diff --git a/workplans/RAIL-PL-WP-0001-platform-baseline.md b/workplans/RAIL-PL-WP-0001-platform-baseline.md
index e53164c..6f2d256 100644
--- a/workplans/RAIL-PL-WP-0001-platform-baseline.md
+++ b/workplans/RAIL-PL-WP-0001-platform-baseline.md
@@ -4,16 +4,22 @@ type: workplan
 title: "S3 Platform Services Baseline"
 domain: railiance
 repo: railiance-platform
-status: active
+status: superseded
 owner: railiance
 topic_slug: railiance
 state_hub_workstream_id: "e4ec133c-7cb9-43c6-95f0-50d6591f13d7"
+superseded_by: RAIL-HO-WP-0004
 created: "2026-03-11"
-updated: "2026-03-11"
+updated: "2026-03-26"
 ---
 
 # S3 Platform Services Baseline
 
+> **SUPERSEDED** by `RAIL-HO-WP-0004` (2026-03-26).
+> This workplan targeted Bitnami postgresql-ha, which is now stale.
+> CloudNative PG (cnpg) is the deployed operator. See WP-0004 T03–T05 for
+> the current cnpg-based platform baseline work.
+
 ## Goal
 
 Establish `railiance-platform` (S3) as a reproducible, OAS-compliant platform