Closes #149. **Outcome:** approving a registration now writes the canonical register record to the **Objecten** API as a `RegisterRecord` object, alongside the ZGW eindstatus. OpenZaak holds the process, Objecten holds the register (ADR-0028). The write goes through the ACL (§8.1) and is idempotent on the zaak id, so a replayed approval updates the existing object rather than creating a second one. S-19 (#20) was split first (CLAUDE.md §13) — it bundled this with re-sourcing the read projection, which is now #150. ### What landed - `IRegisterRecordGateway` + `RegisterRecord` in `Acl.Application`; `ObjectenGateway` in `Acl.Infrastructure` (static Token auth, CRS headers, objecttype resolved by name to its highest **published** version). - `AclService.ApproveZaakAsync` writes the record after the eindstatus, keyed on the zaak UUID with the zaak's identificatie as reference. - Compose wiring for both stacks; `ADR-0028`; demo note; PRD §15 out-of-scope line retired. ### Three things only a live stack found Running the gateway against a real Objecten + Objecttypen pair while writing this turned up blockers CI would have hit after the fact: 1. **Objecten rejects an objecttype it has not been configured with**, by UUID — assigned at seed time by a one-shot that runs *after* Objecten's static setup_configuration. The UUID is now pinned on both sides. 2. **Objecten 500s on every write when its Notificaties config is absent** (`notifications_api_common` raises rather than skipping). Objecten → NRC has no broker, worker, kanaal or abonnement, so notifications are **disabled** rather than wired to drop every message; #150 turns them on for real. 3. **Objecttypen echoes the request Host into the objecttype `url`**, and Objecten only accepts the one matching its configured `api_root` — so the ACL must read Objecttypen at `http://objecttypen:8000`. This is why the new integration test only passes inside the compose network. All three are recorded in ADR-0028. ### Verification - `ObjectenGatewayIntegrationTests` (verify-acl, in-network): two writes for one id leave exactly one object with the second write's status. **Passing locally against live Objecten.** - The **Playwright happy path** asserts, after the behandelaar approves, that Objecten holds exactly one `RegisterRecord` for *that* reference — missing, duplicated, or non-public-safe all fail. - ACL mutation score **92.23%** (baseline 91.37%, break 90). - `make lint` / `make unit` green locally; full-stack `make verify` runs in CI. ## Definition of Done - [x] A linked Gitea issue exists (#149). - [x] Failing test written and committed first. - [x] Implementation makes the test pass. - [x] Refactor commit follows if structure improved. - [x] Conventional Commit messages referencing the issue (`refs #149`). - [x] All Gitea Actions CI jobs green (run 684). - [x] `docker compose up` from a fresh clone reaches green health checks within 3 minutes (verify-stack step 1). - [x] Docs touched — ADR-0028, demo note, PRD §15, BACKLOG. - [x] ADR added: `docs/architecture/adr-0028-objecten-holds-the-register.md`. - [x] Demo note appended to `docs/demo-script.md`. - [x] Closed by the merging PR (`closes #149`). 🤖 Generated with [Claude Code](https://claude.com/claude-code)Reviewed-on: #151