Implement debug_mode for email delivery (vibe-kanban f32190a0)

The EmailDeliveryConfig in api/core/workflow/nodes/human\_input/entities.py has a field `debug_mode`. When this field is set to `True` in `node_data`, the test run (InvokeFrom.DEBUGGER) and the delivery test should only sent test emails to the current user, instead of sending to the specified recipients.

Please implement this logic, write correspond test cases to ensure that the logic works as expected.

api/core/workflow/nodes/human_input/entities.py

@@ -62,6 +62,14 @@ class EmailDeliveryConfig(BaseModel):
     # Body is the content of email, it may contain the speical placeholder `{{#url#}}`, which
     # represent the url to submit the form.
     body: str
+    debug_mode: bool = False
+
+    def with_debug_recipient(self, user_id: str) -> "EmailDeliveryConfig":
+        if not user_id:
+            debug_recipients = EmailRecipients(whole_workspace=False, items=[])
+            return self.model_copy(update={"recipients": debug_recipients})
+        debug_recipients = EmailRecipients(whole_workspace=False, items=[MemberRecipient(user_id=user_id)])
+        return self.model_copy(update={"recipients": debug_recipients})
 
     @classmethod
     def replace_url_placeholder(cls, body: str, url: str | None) -> str:
@@ -98,6 +106,22 @@ class EmailDeliveryMethod(_DeliveryMethodBase):
 DeliveryChannelConfig = Annotated[WebAppDeliveryMethod | EmailDeliveryMethod, Field(discriminator="type")]
 
 
+def apply_debug_email_recipient(
+    method: DeliveryChannelConfig,
+    *,
+    enabled: bool,
+    user_id: str,
+) -> DeliveryChannelConfig:
+    if not enabled:
+        return method
+    if not isinstance(method, EmailDeliveryMethod):
+        return method
+    if not method.config.debug_mode:
+        return method
+    debug_config = method.config.with_debug_recipient(user_id or "")
+    return method.model_copy(update={"config": debug_config})
+
+
 class FormInputPlaceholder(BaseModel):
     """Placeholder configuration for form inputs."""
 

api/core/workflow/nodes/human_input/human_input_node.py

@@ -20,7 +20,7 @@ from core.workflow.workflow_type_encoder import WorkflowRuntimeTypeConverter
 from extensions.ext_database import db
 from libs.datetime_utils import naive_utc_now
 
-from .entities import DeliveryChannelConfig, HumanInputNodeData
+from .entities import DeliveryChannelConfig, HumanInputNodeData, apply_debug_email_recipient
 from .enums import DeliveryMethodType, HumanInputFormStatus, PlaceholderType
 
 if TYPE_CHECKING:
@@ -169,8 +169,15 @@ class HumanInputNode(Node[HumanInputNodeData]):
     def _effective_delivery_methods(self) -> Sequence[DeliveryChannelConfig]:
         enabled_methods = [method for method in self._node_data.delivery_methods if method.enabled]
         if self.invoke_from in {InvokeFrom.DEBUGGER, InvokeFrom.EXPLORE}:
-            return [method for method in enabled_methods if method.type != DeliveryMethodType.WEBAPP]
-        return enabled_methods
+            enabled_methods = [method for method in enabled_methods if method.type != DeliveryMethodType.WEBAPP]
+        return [
+            apply_debug_email_recipient(
+                method,
+                enabled=self.invoke_from == InvokeFrom.DEBUGGER,
+                user_id=self.user_id or "",
+            )
+            for method in enabled_methods
+        ]
 
     def _human_input_required_event(self, form_entity: HumanInputFormEntity) -> HumanInputRequired:
         node_data = self._node_data