fix(plugin): surface dependency install failures

src/langbot/pkg/plugin/connector.py

@@ -11,6 +11,7 @@ import os
 import sys
 import httpx
 import sqlalchemy
+import yaml
 from async_lru import alru_cache
 from langbot_plugin.api.entities.builtin.pipeline.query import provider_session
 
@@ -195,40 +196,110 @@ class PluginRuntimeConnector:
 
         return await self.handler.ping()
 
-    def _extract_deps_metadata(
+    def _inspect_plugin_package(
         self,
         file_bytes: bytes,
         task_context: taskmgr.TaskContext | None,
-    ):
+    ) -> tuple[str | None, str | None]:
-        """Extract dependency count from requirements.txt inside plugin zip."""
+        """Extract plugin identity and dependency metadata from a plugin package."""
-        if task_context is None:
+        plugin_author = None
-            return
+        plugin_name = None
+
         try:
             with zipfile.ZipFile(io.BytesIO(file_bytes)) as zf:
-                for name in zf.namelist():
+                try:
-                    if name.endswith('requirements.txt'):
+                    manifest = yaml.safe_load(zf.read('manifest.yaml').decode('utf-8', errors='ignore')) or {}
-                        content = zf.read(name).decode('utf-8', errors='ignore')
+                    metadata = manifest.get('metadata', {})
-                        deps = [
+                    plugin_author = metadata.get('author')
-                            line.strip()
+                    plugin_name = metadata.get('name')
-                            for line in content.splitlines()
+                except Exception:
-                            if line.strip() and not line.strip().startswith('#')
+                    pass
-                        ]
+
-                        task_context.metadata['deps_total'] = len(deps)
+                if task_context is not None:
-                        task_context.metadata['deps_list'] = deps
+                    for name in zf.namelist():
-                        break
+                        if name.endswith('requirements.txt'):
+                            content = zf.read(name).decode('utf-8', errors='ignore')
+                            deps = [
+                                line.strip()
+                                for line in content.splitlines()
+                                if line.strip() and not line.strip().startswith('#')
+                            ]
+                            task_context.metadata['deps_total'] = len(deps)
+                            task_context.metadata['deps_list'] = deps
+                            break
         except Exception:
             pass
 
+        return plugin_author, plugin_name
+
+    def _build_plugin_startup_failure_message(
+        self,
+        plugin_author: str,
+        plugin_name: str,
+        task_context: taskmgr.TaskContext | None,
+    ) -> str:
+        dep_hint = ''
+        if task_context is not None:
+            current_dep = task_context.metadata.get('current_dep')
+            if current_dep:
+                dep_hint = f' Last dependency: {current_dep}.'
+
+        return (
+            f'Plugin {plugin_author}/{plugin_name} failed to start after installation. '
+            f'Dependency installation or plugin initialization may have failed.{dep_hint} '
+            f'Please check the plugin requirements and runtime logs.'
+        )
+
+    async def _wait_for_installed_plugin_ready(
+        self,
+        plugin_author: str | None,
+        plugin_name: str | None,
+        task_context: taskmgr.TaskContext | None,
+        timeout: float = 30,
+    ):
+        """Wait until the installed plugin is registered by the runtime.
+
+        The plugin runtime launches plugins asynchronously. If dependency installation
+        fails, the plugin process exits before registration; without this check the
+        install task can incorrectly finish successfully.
+        """
+        if not plugin_author or not plugin_name:
+            return
+
+        deadline = time.time() + timeout
+        last_error: Exception | None = None
+        while time.time() < deadline:
+            try:
+                plugin = await self.get_plugin_info(plugin_author, plugin_name)
+                if plugin is not None:
+                    status = plugin.get('status')
+                    if status == 'initialized':
+                        return
+            except Exception as e:
+                last_error = e
+
+            await asyncio.sleep(0.5)
+
+        message = self._build_plugin_startup_failure_message(plugin_author, plugin_name, task_context)
+        if last_error is not None:
+            message = f'{message} Last runtime error: {last_error}'
+        raise RuntimeError(message)
+
     async def install_plugin(
         self,
         install_source: PluginInstallSource,
         install_info: dict[str, Any],
         task_context: taskmgr.TaskContext | None = None,
     ):
+        plugin_author = install_info.get('plugin_author')
+        plugin_name = install_info.get('plugin_name')
+
         if install_source == PluginInstallSource.LOCAL:
             # transfer file before install
             file_bytes = install_info['plugin_file']
-            self._extract_deps_metadata(file_bytes, task_context)
+            plugin_author, plugin_name = self._inspect_plugin_package(file_bytes, task_context)
+            if task_context is not None and plugin_author and plugin_name:
+                task_context.metadata['plugin_name'] = f'{plugin_author}/{plugin_name}'
             file_key = await self.handler.send_file(file_bytes, 'lbpkg')
             install_info['plugin_file_key'] = file_key
             del install_info['plugin_file']
@@ -265,7 +336,9 @@ class PluginRuntimeConnector:
                                 task_context.metadata['download_speed'] = downloaded / elapsed if elapsed > 0 else 0
 
