docs(arch): ADR-0008 read projection store + demo note for the event path (refs #7)

ADR-0008 records the read-projection design: one rebuildable store shared by the Event
Subscriber (writer) and projection-api (reader) as one CQRS bounded context (reconciled
with §8.5), idempotency + rebuild from the notification log (no OpenZaak access, §8.1),
the deferred bsn/naam, and the new EF Core + Npgsql dependency. Add a demo-script entry
walking the OZ→NRC→subscriber→projection-api path and wire both into the MkDocs nav.

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

.config/dotnet-tools.json

@@ -0,0 +1,20 @@
+{
+  "version": 1,
+  "isRoot": true,
+  "tools": {
+    "dotnet-stryker": {
+      "version": "4.15.0",
+      "commands": [
+        "dotnet-stryker"
+      ],
+      "rollForward": false
+    },
+    "dotnet-ef": {
+      "version": "10.0.0",
+      "commands": [
+        "dotnet-ef"
+      ],
+      "rollForward": false
+    }
+  }
+}

.gitea/workflows/ci.yaml

@@ -43,14 +43,55 @@ jobs:
           dotnet-version: '10.0.x'
       - run: make unit
 
-  compose-smoke:
+  mutation:
     runs-on: ubuntu-latest
     steps:
       - uses: https://github.com/actions/checkout@v4
-      - run: make smoke
-      - name: dump container logs on failure
+      - uses: https://github.com/actions/setup-dotnet@v4
+        with:
+          dotnet-version: '10.0.x'
+      - run: make mutation
+      # Publish the Stryker HTML report. `if: always()` uploads it even when the
+      # ratchet fails — that is exactly when you want to inspect the survivors.
+      # Glob handles Stryker's non-deterministic StrykerOutput/<timestamp>/ dir.
+      # Pinned to @v3 deliberately: @v4 refuses to run on Gitea (GHES guard) —
+      # see docs/runbooks/gitea-actions-gotchas.md §4.
+      - uses: https://github.com/actions/upload-artifact@v3
+        if: always()
+        with:
+          name: acl-mutation-report
+          path: services/acl/StrykerOutput/**/reports/mutation-report.html
+          if-no-files-found: warn
+      - uses: https://github.com/actions/upload-artifact@v3
+        if: always()
+        with:
+          name: event-subscriber-mutation-report
+          path: services/event-subscriber/StrykerOutput/**/reports/mutation-report.html
+          if-no-files-found: warn
+
+  # One stage for every check that needs the live stack. On the single self-hosted
+  # runner jobs run sequentially, so booting OpenZaak once (instead of once per job)
+  # is the cheapest layout (issue #58). No setup-dotnet: the ACL test runs in a built
+  # image and everything reaches services by container IP. Needs Docker + egress
+  # (base images, nuget, selectielijst.openzaak.nl).
+  verify-stack:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: https://github.com/actions/checkout@v4
+      # Bring the full stack up + wait for health — this also is the DoD "compose up
+      # reaches green health" smoke (it replaces the old compose-smoke job).
+      - name: Bring up the full stack & wait for health
+        run: make verify-up
+      - name: ACL ↔ OpenZaak integration tests
+        run: make verify-acl
+      - name: OpenZaak → NRC notification delivery
+        run: make verify-nrc
+      - name: OpenZaak → NRC → Event Subscriber → projection-api
+        run: make verify-projection
+      # Log dump must precede teardown (which removes the containers).
+      - name: Dump container logs on failure
         if: failure()
-        run: docker compose -f infra/docker-compose.yml logs --no-color --tail=80 oz-init openzaak nrc-init nrc-web flowable-init keycloak acl bff 2>&1 || true
-      - name: tear down on failure
-        if: failure()
-        run: docker compose -f infra/docker-compose.yml down --volumes 2>&1 || true
+        run: docker compose -f infra/docker-compose.yml logs --no-color --tail=100 oz-init openzaak nrc-init nrc-web nrc-celery nrc-beat flowable-init keycloak acl bff projection-db event-subscriber projection-api 2>&1 || true
+      - name: Tear down
+        if: always()
+        run: make down

.gitignore

@@ -15,6 +15,9 @@ coverage*.json
 coverage*.xml
 *.coverage
 
+# Stryker.NET mutation-testing reports (regenerated by `make mutation`)
+StrykerOutput/
+
 # Rider / VS / VS Code
 .idea/
 .vs/

Makefile

@@ -10,7 +10,7 @@ COMPOSE    := infra/docker-compose.yml
 # Long-running services with a healthcheck — the smoke polls these for readiness
 # (infra/wait-healthy.sh). One-shot init jobs (oz-init, nrc-init, flowable-init)
 # are not polled; they only need to have run. See docs/runbooks/gitea-actions-gotchas.md.
-WAIT_SVCS  := openzaak nrc-web acl bff
+WAIT_SVCS  := openzaak nrc-web acl bff event-subscriber projection-api
 # Config files (OpenZaak data.yaml, Keycloak realms, Flowable BPMN) are streamed
 # into external named volumes via `docker cp` (infra/seed-config.sh) instead of
 # bind-mounted, because bind mounts don't reach sibling containers on the
@@ -18,7 +18,7 @@ WAIT_SVCS  := openzaak nrc-web acl bff
 # volumes are `external`, so compose won't remove them — CFG_VOLS lists them for
 # explicit teardown. See docs/runbooks/gitea-actions-gotchas.md.
 SEED       := bash infra/seed-config.sh
-CFG_VOLS   := rr-oz-config rr-kc-realms rr-fl-bpmn
+CFG_VOLS   := rr-oz-config rr-nrc-config rr-kc-realms rr-fl-bpmn
 # Local-only stack: same services but config is bind-mounted (no seed step), so a
 # plain `docker compose -f infra/docker-compose.local.yml up` works on any local
 # engine. This is the no-make / Windows-friendly path. See that file's header.
@@ -43,10 +43,11 @@ export DOCKER_HOST := unix://$(PODMAN_SOCK)
 endif
 endif
 
-.PHONY: ci lint build unit smoke up down local local-down changelog openzaak-up openzaak-smoke openzaak-seed openzaak-down stack-up stack-smoke stack-down keycloak-up keycloak-smoke keycloak-down flowable-up flowable-smoke flowable-down help
+.PHONY: ci lint build unit mutation integration verify verify-up verify-acl verify-nrc verify-projection verify-notifications smoke up down local local-down changelog openzaak-up openzaak-smoke openzaak-seed openzaak-down stack-up stack-smoke stack-down keycloak-up keycloak-smoke keycloak-down flowable-up flowable-smoke flowable-down help
 
-## ci: run the full pipeline — lint, build, unit, smoke (mirrors Gitea Actions)
-ci: lint build unit smoke
+## ci: run the full pipeline — lint, build, unit, mutation, verify (mirrors Gitea Actions)
+## `verify` is the live-stack stage (full stack up once → ACL + notification checks).
+ci: lint build unit mutation verify
 
 ## lint: verify formatting (no changes)
 lint:
@@ -56,9 +57,19 @@ lint:
 build:
 	dotnet build $(SLN) -c Release
 
-## unit: run unit tests
+## unit: run unit tests (excludes the container-backed Integration lane)
 unit:
-	dotnet test $(SLN) -c Release
+	dotnet test $(SLN) -c Release --filter "Category!=Integration"
+
+## mutation: run the Stryker.NET ratchet on each service with branching logic (fails below baseline)
+# Stryker is pinned as a local dotnet tool (.config/dotnet-tools.json); `tool restore`
+# makes `make mutation` work from a fresh clone. Each service owns its config + break
+# threshold (the ratchet, CLAUDE.md §5): services/acl/stryker-config.json and
+# services/event-subscriber/stryker-config.json. Scores never regress below baseline.
+mutation:
+	dotnet tool restore
+	cd services/acl && dotnet stryker
+	cd services/event-subscriber && dotnet stryker
 
 ## smoke: seed config, bring the whole stack up, wait for health-checked services, tear down
 # SEED populates the external config volumes first (upstream images used verbatim;
@@ -68,14 +79,14 @@ unit:
 # podman-compose, and needing no `--wait` flag or host port access. The one-shots
 # (oz-init, flowable-init) aren't polled; they just need to have run.
 smoke:
-	$(SEED) oz kc fl
+	$(SEED) oz nrc kc fl
 	docker compose -f $(COMPOSE) up -d --build
 	bash -c 'WAIT_TIMEOUT=420 bash infra/wait-healthy.sh $(WAIT_SVCS); rc=$$?; docker compose -f $(COMPOSE) down --volumes; docker volume rm -f $(CFG_VOLS) >/dev/null 2>&1; exit $$rc'
 
 ## up: seed config volumes and start the full stack (use instead of bare
 ## `docker compose up`, which can't self-seed the external config volumes)
 up:
-	$(SEED) oz kc fl
+	$(SEED) oz nrc kc fl
 	docker compose -f $(COMPOSE) up -d --build
 
 ## down: stop and remove the local stack (incl. the external config volumes)
@@ -97,6 +108,54 @@ local-down:
 changelog:
 	git-cliff --output CHANGELOG.md
 
+# ── ZGW verification ───────────────────────────────────────────────────────
+# On the single runner CI jobs run sequentially, so the OpenZaak-dependent checks
+# share ONE full-stack bring-up: the `verify-stack` CI job runs `verify-up` then
+# `verify-acl` + `verify-nrc` as steps against the same stack (issue #58). The
+# check logic lives in stack-agnostic runners that reach services by container IP
+# (gitea-actions-gotchas.md §5/§6); `integration` / `verify-notifications` are local
+# convenience wrappers that bring up a lighter stack and call the same runners.
+
+## verify-up: bring the FULL stack up and wait for health (CI verify-stack step 1;
+## subsumes the old compose-smoke health gate — the DoD "up reaches green" check).
+verify-up:
+	$(SEED) oz nrc kc fl
+	docker compose -f $(COMPOSE) up -d --build
+	WAIT_TIMEOUT=420 bash infra/wait-healthy.sh $(WAIT_SVCS)
+
+## verify-acl: ACL ↔ OpenZaak integration tests against the already-running stack.
+verify-acl:
+	bash infra/run-acl-integration.sh
+
+## verify-nrc: OpenZaak → NRC notification delivery against the already-running stack.
+verify-nrc:
+	bash infra/run-notification-check.sh
+
+## verify-projection: OpenZaak → NRC → Event Subscriber → projection-api end-to-end (S-06),
+## against the already-running stack.
+verify-projection:
+	bash infra/run-projection-check.sh
+
+## verify: local mirror of the CI verify-stack job — full stack up once, all checks,
+## tear down (always). For fast single-concern local iteration use `integration`
+## (oz-only) or `verify-notifications` (oz+nrc) instead.
+verify:
+	$(SEED) oz nrc kc fl
+	docker compose -f $(COMPOSE) up -d --build
+	@bash -c 'set -e; rc=0; \
+	  WAIT_TIMEOUT=420 bash infra/wait-healthy.sh $(WAIT_SVCS) \
+	    && bash infra/run-acl-integration.sh \
+	    && bash infra/run-notification-check.sh \
+	    && bash infra/run-projection-check.sh || rc=$$?; \
+	  docker compose -f $(COMPOSE) down --volumes >/dev/null 2>&1; \
+	  docker volume rm -f $(CFG_VOLS) >/dev/null 2>&1; \
+	  exit $$rc'
+
+## integration: local convenience — ACL integration test against a throwaway
+## OpenZaak-only stack (fast iteration). CI uses verify-acl on the shared stack.
+integration:
+	bash infra/run-integration.sh
+
 ## openzaak-up: start the OpenZaak stack (migrations run on first start)
 openzaak-up:
 	$(SEED) oz
@@ -129,10 +188,16 @@ openzaak-down:
 	docker compose -f $(OZ_COMPOSE) down --volumes
 	-docker volume rm -f rr-oz-config
 
-## stack-up: start OpenZaak + Open Notificaties together (shared network)
+## verify-notifications: local convenience — OpenZaak → NRC notification delivery
+## against a throwaway oz+nrc stack (S-01-c). CI uses verify-nrc on the shared stack.
+verify-notifications:
+	bash infra/verify-notifications.sh
+
+## stack-up: start OpenZaak + Open Notificaties together (shared network), with
+## OpenZaak publishing notifications to NRC (S-01-c).
 stack-up:
-	$(SEED) oz
-	docker compose $(STACK_FILES) up -d
+	$(SEED) oz nrc
+	OZ_NOTIFICATIONS_DISABLED=false docker compose $(STACK_FILES) up -d
 
 ## stack-smoke: start both, assert OpenZaak (403/302/200) and NRC (302) are reachable
 stack-smoke: stack-up
@@ -151,7 +216,7 @@ stack-smoke: stack-up
 ## stack-down: stop and remove both stacks (wipes data)
 stack-down:
 	docker compose $(STACK_FILES) down --volumes
-	-docker volume rm -f rr-oz-config
+	-docker volume rm -f rr-oz-config rr-nrc-config
 
 ## keycloak-up: start Keycloak with the four imported realms
 keycloak-up:

docs/architecture/adr-0005-mutation-testing.md

@@ -0,0 +1,68 @@
+# ADR-0005: Stryker.NET for mutation testing, baseline on the ACL
+
+- **Status:** Accepted
+- **Date:** 2026-06-25
+- **Deciders:** Respellion engineering
+- **Relates to:** S-04b (#47); proposed in #51; supports CLAUDE.md §5 (mutation ratchet) and §3 (Definition of Done)
+
+## Context
+
+CLAUDE.md §5 mandates Stryker on every PR with a **ratchet**: CI fails on a regression
+below the established baseline, and the baseline only ever moves up. §3 lists "mutation
+(ratchet)" as a Definition-of-Done gate for **every** slice. Yet no baseline existed — so,
+strictly, no slice could satisfy that gate. S-04b establishes it.
+
+The ACL is the natural place to set the first baseline: it is the first service with real
+branching logic — `OpenZaakGateway` (HTTP contract, geo CRS headers, error handling),
+`ZgwToken` (HS256 JWT minting), and the `AclService` default-fill mapping. We need a tool
+that:
+
+- mutates C# and runs the existing xUnit suite per mutant,
+- is reproducible (same version locally and in CI, no global install),
+- understands this repo's `.slnx` solution format (used repo-wide),
+- emits a break threshold CI can gate on.
+
+## Decision
+
+**Use [Stryker.NET](https://stryker-mutator.io/docs/stryker-net/) (`dotnet-stryker`),
+pinned as a local dotnet tool**, configured in solution mode against `Acl.slnx`.
+
+- Pinned in `.config/dotnet-tools.json` (v4.15.0); `dotnet tool restore` makes
+  `make mutation` reproducible from a fresh clone, locally and in CI — no global install.
+- **Solution mode** (`stryker-config.json` → `solution: Acl.slnx`) mutates the two projects
+  under test (`Acl.Application`, `Acl.Infrastructure`); `Acl.Api` is untested and skipped.
+  Stryker 4.15 reads `.slnx` directly, so no throwaway `.sln` shim is needed.
+- A `mutation` make target runs it; it is wired into `make ci` and a parallel Gitea Actions
+  `mutation` job, keeping `make ci` an exact mirror of the pipeline.
+
+**Baseline:** writing S-04b's tests surfaced that the ACL suite was thin — the initial
+score was **35%** (survivors: unasserted CRS headers, null guards, error paths, and JWT
+claims). Those tests were strengthened (killing the mutants honestly rather than lowering
+the bar), raising the score to **95%**. The enforced `break` threshold is set to **90%** —
+one-mutant headroom over the ~20-mutant surface, since a single mutant is ≈5%.
+
+## Consequences
+
+- **Positive:** test *strength* is gated, not just coverage; the ratchet protects the ACL's
+  ZGW contract logic; the baseline is repo-wide and ratchets upward per §5.
+- **Cost:** a new dependency (`dotnet-stryker`) and a slower CI job than unit tests (~25 s on
+  the small ACL). Pinned + tool-restored, so reproducible.
+- **One accepted survivor:** a mutation of the empty-response *exception message string*.
+  Asserting exception message text is brittle and the behaviour (type + control flow) is
+  unchanged — treated as an equivalent mutant, not a test gap.
+- **Commitment:** later slices ratchet the threshold up deliberately, never down (§5). New
+  services add their own mutation run as they gain branching logic (BFF, Domain, …).
+- **Replaceable by:** no realistic .NET alternative — Stryker.NET is the tool §5 already
+  names; the fallback is no mutation testing, which §5 forbids.
+
+## Alternatives considered
+
+- **Global `dotnet tool install -g`** — rejected: not reproducible/pinned per clone; the
+  local manifest gives every checkout and the CI runner the same version.
+- **Mutate the whole `register-referentie.slnx`** — rejected for this slice: scopes the
+  baseline to services with no logic yet (BFF skeleton), diluting the signal. Each service
+  opts in as it gains logic.
+- **Application-only scope** — rejected: would leave `Acl.Infrastructure`'s HTTP/JWT logic —
+  the riskiest code — unguarded by the ratchet.
+- **Coverage gate instead of mutation** — rejected: line coverage does not measure whether
+  tests would *catch* a regression; that is the whole point of §5.

