WP-55..60 harden the OpenZaak integration for production (secrets/TLS, idempotent provisioning, least-privilege scopes, real notifications, confidentialiteit config, write-divergence resilience). WP-61..66 stand up a staff-facing behandelportal per ADR-0002, wired to the same backend via BFF-lite decision DTOs. Both phases are independent tracks; WP-60's Decisions block is deliberately left open for a planner-agent kickoff. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
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WP-60 — Write-divergence resilience (local + ZGW writes)
Status: todo Phase: 10 — OpenZaak production hardening
Why
A citizen action today does a local Aanvraag/Document write and a paired ZGW write
(create zaak/status/document); these aren't transactional. If the ZGW call fails after the
local write succeeds (or vice versa), the two diverge silently —
openzaak-integration.md flags this explicitly as "acceptable for a demo backend; a
production arc needs retry/reconciliation or an outbox." This is the one genuine
correctness gap standing between the current integration and something safe to call
production.
Read first
- openzaak-integration.md (the section discussing this gap)
backend/src/BigRegister.Api/Data/ApplicationStore.cs,Zgw/OpenZaakZaakSource.cs(the two write sides)- ADR-0005 — OpenZaak behind the BFF
Decisions
Intentionally left open for kickoff — this is exactly the kind of ambiguous-root-cause,
multi-file design call the planner agent should make, not something pre-decided here.
Options to weigh at kickoff:
- (a) an outbox table — write local + an outbox row in one local transaction, a background worker drains the outbox to ZGW with retry.
- (b) a simpler synchronous retry-with-backoff at the call site, plus a reconciliation job that periodically diffs local vs. ZGW state and flags/repairs divergence.
Pick the smaller one that closes the gap — don't build a generic outbox framework if a bounded retry+reconcile suffices for this POC's actual write volume.
Files
Likely Data/ApplicationStore.cs, a new reconciliation/outbox mechanism,
Zgw/OpenZaakZaakSource.cs, Program.cs (background job registration if needed).
Steps
- Design review with the
planneragent — pick outbox vs. retry+reconcile. - Implement the chosen mechanism for the create-zaak and status-transition write paths.
- Add a test that simulates a ZGW failure mid-write and asserts the system recovers (retries successfully, or is left in a detectably-inconsistent-but-flagged state) rather than silently diverging.
Acceptance criteria
- A simulated ZGW failure after a successful local write no longer leaves permanent silent divergence — either it retries to consistency or the divergence is detectable/flagged.
- No new synchronous latency added to the happy path beyond what the chosen mechanism requires.
Verification
A new integration test that fails a stubbed ZGW call mid-write and asserts
recovery/flagging behavior; cd backend && dotnet test.
Out of scope
A general-purpose outbox framework reusable beyond this one write pair (YAGNI unless a second write pair appears — note WP-66 is exactly that second pair, so revisit scope if WP-66 lands first); UI surfacing of reconciliation state (backend-only fix for now).
Risks
Over-building this (a generic outbox/saga framework) for a POC's actual write volume — ladder check at kickoff: does a bounded retry + periodic reconcile job cover it before reaching for an outbox table?