diff --git a/docs/user-engine-platform-expansion-contract.md b/docs/user-engine-platform-expansion-contract.md
new file mode 100644
index 0000000..279e36b
--- /dev/null
+++ b/docs/user-engine-platform-expansion-contract.md
@@ -0,0 +1,62 @@
+# user-engine platform expansion contract
+
+This contract activates `NK-WP-0024` without weakening the proven portal.
+The current production image continues to use its existing integration path
+until all three endpoints below are deployed and verified together.
+
+## Authorization
+
+user-engine is the protected system and calls flex-auth `POST /v1/check` for
+every domain mutation. Requests use the existing user-engine resource types
+and action names, including `user-engine:user`, `user-engine:membership`,
+`user-engine:invitation`, `user-engine:tenant`, and `user-engine:outbox`.
+
+Policy roles are:
+
+- self: actions whose authorization context has `self=true` and whose target
+  user matches the authenticated subject's user projection;
+- tenant-admin: tenant-scoped membership, invitation, account lifecycle, and
+  recovery actions within the actor's tenant only;
+- platform-admin: tenant creation, platform recovery, outbox delivery, and
+  dead-letter replay across the platform tenant;
+
+The HTTP adapter is fail closed. Unreachable, malformed, timed-out, or
+non-conforming flex-auth responses become a deny decision. The flex-auth
+decision ID is stored on the corresponding user-engine audit record.
+
+Required runtime setting: `USER_ENGINE_FLEX_AUTH_URL`.
+
+## Durable event and mail delivery
+
+The transactional outbox remains the source of delivery state. The worker
+endpoint sends a CloudEvents-like, redacted JSON envelope to the platform
+event receiver and supplies the outbox event ID as `Idempotency-Key`.
+Invitation-created and invitation-resent events are additionally delivered to
+the approved mail receiver using the same idempotency key. Mailbox ownership
+is evidence only and is never passed into an authorization decision as proof
+of authority.
+
+Required runtime settings:
+
+- `USER_ENGINE_EVENT_URL`
+- `USER_ENGINE_MAIL_URL` (optional until the approved receiver exists)
+- `USER_ENGINE_DELIVERY_TOKEN` from the OpenBao-backed runtime lane
+
+Delivery uses bounded attempts already persisted in the user-engine outbox.
+Failures retain a redacted reason, dead-letter at the configured threshold,
+and can be replayed through the platform-operator route.
+
+## Production activation gate
+
+Do not add these environment variables to the live Deployment until:
+
+1. flex-auth has a cluster-local Service and a validated user-engine policy;
+2. the event and mail receivers accept idempotent, authenticated delivery;
+3. their credentials are present under the approved OpenBao user-engine lane;
+4. NetworkPolicies allow only the named receivers;
+5. the deployed failure matrix proves deny/unavailability, receiver failure,
+   dead-letter/replay, invitation expiry/replay, provider outage recovery, and
+   cross-tenant denial.
+
+This gate prevents a partial rollout from making the portal unavailable or
+silently dropping notifications.
diff --git a/tests/test_user_engine_platform_expansion.py b/tests/test_user_engine_platform_expansion.py
new file mode 100644
index 0000000..22c7de4
--- /dev/null
+++ b/tests/test_user_engine_platform_expansion.py
@@ -0,0 +1,30 @@
+from pathlib import Path
+import unittest
+
+
+ROOT = Path(__file__).parents[1]
+
+
+class UserEnginePlatformExpansionContractTests(unittest.TestCase):
+    def test_contract_keeps_authorization_fail_closed(self):
+        text = (ROOT / "docs/user-engine-platform-expansion-contract.md").read_text()
+        self.assertIn("fail closed", text)
+        self.assertIn("decision ID", text)
+        self.assertIn("USER_ENGINE_FLEX_AUTH_URL", text)
+
+    def test_contract_requires_idempotent_bounded_delivery(self):
+        text = (ROOT / "docs/user-engine-platform-expansion-contract.md").read_text()
+        self.assertIn("Idempotency-Key", text)
+        self.assertIn("bounded attempts", text)
+        self.assertIn("dead-letter", text)
+        self.assertIn("OpenBao", text)
+
+    def test_live_manifest_does_not_enable_partial_integration(self):
+        manifest = (ROOT / "sso-mfa/k8s/user-engine/runtime.yaml").read_text()
+        self.assertNotIn("USER_ENGINE_FLEX_AUTH_URL", manifest)
+        self.assertNotIn("USER_ENGINE_EVENT_URL", manifest)
+        self.assertNotIn("USER_ENGINE_MAIL_URL", manifest)
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/workplans/NK-WP-0024-user-engine-portal-integration-expansion.md b/workplans/NK-WP-0024-user-engine-portal-integration-expansion.md
index a4eb3c3..4c5fdac 100644
--- a/workplans/NK-WP-0024-user-engine-portal-integration-expansion.md
+++ b/workplans/NK-WP-0024-user-engine-portal-integration-expansion.md
@@ -4,14 +4,17 @@ type: workplan
 title: "Expand user-engine platform integrations beyond the Binky MVP"
 domain: infotech
 repo: net-kingdom
-status: backlog
+status: active
 owner: codex
 topic_slug: netkingdom
 created: "2026-07-30"
-updated: "2026-07-30"
+updated: "2026-08-08"
 depends_on:
   - NK-WP-0023
   - USER-WP-0021
+  - FLEX-WP-0009
+  - AUDIT-WP-0003
+  - EMAIL-WP-0004
 state_hub_workstream_id: "9bd05700-a839-4014-8f88-8a78f2757721"
 ---
 
