feat(python): workflow context propagation quickstart

[nelson-parente]

Summary

• Adds a new Python quickstart demonstrating workflow history propagation (Dapr 1.18 feature)
• Ported from @cicoyle's canonical Go quickstart: dapr/quickstarts#1315 — same patient intake / e-prescribing scenario, same 3-level hierarchy, same workflow/activity names
• Builds on Python SDK history propagation support landed in dapr/python-sdk#1025 and runtime support in dapr/dapr#9810

Scenario

Patient intake / e-prescribing pipeline. A compliance audit and a pharmacy dispense step refuse to act unless the propagated history proves the required upstream checks (insurance, allergies, drug interactions) actually ran.

PatientIntake (root)
  └─ VerifyInsurance       (activity, no propagation)
  └─ PrescribeMedication   (child wf, PropagationScope.LINEAGE)
        └─ CheckAllergies         (activity, no propagation)
        └─ ScreenDrugInteractions (activity, no propagation)
        └─ ComplianceAudit        (grandchild wf, PropagationScope.LINEAGE)
        |      reads PatientIntake + PrescribeMedication events
        └─ DispenseMedication     (activity, PropagationScope.OWN_HISTORY)
               reads PrescribeMedication events only

ComplianceAudit uses LINEAGE to verify the full ancestor chain. DispenseMedication uses OWN_HISTORY as a trust boundary — the pharmacy step doesn't get to see the upstream patient-intake chain.

Python API used (from dapr/python-sdk#1025)

• PropagationScope.LINEAGE / PropagationScope.OWN_HISTORY
• propagation= kwarg on ctx.call_child_workflow() and ctx.call_activity()
• ctx.get_propagated_history() → PropagatedHistory | None
• PropagatedHistory.get_workflow_by_name(name) → WorkflowResult
• WorkflowResult.get_activity_by_name(name) → ActivityResult (with .completed, .output)
• PropagationNotFoundError

Replay safety

All print() calls inside workflows are guarded by if not ctx.is_replaying: so they only fire on the live execution, not on each durable replay.

Status — DRAFT

Pending before marking ready:

• Smoke-test against Dapr 1.18 RC once dapr-ext-workflow==1.18.0rc0 is available
• Confirm ctx.is_replaying is exposed as a property (not a method) in the Python SDK
• Confirm dapr.yaml resourcesPath: ../../components resolves correctly
• Add to CI matrix for Python quickstarts
• Wait for sibling Go quickstart dapr/quickstarts#1315 to merge

Test plan

• pip3 install -r requirements.txt with dapr-ext-workflow>=1.18.0rc0 available
• dapr run -f . against Dapr 1.18 RC sidecar
• ComplianceAudit reads correct ancestor history via LINEAGE (sees both PatientIntake + PrescribeMedication)
• DispenseMedication sees only PrescribeMedication events via OWN_HISTORY
• Older sidecar (pre-1.18) gracefully returns None from get_propagated_history() without crash

References

• Go quickstart this is ported from: dapr/quickstarts#1315 (@cicoyle)
• Proposal: dapr/proposals#102
• Runtime: dapr/dapr#9810
• Python SDK: dapr/python-sdk#1025
• Go SDK reference: dapr/go-sdk#823
• .NET sibling: dapr/quickstarts#1310
• 1.18 endgame: dapr/dapr#9856