Control Abandoned Child Workflow Cancellation

[roxblnfk]

What was changed

• Added new feature flag FeatureFlags::$cancelAbandonedChildWorkflows in src/Worker/FeatureFlags.php
• Modified ChildWorkflowStub.php to check the feature flag when determining if child workflows should be cancellable
• Updated test configuration in RuntimeBuilder.php to use the new feature flag
• Added comprehensive test coverage in CancelAbandonTest.php with multiple scenarios

Why?

Previously, when a parent workflow was canceled, all child workflows would be canceled, including those with ParentClosePolicy::Abandon. This behavior was incorrect according to Temporal semantics - abandoned child workflows should continue running independently when their parent is canceled.

The feature flag provides:

1. Backward compatibility - defaults to true to maintain existing behavior
2. Gradual migration - allows users to opt into the correct behavior by setting the flag to false
3. Future-proofing - enables changing the default behavior in a future major version

This change ensures that abandoned child workflows behave correctly while allowing existing workflows to continue functioning without breaking changes.

Checklist

1. Closes [Bug] Abandoned Child Workflows Cancellation policy #634
2. How was this tested:

• added acceptance tests

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Project	Deployment	Preview	Comments	Updated (UTC)
php	Ready	Preview	Comment	Aug 26, 2025 6:56am