docs/architecture/adr-0006-integration-test-provisioning.md

@@ -0,0 +1,92 @@
+# ADR-0006: Provision the ACL integration test against the compose stack
+
+- **Status:** Accepted
+- **Date:** 2026-06-29
+- **Deciders:** Respellion engineering
+- **Relates to:** S-04a (#46); proposed in #53; builds on ADR-0001 (loose coupling), ADR-0002 (catalogus design), ADR-0003 (default-fill); supports CLAUDE.md §11 (integration tests via real containers)
+
+## Context
+
+S-04 delivered the ACL's one operation — `OpenZaakGateway.OpenZaakAsync` — with unit
+tests against a stubbed `HttpMessageHandler` and a Reqnroll scenario over an in-memory
+stand-in. The deferred S-04 acceptance criterion (S-04a) is the one a stub cannot meet:
+
+> Integration test using Testcontainers against real OpenZaak passes.
+
+The test must drive the gateway against a **real** OpenZaak — real ZGW JWT auth, the real
+`POST /zaken/api/v1/zaken` contract, real CRS handling — and assert a zaak comes back.
+
+Two ways to stand OpenZaak up were considered (the issue's open question): (a) a full
+**Testcontainers** graph started by the test, or (b) target the **running compose stack**
+the repo already defines (`infra/openzaak/docker-compose.yml`, `make openzaak-up`).
+
+Investigation reversed the initially-favoured Testcontainers option:
+
+1. **Testcontainers .NET has no docker-compose support.** OpenZaak needs PostGIS + Redis +
+   a `setup_configuration` one-shot (the JWT client) + the API. Honouring "full graph" would
+   mean re-implementing that five-service stack — init ordering, the config volume, health
+   gating — by hand in C#, duplicating the maintained compose file and rotting with it. That
+   rubs against CLAUDE.md §13 ("if a test is hard to write, the design is wrong").
+2. **The test cannot be hermetic anyway.** OpenZaak's Zaken API rejects a zaak against a
+   *concept* zaaktype (`not-published`), and a *published* zaaktype requires ≥1 resultaattype,
+   which OpenZaak validates by fetching the external **Selectielijst** reference API
+   (`selectielijst.openzaak.nl`). So a real zaak POST already depends on outbound internet
+   from the OpenZaak container — the self-containment that motivated Testcontainers is lost
+   regardless of how the containers are started.
+
+## Decision
+
+**The ACL integration test targets the running compose stack; it does not start containers
+itself. No new test dependency is added.**
+
+- A gated test project `Acl.IntegrationTests` (`[Trait("Category","Integration")]`) talks to
+  OpenZaak with a plain `HttpClient`, reusing the same endpoint + JWT-client config the seed
+  uses (`OZ_BASE` / `OZ_CLIENT_ID` / `OZ_SECRET`, defaulting to the local stack). It locates
+  the published `BIG-REGISTRATIE` zaaktype via the Catalogi API and exercises the real
+  `OpenZaakGateway` against it.
+- **The lane is kept out of the fast checks.** `make unit` runs with
+  `--filter "Category!=Integration"`; Stryker is pinned to `Acl.Tests` (`test-projects`), so
+  neither the unit nor the mutation lane needs a live stack. A `make integration` target
+  (`infra/run-integration.sh`) brings up a throwaway OpenZaak and runs the lane locally.
+  In CI the check runs as the `verify-acl` step of the consolidated `verify-stack` job
+  (issue #58) — one shared full-stack bring-up. This matches `make` being the single
+  source of truth (ADR-0005).
+- **Publishing is opt-in in the seed.** `infra/openzaak/seed_catalogus.py` gains an
+  `OZ_PUBLISH=1` path that adds the relations OpenZaak's publish requires — two statustypen
+  (begin/eind), a roltype, and a resultaattype whose Selectielijst procestype is matched onto
+  the zaaktype — then publishes. The default seed (S-01 / ADR-0002) still leaves the zaaktype
+  a concept; only `make integration` flips the switch.
+
+## Consequences
+
+- **Positive:** a small, honest test over the real ZGW contract with no bespoke orchestration
+  to maintain; the compose stack is exercised exactly as operators run it; no new dependency.
+- **It caught a real bug.** The gateway sent the zaak body via `JsonContent` without a
+  `Content-Length`, so .NET framed it as `Transfer-Encoding: chunked`, which OpenZaak's uwsgi
+  rejects with 400. A stubbed handler accepts either framing, so only a real OpenZaak surfaced
+  it. Fixed by buffering the body (`LoadIntoBufferAsync`); guarded in the fast lane by a unit
+  test asserting a `Content-Length` is set. This is the concrete justification for §11's
+  integration tier.
+- **External dependency:** the integration job needs the OpenZaak container to reach
+  `selectielijst.openzaak.nl`. It is a stable public reference API (the same one OpenZaak uses
+  in production) but it is a network touchpoint, and a CI environment without egress would need
+  a local Selectielijst service or a recorded fixture. `OZ_SELECTIELIJST` overrides the base URL.
+- **Cost:** the lane needs the stack up first, so it is separate from the fast lanes.
+- **Runs on the hosted runner.** A process *on* the runner can't reach the stack's published
+  ports (Compose starts sibling containers via the host daemon — gitea-actions-gotchas.md §5,
+  same split as §1), so `infra/run-integration.sh` runs both the seed and the test as containers
+  *joined to the OpenZaak network*, reaching it by **container IP** (a single-label host like
+  `openzaak` isn't URL-valid for OpenZaak's own `URLValidator`; an IPv4 literal is). Code is
+  delivered by image build / `docker cp`, never bind mounts. The CI job therefore needs only
+  Docker — no `setup-dotnet`. (This closed the follow-up that was originally split out as #55.)
+
+## Alternatives considered
+
+- **Full Testcontainers graph** — rejected: re-implements the compose stack in C# (brittle,
+  duplicative) for no hermeticity gain, since the Selectielijst dependency remains.
+- **Single OpenZaak container (sqlite/locmem)** — rejected: diverges from the real
+  PostGIS-backed, Redis-cached deployment; the Zaken API is a geo API and the divergence would
+  undermine the contract the test exists to verify.
+- **Mock OpenZaak / record-replay** — rejected: that is what the existing stubbed-handler unit
+  tests already do; it cannot exercise the real contract, and would not have caught the chunked
+  body bug.

docs/architecture/adr-0007-notification-wiring.md

@@ -0,0 +1,77 @@
+# ADR-0007: Wiring OpenZaak → Open Notificaties (NRC) for notifications
+
+- **Status:** Accepted
+- **Date:** 2026-06-29
+- **Deciders:** Respellion engineering
+- **Relates to:** S-01-c (#56); completes S-01 (#2); unblocks the Event Subscriber (#7); builds on ADR-0002 (catalogus/seed) and ADR-0006 (runner-safe container harnesses)
+
+## Context
+
+S-01 brought OpenZaak + Open Notificaties (NRC) up in compose but **deferred the
+notification wiring**: OpenZaak ran with `NOTIFICATIONS_DISABLED=true` and NRC's
+`setup_configuration` was empty. The walking skeleton (PRD §12) needs the upstream
+event path — a zaak created in OpenZaak must publish a notification NRC fans out to
+subscribers — before the Event Subscriber (#7) can consume it.
+
+The OpenZaak↔NRC handshake is intricate and several details are non-obvious; they
+were nailed down by iterating `setup_configuration` against the running stack.
+
+## Decision
+
+**Provision both sides declaratively via `setup_configuration`, authenticate with the
+existing `big-reference-seed` client, and run NRC's celery-beat so deliveries happen.**
+
+- **OpenZaak** (`infra/openzaak/setup_configuration/data.yaml`): a `zgw_consumers`
+  service `nrc` (api_type `nrc`, the NRC API root) plus `notifications_config` naming
+  it. `NOTIFICATIONS_DISABLED` is flipped to `false` **only when NRC is present** —
+  the full stack and the local twin set it; OpenZaak-only bring-ups (`openzaak-up`,
+  the ACL integration test) default it back to `true` via `OZ_NOTIFICATIONS_DISABLED`
+  so they don't 500 publishing to an absent NRC.
+- **NRC** (`infra/opennotificaties/setup_configuration/data.yaml`): the
+  `big-reference-seed` JWT credential (to verify OpenZaak's token), a `zgw_consumers`
+  `ac` service pointing at **OpenZaak's Autorisaties API**, the `autorisaties_api`
+  step delegating authorization to that AC, and the `zaken` kanaal. NRC's init
+  container switches from `migrate` to `/setup_configuration.sh`; its data.yaml is
+  delivered through the `rr-nrc-config` external volume by `infra/seed-config.sh`
+  (the same `docker cp` pattern as OpenZaak — bind mounts don't reach the CI runner's
+  daemon).
+- **celery-beat is required.** NRC accepts a notification and writes a
+  `ScheduledNotification`; a periodic `execute_notifications` task (celery-beat,
+  every `NOTIFICATION_SEC_INTERVAL`s) drains it to the worker for delivery. The lean
+  S-01 stack dropped beat — so notifications were accepted but never delivered. An
+  `nrc-beat` service is added to every compose; the interval is lowered to 5s.
+
+Verification is a runner-safe smoke (`infra/run-notification-check.sh`): it seeds a
+published BIG zaaktype, registers an abonnement to a webhook sink, creates a zaak, and
+asserts the sink receives the `zaken`/`create` notification — all from containers
+**inside** the compose network (ADR-0006). Locally it runs via `make verify-notifications`
+(a throwaway oz+nrc stack); in CI it runs as the `verify-nrc` step of the consolidated
+`verify-stack` job (one shared full-stack bring-up — issue #58).
+
+## Consequences
+
+- **Positive:** the walking-skeleton event path works end to end; #7 can consume real
+  notifications; the wiring is declarative and reproducible from a fresh `make`.
+- **Gotchas captured (see gitea-actions-gotchas.md):**
+  - **Single-label hosts aren't URL-valid.** OpenZaak/NRC reject `http://openzaak…`
+    /`http://nrc-web…` in URLs they validate (Django `URLValidator`); the verify
+    harness reaches services and registers the sink callback **by container IP**.
+  - **Abonnement callbacks must enforce auth.** NRC probes the callback during
+    registration and refuses it (`no-auth-on-callback-url`) unless it returns 401
+    without the configured `Authorization`; the sink enforces a bearer token.
+- **Cost:** an extra long-running service (`nrc-beat`) per stack, and the verify job
+  needs egress (base images + `selectielijst.openzaak.nl`, since the published
+  zaaktype the check creates a zaak against depends on it — ADR-0006).
+- **Dev-only credentials** reused (`big-reference-seed` / its secret) across publish,
+  AC lookup, and seeding — acceptable for the reference app, not production.
+
+## Alternatives considered
+
+- **NRC with its own (non-AC) authorization** — rejected: delegating to OpenZaak's
+  Autorisaties API is the upstream-intended model and reuses the applicatie that
+  already grants `heeft_alle_autorisaties`.
+- **Keep beat out, deliver synchronously** — not an option: Open Notificaties 1.16
+  delivers via scheduled notifications drained by beat; there is no sync path.
+- **A persistent abonnement in `setup_configuration`** instead of registering one in
+  the verify harness — deferred: the real subscriber is #7; the harness's sink
+  abonnement is throwaway and IP-specific.

docs/architecture/adr-0008-read-projection-store.md

@@ -0,0 +1,89 @@
+# ADR-0008: The read projection — a shared, rebuildable store with a writer and a reader
+
+- **Status:** Accepted
+- **Date:** 2026-06-30
+- **Deciders:** Respellion engineering
+- **Relates to:** S-06 (#7); builds on ADR-0001 (loose coupling), ADR-0007 (#56, OZ→NRC wiring); first EF Core usage in the repo
+
+## Context
+
+S-06 (#7) adds the upstream event path's destination: an **Event Subscriber** that consumes
+NRC notifications and a **read projection** the openbaar register reads. The walking-skeleton
+projection (PRD §8.4) holds one row per zaak — `id`, `bsn`, `naam_placeholder`, `status` —
+and must be **idempotent** (NRC redelivers and reorders, CLAUDE.md §8.6) and **rebuildable**
+(a derived artefact, never a write-only source of truth).
+
+Two design questions had no obvious answer:
+
+1. **Where does `bsn` come from?** The NRC `zaken`/`zaak`/`create` notification carries only the
+   zaak URL plus the fixed `kenmerken` (`bronorganisatie`, `zaaktype`, `vertrouwelijkheidaanduiding`).
+   It does **not** carry the bsn. Reading it means calling a ZGW API — which **only the ACL** may
+   do (CLAUDE.md §8.1). The issue's "Touches" lists only `event-subscriber` + `projection-api`,
+   not the ACL.
+2. **Who owns the projection schema?** The subscriber writes the projection; the projection-api
+   reads it. CLAUDE.md §8.5 says "no direct DB access across services; each service owns its
+   schema." Two deployables on one table looks like a violation.
+
+## Decision
+
+**One Postgres database is the read projection. The Event Subscriber writes it (projector) and
+the projection-api reads it (query); both are processes of the single "Read Projection" bounded
+context and share one schema, defined in a shared `Projection.ReadModel` library. `bsn` is
+deferred.**
+
+- **Schema ownership.** The read model — `register_projection` plus the subscriber's
+  `processed_notifications` log — lives in `services/projection-api/Projection.ReadModel`
+  (EF Core + Npgsql). Both services reference it. This is the textbook CQRS read-model split
+  (one writer, one reader over one derived store), **not** the cross-*domain* DB reach §8.5
+  forbids: no domain owns write-state here; the projection is rebuildable (§8.4). §8.5 still
+  holds for every domain database.
+- **Idempotency** is the primary key on `processed_notifications.key` (a deterministic key
+  derived from the immutable notification content). A duplicate insert raises a unique violation,
+  caught and reported as "already recorded", so the duplicate never reaches the projection. The
+  projection upsert is itself idempotent on the zaak id, a second line of defence.
+- **Rebuild replays the log, not OpenZaak.** `POST /admin/rebuild` clears `register_projection`
+  and reprojects every row in `processed_notifications`. So "rebuildable" needs **no** ZGW access
+  (§8.1) and no ACL dependency — keeping S-06 within its stated scope.
+- **`bsn` and `naam_placeholder` are deferred.** They are columns (nullable) but the minimal slice
+  populates only `id` + `status` (`INGEDIEND`) from the notification. Populating personal data
+  requires reading the zaak **through the ACL** (§8.1) and is its own follow-up; the column shape
+  is in place so that change is additive.
+- **New dependency: EF Core 10 + `Npgsql.EntityFrameworkCore.PostgreSQL`.** What it gives us: a
+  migrated relational schema, LINQ queries, and a clean port implementation. What we'd write
+  instead: hand-rolled SQL + a migration runner. Risk: ORM complexity and an extra dependency
+  graph — bounded here to a tiny two-table read model. `dotnet-ef` is pinned as a local tool for
+  migrations; `NuGetAuditMode=direct` keeps EF's design-time-only tooling transitive out of the
+  audited, shipped graph.
+
+The end-to-end path is verified by a runner-safe live-stack smoke (`infra/run-projection-check.sh`,
+the `verify-projection` step of the `verify-stack` job, #58): register an abonnement at the real
+Event Subscriber's callback, create a zaak, assert projection-api serves an `INGEDIEND` row — all
+in-network, reaching services by container IP (ADR-0006/0007).
+
+## Consequences
+
+- **Positive:** the upstream event path reaches a queryable projection; idempotent and rebuildable
+  without OpenZaak; S-06 stays inside its stated touch-set (no ACL change); the projection-api is
+  ready for S-09 to tighten public-safe field filtering.
+- **Negative / deferred:**
+  - `bsn`/`naam_placeholder` stay empty until a follow-up wires zaak reads via the ACL.
+  - The abonnement is registered by the verify harness (by container IP), not provisioned
+    persistently — ADR-0007 already deferred a persistent abonnement, and a single-label service
+    host is not URL-valid for NRC, so persistent registration needs a dotted network alias. Tracked
+    as a follow-up; a plain `make up` therefore needs the abonnement registered before the event
+    path flows.
+  - Two services share one database. Acceptable for a derived read model; revisit if the read and
+    write sides ever need independent scaling or storage.
+
+## Alternatives considered
+
+- **Subscriber reads OpenZaak directly to fill `bsn`** — rejected: breaks §8.1 (only the ACL talks
+  to ZGW) and would need its own ADR to bend the rule.
+- **Extend the ACL with a zaak-read operation, consumed as a library** — viable and §8.1-clean, but
+  it grows S-06 beyond its stated scope (touches the ACL) and pulls personal-data handling forward;
+  deferred to a follow-up.
+- **projection-api owns the DB and exposes an internal write endpoint the subscriber calls** —
+  rejected for the walking skeleton: adds an HTTP hop and a write surface on a read service for no
+  current benefit over a shared, rebuildable read model.
+- **Separate databases for the log and the projection** — rejected as premature: both are the read
+  side's private, rebuildable state; one DB is simpler and still honours §8.5's intent.

docs/demo-script.md

@@ -0,0 +1,35 @@
+# Demo script
+
+A running log of demoable outcomes, one section per slice. Each entry is a short,
+copy-pasteable walkthrough against a local `make up` stack.
+
+---
+
+## S-06 — Event Subscriber + read projection
+
+**Outcome:** a zaak created in OpenZaak flows through NRC to the Event Subscriber, which
+projects it into a rebuildable read projection the projection-api serves.
+
+**The path:** OpenZaak → (notification) NRC → (abonnement callback) Event Subscriber →
+`register_projection` → projection-api `GET /register`.
+
+```bash
+# 1. Bring the full stack up (seeds config, builds our services, waits for health).
+make up
+
+# 2. Register the Event Subscriber's abonnement and create a zaak, then read it back.
+#    (The verify-projection check does exactly this end-to-end and asserts the result.)
+make verify-projection            # → "OK — projection-api serves zaak <uuid> with status INGEDIEND"
+
+# 3. Observe the projection directly via the read API (host port 8120).
+curl -fsS http://localhost:8120/register | jq
+# → [ { "id": "<zaak-uuid>", "status": "INGEDIEND", "bsn": null, "naamPlaceholder": null } ]
+
+# 4. Idempotency + rebuild: replays don't duplicate; a rebuild repopulates from the
+#    notification log (no OpenZaak access needed — ADR-0008).
+curl -fsS -X POST http://localhost:8110/admin/rebuild   # Event Subscriber, host port 8110
+curl -fsS http://localhost:8120/register | jq 'length'  # → unchanged
+```
+
+> `bsn` / `naam_placeholder` are deferred (ADR-0008) — the notification doesn't carry them and
+> the subscriber may not read OpenZaak directly (§8.1). They surface in a later slice.

docs/runbooks/ci.md

@@ -15,14 +15,23 @@ and CI cannot drift:
 |---|---|---|
 | `lint` | `make lint` → `dotnet format … --verify-no-changes` | .NET 10 SDK |
 | `build` | `make build` → `dotnet build … -c Release` | .NET 10 SDK |
-| `unit` | `make unit` → `dotnet test … -c Release` | .NET 10 SDK |
-| `compose-smoke` | `make smoke` → seed config volumes → `up -d` (full stack) → `up --wait` durable services → `down` | container engine + compose v2 |
+| `unit` | `make unit` → `dotnet test … -c Release --filter "Category!=Integration"` | .NET 10 SDK |
+| `mutation` | `make mutation` → `dotnet tool restore` → `dotnet stryker` (ACL); uploads the HTML report as an artifact | .NET 10 SDK |
+| `verify-stack` | the single live-stack stage — steps: `make verify-up` (full stack up + health, the DoD smoke) → `make verify-acl` (ACL ↔ OpenZaak) → `make verify-nrc` (OpenZaak → NRC delivery) → `make down` | container engine + egress (base images, nuget, `selectielijst.openzaak.nl`) |
+
+> **Why one `verify-stack` job, not three.** The single self-hosted runner runs jobs
+> **sequentially**, so booting OpenZaak once (instead of once per check) is the
+> cheapest layout (issue #58). It subsumes the old `integration`, `notifications`, and
+> `compose-smoke` jobs — the bring-up step *is* the "compose up reaches green health"
+> gate. No `setup-dotnet`: the ACL test runs in a built image and every check reaches
+> services by **container IP** (the runner can't reach published ports — see
+> [gitea-actions-gotchas.md §5/§6](gitea-actions-gotchas.md)).
 
 All `uses:` references are absolute, tag-pinned URLs (`https://github.com/actions/checkout@v4`,
 `https://github.com/actions/setup-dotnet@v4`) per CLAUDE.md §8.7 and §15 — Gitea
 Actions resolves them from GitHub.
 
-> **`compose-smoke` runs on a containerized runner.** Workspace bind mounts do
+> **`verify-stack` runs on a containerized runner.** Workspace bind mounts do
 > **not** reach the sibling containers Compose starts, so config/assets are
 > streamed into external named volumes via `docker cp` (`infra/seed-config.sh`),
 > and the upstream images are used verbatim (no build). If you add a service that
@@ -30,6 +39,38 @@ Actions resolves them from GitHub.
 > bare `docker compose up` no longer self-seeds; use `make up`. See
 > [gitea-actions-gotchas.md](gitea-actions-gotchas.md).
 
+## Mutation testing (the ratchet)
+
+The `mutation` job enforces test *strength*, not just coverage (CLAUDE.md §5).
+[Stryker.NET](https://stryker-mutator.io/docs/stryker-net/) is pinned as a local
+dotnet tool (`.config/dotnet-tools.json`), so it runs identically locally and in CI:
+
+```bash
+make mutation     # dotnet tool restore + dotnet stryker on the ACL
+```
+
+Config lives in [`services/acl/stryker-config.json`](../../services/acl/stryker-config.json).
+It runs in **solution mode** against `Acl.slnx`, mutating the two projects under test
+(`Acl.Application`, `Acl.Infrastructure`); `Acl.Api` has no tests and is skipped.
+
+**Baseline (the ratchet):** the ACL is the first service with branching logic, so it
+sets the repo-wide baseline. Observed score **95%**; enforced `break` threshold **90%**
+(one-mutant headroom over the ~20-mutant surface). Stryker exits non-zero — failing the
+job — when the score drops below `break`. Per §5 the baseline only moves **up**, and only
+as a slice's stated outcome; never lower it. New services add their own mutation run as
+they gain logic.
+
+The HTML report is written to `services/acl/StrykerOutput/<timestamp>/reports/` (git-ignored);
+open it to see survived vs. killed mutants.
+
+In CI the `mutation` job publishes that report as the **`acl-mutation-report`** artifact
+(download it from the run's summary page). The upload step uses `if: always()`, so the
+report is available even when the ratchet *fails* — which is exactly when you want to inspect
+the survivors. It is the repo's first use of `actions/upload-artifact`, pinned to **`@v3`**:
+`@v4` refuses to run on Gitea (its `@actions/artifact` v2 library blocks any non-github.com
+server as "GHES"), while `@v3` speaks the artifact protocol Gitea implements. See
+[gitea-actions-gotchas.md §4](gitea-actions-gotchas.md) (§15).
+
 ## Running the stack locally without `make` (Windows / Docker Desktop)
 
 `make` and the bash helpers assume a Unix shell. To bring the whole stack up on a
@@ -52,14 +93,24 @@ the containerized CI runner). Keep the two files in sync.
 
