feat(acl): resolve the zaaktype by identificatie, not a pinned URL (S-27, closes #113) (#118)

## What & why

The ACL was handed a **pinned zaaktype URL** (`Acl__Defaults__ZaaktypeUrl`) + informatieobjecttype URL. OpenZaak assigns those UUIDs at creation, so every stack had to seed the catalogus and then capture + inject the resulting URLs out of band (CI's `run-domain-check.sh`; the local `local-seed`→`acl.env` bootstrap from ADR-0020). Brittle, and a stale/placeholder URL failed opaquely (OpenZaak 400).

Now **the ACL resolves them itself** from OpenZaak's Catalogi API by stable business key:
- config `ZaaktypeIdentificatie` (`BIG-REGISTRATIE`) / `InformatieobjecttypeOmschrijving` (`Diploma`);
- a `CachedZaaktypeCatalog` resolves **lazily on first use** and caches (success only, so a pre-publish miss is retried — no startup ordering coupling);
- a clear "No published … found" error replaces the opaque placeholder 400.

Design in **ADR-0021** (proposed in #117).

Closes #113
Closes #117

## Consequences (the payoff)

No stack captures/injects a server-assigned URL any more — `docker-compose.yml`/`.local.yml`, `run-domain-check.sh` and `local-seed` all drop it; the local `acl.env` shrinks to a single line.

**One thing S-27 can't remove** (confirmed empirically during this work): OpenZaak validates the `zaaktype` field on zaak-create with Django's URLValidator and **rejects a single-label host** (`http://openzaak:8000/…` → `zaaktype: bad-url`). So the ACL's **base URL** must still point at a URL-valid host (a container IP); that base-URL injection from ADR-0020 stays (local `acl.env` now carries only it; CI keeps `ACL_OPENZAAK_BASEURL`). ADR-0021 records this.

## Definition of Done

- [x] Linked issues (#113 slice, #117 adr-proposal).
- [x] TDD — resolver + gateway-lookup unit tests, updated `AclService` tests (50 unit tests green).
- [x] Implementation makes them pass; refactor of both compose stacks + verify scripts follows.
- [x] Conventional Commits referencing #113.
- [ ] CI green — see below.
- [x] `docker compose up` reaches green health — verified: fresh `make local` + `make verify-local` green with **no zaaktype-URL injection**; `acl.env` is base-URL-only.
- [x] Docs — ADR-0021 + demo-script S-27 note.
- [x] ADR added (ADR-0021).
- [x] Demo note appended.

## Verification done locally

- **50 unit tests** pass (resolver resolve/cache/retry-on-failure; gateway match/miss/blank-key; all `AclService` paths).
- **6 ACL integration tests** pass against a live seeded OpenZaak — incl. resolving the zaaktype + Diploma iot by business key, and a clear error for an unknown identificatie.
- **Fresh `make local` + `make verify-local`**: full flow (submit → werkbak → openbaar) green; `acl.env` = `Acl__OpenZaak__BaseUrl` only.
- `make lint` clean; ACL mutation ratchet run locally (see checks).

## Notes for reviewers

- `IZaakGateway` gains two resolve methods; `AclService` depends on the new `IZaaktypeCatalog` (singleton, so the cache persists).
- Supersedes the pinned-URL mechanism; ADR-0021 documents that ADR-0020's `seed-env`/entrypoint shim are **simplified** (base-URL only), not deleted, because of the URLValidator constraint above.

Reviewed-on: #118

services/acl/Acl.Application/AclDefaults.cs

@@ -6,9 +6,12 @@ public sealed class AclDefaults
     public required string Bronorganisatie { get; init; }
     public required string VerantwoordelijkeOrganisatie { get; init; }
     public required string Vertrouwelijkheidaanduiding { get; init; }
-    public required Uri ZaaktypeUrl { get; init; }
 
-    /// <summary>The informatieobjecttype an uploaded diploma is filed under (S-10b). Seeded in the
-    /// catalogus and injected like <see cref="ZaaktypeUrl"/>.</summary>
-    public required Uri InformatieobjecttypeUrl { get; init; }
+    /// <summary>The BIG zaaktype's stable business key. The ACL resolves the (server-assigned) zaaktype
+    /// URL from this via the Catalogi API instead of being handed a pinned URL (S-27, ADR-0021).</summary>
+    public required string ZaaktypeIdentificatie { get; init; }
+
+    /// <summary>The omschrijving of the informatieobjecttype an uploaded diploma is filed under (S-10b);
+    /// resolved to a URL by the Catalogi API, like <see cref="ZaaktypeIdentificatie"/>.</summary>
+    public required string InformatieobjecttypeOmschrijving { get; init; }
 }

services/acl/Acl.Application/AclService.cs

@@ -2,9 +2,9 @@ namespace Acl.Application;
 
