Complete notification expiry and configurable durable delivery (#36)

docs/implementation.md

@@ -480,3 +480,20 @@ in [PR #35](https://git.sendico.io/tech/sxchnge/pulls/35), which remains unmerge
 - Task: <https://git.sendico.io/tech/sxchnge/issues/36>.
   PR: <https://git.sendico.io/tech/sxchnge/pulls/37>, branch `notifications-36`.
   Merge order: [#35](https://git.sendico.io/tech/sxchnge/pulls/35), then #37.
+
+### Notifications completion follow-up (#36 / PR #37)
+
+- Queue configuration now composes shared stream/provisioning settings. NATS
+  replication, retention and app/ops/hybrid provisioning are configurable;
+  production drift is rejected. Shared provisioning calls honor cancellation.
+- Recovery expires queued and retrying notifications and clears rendered content
+  without requiring a working NATS connection, including future-scheduled retries.
+  Expiry queries have a dedicated index. Lost leases are logged with counts.
+- Extended the real Mongo/NATS integration test through authenticated TLS gRPC
+  Send/Get, including caller isolation, idempotency and parameter propagation to
+  the email driver. Added queue configuration, cancellation and retention-drift
+  checks; gRPC now preserves canceled/deadline-exceeded outcomes.
+- Validation: `make test`, `make lint-backend` and interface packaging passed in
+  an isolated clean checkout containing this contribution. Shared-workspace runs
+  initially failed because concurrent product/auth work had missing module
+  dependencies and unformatted files; that work was excluded and left untouched.