 ## Running CI locally (`make ci`)
 
-Until the runner exists, run the full pipeline yourself before pushing:
+`make ci` runs the exact same checks as the pipeline — handy to run before pushing:
 
 ```bash
-make ci          # lint + build + unit + smoke — what the pipeline runs
+make ci          # lint + build + unit + mutation + verify — mirrors the pipeline
 make lint        # or a single stage
-make smoke       # compose up --wait, curl /health, tear down
+make mutation    # Stryker.NET ratchet on the ACL
+make verify      # the live-stack stage: full stack up once → ACL + NRC checks → down
 ```
 
+> **`make verify`** mirrors the CI `verify-stack` job: it boots the full stack once and
+> runs both the ACL ↔ OpenZaak and OpenZaak → NRC checks against it. For fast,
+> single-concern local iteration use a lighter throwaway stack instead:
+>
+> ```bash
+> make integration          # ACL ↔ OpenZaak only (no NRC)
+> make verify-notifications # OpenZaak → NRC delivery only
+> ```
+
 **Prerequisites:** .NET 10 SDK, a container engine with Compose v2, and `curl`.
 
 On a **rootless Podman** box (the default dev setup here), the `smoke` target needs

docs/runbooks/gitea-actions-gotchas.md

@@ -13,6 +13,7 @@ those containers share a filesystem — or a `localhost` — breaks.
 | Bind-mounted config arrives empty | `docker cp` config into external volumes | `infra/seed-config.sh` |
 | `docker compose up --wait` is unsupported / flaky | poll health with `docker inspect` | `infra/wait-healthy.sh` |
 | `pg_isready` passes before PostGIS is ready | add a `PostGIS_Version()` probe | the db healthchecks |
+| `upload-artifact@v4` fails ("not supported on GHES") | pin `@v3` | `.gitea/workflows/ci.yaml` (`mutation` job) |
 
 ---
 
@@ -98,3 +99,83 @@ plus app start.
 container that starts migrating in that window can fail on a missing PostGIS. So
 the db healthchecks add a `SELECT PostGIS_Version()` probe, making dependents wait
 for the extension, not just the port.
+
+---
+
+## 4. `actions/upload-artifact@v4` refuses to run on Gitea
+
+**Symptom** — the `mutation` job's `make mutation` step passes (95% score), but the
+upload step right after it fails the job:
+
+```
+::error::@actions/artifact v2.0.0+, upload-artifact@v4+ and download-artifact@v4+
+are not currently supported on GHES.
+❌  Failure - Main https://github.com/actions/upload-artifact@v4
+```
+
+**Why** — `upload-artifact@v4` bundles `@actions/artifact` v2, which inspects the
+server URL and **hard-aborts on anything that isn't `github.com`**, treating Gitea
+as an unsupported GitHub Enterprise Server. The check fires regardless of whether
+the Gitea server can actually store artifacts (1.24+ can). It is the *action*, not
+the server, that refuses.
+
+**Fix** — pin **`actions/upload-artifact@v3`** (and `download-artifact@v3` if ever
+needed). v3 uses the older artifact protocol that Gitea implements, and has no GHES
+guard. Inputs are the same (`name`, `path`, `if-no-files-found`), so it is a drop-in
+swap. Do **not** bump to `@v4` until act_runner advertises github.com-compatible
+artifact support.
+
+---
+
+## 5. A runner process can't reach a service container's published port
+
+**Symptom** — green locally, but a CI step that runs *on the runner* and talks to a
+compose service over `localhost` fails. The ACL integration test's seed died with:
+
+```
+OpenZaak ready (000)
+urllib.error.URLError: <urlopen error [Errno 111] Connection refused>
+make: *** [Makefile:114: integration] Error 1
+```
+
+OpenZaak was demonstrably up — uwsgi had been serving for ~2 minutes — yet
+`curl`/`urllib` to `localhost:8000` from the runner were refused the whole time.
+
+**Why** — the same sibling-container split as §1. Compose starts the stack via the
+host daemon, so `ports: ["8000:8000"]` publishes to the *daemon host*, not to the job
+container. From the runner, `localhost:8000` has nothing listening. (`make smoke`
+sidesteps this by polling readiness via `docker inspect` (§2), never a service port.)
+
+**Fix** — don't talk to service ports from the runner. Either check state via `docker
+inspect` (health), or run the client **inside the compose network** so it reaches the
+service by name (`http://openzaak:8000`). For a test/seed that needs the repo's own
+code, deliver it via a **built image** (not a bind mount — §1), then
+`docker run --network <stack>_cg …`.
+
+**Applied** — `make integration` (ADR-0006) and `make verify-notifications` (ADR-0007)
+do exactly this: they run the seed/test/driver as containers on the stack network and
+reach services by **container IP** (see §6).
+
+---
+
+## 6. OpenZaak / NRC reject single-label hosts in URLs
+
+**Symptom** — talking to OpenZaak or NRC by compose **service name** fails where a URL
+is validated: catalogus/zaaktype filters, the zaak `zaaktype` URL, and abonnement
+`callbackUrl` come back `400 "Voer een geldige URL in."` — even though the host
+resolves and is reachable.
+
+**Why** — these apps validate URLs with Django's `URLValidator`, which rejects a
+**single-label** host like `openzaak` or `nrc-web` (no dot, and not `localhost`).
+`localhost` passes (so it's invisible in host-port-based local runs); in-network the
+reality is a service name or an IPv4 literal — and only the IP passes.
+
+**Fix** — in-network tooling reaches OpenZaak/NRC by **container IP**
+(`docker inspect -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}'`), not
+service name; the notif verify harness also registers the sink callback by IP.
+(`infra/run-acl-integration.sh`, `infra/run-notification-check.sh`.)
+
+**Related — abonnement callbacks must enforce auth.** NRC probes a callback when an
+abonnement is registered and refuses it (`no-auth-on-callback-url`) unless it returns
+**401** without the configured `Authorization`. The verify sink
+(`infra/notification-sink.py`) enforces a bearer token for exactly this reason.

infra/docker-compose.local.yml

@@ -59,7 +59,8 @@ services:
       CELERY_BROKER_URL: redis://oz-redis:6379/1
       CELERY_RESULT_BACKEND: redis://oz-redis:6379/1
       DISABLE_2FA: "true"
-      NOTIFICATIONS_DISABLED: "true"
+      # Publish notifications to NRC (always present in this twin). See ADR-0007.
+      NOTIFICATIONS_DISABLED: "false"
       OPENZAAK_SUPERUSER_USERNAME: admin
       DJANGO_SUPERUSER_PASSWORD: admin
       OPENZAAK_SUPERUSER_EMAIL: admin@localhost
@@ -122,7 +123,9 @@ services:
     networks: [cg]
 
   nrc-init:
-    # Migrations only (see the canonical compose / ADR-0002); no config needed.
+    # Migrations + setup_configuration (S-01-c): the JWT credential, Autorisaties-API
+    # delegation, and the `zaken` kanaal that let OpenZaak publish. Config is
+    # bind-mounted here (this twin is the local/no-make path). See ADR-0007.
     image: docker.io/openzaak/open-notificaties:${OPENNOTIFICATIES_TAG:-1.16.1}
     environment: &nrc-env
       DJANGO_SETTINGS_MODULE: nrc.conf.docker
@@ -141,7 +144,11 @@ services:
       OPENNOTIFICATIES_SUPERUSER_USERNAME: admin
       DJANGO_SUPERUSER_PASSWORD: admin
       OPENNOTIFICATIES_SUPERUSER_EMAIL: admin@localhost
-    command: ["sh", "-c", "/wait_for_db.sh && OTEL_SDK_DISABLED=True python src/manage.py migrate"]
+      RUN_SETUP_CONFIG: "true"
+      NOTIFICATION_SEC_INTERVAL: "5"
+    command: /setup_configuration.sh
+    volumes:
+      - ./opennotificaties/setup_configuration:/app/setup_configuration:ro,z
     depends_on:
       nrc-db:
         condition: service_healthy
@@ -176,6 +183,17 @@ services:
         condition: service_completed_successfully
     networks: [cg]
 
+  # Celery beat drains scheduled notifications to subscribers — required for
+  # delivery, not optional. See ADR-0007.
+  nrc-beat:
+    image: docker.io/openzaak/open-notificaties:${OPENNOTIFICATIES_TAG:-1.16.1}
+    environment: *nrc-env
+    command: /celery_beat.sh
+    depends_on:
+      nrc-init:
+        condition: service_completed_successfully
+    networks: [cg]
+
   # ── Keycloak (S-02) ──────────────────────────────────────────────────────
   keycloak:
     image: quay.io/keycloak/keycloak:26.1
@@ -287,10 +305,68 @@ services:
       start_period: 10s
     networks: [cg]
 
+  # ── Read projection (S-06) ────────────────────────────────────────────────
+  projection-db:
+    image: docker.io/library/postgres:16
+    environment:
+      POSTGRES_USER: projection
+      POSTGRES_PASSWORD: projection
+      POSTGRES_DB: projection
+    volumes:
+      - projection-db:/var/lib/postgresql/data
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U projection -d projection"]
+      interval: 5s
+      timeout: 3s
+      retries: 10
+    networks: [cg]
+
+  event-subscriber:
+    build:
+      context: ..
+      dockerfile: services/event-subscriber/Dockerfile
+    image: register-referentie/event-subscriber:dev
+    environment:
+      ConnectionStrings__Projection: Host=projection-db;Database=projection;Username=projection;Password=projection
+      EventSubscriber__Webhook__AuthToken: ${NOTIFICATION_WEBHOOK_TOKEN:-Bearer big-reference-notifications}
+    ports:
+      - "8110:8080"
+    healthcheck:
+      test: ["CMD", "curl", "-fsS", "http://localhost:8080/health"]
+      interval: 5s
+      timeout: 3s
+      retries: 5
+      start_period: 15s
+    depends_on:
+      projection-db:
+        condition: service_healthy
+    networks: [cg]
+
+  projection-api:
+    build:
+      context: ..
+      dockerfile: services/projection-api/Dockerfile
+    image: register-referentie/projection-api:dev
+    environment:
+      ConnectionStrings__Projection: Host=projection-db;Database=projection;Username=projection;Password=projection
+    ports:
+      - "8120:8080"
+    healthcheck:
+      test: ["CMD", "curl", "-fsS", "http://localhost:8080/health"]
+      interval: 5s
+      timeout: 3s
+      retries: 5
+      start_period: 15s
+    depends_on:
+      projection-db:
+        condition: service_healthy
+    networks: [cg]
+
 volumes:
   oz-db:
   nrc-db:
   flowable-db:
+  projection-db:
 
 networks:
   cg:

infra/docker-compose.yml

@@ -9,6 +9,8 @@
 #   8080  BFF               GET /health → Healthy
 #   8090  Flowable REST     http://localhost:8090/flowable-rest/service/
 #   8100  ACL               GET /health → Healthy  POST /zaken
+#   8110  Event Subscriber  GET /health → Healthy  POST /notifications
+#   8120  projection-api    GET /health → Healthy  GET /register
 #   8180  Keycloak          (admin: admin / admin)
 #
 #   docker compose -f infra/docker-compose.yml up -d --build --wait
@@ -62,7 +64,10 @@ services:
       CELERY_BROKER_URL: redis://oz-redis:6379/1
       CELERY_RESULT_BACKEND: redis://oz-redis:6379/1
       DISABLE_2FA: "true"
-      NOTIFICATIONS_DISABLED: "true"
+      # Publish notifications to NRC (always present in this full stack). The NRC
+      # service + notifications_config are provisioned by setup_configuration
+      # (infra/openzaak/setup_configuration/data.yaml). See ADR-0007 / S-01-c.
+      NOTIFICATIONS_DISABLED: "false"
       OPENZAAK_SUPERUSER_USERNAME: admin
       DJANGO_SUPERUSER_PASSWORD: admin
       OPENZAAK_SUPERUSER_EMAIL: admin@localhost
@@ -146,11 +151,17 @@ services:
       OPENNOTIFICATIES_SUPERUSER_USERNAME: admin
       DJANGO_SUPERUSER_PASSWORD: admin
       OPENNOTIFICATIES_SUPERUSER_EMAIL: admin@localhost
-    # Migrations only for now. No setup_configuration steps are enabled yet (the
-    # OZ<->NRC notification wiring lands in S-06), and NRC's `setup_configuration`
-    # aborts with "No steps enabled" on the empty data.yaml — so we run `migrate`
-    # directly instead of /setup_configuration.sh. See data.yaml and ADR-0002.
-    command: ["sh", "-c", "/wait_for_db.sh && OTEL_SDK_DISABLED=True python src/manage.py migrate"]
+      RUN_SETUP_CONFIG: "true"
+      # nrc-beat fires `execute_notifications` this often to drain scheduled
+      # notifications to subscribers (upstream default 20s). See ADR-0007.
+      NOTIFICATION_SEC_INTERVAL: "5"
+    # Runs migrations + setup_configuration (S-01-c): the JWT credential, the
+    # Autorisaties-API delegation, and the `zaken` kanaal that let OpenZaak publish.
+    # data.yaml is streamed into rr-nrc-config by infra/seed-config.sh (bind mounts
+    # don't reach sibling containers on the CI runner). See data.yaml + ADR-0007.
+    command: /setup_configuration.sh
+    volumes:
+      - nrc-config:/app/setup_configuration:ro
     depends_on:
       nrc-db:
         condition: service_healthy
@@ -185,6 +196,18 @@ services:
         condition: service_completed_successfully
     networks: [cg]
 
+  # Celery beat drains the ScheduledNotification rows the API creates on publish
+  # and hands them to the worker. Without it, notifications are accepted but never
+  # delivered to subscribers — required, not optional. See ADR-0007.
+  nrc-beat:
+    image: docker.io/openzaak/open-notificaties:${OPENNOTIFICATIES_TAG:-1.16.1}
+    environment: *nrc-env
+    command: /celery_beat.sh
+    depends_on:
+      nrc-init:
+        condition: service_completed_successfully
+    networks: [cg]
+
   # ── Keycloak (S-02) ──────────────────────────────────────────────────────
   keycloak:
     image: quay.io/keycloak/keycloak:26.1
@@ -299,16 +322,85 @@ services:
       start_period: 10s
     networks: [cg]
 
+  # ── Read projection (S-06) ────────────────────────────────────────────────
+  # One Postgres DB backing the rebuildable read projection (PRD §8.4): the Event
+  # Subscriber writes it, projection-api reads it. See ADR-0008.
+  projection-db:
+    image: docker.io/library/postgres:16
+    environment:
+      POSTGRES_USER: projection
+      POSTGRES_PASSWORD: projection
+      POSTGRES_DB: projection
+    volumes:
+      - projection-db:/var/lib/postgresql/data
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U projection -d projection"]
+      interval: 5s
+      timeout: 3s
+      retries: 10
+    networks: [cg]
+
+  # Consumes NRC notifications (abonnement callback) and projects zaak-created events
+  # into register_projection. Build context is the repo root: it shares the read model
+  # in services/projection-api/Projection.ReadModel.
+  event-subscriber:
+    build:
+      context: ..
+      dockerfile: services/event-subscriber/Dockerfile
+    image: register-referentie/event-subscriber:dev
+    environment:
+      ConnectionStrings__Projection: Host=projection-db;Database=projection;Username=projection;Password=projection
+      # The bearer Open Notificaties must present on the abonnement callback. NRC's
+      # registration probe expects a 401 without it (ADR-0007). Dev-only token.
+      EventSubscriber__Webhook__AuthToken: ${NOTIFICATION_WEBHOOK_TOKEN:-Bearer big-reference-notifications}
+    ports:
+      - "8110:8080"
+    healthcheck:
+      test: ["CMD", "curl", "-fsS", "http://localhost:8080/health"]
+      interval: 5s
+      timeout: 3s
+      retries: 5
+      start_period: 15s
+    depends_on:
+      projection-db:
+        condition: service_healthy
+    networks: [cg]
+
+  # The read side of the projection. Shares Projection.ReadModel, so build context is root.
+  projection-api:
+    build:
+      context: ..
+      dockerfile: services/projection-api/Dockerfile
+    image: register-referentie/projection-api:dev
+    environment:
+      ConnectionStrings__Projection: Host=projection-db;Database=projection;Username=projection;Password=projection
+    ports:
+      - "8120:8080"
+    healthcheck:
+      test: ["CMD", "curl", "-fsS", "http://localhost:8080/health"]
+      interval: 5s
+      timeout: 3s
+      retries: 5
+      start_period: 15s
+    depends_on:
+      projection-db:
+        condition: service_healthy
+    networks: [cg]
+
 volumes:
   oz-db:
   nrc-db:
   flowable-db:
+  projection-db:
   # Config volumes — created and populated out-of-band by infra/seed-config.sh
   # (docker cp), because bind mounts don't reach sibling containers on the CI
   # runner. `external` keeps the names deterministic; the seed step manages them.
   oz-config:
     external: true
     name: rr-oz-config
+  nrc-config:
+    external: true
+    name: rr-nrc-config
   kc-realms:
     external: true
     name: rr-kc-realms

infra/notification-sink.py

@@ -0,0 +1,39 @@
+#!/usr/bin/env python3
+"""A throwaway webhook sink for verifying the OpenZaak → NRC notification path.
+
+NRC delivers abonnement callbacks here as POSTs; each body is printed to stdout
+(prefixed `NOTIFICATION `) so the verify harness can assert on `docker logs`.
+
+NRC refuses to register an abonnement whose callback is unauthenticated
+(`no-auth-on-callback`): when validating it sends a probe and expects the callback
+to reject a request without the configured `Authorization` value. So this sink
+enforces that header (EXPECTED_AUTH env) — 401 without it, 204 with it.
+
+Stdlib only. Listens on :9000. See infra/verify-notifications.sh / S-01-c (#56).
+"""
+import http.server
+import os
+import sys
+
+EXPECTED_AUTH = os.environ.get("EXPECTED_AUTH", "Bearer notification-sink-token")
+
+
+class Handler(http.server.BaseHTTPRequestHandler):
+    def do_POST(self):
+        length = int(self.headers.get("content-length", 0))
+        body = self.rfile.read(length).decode("utf-8", "replace")
+        if self.headers.get("Authorization") != EXPECTED_AUTH:
+            self.send_response(401)
+            self.end_headers()
+            return
+        print("NOTIFICATION " + body, flush=True)
+        self.send_response(204)
+        self.end_headers()
+
+    def log_message(self, *args):  # silence default request logging
+        pass
+
+
+if __name__ == "__main__":
+    http.server.HTTPServer(("0.0.0.0", 9000), Handler).serve_forever()
+    sys.exit(0)

infra/opennotificaties/docker-compose.yml

@@ -52,11 +52,18 @@ services:
       OPENNOTIFICATIES_SUPERUSER_USERNAME: admin
       DJANGO_SUPERUSER_PASSWORD: admin
       OPENNOTIFICATIES_SUPERUSER_EMAIL: admin@localhost
-    # Migrations only for now. No setup_configuration steps are enabled yet (the
-    # OZ<->NRC notification wiring lands in S-06), and NRC's `setup_configuration`
-    # aborts with "No steps enabled" on the empty data.yaml — so we run `migrate`
-    # directly instead of /setup_configuration.sh. See data.yaml and ADR-0002.
-    command: ["sh", "-c", "/wait_for_db.sh && OTEL_SDK_DISABLED=True python src/manage.py migrate"]
+      RUN_SETUP_CONFIG: "true"
+      # Delivery cadence: nrc-beat fires `execute_notifications` this often to drain
+      # scheduled notifications to subscribers. Upstream default is 20s; 5s keeps the
+      # walking-skeleton + the verify smoke responsive.
+      NOTIFICATION_SEC_INTERVAL: "5"
+    # Runs migrations + setup_configuration (S-01-c): the JWT credential, the
+    # Autorisaties-API delegation, and the `zaken` kanaal that let OpenZaak publish
+    # notifications. data.yaml is streamed into this external volume by
+    # infra/seed-config.sh (same pattern as oz-init). See data.yaml + ADR-0006.
+    command: /setup_configuration.sh
+    volumes:
+      - nrc-config:/app/setup_configuration:ro
     depends_on:
       nrc-db:
         condition: service_healthy
@@ -89,8 +96,25 @@ services:
         condition: service_completed_successfully
     networks: [cg]
 