 /// <summary>The ACL's single operation: open a zaak from a domain payload,
 /// default-filling the ZGW-mandatory fields (ADR-0003).</summary>
-public sealed class AclService(IZaakGateway gateway, AclDefaults defaults, IClock clock)
+public sealed class AclService(IZaakGateway gateway, AclDefaults defaults, IZaaktypeCatalog catalog, IClock clock)
 {
-    public Task<Uri> OpenZaakAsync(DomainRegistration registration, CancellationToken ct = default)
+    public async Task<Uri> OpenZaakAsync(DomainRegistration registration, CancellationToken ct = default)
     {
         ArgumentNullException.ThrowIfNull(registration);
 
@@ -12,34 +12,34 @@ public sealed class AclService(IZaakGateway gateway, AclDefaults defaults, ICloc
             defaults.Bronorganisatie,
             defaults.VerantwoordelijkeOrganisatie,
             defaults.Vertrouwelijkheidaanduiding,
-            defaults.ZaaktypeUrl,
+            await catalog.GetZaaktypeUrlAsync(ct),
             clock.Today,
             registration.Reference);
 
-        return gateway.OpenZaakAsync(request, ct);
+        return await gateway.OpenZaakAsync(request, ct);
     }
 
     /// <summary>
-    /// Approve a zaak: set it to the eindstatus of the configured BIG zaaktype (ADR-0003 default). The
-    /// domain hands over only the zaak URL; the ACL owns which statustype means "approved" (§8.1).
+    /// Approve a zaak: set it to the eindstatus of the BIG zaaktype (resolved by identificatie, S-27).
+    /// The domain hands over only the zaak URL; the ACL owns which statustype means "approved" (§8.1).
     /// </summary>
-    public Task ApproveZaakAsync(Uri zaakUrl, CancellationToken ct = default)
+    public async Task ApproveZaakAsync(Uri zaakUrl, CancellationToken ct = default)
     {
         ArgumentNullException.ThrowIfNull(zaakUrl);
 
-        return gateway.SetZaakToEindstatusAsync(zaakUrl, defaults.ZaaktypeUrl, clock.Today, ct);
+        await gateway.SetZaakToEindstatusAsync(zaakUrl, await catalog.GetZaaktypeUrlAsync(ct), 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
+    /// Cancel a zaak on document-timeout expiry (S-10c): set it to the 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)
+    public async Task CancelZaakAsync(Uri zaakUrl, CancellationToken ct = default)
     {
         ArgumentNullException.ThrowIfNull(zaakUrl);
 
-        return gateway.SetZaakToCancellationStatusAsync(zaakUrl, defaults.ZaaktypeUrl, clock.Today, ct);
+        await gateway.SetZaakToCancellationStatusAsync(zaakUrl, await catalog.GetZaaktypeUrlAsync(ct), clock.Today, ct);
     }
 
     /// <summary>The zaak's reference (its ZGW identificatie), for the read projection (#78).</summary>
@@ -56,7 +56,7 @@ public sealed class AclService(IZaakGateway gateway, AclDefaults defaults, ICloc
     /// and hand the file to the gateway, which creates the informatieobject and relates it to the zaak.
     /// The domain supplies only the zaak, the bytes, and the file's name/type (§8.1).
     /// </summary>
-    public Task<Uri> StoreDiplomaAsync(Uri zaakUrl, byte[] content, string fileName, string contentType, CancellationToken ct = default)
+    public async Task<Uri> StoreDiplomaAsync(Uri zaakUrl, byte[] content, string fileName, string contentType, CancellationToken ct = default)
     {
         ArgumentNullException.ThrowIfNull(zaakUrl);
         ArgumentNullException.ThrowIfNull(content);
@@ -65,7 +65,7 @@ public sealed class AclService(IZaakGateway gateway, AclDefaults defaults, ICloc
 
         var request = new DocumentRequest(
             defaults.Bronorganisatie,
-            defaults.InformatieobjecttypeUrl,
+            await catalog.GetInformatieobjecttypeUrlAsync(ct),
             defaults.Vertrouwelijkheidaanduiding,
             zaakUrl,
             clock.Today,
@@ -76,6 +76,6 @@ public sealed class AclService(IZaakGateway gateway, AclDefaults defaults, ICloc
             Formaat: contentType,
             Inhoud: content);
 
