get end node support in builder and drafts

src/wf_artifacts/drafts/__init__.py

@@ -8,6 +8,7 @@ from .api import (
 from .models import (
     DraftChooseClause,
     DraftChooseStep,
+    DraftEndStep,
     DraftForeachStep,
     DraftInterruptStep,
     DraftJoinStep,
@@ -22,6 +23,7 @@ __all__ = [
     "DraftDiagnostic",
     "DraftChooseClause",
     "DraftChooseStep",
+    "DraftEndStep",
     "DraftForeachStep",
     "DraftInterruptStep",
     "DraftJoinStep",

src/wf_artifacts/drafts/adapter.py

@@ -7,6 +7,7 @@ from wf_core.paths import GraphSourcePath
 
 from .models import (
     DraftChooseStep,
+    DraftEndStep,
     DraftForeachStep,
     DraftInterruptStep,
     DraftJoinStep,
@@ -29,6 +30,7 @@ def build_workflow_from_draft(draft: WorkflowDraft) -> Workflow:
         input_schema=draft.input_schema,
         state_schema=draft.state_schema,
         output_schema=draft.output_schema,
+        outcomes=draft.outcomes,
     )
     step_refs = {
         step_id: _add_step(builder, step_id, step)
@@ -72,6 +74,8 @@ def _add_step(builder: WorkflowBuilder, step_id: str, step: DraftStep):
         node = JoinNode(id=step_id, type="join")
         builder.nodes.append(node)
         return node
+    if isinstance(step, DraftEndStep):
+        return builder.end(step.end.outcome, id=step_id)
     if isinstance(step, DraftWhenStep):
         return builder.when(
             step.when.if_,

src/wf_artifacts/drafts/models.py

@@ -20,6 +20,7 @@ STEP_KIND_KEYS = frozenset(
         "foreach",
         "interrupt",
         "join",
+        "end",
         "when",
         "choose",
         "match",
@@ -191,6 +192,26 @@ class DraftJoinStep(BaseModel):
     join: JsonObject = Field(default_factory=dict)
 
 
+class DraftEndPayload(BaseModel):
+    """Payload for one explicit workflow terminal outcome."""
+
+    model_config = ConfigDict(extra="forbid")
+
+    outcome: str = Field(default="ok", min_length=1)
+
+
+class DraftEndStep(BaseModel):
+    """Draft step that lowers to core `EndNode`.
+
+    Route to this step when the workflow should finish with a non-`ok` public
+    outcome. Routing directly to `__end__` remains the shorthand for `ok`.
+    """
+
+    model_config = ConfigDict(extra="forbid")
+
+    end: DraftEndPayload = Field(default_factory=DraftEndPayload)
+
+
 class DraftWhenPayload(BaseModel):
     """Payload for one boolean draft decision."""
 
@@ -267,6 +288,7 @@ DraftStep = (
     | DraftForeachStep
     | DraftInterruptStep
     | DraftJoinStep
+    | DraftEndStep
     | DraftWhenStep
     | DraftChooseStep
     | DraftMatchStep
@@ -285,6 +307,7 @@ class WorkflowDraft(BaseModel):
     input_schema: JsonObject
     state_schema: JsonObject
     output_schema: JsonObject
+    outcomes: list[str] = Field(default_factory=lambda: ["ok"], min_length=1)
     output: list[InputBinding] = Field(default_factory=list)
     start: str
     steps: dict[str, DraftStep]