+  # Celery beat: periodically fires `execute_notifications`, which drains the
+  # ScheduledNotification rows the API creates on publish and hands them to the
+  # worker for delivery. Without beat, notifications are accepted but never
+  # delivered to subscribers — so it is required, not optional. See ADR-0007.
+  nrc-beat:
+    image: docker.io/openzaak/open-notificaties:${OPENNOTIFICATIES_TAG:-1.16.1}
+    environment: *nrc-env
+    command: /celery_beat.sh
+    depends_on:
+      nrc-init:
+        condition: service_completed_successfully
+    networks: [cg]
+
 volumes:
   nrc-db:
+  # populated out-of-band by infra/seed-config.sh (docker cp) — see that script.
+  nrc-config:
+    external: true
+    name: rr-nrc-config
 
 networks:
   cg:

infra/opennotificaties/setup_configuration/data.yaml

@@ -1,5 +1,41 @@
-# Open Notificaties setup_configuration.
-# Stage 1 (this commit): intentionally minimal — the init container runs
-# migrations; no steps enabled yet. The OpenZaak<->NRC notification wiring
-# (Services, Authorization, JWT, Kanalen) is added next. See ADR-0002 / S-01-c.
-{}
+# Open Notificaties (NRC) setup_configuration (S-01-c, #56).
+# Wires NRC so OpenZaak can publish notifications:
+#  - the JWT credential OpenZaak authenticates with,
+#  - delegation of authorization checks to OpenZaak's Autorisaties API (AC),
+#  - the `zaken` kanaal OpenZaak publishes zaak events on.
+# Dev-only credentials — not for production. Steps from nrc.setup_configuration.
+
+# 1. JWT credential NRC uses to verify the token OpenZaak presents.
+vng_api_common_credentials_config_enable: true
+vng_api_common_credentials:
+  items:
+    - identifier: big-reference-seed
+      secret: insecure-dev-secret-change-me
+
+# 2. The Autorisaties API (OpenZaak's AC) NRC consults to authorize publishers.
+zgw_consumers_config_enable: true
+zgw_consumers:
+  services:
+    - identifier: openzaak-ac
+      label: OpenZaak Autorisaties API
+      api_type: ac
+      api_root: http://openzaak:8000/autorisaties/api/v1/
+      auth_type: zgw
+      client_id: big-reference-seed
+      secret: insecure-dev-secret-change-me
+
+# 3. Delegate authorization to that AC.
+autorisaties_api_config_enable: true
+autorisaties_api:
+  authorizations_api_service_identifier: openzaak-ac
+
+# 4. The kanaal OpenZaak publishes zaak events on.
+notifications_kanalen_config_enable: true
+notifications_kanalen_config:
+  items:
+    - naam: zaken
+      documentatie_link: https://github.com/VNG-Realisatie/gemma-zaken
+      filters:
+        - bronorganisatie
+        - zaaktype
+        - vertrouwelijkheidaanduiding

infra/openzaak/docker-compose.yml

@@ -47,9 +47,12 @@ services:
       CELERY_BROKER_URL: redis://oz-redis:6379/1
       CELERY_RESULT_BACKEND: redis://oz-redis:6379/1
       DISABLE_2FA: "true"
-      # Notifications go to Open Notificaties (NRC), which arrives in S-01-c.
-      # Until then, disable outbound notifications so writes don't 500.
-      NOTIFICATIONS_DISABLED: "true"
+      # Notifications are OFF by default so OpenZaak-only bring-ups (openzaak-up,
+      # the ACL integration test) don't 500 trying to reach an absent NRC. When
+      # OpenZaak runs together with the NRC stack, set OZ_NOTIFICATIONS_DISABLED=false
+      # (make stack-up does) to publish; the NRC service + notifications_config that
+      # name it are provisioned by setup_configuration (data.yaml, S-01-c).
+      NOTIFICATIONS_DISABLED: "${OZ_NOTIFICATIONS_DISABLED:-true}"
       OPENZAAK_SUPERUSER_USERNAME: admin
       DJANGO_SUPERUSER_PASSWORD: admin
       OPENZAAK_SUPERUSER_EMAIL: admin@localhost

infra/openzaak/seed_catalogus.py

@@ -18,6 +18,16 @@ SECRET = os.environ.get("OZ_SECRET", "insecure-dev-secret-change-me")
 ZTC = f"{BASE}/catalogi/api/v1"
 RSIN = "517439943"  # elfproef-valid test RSIN
 
+# Opt-in: also publish the zaaktype so OpenZaak's Zaken API accepts a zaak against
+# it (a concept zaaktype is rejected with `not-published`). Off by default — the
+# S-01 compose seed keeps it a concept (ADR-0002). The ACL integration test
+# (S-04a, #46) sets OZ_PUBLISH=1. Publishing requires ≥2 statustypen, ≥1 roltype
+# and ≥1 resultaattype; the resultaattype is validated against the external
+# Selectielijst reference API, so this path needs outbound access to it. See ADR-0006.
+PUBLISH = os.environ.get("OZ_PUBLISH", "").lower() in ("1", "true", "yes")
+SELECTIELIJST = os.environ.get(
+    "OZ_SELECTIELIJST", "https://selectielijst.openzaak.nl/api/v1").rstrip("/")
+
 
 def token():
     b64 = lambda b: base64.urlsafe_b64encode(b).rstrip(b"=")
@@ -52,6 +62,68 @@ def find(path):
     return body.get("results", [])
 
 
+def selectielijst(path):
+    """GET the external Selectielijst reference API (no auth). Used only when publishing."""
+    req = urllib.request.Request(f"{SELECTIELIJST}{path}", headers={"Accept": "application/json"})
+    with urllib.request.urlopen(req, timeout=30) as r:
+        return json.loads(r.read())
+
+
+def publish_zaaktype(zt):
+    """Add the relations OpenZaak requires to publish, then publish (idempotent).
+
+    Publish validation (verified against OpenZaak 1.28.2) demands: ≥2 statustypen
+    (begin + eind), ≥1 roltype, ≥1 resultaattype. A resultaattype needs a
+    Selectielijst `selectielijstklasse` whose procestype matches the zaaktype's
+    `selectielijstProcestype`, plus a `resultaattypeomschrijving`.
+    """
+    have_st = {s.get("volgnummer") for s in find(f"/statustypen?zaaktype={zt['url']}&status=alles")}
+    for volgnummer, omschrijving in [(1, "Ontvangen"), (2, "Afgehandeld")]:
+        if volgnummer not in have_st:
+            st, body = api("POST", "/statustypen", {
+                "omschrijving": omschrijving, "zaaktype": zt["url"], "volgnummer": volgnummer})
+            if st != 201:
+                sys.exit(f"create statustype {volgnummer} -> {st}: {json.dumps(body, indent=2)}")
+            print(f"create statustype {volgnummer} ({omschrijving})")
+
+    if find(f"/roltypen?zaaktype={zt['url']}&status=alles"):
+        print("skip   roltype Aanvrager")
+    else:
+        st, body = api("POST", "/roltypen", {
+            "zaaktype": zt["url"], "omschrijving": "Aanvrager", "omschrijvingGeneriek": "initiator"})
+        if st != 201:
+            sys.exit(f"create roltype -> {st}: {json.dumps(body, indent=2)}")
+        print("create roltype Aanvrager")
+
+    if find(f"/resultaattypen?zaaktype={zt['url']}&status=alles"):
+        print("skip   resultaattype Geregistreerd")
+    else:
+        resultaat = selectielijst("/resultaten?pageSize=1")["results"][0]
+        omschrijvingen = selectielijst("/resultaattypeomschrijvingen")
+        oms = (omschrijvingen if isinstance(omschrijvingen, list) else omschrijvingen["results"])[0]["url"]
+        # The selectielijstklasse and the zaaktype must share a procestype.
+        st, body = api("PATCH", zt["url"], {"selectielijstProcestype": resultaat["procesType"]})
+        if st != 200:
+            sys.exit(f"set procestype -> {st}: {json.dumps(body, indent=2)}")
+        st, body = api("POST", "/resultaattypen", {
+            "zaaktype": zt["url"], "omschrijving": "Geregistreerd",
+            "resultaattypeomschrijving": oms, "selectielijstklasse": resultaat["url"],
+            "archiefnominatie": "blijvend_bewaren",
+            "brondatumArchiefprocedure": {"afleidingswijze": "afgehandeld"},
+        })
+        if st != 201:
+            sys.exit(f"create resultaattype -> {st}: {json.dumps(body, indent=2)}")
+        print("create resultaattype Geregistreerd")
+
+    if zt.get("concept", True):
+        st, body = api("POST", f"{zt['url']}/publish")
+        if st != 200:
+            sys.exit(f"publish zaaktype -> {st}: {json.dumps(body, indent=2)}")
+        print(f"publish zaaktype BIG-REGISTRATIE ({zt['url']})")
+    else:
+        print("skip   publish (already published)")
+
+
 def main():
     # 1. Catalogus
     existing = [c for c in find(f"/catalogussen?domein=BIG") if c.get("domein") == "BIG"]
@@ -121,16 +193,24 @@ def main():
     else:
         print("warn   zaaktype already published; cannot add bsn eigenschap")
 
-    # Intentionally NOT published. Publishing requires roltypen, resultaattypen
-    # and statustypen, which go beyond the "lean / schema-mandatory" zaaktype this
-    # slice asks for; they arrive with the workflow/zaak slices. See ADR-0002.
+    # 4. Optionally publish. By default the zaaktype stays a concept: publishing
+    # requires roltypen, resultaattypen and statustypen, beyond the "lean /
+    # schema-mandatory" zaaktype S-01 asks for (ADR-0002). Set OZ_PUBLISH=1 to add
+    # those relations and publish — needed so a real zaak POST is accepted, which
+    # the ACL integration test (S-04a, #46) exercises. See ADR-0006.
+    if PUBLISH:
+        # Re-fetch: the bsn-eigenschap branch above may hold a stale concept flag.
+        zt = next(z for z in find(f"/zaaktypen?catalogus={cat['url']}&status=alles")
+                  if z.get("identificatie") == "BIG-REGISTRATIE")
+        publish_zaaktype(zt)
 
-    # 4. Verify the JWT client can list the zaaktype (concepts included).
+    # 5. Verify the JWT client can list the zaaktype (concepts included).
     zaaktypen = find(f"/zaaktypen?catalogus={cat['url']}&status=alles")
     names = [z.get("identificatie") for z in zaaktypen]
     print(f"zaaktypen in BIG: {names}")
     assert "BIG-REGISTRATIE" in names, "BIG-REGISTRATIE not listed"
-    print("OK — BIG catalogus seeded (BIG-REGISTRATIE concept + bsn eigenschap)")
+    state = "published" if PUBLISH else "concept"
+    print(f"OK — BIG catalogus seeded (BIG-REGISTRATIE {state} + bsn eigenschap)")
 
 
 if __name__ == "__main__":

infra/openzaak/setup_configuration/data.yaml

@@ -20,3 +20,22 @@ vng_api_common_applicaties:
         - big-reference-seed
       label: BIG reference seed client
       heeft_alle_autorisaties: true
+
+# ── OpenZaak → Open Notificaties (NRC) publishing (S-01-c, #56) ─────────────
+# The NRC service OpenZaak posts notifications to, authenticating with the same
+# big-reference-seed client (NRC verifies the JWT and authorizes it via the AC).
+zgw_consumers_config_enable: true
+zgw_consumers:
+  services:
+    - identifier: nrc
+      label: Open Notificaties
+      api_type: nrc
+      api_root: http://nrc-web:8000/api/v1/
+      auth_type: zgw
+      client_id: big-reference-seed
+      secret: insecure-dev-secret-change-me
+
+# Point OpenZaak's notifications at that service. Requires NOTIFICATIONS_DISABLED=false.
+notifications_config_enable: true
+notifications_config:
+  notifications_api_service_identifier: nrc

infra/run-acl-integration.sh

@@ -0,0 +1,37 @@
+#!/usr/bin/env bash
+#
+# Run the ACL integration tests (Category=Integration) against the OpenZaak that is
+# ALREADY running — works for any stack: oz-only (`make integration`), the standalone
+# oz+nrc stack, or the full compose stack (the CI `verify-stack` job). Seeds a
+# published BIG zaaktype (idempotent), then builds + runs the test image on the stack
+# network, reaching OpenZaak by container IP (a single-label host isn't URL-valid;
+# the runner can't reach published ports — see gitea-actions-gotchas.md §5/§6).
+#
+# Does NOT manage the stack lifecycle: the caller owns bring-up + teardown. Plain
+# docker primitives only (docker/podman-portable). See ADR-0006.
+set -euo pipefail
+
+here="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+root="$(cd "$here/.." && pwd)"
+
+# The OpenZaak API container, matched across compose projects + docker/podman naming
+# (`<project>[-_]openzaak[-_]<n>`); the delimiters exclude oz-db / oz-redis / oz-init.
+oz="$(docker ps -q --filter 'name=[-_]openzaak[-_]' | head -1)"
+[ -n "$oz" ] || { echo "ERROR: no running OpenZaak container found — bring the stack up first" >&2; exit 1; }
+net="$(docker inspect -f '{{range $k,$_ := .NetworkSettings.Networks}}{{$k}}{{"\n"}}{{end}}' "$oz" | head -1)"
+oz_ip="$(docker inspect -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' "$oz")"
+oz_base="http://$oz_ip:8000"
+echo ">> OpenZaak at $oz_base on network $net"
+
+echo ">> seeding a published BIG zaaktype (idempotent)"
+sid="$(docker create --network "$net" -e "OZ_BASE=$oz_base" -e OZ_PUBLISH=1 \
+  python:3-slim python /seed.py)"
+docker cp "$here/openzaak/seed_catalogus.py" "$sid:/seed.py" >/dev/null
+docker start -a "$sid"
+docker rm -f "$sid" >/dev/null
+
+echo ">> building the integration test image"
+docker build -f "$root/services/acl/Dockerfile.integration" -t rr-acl-integration "$root/services/acl"
+
+echo ">> running the ACL integration tests (inside the network)"
+docker run --rm --network "$net" -e "OZ_BASE=$oz_base" rr-acl-integration

infra/run-integration.sh

@@ -0,0 +1,34 @@
+#!/usr/bin/env bash
+#
+# Local convenience: run the ACL integration test against a throwaway OpenZaak-only
+# stack (fast iteration on the ACL gateway). Brings OpenZaak up, runs the shared
+# stack-agnostic check (infra/run-acl-integration.sh), then always tears down.
+#
+# CI does not use this — there the full stack is brought up once and the same runner
+# is invoked as a step (see the `verify-stack` job / Makefile `verify-*`). See ADR-0006.
+set -euo pipefail
+
+here="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+OZ_COMPOSE="$here/openzaak/docker-compose.yml"
+
+cleanup() {
+  docker compose -f "$OZ_COMPOSE" down --volumes >/dev/null 2>&1 || true
+  docker volume rm -f rr-oz-config >/dev/null 2>&1 || true
+}
+trap cleanup EXIT
+
+echo ">> bringing OpenZaak up"
+bash "$here/seed-config.sh" oz
+docker compose -f "$OZ_COMPOSE" up -d
+
+echo ">> waiting for the OpenZaak API container to be healthy"
+for _ in $(seq 1 140); do
+  oz="$(docker ps -q --filter 'name=[-_]openzaak[-_]' | head -1)"
+  if [ -n "$oz" ] && [ "$(docker inspect -f '{{if .State.Health}}{{.State.Health.Status}}{{end}}' "$oz" 2>/dev/null || true)" = healthy ]; then
+    break
+  fi
+  sleep 3
+done
+[ -n "${oz:-}" ] || { echo "ERROR: OpenZaak never came up" >&2; exit 1; }
+
+bash "$here/run-acl-integration.sh"

infra/run-notification-check.sh

@@ -0,0 +1,72 @@
+#!/usr/bin/env bash
+#
+# Verify the OpenZaak → NRC notification path against an ALREADY-RUNNING oz+nrc stack
+# (the standalone stack via `make verify-notifications`, or the full compose stack in
+# the CI `verify-stack` job). Seeds a published BIG zaaktype (idempotent), registers
+# an abonnement to a webhook sink, creates a zaak, and asserts the sink receives the
+# `zaken`/`create` notification. All in-network, reaching services by container IP
+# (single-label hosts aren't URL-valid; the runner can't reach published ports).
+#
+# Does NOT manage the stack lifecycle (the caller owns bring-up + teardown), but it
+# cleans up the throwaway sink/driver it creates. Plain docker primitives only.
+# See ADR-0007.
+set -euo pipefail
+
+here="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+SINK_AUTH="Bearer notification-sink-token"
+
+cleanup() { docker rm -f rr-nsink rr-nverify >/dev/null 2>&1 || true; }
+trap cleanup EXIT
+
+ip() { docker inspect -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' "$1"; }
+
+oz="$(docker ps -q --filter 'name=[-_]openzaak[-_]' | head -1)"
+nrc="$(docker ps -q --filter 'name=nrc-web' | head -1)"
+[ -n "$oz" ] && [ -n "$nrc" ] || { echo "ERROR: OpenZaak and/or NRC not running — bring the stack up first" >&2; exit 1; }
+net="$(docker inspect -f '{{range $k,$_ := .NetworkSettings.Networks}}{{$k}}{{"\n"}}{{end}}' "$oz" | head -1)"
+oz_ip="$(ip "$oz")"; nrc_ip="$(ip "$nrc")"
+echo ">> network=$net openzaak=$oz_ip nrc=$nrc_ip"
+
+echo ">> seeding a published BIG zaaktype (idempotent)"
+sid="$(docker create --network "$net" -e "OZ_BASE=http://$oz_ip:8000" -e OZ_PUBLISH=1 \
+  python:3-slim python /seed.py)"
+docker cp "$here/openzaak/seed_catalogus.py" "$sid:/seed.py" >/dev/null
+docker start -a "$sid"
+docker rm -f "$sid" >/dev/null
+
+echo ">> starting the webhook sink"
+docker rm -f rr-nsink >/dev/null 2>&1 || true
+sink="$(docker create --network "$net" --name rr-nsink -e "EXPECTED_AUTH=$SINK_AUTH" \
+  python:3-slim python /sink.py)"
+docker cp "$here/notification-sink.py" "$sink:/sink.py" >/dev/null
+docker start "$sink" >/dev/null
+sleep 1
+sink_ip="$(ip rr-nsink)"
+echo ">> sink at $sink_ip:9000"
+
+echo ">> registering abonnement + creating a zaak"
+docker rm -f rr-nverify >/dev/null 2>&1 || true
+drv="$(docker create --network "$net" --name rr-nverify \
+  -e "OZ_BASE=http://$oz_ip:8000" -e "NRC_BASE=http://$nrc_ip:8000" \
+  -e "SINK_CALLBACK=http://$sink_ip:9000/" -e "SINK_AUTH=$SINK_AUTH" \
+  python:3-slim python /driver.py)"
+docker cp "$here/verify-notification-driver.py" "$drv:/driver.py" >/dev/null
+docker start -a "$drv"
+zaak_url="$(docker logs rr-nverify 2>/dev/null | sed -n 's/^ZAAK_CREATED //p' | head -1)"
+docker rm -f rr-nverify >/dev/null
+[ -n "$zaak_url" ] || { echo "ERROR: driver did not create a zaak" >&2; exit 1; }
+zaak_uuid="${zaak_url##*/}"
+echo ">> zaak created: $zaak_url"
+
+echo ">> waiting for the notification to reach the sink"
+for _ in $(seq 1 30); do
+  if docker logs rr-nsink 2>&1 | grep -q "$zaak_uuid"; then
+    echo "OK — NRC delivered the zaken notification for zaak $zaak_uuid to the sink"
+    docker logs rr-nsink 2>&1 | grep "$zaak_uuid" | tail -1 | cut -c1-300
+    exit 0
+  fi
+  sleep 2
+done
+echo "FAIL — the sink never received a notification for zaak $zaak_uuid" >&2
+echo "--- sink log ---" >&2; docker logs rr-nsink 2>&1 | tail -8 >&2
+exit 1

