Update signature status for hatchet workflow lifecycle

[yedidyakfir]

Summary

Currently the SignatureStatus is updated at the individual task level via SignatureLifecycle.start_task (libs/mageflow/mageflow/lifecycle/signature.py:25-29), which sets the signature to ACTIVE when a task begins executing. However, when a MageflowWorkflow is dispatched with with_signature support (see related #116), the workflow itself has no hook to transition the attached signature's status as the workflow progresses.

This issue tracks adding status updates for hatchet workflow-level signatures — in particular, marking the signature as ACTIVE when the workflow starts running, and ensuring terminal transitions (DONE / FAILED) are handled at workflow completion when the signature is attached at the workflow level rather than per-task.

Features / Details

• Transition signature to SignatureStatus.ACTIVE when a MageflowWorkflow run begins (not only when an inner task begins)
• Transition signature to DONE / FAILED / INTERRUPTED based on the workflow's terminal state when the signature is workflow-level
• Respect existing should_run / is_done / is_canceled guards on TaskStatus so retried or already-completed workflows do not double-transition
• Integrate with the existing MageWorkflow success/failure hooks (libs/mageflow/mageflow/clients/hatchet/workflow.py:29-95) so workflow-level signature updates reuse the same lifecycle machinery as task-level updates
• Must be compatible with workflow-level with_signature (Support with_signature for hatchet workflow requests #116) — the signature carried on the workflow input is the one whose status is updated

Use Cases

• Observability: a caller that dispatched a workflow with a signature can observe the signature transitioning PENDING → ACTIVE → DONE/FAILED without needing to inspect individual inner tasks
• Cancellation / suspension: workflow runners can honor CANCELED / SUSPENDED states set externally before the workflow begins real work
• Idempotency: re-runs of an already DONE workflow signature skip side effects (consistent with existing is_done checks used in task_success / task_failed)

Implementation Considerations

• MageflowWorkflow._serialize_input (libs/mageflow/mageflow/clients/hatchet/workflow.py:109-122) is the natural place to ensure the signature data is carried into the workflow input so a workflow-start hook can resolve and update it
• A workflow-level analogue of SignatureLifecycle.start_task is likely needed — either a dedicated WorkflowSignatureLifecycle or an extension of SignatureLifecycle that knows the unit of work is a workflow
• The existing MageWorkflow.inject_hooks / on_success_task / on_failure_task wrappers already create a TaskSignature.ClientAdapter lifecycle per task; a parallel path is needed for the workflow-level signature (likely a first-task "start" hook or use of hatchet on_start if available, plus the existing success/failure hooks)
• Must not regress the current task-level lifecycle behavior or the idempotency fixes recently landed (070f2d4, f58d2b3, 893d8ac)
• Add / extend the idempotency tests under libs/mageflow/tests/unit/idempotency/ to cover workflow-level signature transitions

Tasks

• Design where the workflow-start hook lives (new lifecycle class vs. extension of SignatureLifecycle)
• Implement workflow-start status transition (PENDING → ACTIVE) for MageflowWorkflow
• Implement workflow-terminal status transitions (DONE / FAILED) for workflow-level signatures
• Guard transitions with should_run / is_done to preserve idempotency on retries
• Wire workflow-level lifecycle into MageWorkflow alongside the existing task-level hooks
• Add unit tests for workflow-level signature status transitions
• Add integration test: dispatch a MageflowWorkflow with a signature and assert PENDING → ACTIVE → DONE
• Add idempotency test: re-running a DONE workflow signature does not re-trigger callbacks
• Update docs / examples if workflow-level signature status is user-visible

Related

• Depends on / relates to Support with_signature for hatchet workflow requests #116 (workflow-level with_signature support)