@@ -20,11 +23,20 @@ state_hub_workstream_id: "9bd05700-a839-4014-8f88-8a78f2757721"
 Track deferred integration breadth separately from the completed live MVP.
 Activate with the corresponding user-engine product-expansion tasks.
 
+Provider workplans established 2026-08-08:
+
+- `FLEX-WP-0009` provides the user-engine policy package and cluster service.
+- `AUDIT-WP-0003` provides authenticated durable event ingestion.
+- `EMAIL-WP-0004` provides transactional invitation-mail delivery.
+
+This workplan remains the consumer-side coordination and deployed integration
+gate; provider implementation status stays authoritative in the owning repos.
+
 ## T01 - Establish flex-auth production authorization
 
 ```task
 id: NK-WP-0024-T01
-status: todo
+status: progress
 priority: high
 state_hub_task_id: "7dff0ac6-c5eb-486c-83db-a1400f30f77d"
 ```
@@ -33,11 +45,18 @@ Define self, tenant-admin, and platform-admin resource/action vocabulary,
 deploy the policy package, replace user-engine's local runtime adapter with a
 fail-closed flex-auth HTTP adapter, and correlate decision IDs with audit.
 
+2026-08-08 implementation: added the fail-closed flex-auth HTTP adapter in
+user-engine, including request mapping, decision-ID propagation, timeout and
+malformed-response denial tests. The role/resource contract and safe rollout
+gate are recorded in `docs/user-engine-platform-expansion-contract.md`.
+Deployment remains pending because no cluster-local flex-auth Service or
+validated user-engine policy package currently exists on railiance01.
+
 ## T02 - Add invitation and verification mail delivery
 
 ```task
 id: NK-WP-0024-T02
-status: todo
+status: progress
 priority: medium
 state_hub_task_id: "9d5f272b-115c-404d-8387-7f987cee65ea"
 ```
@@ -45,11 +64,17 @@ state_hub_task_id: "9d5f272b-115c-404d-8387-7f987cee65ea"
 Deliver invitation and verification messages through approved custody and
 mail lanes. Mailbox ownership remains evidence, never authorization.
 
+2026-08-08 implementation: added authenticated, idempotent invitation-mail
+delivery from durable outbox events. The delivery token is a required runtime
+secret and the NetKingdom contract pins it to the existing OpenBao runtime
+lane. Live completion waits for an approved mail receiver and its custody
+entry; production is deliberately not pointed at a fabricated endpoint.
+
 ## T03 - Operate durable event delivery
 
 ```task
 id: NK-WP-0024-T03
-status: todo
+status: progress
 priority: high
 state_hub_task_id: "17d6390b-05a8-436c-879b-4e0331d85be5"
 ```
@@ -57,11 +82,17 @@ state_hub_task_id: "17d6390b-05a8-436c-879b-4e0331d85be5"
 Connect the user-engine transactional outbox to the platform event lane with
 bounded retries, replay, dead-letter visibility, redaction, and correlation.
 
+2026-08-08 implementation: added an authenticated HTTP event adapter carrying
+event ID, tenant, correlation, occurrence time, and redacted domain payload.
+It uses `Idempotency-Key`; the existing durable store supplies bounded retry,
+dead-letter, diagnostics, and replay. Live completion waits for a selected
+cluster event receiver and scoped delivery credential.
+
 ## T04 - Run expanded integration failure matrix
 
 ```task
 id: NK-WP-0024-T04
-status: todo
+status: progress
 priority: high
 state_hub_task_id: "4c54e8e4-19d9-4470-bb43-3d43cf27af71"
 ```
@@ -69,3 +100,11 @@ state_hub_task_id: "4c54e8e4-19d9-4470-bb43-3d43cf27af71"
 Prove flex-auth denial/unavailability, mail failure, identity-provider outage,
 partial provisioning recovery, invitation replay/expiry, and cross-tenant
 negative behavior through the deployed path.
+
+2026-08-08 source matrix: user-engine's full suite passes 119 tests with three
+external-provider tests skipped. New coverage proves flex-auth allow mapping,
+decision correlation, fail-closed unavailability, invitation mail routing,
+event routing, and idempotency. Existing USER-WP-0021 coverage proves provider
+outage, recovery, invitation expiry/replay, dead-letter/replay, and
+cross-tenant denial. The deployed-path matrix remains pending on the three
+production endpoints above.