fix(plugin): validate plugin id format

src/langbot/pkg/plugin/connector.py

@@ -633,11 +633,12 @@ class PluginRuntimeConnector:
         Raises:
             ValueError: If plugin_id is not in the expected 'author/name' format.
         """
-        if '/' not in plugin_id:
+        segments = plugin_id.split('/')
+        if len(segments) != 2 or not all(segments):
             raise ValueError(
                 f"Invalid plugin_id format: '{plugin_id}'. Expected 'author/name' format (e.g. 'langbot/rag-engine')."
             )
-        return plugin_id.split('/', 1)
+        return segments[0], segments[1]
 
     async def call_rag_ingest(self, plugin_id: str, context_data: dict[str, Any]) -> dict[str, Any]:
         """Call plugin to ingest document.

tests/unit_tests/plugin/test_plugin_id_parsing.py

@@ -0,0 +1,25 @@
+"""Test plugin ID parsing validation."""
+
+import pytest
+
+from src.langbot.pkg.plugin.connector import PluginRuntimeConnector
+
+
+def test_parse_plugin_id_accepts_author_name():
+    assert PluginRuntimeConnector._parse_plugin_id('langbot/rag-engine') == ('langbot', 'rag-engine')
+
+
+@pytest.mark.parametrize(
+    'plugin_id',
+    [
+        '',
+        'author',
+        'author/',
+        '/name',
+        'author/name/extra',
+        '/',
+    ],
+)
+def test_parse_plugin_id_rejects_malformed_ids(plugin_id):
+    with pytest.raises(ValueError, match='Expected'):
+        PluginRuntimeConnector._parse_plugin_id(plugin_id)