Saga compensations

Work in progress. Saga compensations are implemented in the native engine. CI targets lower steps to native jobs; compensation on CI is a follow-up. APIs may change.

When a run ends in failure, the engine automatically runs compensation operations for succeeded steps that declared one, in reverse completion order. A compensation undoes a step's side effects — rollback a deploy, delete a created resource, send a cancellation notice.

Inspired by the Temporal saga pattern, but deliberately simpler: no compensation transactions, no forward recovery, no per-branch scoping — just ordered rollback of completed work.

Declaring a compensationCopy Anchor Link

import { Project, Pipeline, ShellStep, Entry } from "@sverka/workflow";

const proj = new Project("myproj");
const p = new Pipeline(proj, "ci");

new ShellStep(p, "deploy", {
  command: "kubectl apply -f deploy.yaml",
  compensation: {
    kind: "shell",
    command: "kubectl rollout undo deployment/my-app",
  },
});

new ShellStep(p, "notify", {
  command: "curl -X POST $WEBHOOK_URL",
  dependsOn: ["deploy"],
});

new Entry(p, "on-push", { trigger: { kind: "push" }, roots: ["notify"] });

How it worksCopy Anchor Link

1. The engine tracks the order steps succeed during a run.
2. If the run ends in failure (not cancelled), the engine walks the completion list backwards and executes each step's compensation.
3. Compensations run serially via the step's own runtime driver in the step's workspace.
4. A failed compensation emits a warn diagnostic but does not block subsequent compensations — best-effort rollback.
5. If cancel() fires during the compensation phase, remaining compensations are skipped (the abort signal is checked before each compensation).

EventsCopy Anchor Link

Limitations (v1)Copy Anchor Link

• Shell only. Compensation operations must be kind: "shell". Other kinds raise a synthesis error.
• No retries. A compensation runs once. If it needs retry, the command itself implements it.
• No cancellation compensation. Cancelled runs do not trigger compensations — cancellation is intentional.
• No branch scoping. v1 compensates ALL succeeded steps with a declared compensation, in reverse completion order.
• No CI equivalent yet. Compiled workflows lower steps to target-native constructs; if: failure()-style compensation lowering is a follow-up.