infra/run-projection-check.sh

@@ -0,0 +1,68 @@
+#!/usr/bin/env bash
+#
+# Verify the end-to-end read-projection path (S-06) against an ALREADY-RUNNING full stack:
+# OpenZaak → NRC → Event Subscriber → projection → projection-api. Seeds a published BIG
+# zaaktype (idempotent), registers an abonnement on the `zaken` kanaal pointing at the real
+# Event Subscriber's /notifications callback (with the bearer it enforces), creates a zaak,
+# and asserts projection-api serves a row for that zaak with status INGEDIEND.
+#
+# All in-network, reaching services by container IP — single-label hosts aren't URL-valid and
+# the runner can't reach published ports (gitea-actions-gotchas.md §5/§6). Reuses the
+# notification driver to register the abonnement + create the zaak. Does NOT manage the stack
+# lifecycle (the caller owns bring-up + teardown). Plain docker primitives only. See ADR-0007/0008.
+set -euo pipefail
+
+here="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+WEBHOOK_AUTH="${NOTIFICATION_WEBHOOK_TOKEN:-Bearer big-reference-notifications}"
+
+cleanup() { docker rm -f rr-pverify rr-pquery >/dev/null 2>&1 || true; }
+trap cleanup EXIT
+
+ip() { docker inspect -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' "$1"; }
+
+oz="$(docker ps -q --filter 'name=[-_]openzaak[-_]' | head -1)"
+nrc="$(docker ps -q --filter 'name=nrc-web' | head -1)"
+es="$(docker ps -q --filter 'name=event-subscriber' | head -1)"
+proj="$(docker ps -q --filter 'name=projection-api' | head -1)"
+[ -n "$oz" ] && [ -n "$nrc" ] || { echo "ERROR: OpenZaak and/or NRC not running — bring the stack up first" >&2; exit 1; }
+[ -n "$es" ] && [ -n "$proj" ] || { echo "ERROR: event-subscriber and/or projection-api not running — bring the stack up first" >&2; exit 1; }
+net="$(docker inspect -f '{{range $k,$_ := .NetworkSettings.Networks}}{{$k}}{{"\n"}}{{end}}' "$oz" | head -1)"
+oz_ip="$(ip "$oz")"; nrc_ip="$(ip "$nrc")"; es_ip="$(ip "$es")"; proj_ip="$(ip "$proj")"
+echo ">> network=$net openzaak=$oz_ip nrc=$nrc_ip event-subscriber=$es_ip projection-api=$proj_ip"
+
+echo ">> seeding a published BIG zaaktype (idempotent)"
+sid="$(docker create --network "$net" -e "OZ_BASE=http://$oz_ip:8000" -e OZ_PUBLISH=1 \
+  python:3-slim python /seed.py)"
+docker cp "$here/openzaak/seed_catalogus.py" "$sid:/seed.py" >/dev/null
+docker start -a "$sid"
+docker rm -f "$sid" >/dev/null
+
+echo ">> registering abonnement at the Event Subscriber + creating a zaak"
+docker rm -f rr-pverify >/dev/null 2>&1 || true
+drv="$(docker create --network "$net" --name rr-pverify \
+  -e "OZ_BASE=http://$oz_ip:8000" -e "NRC_BASE=http://$nrc_ip:8000" \
+  -e "SINK_CALLBACK=http://$es_ip:8080/notifications" -e "SINK_AUTH=$WEBHOOK_AUTH" \
+  python:3-slim python /driver.py)"
+docker cp "$here/verify-notification-driver.py" "$drv:/driver.py" >/dev/null
+docker start -a "$drv"
+zaak_url="$(docker logs rr-pverify 2>/dev/null | sed -n 's/^ZAAK_CREATED //p' | head -1)"
+docker rm -f rr-pverify >/dev/null
+[ -n "$zaak_url" ] || { echo "ERROR: driver did not create a zaak" >&2; exit 1; }
+zaak_uuid="${zaak_url##*/}"
+echo ">> zaak created: $zaak_url"
+
+echo ">> polling projection-api for the projected row (status INGEDIEND)"
+for _ in $(seq 1 30); do
+  body="$(docker run --rm --network "$net" curlimages/curl:latest \
+    -fsS "http://$proj_ip:8080/register/$zaak_uuid" 2>/dev/null || true)"
+  if echo "$body" | grep -q '"INGEDIEND"'; then
+    echo "OK — projection-api serves zaak $zaak_uuid with status INGEDIEND"
+    echo "$body" | cut -c1-300
+    exit 0
+  fi
+  sleep 2
+done
+echo "FAIL — projection-api never served an INGEDIEND row for zaak $zaak_uuid" >&2
+echo "--- event-subscriber log ---" >&2; docker logs "$es" 2>&1 | tail -10 >&2
+echo "--- projection-api log ---" >&2; docker logs "$proj" 2>&1 | tail -10 >&2
+exit 1

infra/seed-config.sh

@@ -33,11 +33,12 @@ populate() {  # volume  source(file or dir/.)
   echo "  seeded $vol"
 }
 
-[ "$#" -gt 0 ] || { echo "usage: seed-config.sh <oz|kc|fl> ..." >&2; exit 2; }
+[ "$#" -gt 0 ] || { echo "usage: seed-config.sh <oz|nrc|kc|fl> ..." >&2; exit 2; }
 
 for key in "$@"; do
   case "$key" in
     oz) populate rr-oz-config "$here/openzaak/setup_configuration/." ;;
+    nrc) populate rr-nrc-config "$here/opennotificaties/setup_configuration/." ;;
     kc) populate rr-kc-realms "$here/keycloak/realms/." ;;
     fl) populate rr-fl-bpmn  "$here/../workflows/registratie.bpmn" ;;
     *)  echo "unknown seed key: $key" >&2; exit 2 ;;

infra/verify-notification-driver.py

@@ -0,0 +1,90 @@
+#!/usr/bin/env python3
+"""Drive the OpenZaak → NRC notification check from *inside* the compose network.
+
+Registers an abonnement on the `zaken` kanaal pointing at a webhook sink, then
+creates a zaak against the published BIG zaaktype. OpenZaak publishes a
+`zaken`/`create` notification; NRC delivers it to the sink. The host harness
+(infra/verify-notifications.sh) then asserts the sink received it.
+
+Reached by container IP, not service name: OpenZaak/NRC validate URLs with Django's
+URLValidator, which rejects a single-label host like `openzaak`. Stdlib only.
+Env: OZ_BASE, NRC_BASE, SINK_CALLBACK, SINK_AUTH, OZ_CLIENT_ID, OZ_SECRET.
+"""
+import base64
+import hashlib
+import hmac
+import json
+import os
+import sys
+import time
+import urllib.error
+import urllib.request
+
+OZ = os.environ["OZ_BASE"].rstrip("/")
+NRC = os.environ["NRC_BASE"].rstrip("/")
+SINK_CALLBACK = os.environ["SINK_CALLBACK"]
+SINK_AUTH = os.environ.get("SINK_AUTH", "Bearer notification-sink-token")
+CID = os.environ.get("OZ_CLIENT_ID", "big-reference-seed")
+SECRET = os.environ.get("OZ_SECRET", "insecure-dev-secret-change-me")
+RSIN = "517439943"
+
+
+def token():
+    b64 = lambda b: base64.urlsafe_b64encode(b).rstrip(b"=")
+    seg = (
+        b64(json.dumps({"alg": "HS256", "typ": "JWT"}, separators=(",", ":")).encode())
+        + b"."
+        + b64(json.dumps(
+            {"iss": CID, "iat": int(time.time()), "client_id": CID,
+             "user_id": "verify", "user_representation": "verify"},
+            separators=(",", ":")).encode())
+    )
+    return (seg + b"." + b64(hmac.new(SECRET.encode(), seg, hashlib.sha256).digest())).decode()
+
+
+def call(method, url, body=None, crs=False):
+    headers = {"Authorization": "Bearer " + token(),
+               "Content-Type": "application/json", "Accept": "application/json"}
+    if crs:
+        headers["Accept-Crs"] = "EPSG:4326"
+        headers["Content-Crs"] = "EPSG:4326"
+    data = json.dumps(body).encode() if body is not None else None
+    try:
+        with urllib.request.urlopen(
+            urllib.request.Request(url, data=data, method=method, headers=headers), timeout=30
+        ) as r:
+            return r.status, json.loads(r.read() or "null")
+    except urllib.error.HTTPError as e:
+        return e.code, json.loads(e.read() or "null")
+
+
+def main():
+    status, ab = call("POST", f"{NRC}/api/v1/abonnement", {
+        "callbackUrl": SINK_CALLBACK,
+        "auth": SINK_AUTH,
+        "kanalen": [{"naam": "zaken", "filters": {}}],
+    })
+    if status != 201:
+        sys.exit(f"create abonnement -> {status}: {json.dumps(ab)}")
+    print(f"abonnement: {ab['url']}")
+
+    status, body = call(
+        "GET", f"{OZ}/catalogi/api/v1/zaaktypen?identificatie=BIG-REGISTRATIE&status=definitief")
+    results = body.get("results", []) if status == 200 else []
+    if not results:
+        sys.exit("no published BIG-REGISTRATIE zaaktype — seed with OZ_PUBLISH=1 first")
+    zaaktype = results[0]["url"]
+
+    status, zaak = call("POST", f"{OZ}/zaken/api/v1/zaken", {
+        "bronorganisatie": RSIN, "verantwoordelijkeOrganisatie": RSIN,
+        "zaaktype": zaaktype, "startdatum": time.strftime("%Y-%m-%d"),
+        "vertrouwelijkheidaanduiding": "openbaar",
+    }, crs=True)
+    if status != 201:
+        sys.exit(f"create zaak -> {status}: {json.dumps(zaak)}")
+    # The harness greps the sink for this exact URL.
+    print(f"ZAAK_CREATED {zaak['url']}")
+
+
+if __name__ == "__main__":
+    main()

infra/verify-notifications.sh

@@ -0,0 +1,41 @@
+#!/usr/bin/env bash
+#
+# Local convenience: verify the OpenZaak → NRC notification path against a throwaway
+# oz+nrc stack. Brings both up (notifications enabled), runs the shared stack-agnostic
+# check (infra/run-notification-check.sh), then always tears down.
+#
+# CI does not use this — there the full stack is brought up once and the same runner
+# is invoked as a step (see the `verify-stack` job / Makefile `verify-*`). See ADR-0007.
+set -euo pipefail
+
+here="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+OZ_COMPOSE="$here/openzaak/docker-compose.yml"
+NRC_COMPOSE="$here/opennotificaties/docker-compose.yml"
+
+cleanup() {
+  docker compose -f "$OZ_COMPOSE" -f "$NRC_COMPOSE" down --volumes >/dev/null 2>&1 || true
+  docker volume rm -f rr-oz-config rr-nrc-config >/dev/null 2>&1 || true
+}
+trap cleanup EXIT
+
+wait_healthy() {  # name-regex
+  local re="$1" cid
+  for _ in $(seq 1 140); do
+    cid="$(docker ps -q --filter "name=$re" | head -1)"
+    if [ -n "$cid" ] && [ "$(docker inspect -f '{{if .State.Health}}{{.State.Health.Status}}{{end}}' "$cid" 2>/dev/null || true)" = healthy ]; then
+      return 0
+    fi
+    sleep 3
+  done
+  return 1
+}
+
+echo ">> bringing up OpenZaak + Open Notificaties (notifications enabled)"
+bash "$here/seed-config.sh" oz nrc
+OZ_NOTIFICATIONS_DISABLED=false docker compose -f "$OZ_COMPOSE" -f "$NRC_COMPOSE" up -d
+
+echo ">> waiting for OpenZaak + NRC to be healthy"
+wait_healthy '[-_]openzaak[-_]' || { echo "ERROR: OpenZaak not healthy" >&2; exit 1; }
+wait_healthy 'nrc-web' || { echo "ERROR: NRC not healthy" >&2; exit 1; }
+
+bash "$here/run-notification-check.sh"

mkdocs.yml

@@ -26,7 +26,12 @@ nav:
       - "ADR-0002: Catalogus design": architecture/adr-0002-catalogus-design.md
       - "ADR-0003: ACL default-fill": architecture/adr-0003-default-fill.md
       - "ADR-0004: BDD framework": architecture/adr-0004-bdd-framework.md
+      - "ADR-0005: Mutation testing": architecture/adr-0005-mutation-testing.md
+      - "ADR-0006: ACL integration test provisioning": architecture/adr-0006-integration-test-provisioning.md
+      - "ADR-0007: OpenZaak → NRC notification wiring": architecture/adr-0007-notification-wiring.md
+      - "ADR-0008: Read projection store": architecture/adr-0008-read-projection-store.md
   - Working in Gitea: gitea-workflow.md
+  - Demo script: demo-script.md
   - Runbooks:
       - CI: runbooks/ci.md
 

register-referentie.slnx

@@ -4,12 +4,22 @@
     <Project Path="services/acl/Acl.Api/Acl.Api.csproj" />
     <Project Path="services/acl/Acl.Application/Acl.Application.csproj" />
     <Project Path="services/acl/Acl.Infrastructure/Acl.Infrastructure.csproj" />
+    <Project Path="services/acl/Acl.IntegrationTests/Acl.IntegrationTests.csproj" />
     <Project Path="services/acl/Acl.Tests/Acl.Tests.csproj" />
   </Folder>
   <Folder Name="/services/bff/">
     <Project Path="services/bff/Bff.Api/Bff.Api.csproj" />
     <Project Path="services/bff/Bff.Tests/Bff.Tests.csproj" />
   </Folder>
+  <Folder Name="/services/event-subscriber/">
+    <Project Path="services/event-subscriber/EventSubscriber.Api/EventSubscriber.Api.csproj" />
+    <Project Path="services/event-subscriber/EventSubscriber.Application/EventSubscriber.Application.csproj" />
+    <Project Path="services/event-subscriber/EventSubscriber.Tests/EventSubscriber.Tests.csproj" />
+  </Folder>
+  <Folder Name="/services/projection-api/">
+    <Project Path="services/projection-api/Projection.ReadModel/Projection.ReadModel.csproj" />
+    <Project Path="services/projection-api/ProjectionApi.Api/ProjectionApi.Api.csproj" />
+  </Folder>
   <Folder Name="/tests/">
     <Project Path="tests/acceptance/Acceptance.csproj" />
   </Folder>

services/acl/Acl.Infrastructure/OpenZaakGateway.cs

@@ -27,6 +27,11 @@ public sealed class OpenZaakGateway(HttpClient http, OpenZaakOptions options) :
         // ZRC is a geo API; it requires the CRS headers.
         message.Headers.Add("Accept-Crs", "EPSG:4326");
         message.Content.Headers.Add("Content-Crs", "EPSG:4326");
+        // OpenZaak runs behind uwsgi, which rejects a chunked request body with 400.
+        // JsonContent streams without a known length (→ Transfer-Encoding: chunked),
+        // so buffer it first to send a Content-Length instead. Only a real OpenZaak
+        // surfaces this — a stubbed HttpMessageHandler accepts either framing.
+        await message.Content.LoadIntoBufferAsync(ct);
 
         using var response = await http.SendAsync(message, ct);
         response.EnsureSuccessStatusCode();

services/acl/Acl.IntegrationTests/Acl.IntegrationTests.csproj

@@ -0,0 +1,30 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <!-- Integration tests: they talk to a real OpenZaak (the compose stack), so they
+       are gated behind [Trait("Category","Integration")] and excluded from the fast
+       `make unit` / mutation lanes. `make integration` brings the stack up, seeds a
+       published BIG zaaktype (OZ_PUBLISH=1) and runs this project. See ADR-0006. -->
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <IsPackable>false</IsPackable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="coverlet.collector" Version="6.0.4" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
+    <PackageReference Include="xunit" Version="2.9.3" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="3.1.4" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <Using Include="Xunit" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\Acl.Application\Acl.Application.csproj" />
+    <ProjectReference Include="..\Acl.Infrastructure\Acl.Infrastructure.csproj" />
+  </ItemGroup>
+
+</Project>

services/acl/Acl.IntegrationTests/OpenZaakFixture.cs

@@ -0,0 +1,97 @@
+using System.Net.Http.Headers;
+using System.Security.Cryptography;
+using System.Text;
+using System.Text.Json;
+using Acl.Infrastructure;
+
+namespace Acl.IntegrationTests;
+
+/// <summary>
+/// Shared connection to the running OpenZaak compose stack (ADR-0006). Reads the
+/// same endpoint + JWT-client config the seed uses, and locates the published
+/// BIG-REGISTRATIE zaaktype the ACL opens zaken against. Defaults match
+/// `infra/openzaak/seed_catalogus.py`; override via OZ_BASE / OZ_CLIENT_ID / OZ_SECRET.
+/// </summary>
+public sealed class OpenZaakFixture : IDisposable
+{
+    private static string Env(string key, string fallback) =>
+        Environment.GetEnvironmentVariable(key) is { Length: > 0 } v ? v : fallback;
+
+    public Uri BaseUrl { get; } = new(Env("OZ_BASE", "http://localhost:8000"));
+    public string ClientId { get; } = Env("OZ_CLIENT_ID", "big-reference-seed");
+    public string Secret { get; } = Env("OZ_SECRET", "insecure-dev-secret-change-me");
+
+    public HttpClient Http { get; } = new();
+
+    public OpenZaakOptions Options => new()
+    {
+        BaseUrl = BaseUrl,
+        ClientId = ClientId,
+        Secret = Secret,
+    };
+
+    /// <summary>
+    /// The URL of the published BIG-REGISTRATIE zaaktype, or null when none is
+    /// published yet (a concept-only stack). `status=definitief` returns published
+    /// zaaktypen only — a concept zaaktype is deliberately excluded.
+    /// </summary>
+    public async Task<Uri?> FindPublishedBigZaaktypeAsync(CancellationToken ct = default)
+    {
+        var query = new Uri(BaseUrl,
+            "/catalogi/api/v1/zaaktypen?identificatie=BIG-REGISTRATIE&status=definitief");
+        using var message = new HttpRequestMessage(HttpMethod.Get, query);
+        message.Headers.Authorization = new AuthenticationHeaderValue("Bearer", MintToken());
+
+        using var response = await Http.SendAsync(message, ct);
+        response.EnsureSuccessStatusCode();
+
+        using var document = JsonDocument.Parse(await response.Content.ReadAsStringAsync(ct));
+        var results = document.RootElement.GetProperty("results");
+        return results.GetArrayLength() == 0
+            ? null
+            : new Uri(results[0].GetProperty("url").GetString()!);
+    }
+
+    /// <summary>GETs a previously-created zaak to prove it was really persisted.</summary>
+    public async Task<JsonElement> GetZaakAsync(Uri zaakUrl, CancellationToken ct = default)
+    {
+        using var message = new HttpRequestMessage(HttpMethod.Get, zaakUrl);
+        message.Headers.Authorization = new AuthenticationHeaderValue("Bearer", MintToken());
+        message.Headers.Add("Accept-Crs", "EPSG:4326");
+
+        using var response = await Http.SendAsync(message, ct);
+        response.EnsureSuccessStatusCode();
+        var json = await response.Content.ReadAsStringAsync(ct);
+        return JsonDocument.Parse(json).RootElement.Clone();
+    }
+
+    // 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()
+    {
+        static string B64(byte[] b) =>
+            Convert.ToBase64String(b).TrimEnd('=').Replace('+', '-').Replace('/', '_');
+
+        var header = B64(JsonSerializer.SerializeToUtf8Bytes(new { alg = "HS256", typ = "JWT" }));
+        var payload = B64(JsonSerializer.SerializeToUtf8Bytes(new
+        {
+            iss = ClientId,
+            iat = DateTimeOffset.UtcNow.ToUnixTimeSeconds(),
+            client_id = ClientId,
+            user_id = "acl-integration-test",
+            user_representation = "acl-integration-test",
+        }));
+        var signingInput = $"{header}.{payload}";
+        using var hmac = new HMACSHA256(Encoding.UTF8.GetBytes(Secret));
+        var signature = B64(hmac.ComputeHash(Encoding.UTF8.GetBytes(signingInput)));
+        return $"{signingInput}.{signature}";
+    }
+
+    public void Dispose() => Http.Dispose();
+}
+
+[CollectionDefinition(Name)]
+public sealed class OpenZaakCollection : ICollectionFixture<OpenZaakFixture>
+{
+    public const string Name = "OpenZaak";
+}

