Use plugin_util for workflow completion hook discovery

Replace manual hook registration with automatic discovery using
Galaxy's plugin_config.plugins_dict() framework. Hooks are now
discovered via their plugin_type class attribute.

lib/galaxy/workflow/completion_hooks/__init__.py

@@ -8,7 +8,10 @@ a workflow invocation completes.
 To add a new hook:
 1. Create a new module in this package
 2. Define a class that extends WorkflowCompletionHook
-3. Register it in WorkflowCompletionHookRegistry._load_hooks()
+3. Set a unique `plugin_type` class attribute
+4. Export the class via `__all__`
+
+Hooks are automatically discovered via the plugin_type attribute.
 """
 
 import logging
@@ -17,10 +20,10 @@ from typing import (
     TYPE_CHECKING,
 )
 
+import galaxy.workflow.completion_hooks
 from galaxy.structured_app import MinimalManagerApp
+from galaxy.util import plugin_config
 from galaxy.workflow.completion_hooks.base import WorkflowCompletionHook
-from galaxy.workflow.completion_hooks.export import ExportToFileSourceHook
-from galaxy.workflow.completion_hooks.notification import SendNotificationHook
 
 if TYPE_CHECKING:
     from galaxy.model import WorkflowInvocationCompletion
@@ -55,11 +58,8 @@ class WorkflowCompletionHookRegistry:
 
     def _load_hooks(self) -> None:
         """Load and instantiate all available hooks."""
-        # Register all available hooks
-        self.hooks = {
-            "export_to_file_source": ExportToFileSourceHook,
-            "send_notification": SendNotificationHook,
-        }
+        # Auto-discover hooks via plugin_type attribute
+        self.hooks = plugin_config.plugins_dict(galaxy.workflow.completion_hooks, "plugin_type")
 
         # Instantiate all hooks
         for hook_name, hook_class in self.hooks.items():

lib/galaxy/workflow/completion_hooks/base.py

@@ -26,7 +26,7 @@ class WorkflowCompletionHook(ABC):
 
     To implement a hook:
     1. Extend this class
-    2. Set a unique `name` attribute
+    2. Set a unique `plugin_type` attribute
     3. Implement the `execute()` method
     4. Optionally override `is_applicable()` to add conditions
 
@@ -34,8 +34,8 @@ class WorkflowCompletionHook(ABC):
     for the same completion (e.g., after a Celery task retry).
     """
 
-    # Unique identifier for this hook - must be set by subclasses
-    name: str = "base"
+    # Plugin type identifier for automatic discovery - must be set by subclasses
+    plugin_type: str
 
     def __init__(self, app: MinimalManagerApp):
         """

lib/galaxy/workflow/completion_hooks/export.py

@@ -6,6 +6,9 @@ file source (e.g., remote storage).
 """
 
 import logging
+
+__all__ = ("ExportToFileSourceHook",)
+
 from typing import (
     Any,
     Optional,
@@ -52,7 +55,7 @@ class ExportToFileSourceHook(WorkflowCompletionHook):
     }
     """
 
-    name = "export_to_file_source"
+    plugin_type = "export_to_file_source"
 
     def execute(self, completion: "WorkflowInvocationCompletion") -> None:
         """

lib/galaxy/workflow/completion_hooks/notification.py

@@ -5,6 +5,9 @@ This hook sends a notification to the user when their workflow completes.
 """
 
 import logging
+
+__all__ = ("SendNotificationHook",)
+
 from typing import TYPE_CHECKING
 
 from galaxy.schema.notifications import (
@@ -32,7 +35,7 @@ class SendNotificationHook(WorkflowCompletionHook):
     and a summary of job states.
     """
 
-    name = "send_notification"
+    plugin_type = "send_notification"
 
     def execute(self, completion: "WorkflowInvocationCompletion") -> None:
         """