-        return gateway.StoreDocumentAsync(request, ct);
+        return await gateway.StoreDocumentAsync(request, ct);
     }
 }

services/acl/Acl.Application/CachedZaaktypeCatalog.cs

@@ -0,0 +1,46 @@
+namespace Acl.Application;
+
+/// <summary>Resolves the zaaktype + diploma-informatieobjecttype URLs from the Catalogi API on first
+/// use and caches them for the process lifetime (S-27, ADR-0021). Lazy (not at startup) so the ACL
+/// never crash-loops when it boots before the catalogus is seeded/published; a <em>failed</em>
+/// resolution is not cached, so it is retried on the next call (e.g. once the zaaktype is published).
+/// A process restart re-resolves.</summary>
+public sealed class CachedZaaktypeCatalog(IZaakGateway gateway, AclDefaults defaults) : IZaaktypeCatalog
+{
+    private readonly SemaphoreSlim gate = new(1, 1);
+    private Uri? zaaktype;
+    private Uri? informatieobjecttype;
+
+    public Task<Uri> GetZaaktypeUrlAsync(CancellationToken ct = default) =>
+        ResolveOnceAsync(
+            () => zaaktype, value => zaaktype = value,
+            () => gateway.ResolveZaaktypeUrlAsync(defaults.ZaaktypeIdentificatie, ct), ct);
+
+    public Task<Uri> GetInformatieobjecttypeUrlAsync(CancellationToken ct = default) =>
+        ResolveOnceAsync(
+            () => informatieobjecttype, value => informatieobjecttype = value,
+            () => gateway.ResolveInformatieobjecttypeUrlAsync(defaults.InformatieobjecttypeOmschrijving, ct), ct);
+
+    // Double-checked, single-flight resolution: return the cache if set; otherwise resolve under the
+    // gate and cache only on success (a throw leaves the cache empty so the next call retries).
+    private async Task<Uri> ResolveOnceAsync(Func<Uri?> read, Action<Uri> store, Func<Task<Uri>> resolve, CancellationToken ct)
+    {
+        if (read() is { } cached)
+            return cached;
+
+        await gate.WaitAsync(ct);
+        try
+        {
+            if (read() is { } existing)
+                return existing;
+
+            var resolved = await resolve();
+            store(resolved);
+            return resolved;
+        }
+        finally
+        {
+            gate.Release();
+        }
+    }
+}

services/acl/Acl.Application/IZaakGateway.cs

@@ -32,4 +32,12 @@ public interface IZaakGateway
     /// the created informatieobject.
     /// </summary>
     Task<Uri> StoreDocumentAsync(DocumentRequest request, CancellationToken ct = default);
+
+    /// <summary>Resolve the URL of the published zaaktype with the given <paramref name="identificatie"/>
+    /// from the Catalogi API (S-27). Throws if no published zaaktype matches.</summary>
+    Task<Uri> ResolveZaaktypeUrlAsync(string identificatie, CancellationToken ct = default);
+
+    /// <summary>Resolve the URL of the published informatieobjecttype with the given
+    /// <paramref name="omschrijving"/> from the Catalogi API (S-27). Throws if none matches.</summary>
+    Task<Uri> ResolveInformatieobjecttypeUrlAsync(string omschrijving, CancellationToken ct = default);
 }

services/acl/Acl.Application/IZaaktypeCatalog.cs

@@ -0,0 +1,12 @@
+namespace Acl.Application;
+
+/// <summary>Supplies the ACL's zaaktype + diploma-informatieobjecttype URLs, resolved from OpenZaak's
+/// Catalogi API by their stable business keys (<see cref="AclDefaults.ZaaktypeIdentificatie"/> /
+/// <see cref="AclDefaults.InformatieobjecttypeOmschrijving"/>) rather than pinned in config (S-27,
+/// ADR-0021). Implementations resolve lazily on first use and cache the result.</summary>
+public interface IZaaktypeCatalog
+{
+    Task<Uri> GetZaaktypeUrlAsync(CancellationToken ct = default);
+
+    Task<Uri> GetInformatieobjecttypeUrlAsync(CancellationToken ct = default);
+}