services/acl/Acl.IntegrationTests/OpenZaakGatewayIntegrationTests.cs

@@ -0,0 +1,45 @@
+using Acl.Application;
+using Acl.Infrastructure;
+
+namespace Acl.IntegrationTests;
+
+/// <summary>
+/// S-04a (#46): the deferred S-04 acceptance criterion — the ACL's OpenZaakGateway
+/// opening a zaak against a *real* OpenZaak, exercising real ZGW JWT auth and the
+/// real POST /zaken/api/v1/zaken contract (CRS headers, default-fill, the created
+/// zaak URL) that the stubbed-HttpMessageHandler unit tests cannot. See ADR-0006.
+/// </summary>
+[Trait("Category", "Integration")]
+[Collection(OpenZaakCollection.Name)]
+public sealed class OpenZaakGatewayIntegrationTests(OpenZaakFixture stack)
+{
+    [Fact]
+    public async Task Opens_a_real_zaak_against_the_published_big_zaaktype_and_returns_its_url()
+    {
+        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 request = new ZaakRequest(
+            Bronorganisatie: "517439943",
+            VerantwoordelijkeOrganisatie: "517439943",
+            Vertrouwelijkheidaanduiding: "openbaar",
+            Zaaktype: zaaktype!,
+            Startdatum: DateOnly.FromDateTime(DateTime.UtcNow));
+
+        var zaakUrl = await gateway.OpenZaakAsync(request);
+
+        // The gateway returns the canonical zaak URL on OpenZaak's Zaken API...
+        Assert.StartsWith(
+            new Uri(stack.BaseUrl, "/zaken/api/v1/zaken/").ToString(),
+            zaakUrl.ToString());
+
+        // ...and that zaak is really persisted with the default-filled fields.
+        var zaak = await stack.GetZaakAsync(zaakUrl);
+        Assert.Equal(zaaktype.ToString(), zaak.GetProperty("zaaktype").GetString());
+        Assert.Equal("517439943", zaak.GetProperty("bronorganisatie").GetString());
+        Assert.Equal("openbaar", zaak.GetProperty("vertrouwelijkheidaanduiding").GetString());
+    }
+}

services/acl/Acl.Tests/AclServiceTests.cs

@@ -44,4 +44,21 @@ public class AclServiceTests
         Assert.Equal(defaults.ZaaktypeUrl, req.Zaaktype);
         Assert.Equal(new DateOnly(2026, 6, 4), req.Startdatum);
     }
+
+    [Fact]
+    public async Task Rejects_a_null_registration_without_calling_the_gateway()
+    {
+        var gateway = new FakeGateway();
+        var defaults = new AclDefaults
+        {
+            Bronorganisatie = "517439943",
+            VerantwoordelijkeOrganisatie = "517439943",
+            Vertrouwelijkheidaanduiding = "openbaar",
+            ZaaktypeUrl = new("http://openzaak/catalogi/api/v1/zaaktypen/big"),
+        };
+        var service = new AclService(gateway, defaults, new FixedClock(new DateOnly(2026, 6, 4)));
+
+        await Assert.ThrowsAsync<ArgumentNullException>(() => service.OpenZaakAsync(null!));
+        Assert.Null(gateway.Captured);
+    }
 }

services/acl/Acl.Tests/OpenZaakGatewayTests.cs

@@ -1,5 +1,7 @@
 using System.Net;
 using System.Net.Http.Json;
+using System.Text;
+using System.Text.Json;
 using Acl.Application;
 using Acl.Infrastructure;
 
@@ -14,38 +16,139 @@ public class OpenZaakGatewayTests
             => onSend(request);
     }
 
-    [Fact]
-    public async Task Posts_zaak_to_openzaak_with_bearer_and_default_fields_and_returns_url()
+    private static OpenZaakGateway Gateway(StubHandler handler) => new(
+        new HttpClient(handler),
+        new OpenZaakOptions { BaseUrl = new("http://openzaak"), ClientId = "cid", Secret = "sec" });
+
+    private static ZaakRequest SampleRequest() => new(
+        "517439943", "517439943", "openbaar",
+        new("http://openzaak/catalogi/api/v1/zaaktypen/big"), new DateOnly(2026, 6, 4));
+
+    private static StubHandler Created(out RequestCapture capture)
     {
-        HttpRequestMessage? seen = null;
-        string? body = null;
-        var handler = new StubHandler(async req =>
+        var c = new RequestCapture();
+        capture = c;
+        return new StubHandler(async req =>
         {
-            seen = req;
-            body = await req.Content!.ReadAsStringAsync();
+            c.Seen = req;
+            // Capture the length BEFORE reading the body: ReadAsStringAsync buffers the
+            // content and would set ContentLength as a side effect, masking the gateway's
+            // own buffering. Read here to assert the gateway sent a length (not chunked).
+            c.ContentLength = req.Content?.Headers.ContentLength;
+            c.Body = req.Content is null ? null : await req.Content.ReadAsStringAsync();
             return new HttpResponseMessage(HttpStatusCode.Created)
             {
                 Content = JsonContent.Create(new { url = "http://openzaak/zaken/api/v1/zaken/xyz" }),
             };
         });
-        var gateway = new OpenZaakGateway(
-            new HttpClient(handler),
-            new OpenZaakOptions { BaseUrl = new("http://openzaak"), ClientId = "cid", Secret = "sec" });
-        var request = new ZaakRequest(
-            "517439943", "517439943", "openbaar",
-            new("http://openzaak/catalogi/api/v1/zaaktypen/big"), new DateOnly(2026, 6, 4));
+    }
 
-        var url = await gateway.OpenZaakAsync(request);
+    private sealed class RequestCapture
+    {
+        public HttpRequestMessage? Seen;
+        public string? Body;
+        public long? ContentLength;
+    }
+
+    [Fact]
+    public async Task Posts_zaak_to_openzaak_with_bearer_and_default_fields_and_returns_url()
+    {
+        var handler = Created(out var capture);
+
+        var url = await Gateway(handler).OpenZaakAsync(SampleRequest());
 
         Assert.Equal("http://openzaak/zaken/api/v1/zaken/xyz", url.ToString());
-        Assert.Equal(HttpMethod.Post, seen!.Method);
-        Assert.Equal("http://openzaak/zaken/api/v1/zaken", seen.RequestUri!.ToString());
-        Assert.Equal("Bearer", seen.Headers.Authorization!.Scheme);
-        Assert.False(string.IsNullOrWhiteSpace(seen.Headers.Authorization.Parameter));
-        Assert.Contains("\"bronorganisatie\":\"517439943\"", body);
-        Assert.Contains("\"verantwoordelijkeOrganisatie\":\"517439943\"", body);
-        Assert.Contains("\"vertrouwelijkheidaanduiding\":\"openbaar\"", body);
-        Assert.Contains("\"startdatum\":\"2026-06-04\"", body);
-        Assert.Contains("\"zaaktype\":\"http://openzaak/catalogi/api/v1/zaaktypen/big\"", body);
+        Assert.Equal(HttpMethod.Post, capture.Seen!.Method);
+        Assert.Equal("http://openzaak/zaken/api/v1/zaken", capture.Seen.RequestUri!.ToString());
+        Assert.Equal("Bearer", capture.Seen.Headers.Authorization!.Scheme);
+        Assert.False(string.IsNullOrWhiteSpace(capture.Seen.Headers.Authorization.Parameter));
+        Assert.Contains("\"bronorganisatie\":\"517439943\"", capture.Body);
+        Assert.Contains("\"verantwoordelijkeOrganisatie\":\"517439943\"", capture.Body);
+        Assert.Contains("\"vertrouwelijkheidaanduiding\":\"openbaar\"", capture.Body);
+        Assert.Contains("\"startdatum\":\"2026-06-04\"", capture.Body);
+        Assert.Contains("\"zaaktype\":\"http://openzaak/catalogi/api/v1/zaaktypen/big\"", capture.Body);
+    }
+
+    [Fact]
+    public async Task Sends_the_geo_crs_headers_required_by_the_zaken_api()
+    {
+        var handler = Created(out var capture);
+
+        await Gateway(handler).OpenZaakAsync(SampleRequest());
+
+        Assert.Equal("EPSG:4326", Assert.Single(capture.Seen!.Headers.GetValues("Accept-Crs")));
+        Assert.Equal("EPSG:4326", Assert.Single(capture.Seen.Content!.Headers.GetValues("Content-Crs")));
+    }
+
+    [Fact]
+    public async Task Sends_the_body_with_a_content_length_so_it_is_not_chunked()
+    {
+        // OpenZaak's uwsgi rejects a chunked request body (400). The gateway buffers
+        // the body so a Content-Length is sent. JsonContent has no length until
+        // buffered, so this guards the fix the real-OpenZaak integration test found.
+        var handler = Created(out var capture);
+
+        await Gateway(handler).OpenZaakAsync(SampleRequest());
+
+        Assert.NotNull(capture.ContentLength);
+        Assert.True(capture.ContentLength > 0);
+    }
+
+    [Fact]
+    public async Task Mints_a_hs256_jwt_carrying_the_acl_identity_claims()
+    {
+        var handler = Created(out var capture);
+
+        await Gateway(handler).OpenZaakAsync(SampleRequest());
+
+        var parts = capture.Seen!.Headers.Authorization!.Parameter!.Split('.');
+        Assert.Equal(3, parts.Length);
+        using var header = JsonDocument.Parse(DecodeSegment(parts[0]));
+        Assert.Equal("HS256", header.RootElement.GetProperty("alg").GetString());
+        Assert.Equal("JWT", header.RootElement.GetProperty("typ").GetString());
+        using var payload = JsonDocument.Parse(DecodeSegment(parts[1]));
+        Assert.Equal("cid", payload.RootElement.GetProperty("client_id").GetString());
+        Assert.Equal("acl", payload.RootElement.GetProperty("user_id").GetString());
+        Assert.Equal("acl", payload.RootElement.GetProperty("user_representation").GetString());
+    }
+
+    [Fact]
+    public async Task Throws_when_openzaak_rejects_the_request()
+    {
+        var handler = new StubHandler(_ =>
+            Task.FromResult(new HttpResponseMessage(HttpStatusCode.BadRequest)));
+
+        await Assert.ThrowsAsync<HttpRequestException>(
+            () => Gateway(handler).OpenZaakAsync(SampleRequest()));
+    }
+
+    [Fact]
+    public async Task Throws_when_openzaak_returns_an_empty_body()
+    {
+        var handler = new StubHandler(_ =>
+            Task.FromResult(new HttpResponseMessage(HttpStatusCode.Created)
+            {
+                Content = new StringContent("null", Encoding.UTF8, "application/json"),
+            }));
+
+        await Assert.ThrowsAsync<InvalidOperationException>(
+            () => Gateway(handler).OpenZaakAsync(SampleRequest()));
+    }
+
+    [Fact]
+    public async Task Rejects_a_null_request()
+    {
+        var handler = new StubHandler(_ => throw new InvalidOperationException("should not be sent"));
+
+        await Assert.ThrowsAsync<ArgumentNullException>(
+            () => Gateway(handler).OpenZaakAsync(null!));
+    }
+
+    // ZGW tokens are base64url with padding stripped (ZgwToken.B64Url); restore it to decode.
+    private static string DecodeSegment(string segment)
+    {
+        var b64 = segment.Replace('-', '+').Replace('_', '/');
+        b64 = (b64.Length % 4) switch { 2 => b64 + "==", 3 => b64 + "=", _ => b64 };
+        return Encoding.UTF8.GetString(Convert.FromBase64String(b64));
     }
 }

services/acl/Acl.slnx

@@ -2,5 +2,6 @@
   <Project Path="Acl.Api/Acl.Api.csproj" />
   <Project Path="Acl.Application/Acl.Application.csproj" />
   <Project Path="Acl.Infrastructure/Acl.Infrastructure.csproj" />
+  <Project Path="Acl.IntegrationTests/Acl.IntegrationTests.csproj" />
   <Project Path="Acl.Tests/Acl.Tests.csproj" />
 </Solution>

services/acl/Dockerfile.integration

@@ -0,0 +1,26 @@
+# Runs the ACL integration tests (Category=Integration) from *inside* the compose
+# network, so they reach OpenZaak at http://openzaak:8000 by service name. On the
+# hosted CI runner a process on the runner can't reach the stack's published ports
+# (sibling containers — gitea-actions-gotchas.md §5), so the test runs as a
+# container joined to that network instead. See ADR-0006 / #55.
+#
+# Build context is services/acl (like the service Dockerfile). dotnet lives in this
+# image, so the CI `integration` job needs only Docker — no setup-dotnet step.
+FROM mcr.microsoft.com/dotnet/sdk:10.0
+WORKDIR /src
+
+# Restore first (cached unless the .csproj files change). The integration test
+# project pulls in Acl.Application + Acl.Infrastructure via its ProjectReferences.
+COPY Acl.Application/Acl.Application.csproj Acl.Application/
+COPY Acl.Infrastructure/Acl.Infrastructure.csproj Acl.Infrastructure/
+COPY Acl.IntegrationTests/Acl.IntegrationTests.csproj Acl.IntegrationTests/
+RUN dotnet restore Acl.IntegrationTests/Acl.IntegrationTests.csproj
+
+COPY Acl.Application/ Acl.Application/
+COPY Acl.Infrastructure/ Acl.Infrastructure/
+COPY Acl.IntegrationTests/ Acl.IntegrationTests/
+
+# OZ_BASE is supplied at run time (the OpenZaak container IP — see run-integration.sh,
+# which passes `-e OZ_BASE=http://<ip>:8000`; a single-label host is not URL-valid).
+ENTRYPOINT ["dotnet", "test", "Acl.IntegrationTests/Acl.IntegrationTests.csproj", \
+            "-c", "Release", "--filter", "Category=Integration"]

services/acl/stryker-config.json

@@ -0,0 +1,12 @@
+{
+  "stryker-config": {
+    "solution": "Acl.slnx",
+    "test-projects": ["Acl.Tests/Acl.Tests.csproj"],
+    "reporters": ["progress", "html"],
+    "thresholds": {
+      "high": 95,
+      "low": 90,
+      "break": 90
+    }
+  }
+}

services/event-subscriber/Dockerfile

@@ -0,0 +1,32 @@
+# Multi-stage build for the Event Subscriber service (.NET 10).
+# Build context is services/event-subscriber, but it references the shared read model in
+# services/projection-api, so the context is the repo root (see infra/docker-compose.yml).
+FROM mcr.microsoft.com/dotnet/sdk:10.0 AS build
+WORKDIR /src
+
+# Restore first (cached unless .csproj files change).
+COPY services/event-subscriber/EventSubscriber.Api/EventSubscriber.Api.csproj services/event-subscriber/EventSubscriber.Api/
+COPY services/event-subscriber/EventSubscriber.Application/EventSubscriber.Application.csproj services/event-subscriber/EventSubscriber.Application/
+COPY services/projection-api/Projection.ReadModel/Projection.ReadModel.csproj services/projection-api/Projection.ReadModel/
+RUN dotnet restore services/event-subscriber/EventSubscriber.Api/EventSubscriber.Api.csproj
+
+COPY services/event-subscriber/ services/event-subscriber/
+COPY services/projection-api/Projection.ReadModel/ services/projection-api/Projection.ReadModel/
+RUN dotnet publish services/event-subscriber/EventSubscriber.Api/EventSubscriber.Api.csproj -c Release -o /app/publish /p:UseAppHost=false
+
+FROM mcr.microsoft.com/dotnet/aspnet:10.0 AS runtime
+WORKDIR /app
+
+RUN apt-get update \
+    && apt-get install -y --no-install-recommends curl \
+    && rm -rf /var/lib/apt/lists/*
+
+COPY --from=build /app/publish .
+
+ENV ASPNETCORE_URLS=http://+:8080
+EXPOSE 8080
+
+HEALTHCHECK --interval=5s --timeout=3s --start-period=15s --retries=5 \
+    CMD curl -fsS http://localhost:8080/health || exit 1
+
+ENTRYPOINT ["dotnet", "EventSubscriber.Api.dll"]

services/event-subscriber/EventSubscriber.Api/EventSubscriber.Api.csproj

@@ -0,0 +1,14 @@
+<Project Sdk="Microsoft.NET.Sdk.Web">
+
+  <ItemGroup>
+    <ProjectReference Include="..\EventSubscriber.Application\EventSubscriber.Application.csproj" />
+    <ProjectReference Include="..\..\projection-api\Projection.ReadModel\Projection.ReadModel.csproj" />
+  </ItemGroup>
+
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+  </PropertyGroup>
+
+</Project>

services/event-subscriber/EventSubscriber.Api/Program.cs

@@ -0,0 +1,66 @@
+using System.Text.Json;
+using EventSubscriber.Application;
+using Projection.ReadModel;
+
+var builder = WebApplication.CreateBuilder(args);
+
+var connectionString = builder.Configuration.GetConnectionString("Projection")
+    ?? throw new InvalidOperationException("Missing connection string 'ConnectionStrings:Projection'");
+// The exact Authorization header value Open Notificaties sends on each abonnement callback.
+// NRC probes the callback during registration and refuses it unless it returns 401 without
+// this value (ADR-0007), so the webhook enforces it.
+var webhookToken = builder.Configuration["EventSubscriber:Webhook:AuthToken"]
+    ?? throw new InvalidOperationException("Missing configuration 'EventSubscriber:Webhook:AuthToken'");
+
+builder.Services.AddProjectionReadModel(connectionString);
+builder.Services.AddProjectionWriteSide();
+
+var app = builder.Build();
+
+// Apply migrations on start so a fresh stack reaches a usable schema unattended.
+await app.Services.MigrateProjectionAsync();
+
+app.MapGet("/health", () => "Healthy");
+
+// The NRC abonnement callback. Open Notificaties POSTs a notification here; we project it.
+// Auth-on-callback is mandatory: the auth check runs *before* the body is read, so NRC's
+// registration probe (a POST without the configured Authorization, and without a valid
+// notification body) gets the 401 it requires rather than a 400 (ADR-0007).
+app.MapPost("/notifications", async (
+    HttpRequest request,
+    NotificationProjector projector,
+    CancellationToken ct) =>
+{
+    if (request.Headers.Authorization != webhookToken)
+        return Results.Unauthorized();
+
+    var dto = await JsonSerializer.DeserializeAsync<NotificationDto>(
+        request.Body, SerializerOptions, ct);
+    if (dto is null)
+        return Results.BadRequest();
+
+    await projector.HandleAsync(dto.ToNotification(), ct);
+    return Results.NoContent();
+});
+
+// Admin: rebuild the projection from the durable notification log (PRD §8.4 — rebuildable).
+app.MapPost("/admin/rebuild", async (NotificationProjector projector, CancellationToken ct) =>
+{
+    await projector.RebuildAsync(ct);
+    return Results.NoContent();
+});
+
+await app.RunAsync();
+
+/// <summary>The NRC notification body, as Open Notificaties POSTs it. Only the fields the
+/// projection needs are bound; <c>aanmaakdatum</c>/<c>kenmerken</c> are ignored for the minimal slice.</summary>
+public sealed record NotificationDto(string Kanaal, string Resource, string Actie, Uri ResourceUrl)
+{
+    public Notification ToNotification() => new(Kanaal, Resource, Actie, ResourceUrl);
+}
+
+public partial class Program
+{
+    // NRC sends camelCase JSON; match it case-insensitively.
+    private static readonly JsonSerializerOptions SerializerOptions = new(JsonSerializerDefaults.Web);
+}

services/event-subscriber/EventSubscriber.Api/appsettings.json

@@ -0,0 +1,8 @@
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning"
+    }
+  }
+}

services/event-subscriber/EventSubscriber.Application/EventSubscriber.Application.csproj

