feat(workflow): document-wait task + 30-day timeout cancellation (S-10a, closes #102) (#105)

## What & why

S-10a, the **workflow/timeout spine** of the (split) document-upload slice: the registratie process
now parks at a **`WachtOpDocumenten`** user task with an **interrupting `P30D` boundary timer**. When
the documents arrive the task completes and the process continues into the diploma routing (S-13) →
Beoordelen; if the 30 days lapse, the timer cancels the wait, runs a `RegistratieVerlopen`
external-worker task, and the domain expires the aggregate to a new terminal status **`Verlopen`**.
Backend only — the real upload trigger (portal → BFF → ACL → Documenten API) is S-10b (#103).

Closes #102

Mechanism recorded in **ADR-0017**; opened as proposal #104. Mirrors the S-14 escalation
(boundary-timer + external-worker) and S-11 withdrawal (interrupting cancel) patterns.

## Definition of Done

- [x] Linked Gitea issue (above).
- [x] Failing test committed before the implementation (red→green pairs per layer).
- [x] Implementation makes the test pass.
- [x] Conventional Commits referencing the issue (`refs #102`).
- [ ] CI green — all Gitea Actions jobs (pending on this PR).
- [x] `docker compose up` health unaffected (no new services; deploy path unchanged).
- [x] Docs updated (ADR-0017, demo-script, BACKLOG split).
- [x] ADR added (`docs/architecture/adr-0017-document-wait-timeout-cancellation.md`).
- [x] Demo note in `docs/demo-script.md`.

## Notes for reviewers

- **Domain** (`Registration.Expire()` + `Verlopen`), **application** (`ExpireRegistrationWorker`),
  **infra** (`RegistratieVerlopenProcessor`/`Pump`, `IRegistratieVerlopenClient`, Flowable
  acquire/complete + `CompleteDocumentWaitAsync`) — the timeout counterpart to the OpenZaak/escalation
  worker trios; idempotent per §8.6.
- **BPMN** verified live against a `flowable-rest` probe: complete `WachtOpDocumenten` → routes to
  Beoordelen; fire the P30D timer → `RegistratieVerlopen` job (carrying `registrationId`) + the wait
  task cancelled. `verify-domain` exercises both branches in-stack (completes the wait in every existing
  block; fires the timer and asserts `Verlopen` in a new block).
- **Scope boundary:** on expiry the aggregate goes `Verlopen` and the process ends, but the ZGW *zaak*
  is not yet set to a cancellation status — that needs a new ACL method + statustype seeding and is
  folded into S-10b (noted in ADR-0017).
- `CompleteDocumentWaitAsync` is built and HTTP-tested here but not yet called from a domain endpoint;
  S-10b wires the upload trigger to it.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Reviewed-on: #105

services/domain/Big.Infrastructure/FlowableWorkflowClient.cs

@@ -15,12 +15,14 @@ namespace Big.Infrastructure;
 /// The REST contract here is the one verified against a live flowable-rest engine (ADR-0009).
 /// </summary>
 public sealed class FlowableWorkflowClient(HttpClient http, FlowableOptions options)
-    : IWorkflowClient, IExternalWorkerClient, IUserTaskClient, IBeoordelingEscalatieClient
+    : IWorkflowClient, IExternalWorkerClient, IUserTaskClient, IBeoordelingEscalatieClient, IRegistratieVerlopenClient
 {
     private const string Topic = "OpenZaakAanmaken";
     private const string EscalatieTopic = "BeoordelingEscaleren";
+    private const string VerlopenTopic = "RegistratieVerlopen";
     private const string ProcessDefinitionKey = "registratie";
     private const string BeoordelenTaskKey = "Beoordelen";
+    private const string WachtOpDocumentenTaskKey = "WachtOpDocumenten";
     private const string BehandelaarGroup = "behandelaar";
     private const string TeamleadGroup = "teamlead";
     private const string RegistrationIdVariable = "registrationId";
@@ -114,6 +116,25 @@ public sealed class FlowableWorkflowClient(HttpClient http, FlowableOptions opti
         response.EnsureSuccessStatusCode();
     }
 
