feat: add draft step capability helper

src/wf_mcp/workflow_surface/models.py

@@ -265,6 +265,39 @@ class BindOutputToStateRequest(BaseModel):
     )
 
 
+class AddStepFromCapabilityRequest(BaseModel):
+    """Typed MCP request for adding one capability-backed draft step with wiring."""
+
+    workspace_id: WorkspaceId
+    revision: int = Field(ge=1, description="Expected workspace revision.")
+    step_id: str = Field(description="New draft step id.")
+    capability_name: str = Field(description="Qualified capability name.")
+    route_from_step: str | None = Field(
+        default=None,
+        description="Optional existing step whose outcome should route to the new step.",
+    )
+    route_from_outcome: str = Field(
+        default="ok",
+        description="Outcome on route_from_step that should route to the new step.",
+    )
+    route_outcome: str = Field(
+        default="ok",
+        description="Outcome emitted by the new step.",
+    )
+    route_to: str = Field(
+        default="__end__",
+        description="Target step id or __end__ for the new step outcome.",
+    )
+    input_map: dict[str, str] = Field(
+        default_factory=dict,
+        description="Graph source path to node-local target field.",
+    )
+    bind_outputs: dict[str, str] = Field(
+        default_factory=dict,
+        description="Node-local output field to state path with schema projection.",
+    )
+
+
 class DeleteDraftWorkspaceRequest(BaseModel):
     """Typed MCP request payload for deleting one draft workspace."""
 

src/wf_mcp/workflow_surface/tools.py

@@ -13,6 +13,7 @@ from wf_mcp.broker.service.workflow_operation_context import context_from_servic
 
 from .models import (
     AddStateFromOutputRequest,
+    AddStepFromCapabilityRequest,
     BindOutputToStateRequest,
     CallCapabilityResult,
     CreateArtifactFromWorkspaceRequest,
@@ -483,6 +484,32 @@ def register_workflow_tools(server: FastMCP[Any], service: WfMcpService) -> None
             )
         )
 
+    @server.tool(
+        name="wf.workflow.add_step_from_capability",
+        title="Add Step From Capability",
+        description=(
+            "Add one capability-backed draft step with explicit route, input, "
+            "and output-to-state binding hints."
+        ),
+    )
+    async def add_step_from_capability(
+        request: AddStepFromCapabilityRequest,
+    ) -> DraftWorkspaceResult:
+        return DraftWorkspaceResult.model_validate(
+            await handlers.add_step_from_capability(
+                workspace_id=request.workspace_id,
+                revision=request.revision,
+                step_id=request.step_id,
+                capability_name=request.capability_name,
+                route_from_step=request.route_from_step,
+                route_from_outcome=request.route_from_outcome,
+                route_outcome=request.route_outcome,
+                route_to=request.route_to,
+                input_map=request.input_map,
+                bind_outputs=request.bind_outputs,
+            )
+        )
+
     @server.tool(
         name="wf.workflow.create_minimal_draft_workspace",
         title="Create Minimal Draft Workspace",