@@ -0,0 +1,9 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+  </PropertyGroup>
+
+</Project>

services/event-subscriber/EventSubscriber.Application/Notification.cs

@@ -0,0 +1,30 @@
+namespace EventSubscriber.Application;
+
+/// <summary>
+/// An inbound NRC (Open Notificaties) notification, as Open Notificaties POSTs it to an
+/// abonnement callback. Only the fields the projection needs are modelled; the full ZGW
+/// "Notificatie" resource also carries <c>aanmaakdatum</c> and <c>kenmerken</c> which the
+/// minimal projection ignores (bsn is deferred — see ADR-0008). For a <c>zaken</c>/<c>zaak</c>/<c>create</c>
+/// notification <c>hoofdObject</c> and <c>resourceUrl</c> are both the created zaak's URL.
+/// </summary>
+public sealed record Notification(
+    string Kanaal,
+    string Resource,
+    string Actie,
+    Uri ResourceUrl)
+{
+    /// <summary>The only event the walking-skeleton projection reacts to: a zaak being created.</summary>
+    public bool IsZaakCreated =>
+        Kanaal == "zaken" && Resource == "zaak" && Actie == "create";
+
+    /// <summary>The zaak UUID — the trailing path segment of the resource URL — used as the projection key.</summary>
+    public string ZaakId => ResourceUrl.Segments[^1].Trim('/');
+
+    /// <summary>
+    /// A deterministic dedup key. Open Notificaties carries no notification id and may
+    /// redeliver, so the key is derived from the immutable notification content: two
+    /// deliveries of the same zaak-create collapse to one. (NRC may also deliver
+    /// out of order; the projector tolerates that — order does not change the outcome.)
+    /// </summary>
+    public string IdempotencyKey => $"{Kanaal}:{Resource}:{Actie}:{ResourceUrl}";
+}

services/event-subscriber/EventSubscriber.Application/NotificationProjector.cs

@@ -0,0 +1,38 @@
+namespace EventSubscriber.Application;
+
+/// <summary>
+/// Projects inbound NRC notifications into the read projection. Tolerates duplicate and
+/// out-of-order deliveries (CLAUDE.md §8.6): the notification log dedups, and the projection
+/// upsert is idempotent on the zaak id. Rebuilds the projection by replaying the log.
+/// </summary>
+public sealed class NotificationProjector(INotificationLog log, IProjectionStore store)
+{
+    /// <summary>Handle one inbound notification. Ignores anything that is not a zaak-created event.</summary>
+    public async Task HandleAsync(Notification notification, CancellationToken ct = default)
+    {
+        if (!notification.IsZaakCreated)
+            return;
+
+        var recorded = new RecordedNotification(notification.IdempotencyKey, notification.Actie, notification.ZaakId);
+
+        // Atomic record-or-skip: a duplicate (or concurrent) delivery is recognised and dropped
+        // before it touches the projection, so the projection stays a faithful derived artefact.
+        if (!await log.TryRecordAsync(recorded, ct))
+            return;
+
+        await store.UpsertAsync(ToEntry(recorded), ct);
+    }
+
+    /// <summary>Rebuild the projection from the durable notification log (PRD §8.4).</summary>
+    public async Task RebuildAsync(CancellationToken ct = default)
+    {
+        await store.ClearAsync(ct);
+        foreach (var recorded in await log.AllAsync(ct))
+            await store.UpsertAsync(ToEntry(recorded), ct);
+    }
+
+    /// <summary>The minimal projection row for an accepted notification. A zaak-create maps to
+    /// INGEDIEND; bsn/naam are deferred (ADR-0008).</summary>
+    private static RegisterEntry ToEntry(RecordedNotification recorded)
+        => new(recorded.ZaakId, RegistrationStatus.Ingediend);
+}

services/event-subscriber/EventSubscriber.Application/Ports.cs

@@ -0,0 +1,37 @@
+namespace EventSubscriber.Application;
+
+/// <summary>
+/// The durable log of notifications the subscriber has accepted. It is both the idempotency
+/// guard (a replayed notification is recognised and dropped) and the rebuild source: the
+/// projection is a derived artefact (PRD §8.4) regenerated by replaying this log, so a rebuild
+/// needs no access to OpenZaak (CLAUDE.md §8.1). Implemented in Infrastructure over Postgres.
+/// </summary>
+public interface INotificationLog
+{
+    /// <summary>
+    /// Record a notification. Returns <c>true</c> if it was newly recorded, <c>false</c> if an
+    /// entry with the same key already existed (a duplicate delivery). Must be atomic so that
+    /// concurrent duplicate deliveries cannot both observe <c>true</c>.
+    /// </summary>
+    Task<bool> TryRecordAsync(RecordedNotification notification, CancellationToken ct = default);
+
+    /// <summary>Every accepted notification, for rebuilding the projection.</summary>
+    Task<IReadOnlyList<RecordedNotification>> AllAsync(CancellationToken ct = default);
+}
+
+/// <summary>A notification that has been accepted, retaining what a rebuild needs to recompute its projection row.</summary>
+public sealed record RecordedNotification(string Key, string Actie, string ZaakId);
+
+/// <summary>The read projection store. Owned by the projection bounded context (ADR-0008); the
+/// subscriber writes to it and the projection-api reads it.</summary>
+public interface IProjectionStore
+{
+    /// <summary>Insert or update the row for <see cref="RegisterEntry.Id"/>. Idempotent on the id.</summary>
+    Task UpsertAsync(RegisterEntry entry, CancellationToken ct = default);
+
+    /// <summary>Remove every row — the first step of a rebuild.</summary>
+    Task ClearAsync(CancellationToken ct = default);
+
+    /// <summary>Every projection row (used by tests and the rebuild verification).</summary>
+    Task<IReadOnlyList<RegisterEntry>> AllAsync(CancellationToken ct = default);
+}

services/event-subscriber/EventSubscriber.Application/RegisterEntry.cs

@@ -0,0 +1,20 @@
+namespace EventSubscriber.Application;
+
+/// <summary>
+/// A row of the rebuildable read projection (PRD §8.4). For the minimal slice it carries
+/// the zaak id and a status; <c>Bsn</c> and <c>NaamPlaceholder</c> are part of the schema but
+/// are deferred — the NRC notification does not carry them and the subscriber may not read
+/// OpenZaak directly (CLAUDE.md §8.1). Populating them is a follow-up (ADR-0008).
+/// </summary>
+public sealed record RegisterEntry(
+    string Id,
+    string Status,
+    string? Bsn = null,
+    string? NaamPlaceholder = null);
+
+/// <summary>The projection statuses the walking skeleton knows about.</summary>
+public static class RegistrationStatus
+{
+    /// <summary>A zaak has been created; the registration is submitted.</summary>
+    public const string Ingediend = "INGEDIEND";
+}

services/event-subscriber/EventSubscriber.Tests/EventSubscriber.Tests.csproj

@@ -0,0 +1,25 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <IsPackable>false</IsPackable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="coverlet.collector" Version="6.0.4" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
+    <PackageReference Include="xunit" Version="2.9.3" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="3.1.4" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <Using Include="Xunit" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\EventSubscriber.Application\EventSubscriber.Application.csproj" />
+  </ItemGroup>
+
+</Project>

services/event-subscriber/EventSubscriber.Tests/InMemoryStores.cs

@@ -0,0 +1,42 @@
+using EventSubscriber.Application;
+
+namespace EventSubscriber.Tests;
+
+/// <summary>In-memory stand-ins for the projection store and notification log, so the
+/// projector's behaviour is exercised without Postgres (hand-written stubs, the repo's
+/// convention — no mocking library).</summary>
+internal sealed class InMemoryNotificationLog : INotificationLog
+{
+    private readonly Dictionary<string, RecordedNotification> _byKey = [];
+
+    public Task<bool> TryRecordAsync(RecordedNotification notification, CancellationToken ct = default)
+        => Task.FromResult(_byKey.TryAdd(notification.Key, notification));
+
+    public Task<IReadOnlyList<RecordedNotification>> AllAsync(CancellationToken ct = default)
+        => Task.FromResult<IReadOnlyList<RecordedNotification>>([.. _byKey.Values]);
+}
+
+internal sealed class InMemoryProjectionStore : IProjectionStore
+{
+    private readonly Dictionary<string, RegisterEntry> _byId = [];
+
+    /// <summary>How many times a write was attempted — lets a test prove a deduped delivery
+    /// never reaches the store (an idempotent upsert hides the difference in row count alone).</summary>
+    public int UpsertCount { get; private set; }
+
+    public Task UpsertAsync(RegisterEntry entry, CancellationToken ct = default)
+    {
+        UpsertCount++;
+        _byId[entry.Id] = entry;
+        return Task.CompletedTask;
+    }
+
+    public Task ClearAsync(CancellationToken ct = default)
+    {
+        _byId.Clear();
+        return Task.CompletedTask;
+    }
+
+    public Task<IReadOnlyList<RegisterEntry>> AllAsync(CancellationToken ct = default)
+        => Task.FromResult<IReadOnlyList<RegisterEntry>>([.. _byId.Values]);
+}

services/event-subscriber/EventSubscriber.Tests/NotificationProjectorTests.cs

@@ -0,0 +1,89 @@
+using EventSubscriber.Application;
+
+namespace EventSubscriber.Tests;
+
+/// <summary>Behaviour of the projector that turns NRC notifications into projection rows.
+/// The walking skeleton reacts only to a zaak being created (status INGEDIEND) and must
+/// tolerate duplicate and out-of-order deliveries (CLAUDE.md §8.6).</summary>
+public sealed class NotificationProjectorTests
+{
+    private const string ZaakUrl = "http://openzaak:8000/zaken/api/v1/zaken/11111111-1111-1111-1111-111111111111";
+
+    private readonly InMemoryNotificationLog _log = new();
+    private readonly InMemoryProjectionStore _store = new();
+
+    private NotificationProjector Projector() => new(_log, _store);
+
+    private static Notification ZaakCreated(string url = ZaakUrl)
+        => new("zaken", "zaak", "create", new Uri(url));
+
+    [Fact]
+    public async Task creating_a_zaak_writes_one_row_with_status_ingediend()
+    {
+        await Projector().HandleAsync(ZaakCreated());
+
+        var entry = Assert.Single(await _store.AllAsync());
+        Assert.Equal("11111111-1111-1111-1111-111111111111", entry.Id);
+        Assert.Equal(RegistrationStatus.Ingediend, entry.Status);
+    }
+
+    [Fact]
+    public async Task replaying_the_same_notification_keeps_a_single_row()
+    {
+        var projector = Projector();
+        await projector.HandleAsync(ZaakCreated());
+        await projector.HandleAsync(ZaakCreated());
+
+        Assert.Single(await _store.AllAsync());
+    }
+
+    [Fact]
+    public async Task a_replayed_notification_never_reaches_the_projection_store()
+    {
+        var projector = Projector();
+        await projector.HandleAsync(ZaakCreated());
+        await projector.HandleAsync(ZaakCreated());
+
+        // The duplicate is dropped at the log, before the (idempotent) upsert — so the store
+        // is written exactly once. Row count alone can't see this; the upsert count can.
+        Assert.Equal(1, _store.UpsertCount);
+    }
+
+    [Fact]
+    public async Task two_different_zaken_each_get_their_own_row()
+    {
+        var projector = Projector();
+        await projector.HandleAsync(ZaakCreated());
+        await projector.HandleAsync(ZaakCreated(ZaakUrl[..^1] + "2")); // a distinct zaak url
+
+        Assert.Equal(2, (await _store.AllAsync()).Count);
+    }
+
+    [Theory]
+    [InlineData("documenten", "enkelvoudiginformatieobject", "create")] // wrong kanaal + resource
+    [InlineData("documenten", "zaak", "create")]                        // wrong kanaal only
+    [InlineData("zaken", "status", "create")]                           // wrong resource only
+    [InlineData("zaken", "zaak", "update")]                             // wrong actie
+    [InlineData("zaken", "zaak", "destroy")]                            // wrong actie
+    public async Task only_a_zaken_zaak_create_notification_is_projected(string kanaal, string resource, string actie)
+    {
+        await Projector().HandleAsync(new Notification(kanaal, resource, actie, new Uri(ZaakUrl)));
+
+        Assert.Empty(await _store.AllAsync());
+    }
+
+    [Fact]
+    public async Task rebuild_clears_stale_rows_and_repopulates_from_the_notification_log()
+    {
+        var projector = Projector();
+        await projector.HandleAsync(ZaakCreated());
+        // A stale row that is not backed by any logged notification must not survive a rebuild.
+        await _store.UpsertAsync(new RegisterEntry("stale-9999", RegistrationStatus.Ingediend));
+
+        await projector.RebuildAsync();
+
+        var entry = Assert.Single(await _store.AllAsync());
+        Assert.Equal("11111111-1111-1111-1111-111111111111", entry.Id);
+        Assert.Equal(RegistrationStatus.Ingediend, entry.Status);
+    }
+}

services/event-subscriber/EventSubscriber.slnx

@@ -0,0 +1,4 @@
+<Solution>
+  <Project Path="EventSubscriber.Application/EventSubscriber.Application.csproj" />
+  <Project Path="EventSubscriber.Tests/EventSubscriber.Tests.csproj" />
+</Solution>

services/event-subscriber/stryker-config.json

@@ -0,0 +1,12 @@
+{
+  "stryker-config": {
+    "solution": "EventSubscriber.slnx",
+    "test-projects": ["EventSubscriber.Tests/EventSubscriber.Tests.csproj"],
+    "reporters": ["progress", "html"],
+    "thresholds": {
+      "high": 95,
+      "low": 90,
+      "break": 90
+    }
+  }
+}

services/projection-api/Dockerfile

@@ -0,0 +1,31 @@
+# Multi-stage build for the projection-api service (.NET 10).
+# Build context is the repo root (it shares Projection.ReadModel — see infra/docker-compose.yml).
+FROM mcr.microsoft.com/dotnet/sdk:10.0 AS build
+WORKDIR /src
+
+# Restore first (cached unless .csproj files change).
+COPY services/projection-api/ProjectionApi.Api/ProjectionApi.Api.csproj services/projection-api/ProjectionApi.Api/
+COPY services/projection-api/Projection.ReadModel/Projection.ReadModel.csproj services/projection-api/Projection.ReadModel/
+COPY services/event-subscriber/EventSubscriber.Application/EventSubscriber.Application.csproj services/event-subscriber/EventSubscriber.Application/
+RUN dotnet restore services/projection-api/ProjectionApi.Api/ProjectionApi.Api.csproj
+
+COPY services/projection-api/ services/projection-api/
+COPY services/event-subscriber/EventSubscriber.Application/ services/event-subscriber/EventSubscriber.Application/
+RUN dotnet publish services/projection-api/ProjectionApi.Api/ProjectionApi.Api.csproj -c Release -o /app/publish /p:UseAppHost=false
+
+FROM mcr.microsoft.com/dotnet/aspnet:10.0 AS runtime
+WORKDIR /app
+
+RUN apt-get update \
+    && apt-get install -y --no-install-recommends curl \
+    && rm -rf /var/lib/apt/lists/*
+
+COPY --from=build /app/publish .
+
+ENV ASPNETCORE_URLS=http://+:8080
+EXPOSE 8080
+
+HEALTHCHECK --interval=5s --timeout=3s --start-period=15s --retries=5 \
+    CMD curl -fsS http://localhost:8080/health || exit 1
+
+ENTRYPOINT ["dotnet", "ProjectionApi.Api.dll"]

services/projection-api/Projection.ReadModel/DesignTimeProjectionDbContextFactory.cs

@@ -0,0 +1,18 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Design;
+
+namespace Projection.ReadModel;
+
+/// <summary>Lets <c>dotnet ef migrations</c> build the context at design time without a running
+/// database or the host's DI. The connection string is a placeholder — migrations only need the
+/// provider to emit Postgres-shaped SQL.</summary>
+public sealed class DesignTimeProjectionDbContextFactory : IDesignTimeDbContextFactory<ProjectionDbContext>
+{
+    public ProjectionDbContext CreateDbContext(string[] args)
+    {
+        var options = new DbContextOptionsBuilder<ProjectionDbContext>()
+            .UseNpgsql("Host=localhost;Database=projection;Username=projection;Password=projection")
+            .Options;
+        return new ProjectionDbContext(options);
+    }
+}

services/projection-api/Projection.ReadModel/EfNotificationLog.cs

@@ -0,0 +1,39 @@
+using EventSubscriber.Application;
+using Microsoft.EntityFrameworkCore;
+
+namespace Projection.ReadModel;
+
+/// <summary>EF Core implementation of the notification log. Idempotency is enforced atomically
+/// by the primary key on <c>key</c>: a duplicate insert raises a unique violation, which is
+/// caught and reported as "already recorded" rather than failing the request.</summary>
+public sealed class EfNotificationLog(ProjectionDbContext db) : INotificationLog
+{
+    public async Task<bool> TryRecordAsync(RecordedNotification notification, CancellationToken ct = default)
+    {
+        db.ProcessedNotifications.Add(new ProcessedNotificationRow
+        {
+            Key = notification.Key,
+            Actie = notification.Actie,
+            ZaakId = notification.ZaakId,
+            ReceivedAt = DateTimeOffset.UtcNow,
+        });
+
+        try
+        {
+            await db.SaveChangesAsync(ct);
+            return true;
+        }
+        catch (DbUpdateException)
+        {
+            // Already recorded by an earlier (or concurrent) delivery — drop this duplicate.
+            db.ChangeTracker.Clear();
+            return false;
+        }
+    }
+
+    public async Task<IReadOnlyList<RecordedNotification>> AllAsync(CancellationToken ct = default)
+        => await db.ProcessedNotifications
+            .OrderBy(r => r.ReceivedAt)
+            .Select(r => new RecordedNotification(r.Key, r.Actie, r.ZaakId))
+            .ToListAsync(ct);
+}

services/projection-api/Projection.ReadModel/EfProjectionStore.cs

@@ -0,0 +1,40 @@
+using EventSubscriber.Application;
+using Microsoft.EntityFrameworkCore;
+
+namespace Projection.ReadModel;
+
+/// <summary>EF Core implementation of the projection store over <see cref="ProjectionDbContext"/>.</summary>
+public sealed class EfProjectionStore(ProjectionDbContext db) : IProjectionStore
+{
+    public async Task UpsertAsync(RegisterEntry entry, CancellationToken ct = default)
+    {
+        var row = await db.RegisterEntries.FindAsync([entry.Id], ct);
+        if (row is null)
+        {
+            db.RegisterEntries.Add(new RegisterEntryRow
+            {
+                Id = entry.Id,
+                Status = entry.Status,
+                Bsn = entry.Bsn,
+                NaamPlaceholder = entry.NaamPlaceholder,
+            });
+        }
+        else
+        {
+            row.Status = entry.Status;
+            row.Bsn = entry.Bsn;
+            row.NaamPlaceholder = entry.NaamPlaceholder;
+        }
+
+        await db.SaveChangesAsync(ct);
+    }
+
+    public async Task ClearAsync(CancellationToken ct = default)
+        => await db.RegisterEntries.ExecuteDeleteAsync(ct);
+
+    public async Task<IReadOnlyList<RegisterEntry>> AllAsync(CancellationToken ct = default)
+        => await db.RegisterEntries
+            .OrderBy(r => r.Id)
+            .Select(r => new RegisterEntry(r.Id, r.Status, r.Bsn, r.NaamPlaceholder))
+            .ToListAsync(ct);
+}

services/projection-api/Projection.ReadModel/Migrations/20260630125055_InitialProjection.Designer.cs

