feat: add safe artifact delete

src/wf_api/artifacts.py

@@ -276,6 +276,32 @@ class WorkflowArtifactApi:
         artifact = self._artifact_store().get_artifact(artifact_id, version)
         return artifact.model_dump(mode="json")
 
+    async def delete_artifact(
+        self, *, artifact_id: str, version: int
+    ) -> dict[str, Any]:
+        store = self._artifact_store()
+        blockers = store.deployments_for_artifact(artifact_id, version)
+        blocker_ids = [deployment.id for deployment in blockers]
+        if blocker_ids:
+            return {
+                "artifact_id": artifact_id,
+                "version": version,
+                "deleted": False,
+                "blocked_by_deployments": blocker_ids,
+            }
+        store.delete_artifact(artifact_id, version)
+        self.context.events.record_workflow_event(
+            "workflow_artifact_deleted",
+            capability_id=f"{artifact_id}@{version}",
+            payload={"artifact_id": artifact_id, "version": version},
+        )
+        return {
+            "artifact_id": artifact_id,
+            "version": version,
+            "deleted": True,
+            "blocked_by_deployments": [],
+        }
+
 
 def _suggested_self_bindings(required_sources: Sequence[str]) -> dict[str, str]:
     """Suggest local bindings for built-in sources that deploy to themselves."""

src/wf_api/service.py

@@ -95,6 +95,17 @@ class WorkflowApi:
             version=version,
         )
 
+    async def delete_artifact(
+        self,
+        *,
+        artifact_id: str,
+        version: int,
+    ) -> dict[str, Any]:
+        return await self.artifacts.delete_artifact(
+            artifact_id=artifact_id,
+            version=version,
+        )
+
     async def save_artifact(
         self,
         artifact: dict[str, Any],

src/wf_api/surface.py

@@ -137,6 +137,13 @@ class WorkflowArtifactSurface(Protocol):
         version: int,
     ) -> dict[str, Any]: ...
 
+    async def delete_artifact(
+        self,
+        *,
+        artifact_id: str,
+        version: int,
+    ) -> dict[str, Any]: ...
+
 
 class WorkflowDeploymentSurface(Protocol):
     """Deployment methods exposed by workflow frontends."""