Add support for workflow history propagation

[cicoyle]

Background

Dapr Workflows now supports propagating execution history from a parent workflow to its child workflows and activities. This lets downstream code inspect what happened upstream — useful for chain-of-custody verification, fraud detection, audit, and AI-agent context flow.

Two scopes are exposed:

• PropagateLineage — caller's own events plus the full ancestor chain
• PropagateOwnHistory — caller's events only (a trust boundary; ancestors are dropped)

The Go path is implemented end-to-end. To use this feature from a Python app, this SDK needs the matching API.

Proto surface

From dapr/durabletask-protobuf (PR #38):

• history_events.proto
  • TaskScheduledEvent.historyPropagationScope (optional, field 7)
  • ChildWorkflowInstanceCreatedEvent.historyPropagationScope (optional, field 7)
  • new PropagatedHistory { repeated HistoryEvent events; HistoryPropagationScope scope; repeated PropagatedHistoryChunk chunks; }
  • new PropagatedHistoryChunk { string appId; int32 startEventIndex; int32 eventCount; string instanceId; string workflowName; }
• orchestration.proto
  • new HistoryPropagationScope enum: HISTORY_PROPAGATION_SCOPE_NONE = 0, HISTORY_PROPAGATION_SCOPE_OWN_HISTORY = 1, HISTORY_PROPAGATION_SCOPE_LINEAGE = 2
• orchestrator_actions.proto
  • ScheduleTaskAction.historyPropagationScope (optional, field 6)
  • CreateChildWorkflowAction.historyPropagationScope (optional, field 6)

What needs to happen here

1. Proto regen + plumbing

• Pull the updated .proto files from dapr/durabletask-protobuf and regenerate the Python protobuf classes
• Plumb the new historyPropagationScope field through the schedule-task / create-child-workflow code paths
• Surface the received PropagatedHistory to the workflow runtime so it can be handed to user code

2. User-facing API to add

Schedule-side (parent workflow author):

• with_history_propagation(scope) keyword/option on call_activity / call_child_workflow
• propagate_lineage() and propagate_own_history() helper functions returning a scope value (or expose the enum directly as HistoryPropagationScope.LINEAGE / HistoryPropagationScope.OWN_HISTORY)

Receive-side (child workflow / activity author):

• get_propagated_history() returning Optional[PropagatedHistory] on both workflow and activity contexts
• PropagatedHistory dataclass with:
  • events — list of HistoryEvent
  • scope — the scope enum value
  • workflows — chunks (each with app_id, workflow_name, instance_id, start_event_index, event_count)
  • app_ids — deduplicated list of app IDs in the chain
  • convenience filters: get_workflow_by_name(name), get_events_by_app_id(app_id), get_events_by_instance_id(id), get_events_by_workflow_name(name)
  • raises PropagationNotFoundError (or returns None) for missing names

3. Example to add

examples/workflow_history_propagation/ mirroring the Go demo: a 3-tier payment workflow (parent → activity → child workflow with propagate_lineage → activity with propagate_own_history). Standalone dapr run mode at minimum; K8s + signing variant a stretch.

4. Tests

At least one test per scope:

• Lineage: parent → child receives parent's events
• OwnHistory: parent → child receives caller's events but NOT grandparent's

References

• dapr/dapr runtime PR: wf history ctx propagation dapr#9810
• dapr/durabletask-go PR: wf history ctx propagation durabletask-go#85
• dapr/durabletask-protobuf PR: wf history context propagation protos durabletask-protobuf#38
• dapr/go-sdk reference implementation: Feature workflow history propagation go-sdk#823
• Go SDK example: examples/workflow-history-propagation/