attune/work-summary/2026-03-09-workflow-cancellation-policy.md

Work Summary: Workflow Cancellation Policy

Date: 2026-03-09

Overview

Added configurable cancellation behavior for workflows. When a workflow is cancelled, the policy controls whether currently running tasks are allowed to finish (default) or are forcefully terminated via SIGTERM.

Changes

Backend (Rust)

crates/common/src/workflow/parser.rs

• Added CancellationPolicy enum with two variants: AllowFinish (default) and CancelRunning
• Added cancellation_policy field to WorkflowDefinition with #[serde(default, skip_serializing_if)] for backward compatibility
• Added 5 unit tests covering default behavior, explicit values, JSON round-trip, and deserialization of legacy definitions without the field

crates/common/src/workflow/mod.rs

• Re-exported CancellationPolicy from the workflow module

crates/api/src/routes/executions.rs

• Added resolve_cancellation_policy() helper that loads the workflow definition from DB and extracts the policy (falls back to AllowFinish on any failure)
• Refactored cancel_workflow_children() to resolve the policy and delegate to cancel_workflow_children_with_policy()
• cancel_workflow_children_with_policy() respects the policy:
  • AllowFinish: Only cancels pre-running children (Requested/Scheduling/Scheduled). Running children are left alone to complete naturally. advance_workflow sees the cancelled workflow_execution and stops dispatching new tasks.
  • CancelRunning: Cancels all children including running ones via SIGINT→SIGTERM→SIGKILL MQ messages to workers (previous hard-coded behavior).
• Policy is inherited through recursive cancellation of nested workflows

Frontend (TypeScript/React)

web/src/types/workflow.ts

• Added CancellationPolicy type and CANCELLATION_POLICY_LABELS constant
• Added cancellationPolicy field to WorkflowBuilderState
• Added cancellation_policy field to WorkflowYamlDefinition and WorkflowGraphDefinition
• Updated builderStateToDefinition() and builderStateToGraph() to include the field (omitted when default)
• Updated definitionToBuilderState() to read the field back

web/src/pages/actions/WorkflowBuilderPage.tsx

• Added cancellationPolicy to INITIAL_STATE
• Added a dropdown select in the metadata row for choosing the cancellation policy
• The setting persists into both the full definition and the raw YAML graph view

Design Decisions

• Default is AllowFinish: This is the safest behavior — running tasks complete naturally, preventing data corruption from interrupted operations.
• No migration needed: The field is stored inside the workflow_definition.definition JSONB column. #[serde(default)] handles existing definitions that lack the field.
• Policy inherited by nested workflows: When a parent workflow is cancelled, its cancellation policy propagates to all descendant workflows rather than each resolving its own.
• skip_serializing_if: The default value is omitted from serialized JSON to keep stored definitions compact and backward-compatible.

Testing

• 29/29 workflow parser tests pass (5 new)
• Zero warnings across entire Rust workspace
• Zero TypeScript errors