feat: extract model runtime

Signed-off-by: -LAN- <laipz8200@outlook.com>

api/dify_graph/template_rendering.py

@@ -0,0 +1,39 @@
+from __future__ import annotations
+
+from collections.abc import Mapping
+from typing import Any, Protocol
+
+from dify_graph.nodes.code.code_node import WorkflowCodeExecutor
+from dify_graph.nodes.code.entities import CodeLanguage
+
+
+class TemplateRenderError(ValueError):
+    """Raised when rendering a template fails."""
+
+
+class Jinja2TemplateRenderer(Protocol):
+    """Shared contract for rendering Jinja2 templates in graph nodes."""
+
+    def render_template(self, template: str, variables: Mapping[str, Any]) -> str: ...
+
+
+class CodeExecutorJinja2TemplateRenderer(Jinja2TemplateRenderer):
+    """Adapter that renders Jinja2 templates via the workflow code executor."""
+
+    _code_executor: WorkflowCodeExecutor
+
+    def __init__(self, code_executor: WorkflowCodeExecutor) -> None:
+        self._code_executor = code_executor
+
+    def render_template(self, template: str, variables: Mapping[str, Any]) -> str:
+        try:
+            result = self._code_executor.execute(language=CodeLanguage.JINJA2, code=template, inputs=variables)
+        except Exception as exc:
+            if self._code_executor.is_execution_error(exc):
+                raise TemplateRenderError(str(exc)) from exc
+            raise
+
+        rendered = result.get("result")
+        if not isinstance(rendered, str):
+            raise TemplateRenderError("Template render result must be a string.")
+        return rendered