+    public async Task CompleteDocumentWaitAsync(string processInstanceId, CancellationToken ct = default)
+    {
+        // Find the still-open WachtOpDocumenten task in this instance and complete it, so the process
+        // leaves the 30-day wait and continues to beoordeling (S-10a, ADR-0017). If the instance is no
+        // longer parked there (already continued, or the timer already cancelled it) this is a
+        // best-effort no-op — mirroring the withdrawal/escalation correlation (§8.6).
+        var query = new TaskByInstanceQueryRequest(processInstanceId, WachtOpDocumentenTaskKey);
+        var page = await PostAsync<TaskByInstanceQueryRequest, TaskQueryResult>(
+            "service/query/tasks", query, ct);
+
+        var task = page?.Data?.FirstOrDefault();
+        if (task is null)
+            return;
+
+        using var response = await SendAsync(
+            $"service/runtime/tasks/{task.Id}", new CompleteTaskRequest("complete", []), ct);
+        response.EnsureSuccessStatusCode();
+    }
+
     public async Task<IReadOnlyList<EscalatieJob>> AcquireBeoordelingEscalatieJobsAsync(int maxJobs, CancellationToken ct = default)
     {
         var request = new AcquireJobsRequest(EscalatieTopic, options.LockDuration, maxJobs, options.WorkerId);
@@ -155,6 +176,23 @@ public sealed class FlowableWorkflowClient(HttpClient http, FlowableOptions opti
         response.EnsureSuccessStatusCode();
     }
 
+    public async Task<IReadOnlyList<RegistratieVerlopenJob>> AcquireRegistratieVerlopenJobsAsync(int maxJobs, CancellationToken ct = default)
+    {
+        var request = new AcquireJobsRequest(VerlopenTopic, options.LockDuration, maxJobs, options.WorkerId);
+
+        var jobs = await PostAsync<AcquireJobsRequest, List<AcquiredJob>>(
+            "external-job-api/acquire/jobs", request, ct) ?? [];
+
+        return [.. jobs.Select(job => new RegistratieVerlopenJob(job.Id, RegistrationId.Parse(job.RegistrationId())))];
+    }
+
+    public async Task CompleteRegistratieVerlopenJobAsync(string jobId, CancellationToken ct = default)
+    {
+        using var response = await SendAsync(
+            $"external-job-api/acquire/jobs/{jobId}/complete", new CompleteJobRequest(options.WorkerId, []), ct);
+        response.EnsureSuccessStatusCode();
+    }
+
     private async Task<TResponse?> GetAsync<TResponse>(string path, CancellationToken ct)
     {
         var message = new HttpRequestMessage(HttpMethod.Get, new Uri(options.BaseUrl, path));

services/domain/Big.Infrastructure/IExternalWorkerClient.cs

@@ -36,3 +36,19 @@ public interface IBeoordelingEscalatieClient
     /// <summary>Complete an acquired escalation job so its token reaches the escalation end event.</summary>
     Task CompleteBeoordelingEscalatieJobAsync(string jobId, CancellationToken ct = default);
 }
+
+/// <summary>
+/// The document-timeout side of the Workflow Client (S-10a): the <c>RegistratieVerlopen</c>
+/// external-worker jobs parked by the 30-day boundary timer on <c>WachtOpDocumenten</c>. Kept separate
+/// from the other worker ports (interface segregation) so neither the OpenZaak nor escalation worker
+/// sees expiry. Implemented by <see cref="FlowableWorkflowClient"/> — the only code that talks to
+/// Flowable (§8.2, ADR-0017).
+/// </summary>
+public interface IRegistratieVerlopenClient
+{
+    /// <summary>Acquire and lock up to <paramref name="maxJobs"/> <c>RegistratieVerlopen</c> jobs.</summary>
+    Task<IReadOnlyList<RegistratieVerlopenJob>> AcquireRegistratieVerlopenJobsAsync(int maxJobs, CancellationToken ct = default);
+
+    /// <summary>Complete an acquired expiry job so its token reaches the <c>endVerlopen</c> end event.</summary>
+    Task CompleteRegistratieVerlopenJobAsync(string jobId, CancellationToken ct = default);
+}

services/domain/Big.Infrastructure/RegistratieVerlopenProcessor.cs

@@ -0,0 +1,41 @@
+using Big.Application;
+using Microsoft.Extensions.Logging;
+
+namespace Big.Infrastructure;
+
+/// <summary>
+/// One poll tick of the document-timeout worker (S-10a, ADR-0017): acquire the parked
+/// <c>RegistratieVerlopen</c> jobs — the tokens the 30-day boundary timer on <c>WachtOpDocumenten</c>
+/// spawns — expire each correlated registration via the <see cref="ExpireRegistrationWorker"/>, and
+/// complete the job so its token reaches <c>endVerlopen</c>. A job that fails is logged and left
+/// un-completed so Flowable redelivers it (§8.6). Split out from the hosted pump so the
+/// acquire→expire→complete logic is unit-testable without a running host. Mirrors
+/// <see cref="OpenZaakJobProcessor"/> and <see cref="BeoordelingEscalatieProcessor"/>.
+/// </summary>
+public sealed class RegistratieVerlopenProcessor(
+    IRegistratieVerlopenClient client,
+    ExpireRegistrationWorker worker,
+    ILogger<RegistratieVerlopenProcessor> logger)
+{
+    /// <summary>Acquire and process up to <paramref name="maxJobs"/> jobs. Returns the number acquired.</summary>
+    public async Task<int> PumpOnceAsync(int maxJobs, CancellationToken ct = default)
+    {
+        var jobs = await client.AcquireRegistratieVerlopenJobsAsync(maxJobs, ct);
+
+        foreach (var job in jobs)
+        {
+            try
+            {
+                await worker.HandleAsync(job, ct);
+                await client.CompleteRegistratieVerlopenJobAsync(job.JobId, ct);
+            }
+            catch (Exception ex)
+            {
+                // Leave the job un-completed: its lock expires and Flowable redelivers it (§8.6).
+                logger.LogError(ex, "RegistratieVerlopen job {JobId} failed; leaving it for redelivery.", job.JobId);
+            }
+        }
+
+        return jobs.Count;
+    }
+}

services/domain/Big.Infrastructure/RegistratieVerlopenPump.cs

@@ -0,0 +1,49 @@
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Logging;
+
+namespace Big.Infrastructure;
+
+/// <summary>
+/// The hosted polling loop of the document-timeout worker (S-10a, ADR-0017): on an interval it
+/// resolves a scoped <see cref="RegistratieVerlopenProcessor"/> and asks it to drain the parked
+/// <c>RegistratieVerlopen</c> jobs. A deliberately thin shell — all acquire/expire/complete logic
+/// lives in the processor, which is unit-tested; this class only owns the timer, the per-tick scope,
+/// and loop resilience. Structurally identical to <see cref="BeoordelingEscalatiePump"/>.
+/// </summary>
+public sealed class RegistratieVerlopenPump(
+    IServiceScopeFactory scopeFactory,
+    FlowableOptions options,
+    ILogger<RegistratieVerlopenPump> logger) : BackgroundService
+{
+    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
+    {
+        while (!stoppingToken.IsCancellationRequested)
+        {
+            try
+            {
+                using var scope = scopeFactory.CreateScope();
+                var processor = scope.ServiceProvider.GetRequiredService<RegistratieVerlopenProcessor>();
+                await processor.PumpOnceAsync(options.MaxJobsPerPoll, stoppingToken);
+            }
+            catch (OperationCanceledException) when (stoppingToken.IsCancellationRequested)
+            {
+                break;
+            }
+            catch (Exception ex)
+            {
+                // A transient fault (e.g. Flowable briefly unreachable) must not kill the loop.
+                logger.LogError(ex, "RegistratieVerlopen job poll failed; retrying after the poll interval.");
+            }
+
+            try
+            {
+                await Task.Delay(options.PollInterval, stoppingToken);
+            }
+            catch (OperationCanceledException) when (stoppingToken.IsCancellationRequested)
+            {
+                break;
+            }
+        }
+    }
+}