## What & why
Second sub-slice of **S-12 (#13)** — the **Workflow Client gains behandelaar user-task operations**, and the process model gains the beoordeling step.
- **BPMN:** `registratie.bpmn` now parks at a `Beoordelen` **userTask** (candidate group `behandelaar`) after `OpenZaakAanmaken`; `registrationId` rides along as a process variable so the werkbak can correlate each task to its aggregate.
- **Workflow Client** (`IUserTaskClient`, the only code that talks to Flowable §8.2):
- `GetOpenBeoordelingenAsync()` — the werkbak (open `Beoordelen` tasks + their `registrationId`)
- `ClaimAsync(taskId, behandelaar)`
- `CompleteBeoordelingAsync(taskId, besluit)` — carries the decision into the process as the `besluit` variable
- **Live integration:** `verify-domain` now drives the full user-task lifecycle against a real Flowable — after the worker opens the zaak, it polls for the task, claims it as `merel-behandelaar`, completes it (`goedkeuren`), and asserts the process finishes. This proves the exact REST contract (`service/runtime/tasks/query` + `…/{id}` claim/complete) the client depends on.
The walking skeleton is unaffected: the temporary `/approve` path still sets the zaak status directly; wiring the domain decision to *complete this task* (and driving the werkbak from the BFF) lands in **S-12c**.
## Definition of Done
- [x] Linked issue: #13 (umbrella; `refs`, does not close)
- [x] Tests first; red → green
- [x] Unit + acceptance green (`make unit`): domain 76, acceptance 9 (acl/event-subscriber/bff unaffected)
- [x] Mutation ≥ break(90): **domain 100%** (killed the new survivors *and* the pre-existing `FlowableWorkflowClient` baseline)
- [x] Live Flowable user-task lifecycle asserted in `verify-domain`
- [ ] CI green (pending)
Part of #13.
Reviewed-on: #83
Stryker.NET config for the domain service (break 90, the repo's ratchet floor),
excluding the OpenZaakJobPump hosted-shell from mutation. Hardened the unit tests
to kill survivors — Basic-credential value, variable types, null/failure response
paths, option defaults, guard clauses, save counts and log output — leaving only
two documented equivalent mutants (Stryker-disabled). make mutation runs the domain
ratchet and CI uploads its report alongside the others.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Failing infrastructure unit tests (stub HttpMessageHandler, fakes):
- FlowableWorkflowClient starts a process with the registrationId variable and
returns the instance id; acquires OpenZaakAanmaken jobs (topic/workerId/lock)
and parses their registrationId; completes a job with the zaakUrl variable —
request URIs match flowable-rest's service/ and external-job-api/ paths.
- AclHttpClient POSTs the bsn to the ACL and returns the zaak URL.
- InMemoryRegistrationStore saves/reads/upserts by id.
- OpenZaakJobProcessor acquires, opens a zaak, completes the job; leaves a failing
job uncompleted for redelivery; polls harmlessly when idle.
Adapters are stubs so the tests compile and fail on their assertions; the green
commit implements them against the REST contract verified on a live Flowable.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
