feat(workflow): workflow as tool output schema (#26241)

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
Co-authored-by: crazywoola <100913391+crazywoola@users.noreply.github.com>
Co-authored-by: Novice <novice12185727@gmail.com>

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

@@ -5,7 +5,7 @@ from collections.abc import Sequence
 from enum import StrEnum
 from typing import Any, Union
 
-from pydantic import BaseModel, model_validator
+from pydantic import BaseModel, field_validator, model_validator
 
 from core.workflow.enums import ErrorStrategy
 
@@ -35,6 +35,45 @@ class VariableSelector(BaseModel):
     value_selector: Sequence[str]
 
 
+class OutputVariableType(StrEnum):
+    STRING = "string"
+    NUMBER = "number"
+    INTEGER = "integer"
+    SECRET = "secret"
+    BOOLEAN = "boolean"
+    OBJECT = "object"
+    FILE = "file"
+    ARRAY = "array"
+    ARRAY_STRING = "array[string]"
+    ARRAY_NUMBER = "array[number]"
+    ARRAY_OBJECT = "array[object]"
+    ARRAY_BOOLEAN = "array[boolean]"
+    ARRAY_FILE = "array[file]"
+    ANY = "any"
+    ARRAY_ANY = "array[any]"
+
+
+class OutputVariableEntity(BaseModel):
+    """
+    Output Variable Entity.
+    """
+
+    variable: str
+    value_type: OutputVariableType
+    value_selector: Sequence[str]
+
+    @field_validator("value_type", mode="before")
+    @classmethod
+    def normalize_value_type(cls, v: Any) -> Any:
+        """
+        Normalize value_type to handle case-insensitive array types.
+        Converts 'Array[...]' to 'array[...]' for backward compatibility.
+        """
+        if isinstance(v, str) and v.startswith("Array["):
+            return v.lower()
+        return v
+
+
 class DefaultValueType(StrEnum):
     STRING = "string"
     NUMBER = "number"

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

@@ -1,7 +1,6 @@
 from pydantic import BaseModel, Field
 
-from core.workflow.nodes.base import BaseNodeData
-from core.workflow.nodes.base.entities import VariableSelector
+from core.workflow.nodes.base.entities import BaseNodeData, OutputVariableEntity
 
 
 class EndNodeData(BaseNodeData):
@@ -9,7 +8,7 @@ class EndNodeData(BaseNodeData):
     END Node Data.
     """
 
-    outputs: list[VariableSelector]
+    outputs: list[OutputVariableEntity]
 
 
 class EndStreamParam(BaseModel):