move / dedup some wf_mcp things

src/wf_api/__init__.py

@@ -1,6 +1,25 @@
 from __future__ import annotations
 
 from .backend import TraceRange, WorkflowApiBackend
+from .constants import (
+    DEFAULT_CALL_STEP_ID,
+    DEFAULT_ERROR_OUTCOME,
+    DEFAULT_ERROR_STEP_ID,
+    DEFAULT_OK_OUTCOME,
+    RUNTIME_ERROR_CAPABILITY,
+)
+from .refs import WorkflowSurfaceCapabilityId, parse_workflow_surface_capability_id
 from .service import WorkflowApi
 
-__all__ = ["TraceRange", "WorkflowApi", "WorkflowApiBackend"]
+__all__ = [
+    "DEFAULT_CALL_STEP_ID",
+    "DEFAULT_ERROR_OUTCOME",
+    "DEFAULT_ERROR_STEP_ID",
+    "DEFAULT_OK_OUTCOME",
+    "RUNTIME_ERROR_CAPABILITY",
+    "TraceRange",
+    "WorkflowApi",
+    "WorkflowApiBackend",
+    "WorkflowSurfaceCapabilityId",
+    "parse_workflow_surface_capability_id",
+]