@@ -0,0 +1,79 @@
+// <auto-generated />
+using System;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+using Microsoft.EntityFrameworkCore.Migrations;
+using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+using Npgsql.EntityFrameworkCore.PostgreSQL.Metadata;
+using Projection.ReadModel;
+
+#nullable disable
+
+namespace Projection.ReadModel.Migrations
+{
+    [DbContext(typeof(ProjectionDbContext))]
+    [Migration("20260630125055_InitialProjection")]
+    partial class InitialProjection
+    {
+        /// <inheritdoc />
+        protected override void BuildTargetModel(ModelBuilder modelBuilder)
+        {
+#pragma warning disable 612, 618
+            modelBuilder
+                .HasAnnotation("ProductVersion", "10.0.0")
+                .HasAnnotation("Relational:MaxIdentifierLength", 63);
+
+            NpgsqlModelBuilderExtensions.UseIdentityByDefaultColumns(modelBuilder);
+
+            modelBuilder.Entity("Projection.ReadModel.ProcessedNotificationRow", b =>
+                {
+                    b.Property<string>("Key")
+                        .HasColumnType("text")
+                        .HasColumnName("key");
+
+                    b.Property<string>("Actie")
+                        .IsRequired()
+                        .HasColumnType("text")
+                        .HasColumnName("actie");
+
+                    b.Property<DateTimeOffset>("ReceivedAt")
+                        .HasColumnType("timestamp with time zone")
+                        .HasColumnName("received_at");
+
+                    b.Property<string>("ZaakId")
+                        .IsRequired()
+                        .HasColumnType("text")
+                        .HasColumnName("zaak_id");
+
+                    b.HasKey("Key");
+
+                    b.ToTable("processed_notifications", (string)null);
+                });
+
+            modelBuilder.Entity("Projection.ReadModel.RegisterEntryRow", b =>
+                {
+                    b.Property<string>("Id")
+                        .HasColumnType("text")
+                        .HasColumnName("id");
+
+                    b.Property<string>("Bsn")
+                        .HasColumnType("text")
+                        .HasColumnName("bsn");
+
+                    b.Property<string>("NaamPlaceholder")
+                        .HasColumnType("text")
+                        .HasColumnName("naam_placeholder");
+
+                    b.Property<string>("Status")
+                        .IsRequired()
+                        .HasColumnType("text")
+                        .HasColumnName("status");
+
+                    b.HasKey("Id");
+
+                    b.ToTable("register_projection", (string)null);
+                });
+#pragma warning restore 612, 618
+        }
+    }
+}

services/projection-api/Projection.ReadModel/Migrations/20260630125055_InitialProjection.cs

@@ -0,0 +1,53 @@
+using System;
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace Projection.ReadModel.Migrations
+{
+    /// <inheritdoc />
+    public partial class InitialProjection : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.CreateTable(
+                name: "processed_notifications",
+                columns: table => new
+                {
+                    key = table.Column<string>(type: "text", nullable: false),
+                    actie = table.Column<string>(type: "text", nullable: false),
+                    zaak_id = table.Column<string>(type: "text", nullable: false),
+                    received_at = table.Column<DateTimeOffset>(type: "timestamp with time zone", nullable: false)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_processed_notifications", x => x.key);
+                });
+
+            migrationBuilder.CreateTable(
+                name: "register_projection",
+                columns: table => new
+                {
+                    id = table.Column<string>(type: "text", nullable: false),
+                    status = table.Column<string>(type: "text", nullable: false),
+                    bsn = table.Column<string>(type: "text", nullable: true),
+                    naam_placeholder = table.Column<string>(type: "text", nullable: true)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_register_projection", x => x.id);
+                });
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropTable(
+                name: "processed_notifications");
+
+            migrationBuilder.DropTable(
+                name: "register_projection");
+        }
+    }
+}

services/projection-api/Projection.ReadModel/Migrations/ProjectionDbContextModelSnapshot.cs

@@ -0,0 +1,76 @@
+// <auto-generated />
+using System;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+using Npgsql.EntityFrameworkCore.PostgreSQL.Metadata;
+using Projection.ReadModel;
+
+#nullable disable
+
+namespace Projection.ReadModel.Migrations
+{
+    [DbContext(typeof(ProjectionDbContext))]
+    partial class ProjectionDbContextModelSnapshot : ModelSnapshot
+    {
+        protected override void BuildModel(ModelBuilder modelBuilder)
+        {
+#pragma warning disable 612, 618
+            modelBuilder
+                .HasAnnotation("ProductVersion", "10.0.0")
+                .HasAnnotation("Relational:MaxIdentifierLength", 63);
+
+            NpgsqlModelBuilderExtensions.UseIdentityByDefaultColumns(modelBuilder);
+
+            modelBuilder.Entity("Projection.ReadModel.ProcessedNotificationRow", b =>
+                {
+                    b.Property<string>("Key")
+                        .HasColumnType("text")
+                        .HasColumnName("key");
+
+                    b.Property<string>("Actie")
+                        .IsRequired()
+                        .HasColumnType("text")
+                        .HasColumnName("actie");
+
+                    b.Property<DateTimeOffset>("ReceivedAt")
+                        .HasColumnType("timestamp with time zone")
+                        .HasColumnName("received_at");
+
+                    b.Property<string>("ZaakId")
+                        .IsRequired()
+                        .HasColumnType("text")
+                        .HasColumnName("zaak_id");
+
+                    b.HasKey("Key");
+
+                    b.ToTable("processed_notifications", (string)null);
+                });
+
+            modelBuilder.Entity("Projection.ReadModel.RegisterEntryRow", b =>
+                {
+                    b.Property<string>("Id")
+                        .HasColumnType("text")
+                        .HasColumnName("id");
+
+                    b.Property<string>("Bsn")
+                        .HasColumnType("text")
+                        .HasColumnName("bsn");
+
+                    b.Property<string>("NaamPlaceholder")
+                        .HasColumnType("text")
+                        .HasColumnName("naam_placeholder");
+
+                    b.Property<string>("Status")
+                        .IsRequired()
+                        .HasColumnType("text")
+                        .HasColumnName("status");
+
+                    b.HasKey("Id");
+
+                    b.ToTable("register_projection", (string)null);
+                });
+#pragma warning restore 612, 618
+        }
+    }
+}

services/projection-api/Projection.ReadModel/Projection.ReadModel.csproj

@@ -0,0 +1,28 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <!-- Audit only the packages we choose directly. The one flagged transitive
+         (System.Security.Cryptography.Xml, NU1903) comes via EF Core's design-time
+         migration tooling (Microsoft.EntityFrameworkCore.Design, PrivateAssets=all) and
+         is never shipped at runtime — it is out of our control to upgrade. -->
+    <NuGetAuditMode>direct</NuGetAuditMode>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\event-subscriber\EventSubscriber.Application\EventSubscriber.Application.csproj" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.EntityFrameworkCore" Version="10.0.0" />
+    <PackageReference Include="Microsoft.EntityFrameworkCore.Relational" Version="10.0.0" />
+    <PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="10.0.0">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
+    <PackageReference Include="Npgsql.EntityFrameworkCore.PostgreSQL" Version="10.0.0" />
+  </ItemGroup>
+
+</Project>

services/projection-api/Projection.ReadModel/ProjectionDbContext.cs

@@ -0,0 +1,59 @@
+using Microsoft.EntityFrameworkCore;
+
+namespace Projection.ReadModel;
+
+/// <summary>
+/// The read projection's persistence. This single store is the system's rebuildable read model
+/// (PRD §8.4): the Event Subscriber writes to it (projector) and the projection-api reads it
+/// (query). Both processes are the one "Read Projection" bounded context and share this schema —
+/// not a cross-domain DB share (ADR-0008 reconciles this with CLAUDE.md §8.5).
+/// </summary>
+public sealed class ProjectionDbContext(DbContextOptions<ProjectionDbContext> options) : DbContext(options)
+{
+    /// <summary>The public-facing register rows (public-safe filtering is tightened in S-09).</summary>
+    public DbSet<RegisterEntryRow> RegisterEntries => Set<RegisterEntryRow>();
+
+    /// <summary>The Event Subscriber's durable log of accepted notifications — idempotency guard and rebuild source.</summary>
+    public DbSet<ProcessedNotificationRow> ProcessedNotifications => Set<ProcessedNotificationRow>();
+
+    protected override void OnModelCreating(ModelBuilder modelBuilder)
+    {
+        modelBuilder.Entity<RegisterEntryRow>(e =>
+        {
+            e.ToTable("register_projection");
+            e.HasKey(r => r.Id);
+            e.Property(r => r.Id).HasColumnName("id");
+            e.Property(r => r.Status).HasColumnName("status").IsRequired();
+            e.Property(r => r.Bsn).HasColumnName("bsn");
+            e.Property(r => r.NaamPlaceholder).HasColumnName("naam_placeholder");
+        });
+
+        modelBuilder.Entity<ProcessedNotificationRow>(e =>
+        {
+            e.ToTable("processed_notifications");
+            e.HasKey(r => r.Key);
+            e.Property(r => r.Key).HasColumnName("key");
+            e.Property(r => r.Actie).HasColumnName("actie").IsRequired();
+            e.Property(r => r.ZaakId).HasColumnName("zaak_id").IsRequired();
+            e.Property(r => r.ReceivedAt).HasColumnName("received_at");
+        });
+    }
+}
+
+/// <summary>A register projection row. <c>Bsn</c>/<c>NaamPlaceholder</c> are deferred (ADR-0008).</summary>
+public sealed class RegisterEntryRow
+{
+    public required string Id { get; set; }
+    public required string Status { get; set; }
+    public string? Bsn { get; set; }
+    public string? NaamPlaceholder { get; set; }
+}
+
+/// <summary>An accepted notification, retained so the projection can be rebuilt without OpenZaak (§8.1).</summary>
+public sealed class ProcessedNotificationRow
+{
+    public required string Key { get; set; }
+    public required string Actie { get; set; }
+    public required string ZaakId { get; set; }
+    public DateTimeOffset ReceivedAt { get; set; }
+}

services/projection-api/Projection.ReadModel/ServiceCollectionExtensions.cs

@@ -0,0 +1,30 @@
+using EventSubscriber.Application;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace Projection.ReadModel;
+
+public static class ServiceCollectionExtensions
+{
+    /// <summary>Register the projection <see cref="ProjectionDbContext"/> against Postgres.</summary>
+    public static IServiceCollection AddProjectionReadModel(this IServiceCollection services, string connectionString)
+        => services.AddDbContext<ProjectionDbContext>(o => o.UseNpgsql(connectionString));
+
+    /// <summary>Register the write-side ports (projector store + notification log) used by the Event Subscriber.</summary>
+    public static IServiceCollection AddProjectionWriteSide(this IServiceCollection services)
+    {
+        services.AddScoped<IProjectionStore, EfProjectionStore>();
+        services.AddScoped<INotificationLog, EfNotificationLog>();
+        services.AddScoped<NotificationProjector>();
+        return services;
+    }
+
+    /// <summary>Apply any pending EF migrations. Called once on service start so a fresh stack
+    /// reaches a usable schema without a manual migration step (DoD: compose up reaches green).</summary>
+    public static async Task MigrateProjectionAsync(this IServiceProvider services, CancellationToken ct = default)
+    {
+        await using var scope = services.CreateAsyncScope();
+        var db = scope.ServiceProvider.GetRequiredService<ProjectionDbContext>();
+        await db.Database.MigrateAsync(ct);
+    }
+}

services/projection-api/ProjectionApi.Api/Program.cs

@@ -0,0 +1,43 @@
+using Microsoft.EntityFrameworkCore;
+using Projection.ReadModel;
+
+var builder = WebApplication.CreateBuilder(args);
+
+var connectionString = builder.Configuration.GetConnectionString("Projection")
+    ?? throw new InvalidOperationException("Missing connection string 'ConnectionStrings:Projection'");
+
+builder.Services.AddProjectionReadModel(connectionString);
+
+var app = builder.Build();
+
+// Ensure the schema exists before serving reads. EF serialises concurrent migrators via the
+// migrations-history lock, so it is safe that the Event Subscriber migrates too.
+await app.Services.MigrateProjectionAsync();
+
+app.MapGet("/health", () => "Healthy");
+
+// The read side of the projection. Public-safe field filtering is tightened in S-09; for now
+// the minimal projection only carries id + status (bsn/naam deferred — ADR-0008).
+app.MapGet("/register", async (ProjectionDbContext db, CancellationToken ct) =>
+{
+    var rows = await db.RegisterEntries
+        .OrderBy(r => r.Id)
+        .Select(r => new RegisterEntryDto(r.Id, r.Status, r.Bsn, r.NaamPlaceholder))
+        .ToListAsync(ct);
+    return Results.Ok(rows);
+});
+
+app.MapGet("/register/{id}", async (string id, ProjectionDbContext db, CancellationToken ct) =>
+{
+    var row = await db.RegisterEntries
+        .Where(r => r.Id == id)
+        .Select(r => new RegisterEntryDto(r.Id, r.Status, r.Bsn, r.NaamPlaceholder))
+        .SingleOrDefaultAsync(ct);
+    return row is null ? Results.NotFound() : Results.Ok(row);
+});
+
+await app.RunAsync();
+
+public sealed record RegisterEntryDto(string Id, string Status, string? Bsn, string? NaamPlaceholder);
+
+public partial class Program;

services/projection-api/ProjectionApi.Api/ProjectionApi.Api.csproj

@@ -0,0 +1,13 @@
+<Project Sdk="Microsoft.NET.Sdk.Web">
+
+  <ItemGroup>
+    <ProjectReference Include="..\Projection.ReadModel\Projection.ReadModel.csproj" />
+  </ItemGroup>
+
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+  </PropertyGroup>
+
+</Project>

services/projection-api/ProjectionApi.Api/appsettings.json

@@ -0,0 +1,8 @@
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning"
+    }
+  }
+}

tests/acceptance/Acceptance.csproj

@@ -18,6 +18,7 @@
   <ItemGroup>
     <ProjectReference Include="..\..\services\acl\Acl.Application\Acl.Application.csproj" />
     <ProjectReference Include="..\..\services\acl\Acl.Infrastructure\Acl.Infrastructure.csproj" />
+    <ProjectReference Include="..\..\services\event-subscriber\EventSubscriber.Application\EventSubscriber.Application.csproj" />
   </ItemGroup>
 
 </Project>

tests/acceptance/Features/RegisterProjectieBijwerken.feature

@@ -0,0 +1,19 @@
+# language: en
+# Drives S-06 (#7). On a zaak-created notification from NRC the Event Subscriber writes a
+# rebuildable read-projection row (PRD §8.4). This scenario exercises the use case against an
+# in-memory stand-in for the projection store and notification log; real OpenZaak → NRC →
+# subscriber delivery is verified by the live-stack check (verify-projection, ADR-0007/#58).
+Feature: Register-projectie bijwerken op een zaaknotificatie
+  Als openbaar register wil ik dat een aangemaakte zaak in de projectie verschijnt
+  zodat het register de ingediende registratie kan tonen.
+
+  Scenario: Een zaaknotificatie levert een rij met status INGEDIEND
+    Given a zaak is created in OpenZaak with id "11111111-1111-1111-1111-111111111111"
+    When the NRC notification for that zaak is delivered to the event subscriber
+    Then the register projection contains a row for "11111111-1111-1111-1111-111111111111" with status "INGEDIEND"
+
+  Scenario: Dezelfde notificatie tweemaal levert geen duplicaat
+    Given a zaak is created in OpenZaak with id "22222222-2222-2222-2222-222222222222"
+    When the NRC notification for that zaak is delivered to the event subscriber
+    And the same NRC notification is delivered again
+    Then the register projection contains exactly one row for "22222222-2222-2222-2222-222222222222"

tests/acceptance/Steps/RegisterProjectieBijwerkenSteps.cs

@@ -0,0 +1,48 @@
+using Acceptance.Support;
+using EventSubscriber.Application;
+using Reqnroll;
+using Xunit;
+
+namespace Acceptance.Steps;
+
+/// <summary>Bindings for <c>RegisterProjectieBijwerken.feature</c> (S-06). Reqnroll creates
+/// one instance per scenario, so instance fields hold scenario-scoped state.</summary>
+[Binding]
+public sealed class RegisterProjectieBijwerkenSteps
+{
+    private const string ZaakBase = "http://openzaak:8000/zaken/api/v1/zaken/";
+
+    private readonly InMemoryNotificationLog _log = new();
+    private readonly InMemoryProjectionStore _store = new();
+    private readonly NotificationProjector _projector;
+    private Notification? _notification;
+
+    public RegisterProjectieBijwerkenSteps() => _projector = new NotificationProjector(_log, _store);
+
+    [Given("a zaak is created in OpenZaak with id \"(.*)\"")]
+    public void GivenAZaakIsCreatedInOpenZaakWithId(string id)
+        => _notification = new Notification("zaken", "zaak", "create", new Uri(ZaakBase + id));
+
+    [When("the NRC notification for that zaak is delivered to the event subscriber")]
+    public Task WhenTheNotificationIsDelivered()
+        => _projector.HandleAsync(_notification!);
+
+    [When("the same NRC notification is delivered again")]
+    public Task WhenTheSameNotificationIsDeliveredAgain()
+        => _projector.HandleAsync(_notification!);
+
+    [Then("the register projection contains a row for \"(.*)\" with status \"(.*)\"")]
+    public async Task ThenTheProjectionContainsARowWithStatus(string id, string status)
+    {
+        var entry = Assert.Single(await _store.AllAsync());
+        Assert.Equal(id, entry.Id);
+        Assert.Equal(status, entry.Status);
+    }
+
+    [Then("the register projection contains exactly one row for \"(.*)\"")]
+    public async Task ThenTheProjectionContainsExactlyOneRowFor(string id)
+    {
+        await _store.AllAsync();
+        Assert.Single(_store.RowsFor(id));
+    }
+}

tests/acceptance/Support/InMemoryProjectionStores.cs

@@ -0,0 +1,40 @@
+using EventSubscriber.Application;
+
+namespace Acceptance.Support;
+
+/// <summary>In-memory stand-ins for the Event Subscriber's projection store and notification
+/// log, so the S-06 acceptance scenario runs without Postgres (real delivery is a live-stack
+/// check). Mirrors the <c>InMemoryZaakGateway</c> approach used for the ACL scenario.</summary>
+public sealed class InMemoryNotificationLog : INotificationLog
+{
+    private readonly Dictionary<string, RecordedNotification> _byKey = [];
+
+    public Task<bool> TryRecordAsync(RecordedNotification notification, CancellationToken ct = default)
+        => Task.FromResult(_byKey.TryAdd(notification.Key, notification));
+
+    public Task<IReadOnlyList<RecordedNotification>> AllAsync(CancellationToken ct = default)
+        => Task.FromResult<IReadOnlyList<RecordedNotification>>([.. _byKey.Values]);
+}
+
+public sealed class InMemoryProjectionStore : IProjectionStore
+{
+    private readonly Dictionary<string, RegisterEntry> _byId = [];
+
+    public Task UpsertAsync(RegisterEntry entry, CancellationToken ct = default)
+    {
+        _byId[entry.Id] = entry;
+        return Task.CompletedTask;
+    }
+
+    public Task ClearAsync(CancellationToken ct = default)
+    {
+        _byId.Clear();
+        return Task.CompletedTask;
+    }
+
+    public Task<IReadOnlyList<RegisterEntry>> AllAsync(CancellationToken ct = default)
+        => Task.FromResult<IReadOnlyList<RegisterEntry>>([.. _byId.Values]);
+
+    public IReadOnlyList<RegisterEntry> RowsFor(string id)
+        => [.. _byId.Values.Where(e => e.Id == id)];
+}