diff --git a/docs/superpowers/specs/2026-05-29-zombie-invasion-backend-design.md b/docs/superpowers/specs/2026-05-29-zombie-invasion-backend-design.md
index 83ccf2f..758c435 100644
--- a/docs/superpowers/specs/2026-05-29-zombie-invasion-backend-design.md
+++ b/docs/superpowers/specs/2026-05-29-zombie-invasion-backend-design.md
@@ -390,7 +390,7 @@ services:
   app:
     build: .
     ports:
-      - "3000:3000"
+      - "6100:3000"             # Host:6100 → Container:3000
     volumes:
       - ./data:/app/data          # Persist SQLite DB
     environment: