docs(backlog): add S-26 self-service resume slice (refs #111)

Mirror the new self-service "resume after refresh" slice into the
Iteration 2 section of the curated backlog. Tracked in Gitea as #111.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

BACKLOG.md

@@ -215,7 +215,9 @@ Split (issue #11 closed) into two independently-demoable slices per §13 — the
 
 #### S-10c · Close the ZGW zaak on document-timeout expiry — #106
 
-**Outcome:** when the 30-day term lapses (S-10a `RegistratieVerlopen`), the ZGW zaak is set to a cancellation status (not just the domain aggregate → `Verlopen`). Adds a cancellation statustype/resultaattype to the seed + an ACL method + expiry-worker wiring. Carved from S-10b (ADR-0017/0018). Depends on #103.
+**Outcome:** when the 30-day term lapses (S-10a `RegistratieVerlopen`), the ZGW zaak is set to a distinct non-terminal `Geannuleerd` status + `Vervallen` resultaat (not just the domain aggregate → `Verlopen`), resolved by name in the ACL. Adds the cancellation statustype/resultaattype to the seed + an ACL `CancelZaakAsync`/`POST /annuleringen` + expiry-worker wiring. Carved from S-10b (ADR-0017/0018/0019). Depends on #103.
+
+**Acceptance:** ACL↔OpenZaak integration test (cancellation records `Geannuleerd` + a resultaat, live); the domain verify script fires the P30D timer and asserts the zaak reaches `Geannuleerd` end-to-end; BDD asserts the zaak is cancelled on timeout but untouched when documents arrive in time.
 
 ### S-11 · Withdrawal (Flow 3)
 
@@ -237,6 +239,12 @@ Split (issue #11 closed) into two independently-demoable slices per §13 — the
 
 **Outcome:** Boundary timer on beoordeling user task — 14 days. On timeout, reassigns to a teamlead role.
 
+### S-26 · Self-service — resume an existing registration after refresh — #111
+
+**Outcome:** a signed-in zorgprofessional who reloads the self-service portal (or returns later) gets back to their in-flight registration and its actions (Documenten aanleveren, Trek aanvraag in), instead of a blank submit form with the reference lost. Today all post-submit state lives in in-memory signals, the reference is not in the URL, and there is no self-service read endpoint — so a reload strands the registration. Adds an owner-scoped (DigiD bsn) `GET /self-service/registrations` on the BFF/domain and a load-on-init/route restore in the portal.
+
+**Acceptance:** BDD — resume after refresh shows the existing registration; lookup is owner-scoped (never another citizen's); a user with no in-flight registration still sees the submit form. Playwright e2e reloads mid-flow and asserts the actions remain reachable.
+
 ---
 
 ## Iteration 3 — Maintenance portal and observability *(milestone: `Iteration 3 — Beheer & Observability`)*

docs/architecture/adr-0019-zaak-cancellation-on-timeout.md

@@ -0,0 +1,81 @@
+# ADR-0019: A timed-out zaak is cancelled with a distinct status + resultaat, resolved by name
+
+- **Status:** Accepted
+- **Date:** 2026-07-21
+- **Deciders:** Respellion engineering
+- **Relates to:** S-10c (#106). Completes the S-10a/S-10b boundary noted in ADR-0017 (§Consequences) and
+  reuses the ACL close-zaak machinery from S-09b (approval) and the Documenten work in ADR-0018.
+
+## Context
+
+ADR-0017 (S-10a) cancels the *process* and marks the domain aggregate `Verlopen` when the 30-day
+document term lapses, but explicitly deferred setting the ZGW **zaak** to a cancellation status. Left
+open, a timed-out zaak stays open in OpenZaak while the register shows the registration as lapsed — the
+two diverge. S-10c closes that gap: on expiry the domain must also cancel the zaak through the ACL
+(§8.1, the only code that talks to ZGW).
+
+The non-obvious part is *how to represent "cancelled" in ZGW* alongside the existing "approved" close.
+The approval path (S-09b) sets the zaak's **eindstatus** (the terminal statustype) plus a resultaat. In
+ZGW a zaaktype has exactly one eindstatus — the highest-`volgnummer` statustype — and setting it is what
+closes the zaak (`einddatum`). A second *terminal* status would collide with that single-eindstatus rule.
+
+## Decision
+
+**Model cancellation as a distinct, non-terminal `Geannuleerd` statustype plus a distinct `Vervallen`
+resultaat, and resolve both the approval and cancellation statustype/resultaat by their omschrijving
+(name) rather than by position or the eindstatus flag alone.**
+
+- **Seed.** `Geannuleerd` is seeded at `volgnummer` 2 — between `Ontvangen` (1) and the `Afgehandeld`
+  eindstatus (3) — so it is a *non-terminal* status and never displaces the eindstatus the approval path
+  resolves. A second resultaattype `Vervallen` (archiefnominatie `vernietigen`) is seeded beside the
+  approval `Geregistreerd` (`blijvend_bewaren`); both draw their `selectielijstklasse` from the
+  zaaktype's single `selectielijstProcestype` so they validate on publish.
+- **The ACL owns the mapping.** `OpenZaakGateway.SetZaakToCancellationStatusAsync` resolves `Geannuleerd`
+  + `Vervallen` by omschrijving and POSTs the resultaat then the status (OpenZaak requires a resultaat
+  before a closing/terminal status), mirroring `SetZaakToEindstatusAsync`. Exposed as
+  `AclService.CancelZaakAsync` behind the ACL endpoint `POST /annuleringen`. The omschrijvingen live as
+  constants in the gateway — the ACL, not the domain, knows which ZGW status means what (§8.1).
+- **Approval now resolves its resultaat by name too.** With two resultaattypen present, taking the first
+  is ambiguous (the Zaken API does not guarantee order), so the approval path resolves `Geregistreerd`
+  by omschrijving. Its statustype resolution is unchanged (still the eindstatus).
+- **Domain wiring.** The `ExpireRegistrationWorker` calls `IAclClient.CancelZaakAsync(zaakUrl)` **before**
+  advancing the aggregate to `Verlopen` (ACL-first, mirroring approval): if the ACL call fails the job is
+  redelivered (§8.6) rather than leaving the aggregate `Verlopen` with an open zaak. The existing
+  open-state guard stops a redelivered job from cancelling twice (a second resultaat would be a 400); a
+  registration that lapsed before its zaak was opened has nothing to cancel.
+
+## Consequences
+
+**Positive**
+
+- The domain aggregate and the ZGW zaak no longer diverge on timeout — both reflect the cancellation.
+- Reuses the approval close machinery (resultaat-then-status, ACL endpoint shape, ACL-first ordering), so
+  the change is additive and §8 stays clean (only the ACL talks to ZGW).
+- Verified at two levels: an ACL↔OpenZaak integration test asserts the live zaak reaches `Geannuleerd`
+  with a resultaat, and the domain verify script fires the real P30D timer and confirms the zaak is
+  cancelled end-to-end.
+
+**Negative / costs**
+
+- `Geannuleerd` is non-terminal, so the cancelled zaak's `einddatum` is not set — it carries a
+  cancellation status + resultaat but is not formally "closed" in ZGW. Accepted: the register reads the
+  domain aggregate's status, and a single eindstatus per zaaktype is a ZGW constraint we chose not to
+  fight. Formally closing a cancelled zaak (a second eindstatus, or reusing `Afgehandeld` with a
+  `Vervallen` resultaat) is a possible follow-up.
+- The ACL couples to the seeded omschrijvingen (`Geregistreerd`/`Geannuleerd`/`Vervallen`) by string
+  constants. This mirrors the existing implicit coupling to the catalogus (zaaktype URL, eindstatus) and
+  is documented in the gateway.
+- Renumbering `Afgehandeld` from `volgnummer` 2 to 3 means a *stale* local catalogus must have its
+  OpenZaak volumes reset for the change to take effect; CI reseeds a fresh catalogus each run.
+
+## Alternatives considered
+
+- **Shared eindstatus, distinct resultaat only** (reuse `Afgehandeld`, distinguish approval vs
+  cancellation purely by the resultaat). ZGW-idiomatic and would set `einddatum` on cancellation too, but
+  the register would show no visibly distinct cancellation *status*. Rejected in favour of the issue's
+  explicit "distinct statustype + resultaattype" outcome, which makes the cancellation legible in ZGW.
+- **A second terminal (eindstatus) `Geannuleerd`.** Rejected: ZGW allows only one eindstatus per
+  zaaktype (highest volgnummer); a second terminal status would either not close the zaak or collide with
+  the approval eindstatus resolution.
+- **Passing the target omschrijvingen from the domain.** Rejected: which ZGW status means "cancelled" is
+  ZGW vocabulary the ACL owns (§8.1); the domain says only "cancel this zaak".

docs/demo-script.md

@@ -461,4 +461,24 @@ make verify-acl        # → "Storing a diploma creates a real informatieobject
 `ProvideDocuments` → ACL `POST /documenten` → ZGW `enkelvoudiginformatieobjecten` +
 `zaakinformatieobjecten`; the wait is then completed and the case advances to Beoordelen (§8.1, ADR-0018).
 
-> Setting the ZGW zaak to a cancellation status on 30-day expiry is a follow-up (S-10c, #106).
+## S-10c — the ZGW zaak is cancelled when the document term lapses (#106)
+
+When the 30-day document term lapses (S-10a), the domain no longer only marks the aggregate `Verlopen` —
+it now also cancels the **ZGW zaak** through the ACL, so OpenZaak and the register agree. The zaak is set
+to a distinct, non-terminal **`Geannuleerd`** status with a **`Vervallen`** resultaat (as opposed to the
+approval `Afgehandeld` + `Geregistreerd`), resolved by name in the ACL (§8.1, ADR-0019).
+
+```bash
+# 1. The ACL integration test proves cancellation records the Geannuleerd status + a resultaat
+#    against a live OpenZaak:
+make verify-acl        # → "Cancelling a zaak records the geannuleerd status and a resultaat"
+#
+# 2. End-to-end: the domain check submits a registration, fires its 30-day timer early, and asserts
+#    the timeout worker both expires the registration (VERLOPEN) and cancels its zaak (Geannuleerd):
+make verify-domain     # → "the timed-out registration's zaak was cancelled to Geannuleerd in OpenZaak"
+```
+
+**The path:** Flowable P30D timer → `RegistratieVerlopen` job → domain `ExpireRegistrationWorker` → ACL
+`POST /annuleringen` → ZGW `resultaten` + `statussen` (Geannuleerd); the aggregate then moves to
+`Verlopen`. The ACL cancels the zaak **before** the aggregate is expired, so a failed ZGW call leaves the
+job for redelivery rather than diverging the two (ADR-0019).

infra/openzaak/seed_catalogus.py

@@ -10,7 +10,7 @@ Creates (if absent):
 Auth uses the JWT client provisioned by setup_configuration (see ADR-0002).
 Stdlib only — no pip deps. Re-running is safe (matches existing by identifier).
 """
-import base64, hashlib, hmac, json, os, sys, time, urllib.error, urllib.request
+import base64, hashlib, hmac, json, os, sys, time, urllib.error, urllib.parse, urllib.request
 
 BASE = os.environ.get("OZ_BASE", "http://localhost:8000")
 CLIENT_ID = os.environ.get("OZ_CLIENT_ID", "big-reference-seed")
@@ -77,8 +77,12 @@ def publish_zaaktype(zt):
     Selectielijst `selectielijstklasse` whose procestype matches the zaaktype's
     `selectielijstProcestype`, plus a `resultaattypeomschrijving`.
     """
+    # Ontvangen (begin) → Afgehandeld (eind, highest volgnummer). "Geannuleerd" (S-10c) sits between
+    # them: a non-terminal status the document-timeout branch sets, so it never displaces the Afgehandeld
+    # eindstatus the approval path resolves. Keyed by volgnummer on a fresh catalogus (CI reseeds); a
+    # stale local stack must reset its OpenZaak volumes for the renumbering to take effect.
     have_st = {s.get("volgnummer") for s in find(f"/statustypen?zaaktype={zt['url']}&status=alles")}
-    for volgnummer, omschrijving in [(1, "Ontvangen"), (2, "Afgehandeld")]:
+    for volgnummer, omschrijving in [(1, "Ontvangen"), (2, "Geannuleerd"), (3, "Afgehandeld")]:
         if volgnummer not in have_st:
             st, body = api("POST", "/statustypen", {
                 "omschrijving": omschrijving, "zaaktype": zt["url"], "volgnummer": volgnummer})
@@ -95,25 +99,42 @@ def publish_zaaktype(zt):
             sys.exit(f"create roltype -> {st}: {json.dumps(body, indent=2)}")
         print("create roltype Aanvrager")
 
-    if find(f"/resultaattypen?zaaktype={zt['url']}&status=alles"):
+    # Two resultaattypen, keyed by omschrijving so each is created independently (idempotent):
-        print("skip   resultaattype Geregistreerd")
+    #   "Geregistreerd" — the approval outcome (S-09b)
+    #   "Vervallen"     — the document-timeout cancellation outcome (S-10c)
+    # Both selectielijstklassen must share the zaaktype's selectielijstProcestype, so pick two
+    # Selectielijst resultaten from a single procestype and set that procestype on the zaaktype.
+    have_rt = {r.get("omschrijving") for r in find(f"/resultaattypen?zaaktype={zt['url']}&status=alles")}
+    wanted = [("Geregistreerd", "blijvend_bewaren"), ("Vervallen", "vernietigen")]
+    if all(naam in have_rt for naam, _ in wanted):
+        print("skip   resultaattypen Geregistreerd + Vervallen")
     else:
-        resultaat = selectielijst("/resultaten?pageSize=1")["results"][0]
+        # Anchor on the procestype of an arbitrary resultaat, then fetch that procestype's resultaten so
+        # both klassen validate against the zaaktype's selectielijstProcestype.
+        procestype = selectielijst("/resultaten?pageSize=1")["results"][0]["procesType"]
+        resultaten = selectielijst(f"/resultaten?procesType={urllib.parse.quote(procestype, safe='')}")["results"]
+        if len(resultaten) < len(wanted):
+            sys.exit(f"selectielijst procestype has too few resultaten ({len(resultaten)}) for {len(wanted)} resultaattypen")
         omschrijvingen = selectielijst("/resultaattypeomschrijvingen")
-        oms = (omschrijvingen if isinstance(omschrijvingen, list) else omschrijvingen["results"])[0]["url"]
+        oms_list = omschrijvingen if isinstance(omschrijvingen, list) else omschrijvingen["results"]
-        # The selectielijstklasse and the zaaktype must share a procestype.
+
-        st, body = api("PATCH", zt["url"], {"selectielijstProcestype": resultaat["procesType"]})
+        st, body = api("PATCH", zt["url"], {"selectielijstProcestype": procestype})
         if st != 200:
             sys.exit(f"set procestype -> {st}: {json.dumps(body, indent=2)}")
+
+        for i, (naam, archiefnominatie) in enumerate(wanted):
+            if naam in have_rt:
+                print(f"skip   resultaattype {naam}")
+                continue
             st, body = api("POST", "/resultaattypen", {
-            "zaaktype": zt["url"], "omschrijving": "Geregistreerd",
+                "zaaktype": zt["url"], "omschrijving": naam,
-            "resultaattypeomschrijving": oms, "selectielijstklasse": resultaat["url"],
+                "resultaattypeomschrijving": oms_list[i]["url"], "selectielijstklasse": resultaten[i]["url"],
-            "archiefnominatie": "blijvend_bewaren",
+                "archiefnominatie": archiefnominatie,
                 "brondatumArchiefprocedure": {"afleidingswijze": "afgehandeld"},
             })
             if st != 201:
-            sys.exit(f"create resultaattype -> {st}: {json.dumps(body, indent=2)}")
+                sys.exit(f"create resultaattype {naam} -> {st}: {json.dumps(body, indent=2)}")
-        print("create resultaattype Geregistreerd")
+            print(f"create resultaattype {naam}")
 
     if zt.get("concept", True):
         st, body = api("POST", f"{zt['url']}/publish")

infra/run-domain-check.sh

@@ -309,10 +309,11 @@ done
 [ -n "$escalated" ] || { echo "FAIL — Beoordelen task not reassigned to teamlead (candidate groups: '$groups')" >&2; docker logs "$dom" 2>&1 | tail -15 >&2; exit 1; }
 echo "OK — the 14-day timer escalated the still-open Beoordelen task to the teamlead"
 
-# ── S-10a: document timeout. A registration parks at WachtOpDocumenten and — unlike every block above —
+# ── S-10a/S-10c: document timeout. A registration parks at WachtOpDocumenten and — unlike every block
-# its documents never arrive. We fire its 30-day boundary timer early via the management API; the
+# above — its documents never arrive. We fire its 30-day boundary timer early via the management API;
-# INTERRUPTING timer cancels the wait and routes a token to the RegistratieVerlopen external task. The
+# the INTERRUPTING timer cancels the wait and routes a token to the RegistratieVerlopen external task.
-# domain's timeout worker acquires it and expires the registration to VERLOPEN (ADR-0017). ────────────
+# The domain's timeout worker acquires it, cancels the ZGW zaak via the ACL (S-10c), and expires the
+# registration to VERLOPEN (ADR-0017). ─────────────────────────────────────────────────────────────
 echo ">> submitting a registration to let its document term lapse"
 locv="$(docker run --rm --network "$net" curlimages/curl:latest \
   -fsS -D - -o /dev/null -X POST "http://$dom_ip:8080/registrations" \
@@ -354,4 +355,47 @@ for _ in $(seq 1 30); do
 done
 [ -n "$verlopen" ] || { echo "FAIL — registration $reg_idv not VERLOPEN after the document timer fired (body: $body)" >&2; docker logs "$dom" 2>&1 | tail -15 >&2; exit 1; }
 echo "OK — the 30-day document timer expired the registration to VERLOPEN"
+
+# S-10c: the worker cancels the ZGW zaak (ACL-first, before it expires the aggregate), so a VERLOPEN
+# registration must carry a zaak whose current status is "Geannuleerd". Read it back from OpenZaak with
+# a ZGW token minted like the seed's client (the same client OpenZaak trusts for this stack).
+zaak_url_v="$(printf '%s' "$body" | grep -oiE 'http://[^"]*/zaken/api/v1/zaken/[a-f0-9-]+' | head -1)"
+[ -n "$zaak_url_v" ] || { echo "FAIL — VERLOPEN registration $reg_idv exposes no zaak URL (body: $body)" >&2; exit 1; }
+echo ">> confirming the zaak $zaak_url_v reached the Geannuleerd status in OpenZaak"
+
+read_zaak_status() {
+  # -i so the heredoc reaches `python -` on the container's stdin (without it the script is empty).
+  docker run --rm -i --network "$net" \
+    -e OZ_CLIENT_ID="${OZ_CLIENT_ID:-big-reference-seed}" \
+    -e OZ_SECRET="${OZ_SECRET:-insecure-dev-secret-change-me}" \
+    python:3-slim python - "$1" <<'PY'
+import base64, hashlib, hmac, json, os, sys, time, urllib.request
+cid, sec = os.environ["OZ_CLIENT_ID"], os.environ["OZ_SECRET"]
+b64 = lambda b: base64.urlsafe_b64encode(b).rstrip(b"=")
+def token():
+    hdr = {"alg": "HS256", "typ": "JWT"}
+    pl = {"iss": cid, "iat": int(time.time()), "client_id": cid, "user_id": "verify", "user_representation": "verify"}
+    seg = b64(json.dumps(hdr, separators=(",", ":")).encode()) + b"." + b64(json.dumps(pl, separators=(",", ":")).encode())
+    return (seg + b"." + b64(hmac.new(sec.encode(), seg, hashlib.sha256).digest())).decode()
+def get(url):
+    req = urllib.request.Request(url, headers={
+        "Authorization": "Bearer " + token(), "Accept": "application/json", "Accept-Crs": "EPSG:4326"})
+    with urllib.request.urlopen(req, timeout=30) as r:
+        return json.loads(r.read())
+zaak = get(sys.argv[1])
+status_url = zaak.get("status")
+if not status_url:
+    print(""); sys.exit(0)
+print(get(get(status_url)["statustype"]).get("omschrijving", ""))
+PY
+}
+
+geannuleerd=""
+for _ in $(seq 1 15); do
+  oms="$(read_zaak_status "$zaak_url_v" 2>/dev/null | tr -d '\r' || true)"
+  [ "$oms" = "Geannuleerd" ] && { geannuleerd=1; break; }
+  sleep 2
+done
+[ -n "$geannuleerd" ] || { echo "FAIL — zaak $zaak_url_v not Geannuleerd after timeout (current status omschrijving: '$oms')" >&2; docker logs "$dom" 2>&1 | tail -15 >&2; exit 1; }
+echo "OK — the timed-out registration's zaak was cancelled to Geannuleerd in OpenZaak"
 exit 0

services/acl/Acl.Api/Program.cs

@@ -32,6 +32,14 @@ app.MapPost("/statussen", async (SetStatusRequest body, AclService acl, Cancella
     return Results.NoContent();
 });
 
+// Cancel a zaak on document-timeout expiry (S-10c): set it to its zaaktype's cancellation statustype
+// + resultaat. The domain hands over only the zaak URL; the ACL owns the ZGW resolution (§8.1).
+app.MapPost("/annuleringen", async (CancelZaakRequest body, AclService acl, CancellationToken ct) =>
+{
+    await acl.CancelZaakAsync(new Uri(body.ZaakUrl), ct);
+    return Results.NoContent();
+});
+
 // Read a zaak's public-safe reference (its identificatie). The Event Subscriber calls this to enrich
 // the read projection without reading ZGW itself (§8.1, #78).
 app.MapPost("/zaken/reference", async (ZaakReferenceRequest body, AclService acl, CancellationToken ct) =>
@@ -55,6 +63,8 @@ public sealed record OpenZaakRequest(string Bsn, string Reference);
 
 public sealed record SetStatusRequest(string ZaakUrl);
 
+public sealed record CancelZaakRequest(string ZaakUrl);
+
 public sealed record ZaakReferenceRequest(string ZaakUrl);
 
 public sealed record StoreDocumentRequest(string ZaakUrl, string ContentBase64, string FileName, string ContentType);

services/acl/Acl.Application/AclService.cs

@@ -30,6 +30,18 @@ public sealed class AclService(IZaakGateway gateway, AclDefaults defaults, ICloc
         return gateway.SetZaakToEindstatusAsync(zaakUrl, defaults.ZaaktypeUrl, clock.Today, ct);
     }
 
+    /// <summary>
+    /// Cancel a zaak on document-timeout expiry (S-10c): set it to the configured BIG zaaktype's
+    /// cancellation statustype + resultaat. The domain hands over only the zaak URL; the ACL owns which
+    /// statustype/resultaat means "cancelled" (§8.1).
+    /// </summary>
+    public Task CancelZaakAsync(Uri zaakUrl, CancellationToken ct = default)
+    {
+        ArgumentNullException.ThrowIfNull(zaakUrl);
+
+        return gateway.SetZaakToCancellationStatusAsync(zaakUrl, defaults.ZaaktypeUrl, clock.Today, ct);
+    }
+
     /// <summary>The zaak's reference (its ZGW identificatie), for the read projection (#78).</summary>
     public Task<string> GetZaakReferenceAsync(Uri zaakUrl, CancellationToken ct = default)
     {

services/acl/Acl.Application/IZaakGateway.cs

@@ -13,6 +13,15 @@ public interface IZaakGateway
     /// </summary>
     Task SetZaakToEindstatusAsync(Uri zaakUrl, Uri zaaktypeUrl, DateOnly datumStatusGezet, CancellationToken ct = default);
 
+    /// <summary>
+    /// Set the given zaak to the <em>cancellation</em> statustype ("Geannuleerd") and record the
+    /// matching cancellation resultaat ("Vervallen") — the ZGW translation of "the 30-day document term
+    /// lapsed" (S-10c). Distinct from <see cref="SetZaakToEindstatusAsync"/> (approval): the gateway
+    /// resolves both the cancellation statustype and resultaattype from the catalogus by their
+    /// omschrijving, POSTs the resultaat then the status, dated <paramref name="datumStatusGezet"/>.
+    /// </summary>
+    Task SetZaakToCancellationStatusAsync(Uri zaakUrl, Uri zaaktypeUrl, DateOnly datumStatusGezet, CancellationToken ct = default);
+
     /// <summary>Read the zaak's <c>identificatie</c> — the public-safe reference the register shows.
     /// The Event Subscriber calls this through the ACL rather than reading ZGW itself (§8.1, #78).</summary>
     Task<string> GetZaakIdentificatieAsync(Uri zaakUrl, CancellationToken ct = default);

services/acl/Acl.Infrastructure/OpenZaakGateway.cs

@@ -8,6 +8,12 @@ namespace Acl.Infrastructure;
 /// <summary>The only code that talks to OpenZaak's Zaken API (ADR-0001).</summary>
 public sealed class OpenZaakGateway(HttpClient http, OpenZaakOptions options) : IZaakGateway
 {
+    // The ACL owns which ZGW statustype/resultaat carries each domain outcome (§8.1). These
+    // omschrijvingen match the seeded BIG catalogus (infra/openzaak/seed_catalogus.py).
+    private const string GeregistreerdResultaat = "Geregistreerd";   // approval outcome
+    private const string GeannuleerdStatus = "Geannuleerd";          // document-timeout cancellation status (S-10c)
+    private const string VervallenResultaat = "Vervallen";           // document-timeout cancellation outcome (S-10c)
+
     public async Task<Uri> OpenZaakAsync(ZaakRequest request, CancellationToken ct = default)
     {
         ArgumentNullException.ThrowIfNull(request);
@@ -48,7 +54,9 @@ public sealed class OpenZaakGateway(HttpClient http, OpenZaakOptions options) :
         ArgumentNullException.ThrowIfNull(zaaktypeUrl);
 
         var eindstatus = await ResolveEindstatusAsync(zaaktypeUrl, ct);
-        var resultaattype = await ResolveResultaattypeAsync(zaaktypeUrl, ct);
+        // Resolve the approval resultaat by name: once S-10c adds the Vervallen resultaattype, taking
+        // the first would be ambiguous (the Zaken API does not guarantee order).
+        var resultaattype = await ResolveResultaattypeByOmschrijvingAsync(zaaktypeUrl, GeregistreerdResultaat, ct);
 
         // OpenZaak refuses to set a zaak's eindstatus unless the zaak has a resultaat
         // ("resultaat-does-not-exist"), so record the resultaat first, then the status.
@@ -62,6 +70,27 @@ public sealed class OpenZaakGateway(HttpClient http, OpenZaakOptions options) :
             "Setting the zaak status", ct);
     }
 
+    public async Task SetZaakToCancellationStatusAsync(Uri zaakUrl, Uri zaaktypeUrl, DateOnly datumStatusGezet, CancellationToken ct = default)
+    {
+        ArgumentNullException.ThrowIfNull(zaakUrl);
+        ArgumentNullException.ThrowIfNull(zaaktypeUrl);
+
+        // Distinct from approval: resolve the cancellation statustype + resultaat by name (Geannuleerd
+        // is a non-terminal statustype, so it is never the eindstatus the approval path resolves).
+        var cancellationStatus = await ResolveStatustypeByOmschrijvingAsync(zaaktypeUrl, GeannuleerdStatus, ct);
+        var cancellationResultaat = await ResolveResultaattypeByOmschrijvingAsync(zaaktypeUrl, VervallenResultaat, ct);
+
+        // As with approval, OpenZaak wants the resultaat recorded before the status.
+        await PostAsync("/zaken/api/v1/resultaten",
+            new ResultaatDto(zaakUrl.ToString(), cancellationResultaat.ToString()),
+            "Setting the zaak cancellation resultaat", ct);
+
+        await PostAsync("/zaken/api/v1/statussen",
+            new StatusDto(zaakUrl.ToString(), cancellationStatus.ToString(),
+                datumStatusGezet.ToDateTime(TimeOnly.MinValue, DateTimeKind.Utc).ToString("yyyy-MM-ddTHH:mm:ssZ")),
+            "Setting the zaak cancellation status", ct);
+    }
+
     public async Task<string> GetZaakIdentificatieAsync(Uri zaakUrl, CancellationToken ct = default)
     {
         ArgumentNullException.ThrowIfNull(zaakUrl);
@@ -174,13 +203,23 @@ public sealed class OpenZaakGateway(HttpClient http, OpenZaakOptions options) :
         return new Uri(eindstatus.Url);
     }
 
-    /// <summary>Resolve the zaaktype's resultaattype from the catalogus (the seed defines one).</summary>
+    /// <summary>Resolve a specific statustype from the catalogus by its omschrijving (e.g. "Geannuleerd").</summary>
-    private async Task<Uri> ResolveResultaattypeAsync(Uri zaaktypeUrl, CancellationToken ct)
+    private async Task<Uri> ResolveStatustypeByOmschrijvingAsync(Uri zaaktypeUrl, string omschrijving, CancellationToken ct)
+    {
+        var page = await GetCatalogusAsync<StatustypePage>("statustypen", zaaktypeUrl, "statustypen", ct);
+        var match = (page.Results ?? []).FirstOrDefault(s => s.Omschrijving == omschrijving)
+            ?? throw new InvalidOperationException($"No '{omschrijving}' statustype found for zaaktype {zaaktypeUrl}");
+        return new Uri(match.Url);
+    }
+
+    /// <summary>Resolve a specific resultaattype from the catalogus by its omschrijving (the seed defines
+    /// "Geregistreerd" for approval and "Vervallen" for a document-timeout cancellation).</summary>
+    private async Task<Uri> ResolveResultaattypeByOmschrijvingAsync(Uri zaaktypeUrl, string omschrijving, CancellationToken ct)
     {
         var page = await GetCatalogusAsync<ResultaattypePage>("resultaattypen", zaaktypeUrl, "resultaattypen", ct);
-        var resultaattype = (page.Results ?? []).FirstOrDefault()
+        var match = (page.Results ?? []).FirstOrDefault(r => r.Omschrijving == omschrijving)
-            ?? throw new InvalidOperationException($"No resultaattypen found for zaaktype {zaaktypeUrl}");
+            ?? throw new InvalidOperationException($"No '{omschrijving}' resultaattype found for zaaktype {zaaktypeUrl}");
-        return new Uri(resultaattype.Url);
+        return new Uri(match.Url);
     }
 
     // GETs a catalogus collection filtered by zaaktype (status=alles includes concept + published).
@@ -224,7 +263,8 @@ public sealed class OpenZaakGateway(HttpClient http, OpenZaakOptions options) :
     private sealed record StatustypeDto(
         [property: JsonPropertyName("url")] string Url,
         [property: JsonPropertyName("volgnummer")] int Volgnummer,
-        [property: JsonPropertyName("isEindstatus")] bool IsEindstatus);
+        [property: JsonPropertyName("isEindstatus")] bool IsEindstatus,
+        [property: JsonPropertyName("omschrijving")] string? Omschrijving);
 
     private sealed record ResultaatDto(
         [property: JsonPropertyName("zaak")] string Zaak,
@@ -234,7 +274,8 @@ public sealed class OpenZaakGateway(HttpClient http, OpenZaakOptions options) :
         [property: JsonPropertyName("results")] IReadOnlyList<ResultaattypeDto>? Results);
 
     private sealed record ResultaattypeDto(
-        [property: JsonPropertyName("url")] string Url);
+        [property: JsonPropertyName("url")] string Url,
+        [property: JsonPropertyName("omschrijving")] string? Omschrijving);
 
     private sealed record CreatedDto(
         [property: JsonPropertyName("url")] string Url);

services/acl/Acl.IntegrationTests/OpenZaakFixture.cs

@@ -114,6 +114,19 @@ public sealed class OpenZaakFixture : IDisposable
         return fallback ?? throw new InvalidOperationException($"No statustypen for zaaktype {zaaktypeUrl}");
     }
 
+    /// <summary>Resolve a statustype by its omschrijving (e.g. the S-10c "Geannuleerd" cancellation status).</summary>
+    public async Task<Uri> FindStatustypeByOmschrijvingAsync(Uri zaaktypeUrl, string omschrijving, CancellationToken ct = default)
+    {
+        var query = new Uri(BaseUrl,
+            "/catalogi/api/v1/statustypen?status=alles&zaaktype=" + Uri.EscapeDataString(zaaktypeUrl.ToString()));
+        var page = await GetJsonAsync(query, ct);
+        foreach (var st in page.GetProperty("results").EnumerateArray())
+            if (st.TryGetProperty("omschrijving", out var o) && o.GetString() == omschrijving)
+                return new Uri(st.GetProperty("url").GetString()!);
+
+        throw new InvalidOperationException($"No '{omschrijving}' statustype for zaaktype {zaaktypeUrl}");
+    }
+
     // A ZGW (vng-api-common) HS256 JWT, mirroring the seed's client. Minted here
     // rather than reusing Acl.Infrastructure's internal minter to keep that internal.
     private string MintToken()

services/acl/Acl.IntegrationTests/OpenZaakGatewayIntegrationTests.cs

@@ -75,6 +75,39 @@ public sealed class OpenZaakGatewayIntegrationTests(OpenZaakFixture stack)
         Assert.Equal(eindstatustype.ToString(), status.GetProperty("statustype").GetString());
     }
 
+    [Fact]
+    public async Task Cancelling_a_zaak_records_the_geannuleerd_status_and_a_resultaat()
+    {
+        var zaaktype = await stack.FindPublishedBigZaaktypeAsync();
+        Assert.True(zaaktype is not null,
+            "No published BIG-REGISTRATIE zaaktype found in OpenZaak — bring the stack up and " +
+            "seed it with OZ_PUBLISH=1 (`make integration` does this).");
+
+        var gateway = new OpenZaakGateway(stack.Http, stack.Options);
+        var zaakUrl = await gateway.OpenZaakAsync(new ZaakRequest(
+            Bronorganisatie: "517439943",
+            VerantwoordelijkeOrganisatie: "517439943",
+            Vertrouwelijkheidaanduiding: "openbaar",
+            Zaaktype: zaaktype!,
+            Startdatum: DateOnly.FromDateTime(DateTime.UtcNow),
+            Identificatie: Guid.NewGuid().ToString()));
+
+        await gateway.SetZaakToCancellationStatusAsync(zaakUrl, zaaktype!, DateOnly.FromDateTime(DateTime.UtcNow));
+
+        // The zaak's current status is the Geannuleerd statustype — distinct from the approval eindstatus.
+        var zaak = await stack.GetZaakAsync(zaakUrl);
+        var statusUrl = zaak.GetProperty("status").GetString();
+        Assert.False(string.IsNullOrEmpty(statusUrl), "the cancelled zaak has no current status");
+
+        var status = await stack.GetJsonAsync(new Uri(statusUrl!));
+        var geannuleerd = await stack.FindStatustypeByOmschrijvingAsync(zaaktype!, "Geannuleerd");
+        Assert.Equal(geannuleerd.ToString(), status.GetProperty("statustype").GetString());
+
+        // ...and a resultaat is recorded (OpenZaak requires it before a closing/terminal status).
+        Assert.False(string.IsNullOrEmpty(zaak.GetProperty("resultaat").GetString()),
+            "the cancelled zaak has no resultaat");
+    }
+
     [Fact]
     public async Task Storing_a_diploma_creates_a_real_informatieobject_related_to_the_zaak()
     {

services/acl/Acl.Tests/AclServiceTests.cs

@@ -23,6 +23,14 @@ public class AclServiceTests
             return Task.CompletedTask;
         }
 
+        public (Uri Zaak, Uri Zaaktype, DateOnly Datum)? Cancelled;
+
+        public Task SetZaakToCancellationStatusAsync(Uri zaakUrl, Uri zaaktypeUrl, DateOnly datumStatusGezet, CancellationToken ct = default)
+        {
+            Cancelled = (zaakUrl, zaaktypeUrl, datumStatusGezet);
+            return Task.CompletedTask;
+        }
+
         public Uri? ReadReferenceFor;
 
         public Task<string> GetZaakIdentificatieAsync(Uri zaakUrl, CancellationToken ct = default)
@@ -126,6 +134,34 @@ public class AclServiceTests
         Assert.Null(gateway.Approved);
     }
 
+    [Fact]
+    public async Task Cancelling_a_zaak_sets_it_to_the_cancellation_status_dated_today()
+    {
+        var gateway = new FakeGateway();
+        var defaults = Defaults();
+        var service = new AclService(gateway, defaults, new FixedClock(new DateOnly(2026, 6, 4)));
+        var zaak = new Uri("http://openzaak/zaken/api/v1/zaken/abc");
+
+        await service.CancelZaakAsync(zaak);
+
+        Assert.NotNull(gateway.Cancelled);
+        Assert.Equal(zaak, gateway.Cancelled!.Value.Zaak);
+        Assert.Equal(defaults.ZaaktypeUrl, gateway.Cancelled.Value.Zaaktype);
+        Assert.Equal(new DateOnly(2026, 6, 4), gateway.Cancelled.Value.Datum);
+        // Cancellation must not touch the approval path.
+        Assert.Null(gateway.Approved);
+    }
+
+    [Fact]
+    public async Task Cancelling_a_null_zaak_is_rejected_without_touching_the_gateway()
+    {
+        var gateway = new FakeGateway();
+        var service = new AclService(gateway, Defaults(), new FixedClock(new DateOnly(2026, 6, 4)));
+
+        await Assert.ThrowsAsync<ArgumentNullException>(() => service.CancelZaakAsync(null!));
+        Assert.Null(gateway.Cancelled);
+    }
+
     [Fact]
     public async Task Storing_a_diploma_default_fills_the_document_fields_and_returns_its_url()
     {

services/acl/Acl.Tests/OpenZaakGatewayTests.cs

@@ -173,7 +173,8 @@ public class OpenZaakGatewayTests
     private sealed class OzRoutes
     {
         public string StatustypenJson { get; init; } = StatustypenPage(withEindstatusFlag: true);
-        public string ResultaattypenJson { get; init; } = """{"results":[{"url":"http://openzaak/catalogi/api/v1/resultaattypen/1"}]}""";
+        public string ResultaattypenJson { get; init; } =
+            """{"results":[{"url":"http://openzaak/catalogi/api/v1/resultaattypen/1","omschrijving":"Geregistreerd"}]}""";
         public HttpStatusCode StatustypenStatus { get; init; } = HttpStatusCode.OK;
         public HttpStatusCode ResultaattypenStatus { get; init; } = HttpStatusCode.OK;
         public HttpStatusCode ResultaatPostStatus { get; init; } = HttpStatusCode.Created;
@@ -251,6 +252,138 @@ public class OpenZaakGatewayTests
         Assert.True(status.Length > 0);
     }
 
+    [Fact]
+    public async Task Approving_selects_the_geregistreerd_resultaat_by_name_when_several_exist()
+    {
+        // Once S-10c adds a second resultaattype (Vervallen), picking the first is ambiguous — the
+        // Zaken API does not guarantee order. Approval must resolve its resultaat by omschrijving.
+        var rec = new Recorder();
+        var twoResultaattypen = """
+            {"results":[
+              {"url":"http://openzaak/catalogi/api/v1/resultaattypen/vervallen","omschrijving":"Vervallen"},
+              {"url":"http://openzaak/catalogi/api/v1/resultaattypen/geregistreerd","omschrijving":"Geregistreerd"}
+            ]}
+            """;
+
+        await Gateway(ApprovalStub(rec, new OzRoutes { ResultaattypenJson = twoResultaattypen }))
+            .SetZaakToEindstatusAsync(new Uri(ZaakUrl), Zaaktype, new DateOnly(2026, 6, 4));
+
+        Assert.Contains("\"resultaattype\":\"http://openzaak/catalogi/api/v1/resultaattypen/geregistreerd\"",
+            rec.Sent("/resultaten").Body);
+    }
+
+    // --- SetZaakToCancellationStatusAsync (document-timeout cancellation / S-10c) ---
+
+    // A catalogus with the three statustypen S-10c seeds (Geannuleerd is non-terminal, below the
+    // Afgehandeld eindstatus) and both resultaattypen. Cancellation must resolve "Geannuleerd" and
+    // "Vervallen" by omschrijving, never the approval pair.
+    private const string CancellationStatustypenJson = """
+        {"results":[
+          {"url":"http://openzaak/catalogi/api/v1/statustypen/ontvangen","volgnummer":1,"omschrijving":"Ontvangen","isEindstatus":false},
+          {"url":"http://openzaak/catalogi/api/v1/statustypen/geannuleerd","volgnummer":2,"omschrijving":"Geannuleerd","isEindstatus":false},
+          {"url":"http://openzaak/catalogi/api/v1/statustypen/afgehandeld","volgnummer":3,"omschrijving":"Afgehandeld","isEindstatus":true}
+        ]}
+        """;
+
+    private const string CancellationResultaattypenJson = """
+        {"results":[
+          {"url":"http://openzaak/catalogi/api/v1/resultaattypen/geregistreerd","omschrijving":"Geregistreerd"},
+          {"url":"http://openzaak/catalogi/api/v1/resultaattypen/vervallen","omschrijving":"Vervallen"}
+        ]}
+        """;
+
+    [Fact]
+    public async Task Cancelling_records_the_vervallen_resultaat_then_the_geannuleerd_status_against_the_zaak()
+    {
+        var rec = new Recorder();
+
+        await Gateway(ApprovalStub(rec, new OzRoutes
+        {
+            StatustypenJson = CancellationStatustypenJson,
+            ResultaattypenJson = CancellationResultaattypenJson,
+        })).SetZaakToCancellationStatusAsync(new Uri(ZaakUrl), Zaaktype, new DateOnly(2026, 6, 4));
+
+        // Resultaat precedes status (OpenZaak requires a resultaat before a closing/terminal status).
+        Assert.True(rec.IndexOf("/resultaten") < rec.IndexOf("/statussen"));
+
+        var resultaat = rec.Sent("/resultaten");
+        Assert.Contains("\"zaak\":\"" + ZaakUrl + "\"", resultaat.Body);
+        // The cancellation resultaat (Vervallen) is chosen by name — not the approval one (Geregistreerd).
+        Assert.Contains("\"resultaattype\":\"http://openzaak/catalogi/api/v1/resultaattypen/vervallen\"", resultaat.Body);
+
+        var status = rec.Sent("/statussen");
+        Assert.Contains("\"zaak\":\"" + ZaakUrl + "\"", status.Body);
+        // The Geannuleerd statustype is chosen by name — not the Afgehandeld eindstatus (approval).
+        Assert.Contains("\"statustype\":\"http://openzaak/catalogi/api/v1/statustypen/geannuleerd\"", status.Body);
+        Assert.Contains("\"datumStatusGezet\":\"2026-06-04T00:00:00Z\"", status.Body);
+    }
+
+    [Fact]
+    public async Task Cancelling_throws_when_the_zaaktype_has_no_geannuleerd_statustype()
+    {
+        var rec = new Recorder();
+
+        var ex = await Assert.ThrowsAsync<InvalidOperationException>(() =>
+            Gateway(ApprovalStub(rec, new OzRoutes
+            {
+                // Only the approval statustypen — no "Geannuleerd".
+                StatustypenJson = StatustypenPage(withEindstatusFlag: true),
+                ResultaattypenJson = CancellationResultaattypenJson,
+            })).SetZaakToCancellationStatusAsync(new Uri(ZaakUrl), Zaaktype, new DateOnly(2026, 6, 4)));
+
+        Assert.Contains("Geannuleerd", ex.Message);
+    }
+
+    [Fact]
+    public async Task Cancelling_rejects_a_null_zaak_without_calling_openzaak()
+    {
+        var handler = new StubHandler(_ => throw new InvalidOperationException("should not be sent"));
+        await Assert.ThrowsAsync<ArgumentNullException>(() =>
+            Gateway(handler).SetZaakToCancellationStatusAsync(null!, Zaaktype, new DateOnly(2026, 6, 4)));
+    }
+
+    [Fact]
+    public async Task Cancelling_rejects_a_null_zaaktype_without_calling_openzaak()
+    {
+        var handler = new StubHandler(_ => throw new InvalidOperationException("should not be sent"));
+        await Assert.ThrowsAsync<ArgumentNullException>(() =>
+            Gateway(handler).SetZaakToCancellationStatusAsync(new Uri(ZaakUrl), null!, new DateOnly(2026, 6, 4)));
+    }
+
+    [Fact]
+    public async Task Cancelling_surfaces_the_failure_when_recording_the_resultaat_is_rejected()
+    {
+        var rec = new Recorder();
+
+        var ex = await Assert.ThrowsAsync<HttpRequestException>(() =>
+            Gateway(ApprovalStub(rec, new OzRoutes
+            {
+                StatustypenJson = CancellationStatustypenJson,
+                ResultaattypenJson = CancellationResultaattypenJson,
+                ResultaatPostStatus = HttpStatusCode.BadRequest,
+            })).SetZaakToCancellationStatusAsync(new Uri(ZaakUrl), Zaaktype, new DateOnly(2026, 6, 4)));
+
+        Assert.Contains("cancellation resultaat", ex.Message);
+        // It fails on the resultaat, before it ever posts the status.
+        Assert.Equal(-1, rec.IndexOf("/statussen"));
+    }
+
+    [Fact]
+    public async Task Cancelling_surfaces_the_failure_when_recording_the_status_is_rejected()
+    {
+        var rec = new Recorder();
+
+        var ex = await Assert.ThrowsAsync<HttpRequestException>(() =>
+            Gateway(ApprovalStub(rec, new OzRoutes
+            {
+                StatustypenJson = CancellationStatustypenJson,
+                ResultaattypenJson = CancellationResultaattypenJson,
+                StatusPostStatus = HttpStatusCode.BadRequest,
+            })).SetZaakToCancellationStatusAsync(new Uri(ZaakUrl), Zaaktype, new DateOnly(2026, 6, 4)));
+
+        Assert.Contains("cancellation status", ex.Message);
+    }
+
     [Fact]
     public async Task Approving_falls_back_to_the_highest_volgnummer_when_no_eindstatus_is_flagged()
     {
@@ -325,7 +458,7 @@ public class OpenZaakGatewayTests
             Gateway(ApprovalStub(rec, new OzRoutes { ResultaattypenJson = "{}" }))
                 .SetZaakToEindstatusAsync(new Uri(ZaakUrl), Zaaktype, new DateOnly(2026, 6, 4)));
 
-        Assert.Contains("No resultaattypen found", ex.Message);
+        Assert.Contains("'Geregistreerd' resultaattype", ex.Message);
         // Resolved the eindstatus + queried resultaattypen, but posted nothing.
         Assert.Equal(-1, rec.IndexOf("/resultaten"));
         Assert.Equal(-1, rec.IndexOf("/statussen"));

services/domain/Big.Application/ExpireRegistrationWorker.cs

@@ -9,7 +9,7 @@ namespace Big.Application;
 /// nothing of Flowable. The polling loop that feeds it jobs lives in Infrastructure. Mirrors
 /// <see cref="OpenZaakWorker"/>.
 /// </summary>
-public sealed class ExpireRegistrationWorker(IRegistrationStore store)
+public sealed class ExpireRegistrationWorker(IRegistrationStore store, IAclClient acl)
 {
     /// <summary>
     /// Process the job. Idempotent and tolerant of races (§8.6, at-least-once delivery): a job whose
@@ -31,6 +31,14 @@ public sealed class ExpireRegistrationWorker(IRegistrationStore store)
         if (registration.Status is not (RegistrationStatus.Ingediend or RegistrationStatus.InBehandeling))
             return;
 
+        // Cancel the ZGW zaak before advancing the aggregate (mirrors the approval path): if the ACL
+        // call fails it throws, the aggregate stays open, and the job is redelivered (§8.6) — rather
+        // than leaving the aggregate VERLOPEN while the zaak stays open. The status guard above stops a
+        // redelivered job from cancelling the zaak twice (a second resultaat would be a 400). A
+        // registration expired before its zaak was opened has nothing to cancel.
+        if (registration.ZaakUrl is not null)
+            await acl.CancelZaakAsync(registration.ZaakUrl, ct);
+
         registration.Expire();
         await store.SaveAsync(registration, ct);
     }

services/domain/Big.Application/Ports.cs

@@ -59,6 +59,12 @@ public interface IAclClient
     /// zaak (§8.1). Returns the stored document's URL.
     /// </summary>
     Task<Uri> StoreDiplomaAsync(Uri zaakUrl, byte[] content, string fileName, string contentType, CancellationToken ct = default);
+
+    /// <summary>
+    /// Cancel the zaak on document-timeout expiry (S-10c): the 30-day document term lapsed, so the ACL
+    /// translates this to the ZGW cancellation status/resultaat. The domain never names statustypen.
+    /// </summary>
+    Task CancelZaakAsync(Uri zaakUrl, CancellationToken ct = default);
 }
 
 /// <summary>

services/domain/Big.Infrastructure/AclHttpClient.cs

@@ -31,6 +31,15 @@ public sealed class AclHttpClient(HttpClient http, AclOptions options) : IAclCli
         response.EnsureSuccessStatusCode();
     }
 
+    public async Task CancelZaakAsync(Uri zaakUrl, CancellationToken ct = default)
+    {
+        ArgumentNullException.ThrowIfNull(zaakUrl);
+
+        using var response = await http.PostAsJsonAsync(
+            new Uri(options.BaseUrl, "annuleringen"), new CancelZaakRequest(zaakUrl.ToString()), ct);
+        response.EnsureSuccessStatusCode();
+    }
+
     public async Task<Uri> StoreDiplomaAsync(Uri zaakUrl, byte[] content, string fileName, string contentType, CancellationToken ct = default)
     {
         ArgumentNullException.ThrowIfNull(zaakUrl);
@@ -56,6 +65,8 @@ public sealed class AclHttpClient(HttpClient http, AclOptions options) : IAclCli
 
     private sealed record SetStatusRequest([property: JsonPropertyName("zaakUrl")] string ZaakUrl);
 
+    private sealed record CancelZaakRequest([property: JsonPropertyName("zaakUrl")] string ZaakUrl);
+
     private sealed record StoreDocumentRequest(
         [property: JsonPropertyName("zaakUrl")] string ZaakUrl,
         [property: JsonPropertyName("contentBase64")] string ContentBase64,

services/domain/Big.Tests/ExpireRegistrationWorkerTests.cs

@@ -10,10 +10,13 @@ public class ExpireRegistrationWorkerTests
 {
     private const string Bsn = "123456782";
 
-    private static Registration Submitted(string processInstanceId = "proc-1")
+    // By the time the 30-day document timer fires, the zaak was opened long ago (OpenZaakAanmaken runs
+    // early in the flow), so a timed-out registration carries a zaak the worker can cancel.
+    private static Registration Submitted(string processInstanceId = "proc-1", Uri? zaakUrl = null)
     {
         var registration = Registration.Submit(Bsn);
         registration.RecordProcessStarted(processInstanceId);
+        registration.AttachZaak(zaakUrl ?? FakeAclClient.DefaultZaakUrl);
         return registration;
     }
 
@@ -24,7 +27,7 @@ public class ExpireRegistrationWorkerTests
         var registration = Submitted();
         store.Seed(registration);
 
-        await new ExpireRegistrationWorker(store).HandleAsync(
+        await new ExpireRegistrationWorker(store, new FakeAclClient()).HandleAsync(
             new RegistratieVerlopenJob("job-7", registration.Id));
 
         var saved = await store.GetAsync(registration.Id);
@@ -33,37 +36,60 @@ public class ExpireRegistrationWorkerTests
     }
 
     [Fact]
-    public async Task An_already_verlopen_registration_is_not_persisted_again()
+    public async Task Cancels_the_zaak_via_the_acl_when_expiring_a_still_open_registration()
     {
-        // A redelivered job (§8.6) finds the aggregate already VERLOPEN: a no-op, not saved again.
+        // S-10c: expiring the aggregate is not enough — the ZGW zaak must also be set to its
+        // cancellation status, which the ACL owns (§8.1). The worker hands the ACL the zaak URL.
+        var store = new FakeRegistrationStore();
+        var zaak = new Uri("http://openzaak/zaken/api/v1/zaken/timed-out");
+        var registration = Submitted(zaakUrl: zaak);
+        store.Seed(registration);
+        var acl = new FakeAclClient();
+
+        await new ExpireRegistrationWorker(store, acl).HandleAsync(
+            new RegistratieVerlopenJob("job-7", registration.Id));
+
+        Assert.Equal(1, acl.CancelCallCount);
+        Assert.Equal(zaak, acl.CancelledZaakUrl);
+    }
+
+    [Fact]
+    public async Task An_already_verlopen_registration_is_not_persisted_again_and_the_zaak_is_not_recancelled()
+    {
+        // A redelivered job (§8.6) finds the aggregate already VERLOPEN: a no-op, not saved again — and
+        // the ACL is not asked to cancel the zaak a second time (posting a second resultaat would 400).
         var store = new FakeRegistrationStore();
         var registration = Submitted();
         registration.Expire();
         store.Seed(registration);
+        var acl = new FakeAclClient();
 
-        await new ExpireRegistrationWorker(store).HandleAsync(
+        await new ExpireRegistrationWorker(store, acl).HandleAsync(
             new RegistratieVerlopenJob("job-7", registration.Id));
 
         Assert.Equal(0, store.SaveCount);
+        Assert.Equal(0, acl.CancelCallCount);
         Assert.Equal(RegistrationStatus.Verlopen, (await store.GetAsync(registration.Id))!.Status);
     }
 