                     file_bytes = b''.join(chunks)
-                    self._extract_deps_metadata(file_bytes, task_context)
+                    plugin_author, plugin_name = self._inspect_plugin_package(file_bytes, task_context)
+                    if task_context is not None and plugin_author and plugin_name:
+                        task_context.metadata['plugin_name'] = f'{plugin_author}/{plugin_name}'
                     file_key = await self.handler.send_file(file_bytes, 'lbpkg')
                     install_info['plugin_file_key'] = file_key
                     self.ap.logger.info(f'Transfered file {file_key} to plugin runtime')
@@ -289,6 +362,8 @@ class PluginRuntimeConnector:
             if metadata is not None and task_context is not None:
                 task_context.metadata.update(metadata)
 
+        await self._wait_for_installed_plugin_ready(plugin_author, plugin_name, task_context)
+
     async def upgrade_plugin(
         self,
         plugin_author: str,

web/src/app/home/market/page.tsx

@@ -76,10 +76,12 @@ function MarketplaceContent() {
 
   // Register task completion callback for toast and plugin list refresh
   useEffect(() => {
-    const onComplete = (_taskId: number, success: boolean) => {
+    const onComplete = (_taskId: number, success: boolean, error?: string) => {
       if (success) {
         toast.success(t('plugins.installSuccess'));
         refreshPlugins();
+      } else {
+        toast.error(error || t('plugins.installFailed'));
       }
     };
     registerOnTaskComplete(onComplete);

web/src/app/home/plugins/components/plugin-install-task/PluginInstallTaskContext.tsx

@@ -45,7 +45,11 @@ export interface PluginInstallTask {
   currentAction: string; // raw backend action string
 }
 
-type OnTaskCompleteCallback = (taskId: number, success: boolean) => void;
+type OnTaskCompleteCallback = (
+  taskId: number,
+  success: boolean,
+  error?: string,
+) => void;
 
 interface PluginInstallTaskContextValue {
   tasks: PluginInstallTask[];
@@ -224,13 +228,16 @@ export function PluginInstallTaskProvider({
     onTaskCompleteCallbacks.current.delete(cb);
   }, []);
 
-  const notifyTaskComplete = useCallback((taskId: number, success: boolean) => {
+  const notifyTaskComplete = useCallback(
-    if (notifiedTaskIds.current.has(taskId)) return;
+    (taskId: number, success: boolean, error?: string) => {
-    notifiedTaskIds.current.add(taskId);
+      if (notifiedTaskIds.current.has(taskId)) return;
-    onTaskCompleteCallbacks.current.forEach((cb) => {
+      notifiedTaskIds.current.add(taskId);
-      cb(taskId, success);
+      onTaskCompleteCallbacks.current.forEach((cb) => {
-    });
+        cb(taskId, success, error);
-  }, []);
+      });
+    },
+    [],
+  );
 
   const pollTask = useCallback(
     (taskKey: string, taskId: number) => {
@@ -289,7 +296,7 @@ export function PluginInstallTaskProvider({
                   }
 
                   if (exception) {
-                    notifyTaskComplete(taskId, false);
+                    notifyTaskComplete(taskId, false, exception);
                     return {
                       ...t,
                       stage: InstallStage.ERROR,

web/src/app/home/plugins/page.tsx

@@ -167,11 +167,13 @@ function PluginListView() {
 
   // Register task completion callback for toast and plugin list refresh
   useEffect(() => {
-    const onComplete = (_taskId: number, success: boolean) => {
+    const onComplete = (_taskId: number, success: boolean, error?: string) => {
       if (success) {
         toast.success(t('plugins.installSuccess'));
         pluginInstalledRef.current?.refreshPluginList();
         refreshPlugins();
+      } else {
+        toast.error(error || t('plugins.installFailed'));
       }
     };
     registerOnTaskComplete(onComplete);