diff --git a/workplans/CORE-WP-0004-interhub-compatibility-and-consumer-smoke.md b/workplans/CORE-WP-0004-interhub-compatibility-and-consumer-smoke.md
new file mode 100644
index 0000000..8c6c06e
--- /dev/null
+++ b/workplans/CORE-WP-0004-interhub-compatibility-and-consumer-smoke.md
@@ -0,0 +1,61 @@
+---
+id: CORE-WP-0004
+type: workplan
+title: "Implement Inter-Hub compatibility and consumer smokes"
+domain: infotech
+repo: core-hub
+status: active
+owner: codex
+topic_slug: custodian
+created: "2026-06-27"
+updated: "2026-06-27"
+state_hub_workstream_id: "ef13b0e9-f626-4d2c-9e00-ccb4906c3a3d"
+---
+
+# Implement Inter-Hub compatibility and consumer smokes
+
+Preserve the Inter-Hub `/api/v2` behavior required by current consumers while Core Hub-native contracts mature.
+
+## Public Registry Compatibility
+
+```task
+id: CORE-WP-0004-T01
+status: todo
+priority: high
+state_hub_task_id: "4e24ab14-d5cf-4466-8287-21eaf075cb44"
+```
+
+Implement public read compatibility for hubs, manifests, catalogs, OpenAPI, and docs endpoints.
+
+## Protected Bootstrap Compatibility
+
+```task
+id: CORE-WP-0004-T02
+status: todo
+priority: high
+state_hub_task_id: "87073ee7-0213-4eed-881a-b18ab764ae65"
+```
+
+Implement protected compatibility for API consumers, token flow, widgets, interaction events, hub registry, annotations, and evidence records. Preserve auth-before-business-logic behavior.
+
+## ops-hub Smoke
+
+```task
+id: CORE-WP-0004-T03
+status: wait
+priority: high
+state_hub_task_id: "2d18f575-135b-4ba8-9537-6920d0c61e1b"
+```
+
+Run ops-hub bootstrap/gate probes against Core Hub using approved credential routing. No secrets in logs, workplans, or chat.
+
+## activity-core Smoke
+
+```task
+id: CORE-WP-0004-T04
+status: wait
+priority: medium
+state_hub_task_id: "c3d1c153-0059-470c-bb2d-0b14f2d77b94"
+```
+
+Run the activity-core Inter-Hub sink smoke against Core Hub or explicitly record State Hub fallback as the transition path.