     [Fact]
-    public async Task An_already_resolved_registration_is_left_alone_and_the_job_completes()
+    public async Task An_already_resolved_registration_is_left_alone_and_the_zaak_is_not_cancelled()
     {
         // Race with S-11: the citizen withdrew while parked at WachtOpDocumenten, so the aggregate is
         // already terminal (INGETROKKEN) when the timer's job arrives. Expiring it would violate the
         // aggregate's invariant; the worker must instead no-op (and let the job complete), not throw
-        // into a redelivery loop.
+        // into a redelivery loop — and it must not cancel the zaak of a registration it didn't expire.
         var store = new FakeRegistrationStore();
         var registration = Submitted();
         registration.Withdraw();
         store.Seed(registration);
+        var acl = new FakeAclClient();
 
-        await new ExpireRegistrationWorker(store).HandleAsync(
+        await new ExpireRegistrationWorker(store, acl).HandleAsync(
             new RegistratieVerlopenJob("job-7", registration.Id));
 
         Assert.Equal(0, store.SaveCount);
+        Assert.Equal(0, acl.CancelCallCount);
         Assert.Equal(RegistrationStatus.Ingetrokken, (await store.GetAsync(registration.Id))!.Status);
     }
 
@@ -73,12 +99,12 @@ public class ExpireRegistrationWorkerTests
         var store = new FakeRegistrationStore();
 
         await Assert.ThrowsAsync<InvalidOperationException>(() =>
-            new ExpireRegistrationWorker(store).HandleAsync(
+            new ExpireRegistrationWorker(store, new FakeAclClient()).HandleAsync(
                 new RegistratieVerlopenJob("job-7", RegistrationId.New())));
     }
 
     [Fact]
     public async Task Rejects_a_null_job()
         => await Assert.ThrowsAsync<ArgumentNullException>(() =>
-            new ExpireRegistrationWorker(new FakeRegistrationStore()).HandleAsync(null!));
+            new ExpireRegistrationWorker(new FakeRegistrationStore(), new FakeAclClient()).HandleAsync(null!));
 }

services/domain/Big.Tests/Fakes.cs

@@ -119,4 +119,14 @@ internal sealed class FakeAclClient(Uri? zaakUrl = null) : IAclClient
         StoredDiploma = (zaakUrl, content, fileName, contentType);
         return Task.FromResult(DefaultDocumentUrl);
     }
+
+    public Uri? CancelledZaakUrl { get; private set; }
+    public int CancelCallCount { get; private set; }
+
+    public Task CancelZaakAsync(Uri zaakUrl, CancellationToken ct = default)
+    {
+        CancelCallCount++;
+        CancelledZaakUrl = zaakUrl;
+        return Task.CompletedTask;
+    }
 }

services/domain/Big.Tests/RegistratieVerlopenProcessorTests.cs

@@ -30,7 +30,7 @@ public class RegistratieVerlopenProcessorTests
         }
     }
 
-    private static ExpireRegistrationWorker Worker(FakeRegistrationStore store) => new(store);
+    private static ExpireRegistrationWorker Worker(FakeRegistrationStore store) => new(store, new FakeAclClient());
 
     [Fact]
     public async Task Acquires_a_job_expires_the_registration_and_completes_the_job()

tests/acceptance/Features/EenDocumentTermijnVerlopen.feature

@@ -14,6 +14,7 @@ Feature: Een documenttermijn laten verlopen
     When the 30-day document timer fires
     And the document-timeout worker runs
     Then the registration is verlopen
+    And the zaak is cancelled in ZGW
 
   Scenario: Tijdig aangeleverde documenten laten de registratie niet vervallen
     Given a registration parked at the WachtOpDocumenten task
@@ -21,3 +22,4 @@ Feature: Een documenttermijn laten verlopen
     And the 30-day document timer fires
     And the document-timeout worker runs
     Then the registration is not verlopen
+    And the zaak is not cancelled in ZGW

tests/acceptance/Steps/EenDocumentTermijnVerlopenSteps.cs

@@ -17,8 +17,11 @@ namespace Acceptance.Steps;
 [Scope(Feature = "Een documenttermijn laten verlopen")]
 public sealed class EenDocumentTermijnVerlopenSteps
 {
+    private static readonly Uri ZaakUrl = new("http://openzaak/zaken/api/v1/zaken/acc-timeout");
+
     private readonly InMemoryDocumentTimeoutClient _flowable = new();
     private readonly Support.InMemoryRegistrationStore _store = new();
+    private readonly InMemoryAclClient _acl = new();
     private Registration _registration = null!;
     private string _processInstanceId = "";
 
@@ -26,6 +29,9 @@ public sealed class EenDocumentTermijnVerlopenSteps
     public async Task GivenARegistrationParkedAtWachtOpDocumenten()
     {
         _registration = Registration.Submit("123456782");
+        // By the time it parks at WachtOpDocumenten its zaak has been opened (OpenZaakAanmaken runs
+        // earlier), so a timeout has a zaak to cancel.
+        _registration.AttachZaak(ZaakUrl);
         await _store.SaveAsync(_registration);
         _processInstanceId = _flowable.ParkWaitingForDocuments(_registration.Id);
     }
@@ -39,7 +45,7 @@ public sealed class EenDocumentTermijnVerlopenSteps
     [When("the document-timeout worker runs")]
     public async Task WhenTheTimeoutWorkerRuns()
         => await new RegistratieVerlopenProcessor(
-            _flowable, new ExpireRegistrationWorker(_store),
+            _flowable, new ExpireRegistrationWorker(_store, _acl),
             NullLogger<RegistratieVerlopenProcessor>.Instance).PumpOnceAsync(5);
 
     [Then("the registration is verlopen")]
@@ -49,4 +55,10 @@ public sealed class EenDocumentTermijnVerlopenSteps
     [Then("the registration is not verlopen")]
     public async Task ThenTheRegistrationIsNotVerlopen()
         => Assert.Equal(RegistrationStatus.Ingediend, (await _store.GetAsync(_registration.Id))!.Status);
+
+    [Then("the zaak is cancelled in ZGW")]
+    public void ThenTheZaakIsCancelled() => Assert.Equal(ZaakUrl, _acl.CancelledZaakUrl);
+
+    [Then("the zaak is not cancelled in ZGW")]
+    public void ThenTheZaakIsNotCancelled() => Assert.Null(_acl.CancelledZaakUrl);
 }

tests/acceptance/Support/InMemoryDomainPorts.cs

@@ -60,6 +60,14 @@ public sealed class InMemoryAclClient : IAclClient
         return Task.CompletedTask;
     }
 
+    public Uri? CancelledZaakUrl { get; private set; }
+
+    public Task CancelZaakAsync(Uri zaakUrl, CancellationToken ct = default)
+    {
+        CancelledZaakUrl = zaakUrl;
+        return Task.CompletedTask;
+    }
+
     public (Uri ZaakUrl, string FileName)? StoredDiploma { get; private set; }
 
     public Task<Uri> StoreDiplomaAsync(Uri zaakUrl, byte[] content, string fileName, string contentType, CancellationToken ct = default)

tests/acceptance/Support/InMemoryZaakGateway.cs

@@ -12,6 +12,7 @@ public sealed class InMemoryZaakGateway : IZaakGateway
 
     public ZaakRequest? Captured { get; private set; }
     public (Uri Zaak, Uri Zaaktype, DateOnly Datum)? Approved { get; private set; }
+    public (Uri Zaak, Uri Zaaktype, DateOnly Datum)? Cancelled { get; private set; }
 
     public Task<Uri> OpenZaakAsync(ZaakRequest request, CancellationToken ct = default)
     {
@@ -25,6 +26,12 @@ public sealed class InMemoryZaakGateway : IZaakGateway
         return Task.CompletedTask;
     }
 
+    public Task SetZaakToCancellationStatusAsync(Uri zaakUrl, Uri zaaktypeUrl, DateOnly datumStatusGezet, CancellationToken ct = default)
+    {
+        Cancelled = (zaakUrl, zaaktypeUrl, datumStatusGezet);
+        return Task.CompletedTask;
+    }
+
     public Task<string> GetZaakIdentificatieAsync(Uri zaakUrl, CancellationToken ct = default)
         => Task.FromResult("ACC-REF-1");