 1, "id": "sample.plugin", "name": "Sample", "version": "0.1.0",
+            "description": "Sample", "author": "test", "main": "main.js", "permissions": [],
+            "engines": {"piDesktop": ">=0.2.0"},
+            "i18n": {
+                "en": {"name": "Sample", "description": "Sample", "safetyNotes": "None"},
+                "zh-CN": {"name": "Sample", "description": "Sample", "safetyNotes": "None"},
+            },
+        }), encoding="utf-8")
+
+    def run_audit(self, args):
+        output = io.StringIO()
+        with patch.object(audit, "ROOT", self.repo), patch.object(audit, "PLUGINS", self.repo / "plugins"), \
+                contextlib.redirect_stdout(output), contextlib.redirect_stderr(output):
+            result = audit.main(args)
+        return result, output.getvalue()
+
+    def test_absolute_and_relative_external_paths_are_audited(self):
+        for path in (str(self.plugin), "../sample.plugin"):
+            with self.subTest(path=path):
+                status, output = self.run_audit([path])
+                self.assertEqual(status, 0, output)
+                self.assertIn("1 plugin source(s), 0 blocker(s)", output)
+                self.assertNotIn("Source audit skipped", output)
+
+    def test_external_source_still_fails_static_blockers(self):
+        (self.plugin / "main.js").write_text("eval(input);\n", encoding="utf-8")
+        status, output = self.run_audit([str(self.plugin)])
+        self.assertEqual(status, 1)
+        self.assertIn("dynamic or remote code execution: eval()", output)
+        self.assertNotIn("Source audit skipped", output)
+
+    def test_missing_and_file_paths_fail(self):
+        for path in (self.root / "missing", self.plugin / "main.js"):
+            with self.subTest(path=path):
+                status, output = self.run_audit([str(path)])
+                self.assertEqual(status, 1)
+                self.assertIn("plugin path must be a directory", output)
+
+    def test_no_default_sources_reports_skip(self):
+        status, output = self.run_audit([])
+        self.assertEqual(status, 0, output)
+        self.assertIn("Source audit skipped", output)
+        self.assertNotIn("every package in packages/ is audited", output)
+
+
+if __name__ == "__main__":
+    unittest.main()