diff --git a/scripts/instance/instance_create.sh b/scripts/instance/instance_create.sh
index cb6c463..dbbe5c8 100644
--- a/scripts/instance/instance_create.sh
+++ b/scripts/instance/instance_create.sh
@@ -182,6 +182,14 @@ instanceCreate() {
     type_title=$(instanceTypeCfg "$type" "TITLE")
     [[ -z "$type_title" ]] && type_title="$type"
 
+    # APP_NAME must follow the slug. The sed above re-namespaces the KEY but
+    # leaves the VALUE at the type ("bookstack"), and installApp resolves the app
+    # it operates on from CFG_<SLUG>_APP_NAME — so an instance install ran the
+    # whole pipeline against the BASE app instead: same deployed dir, same ports,
+    # compose down/up on the already-running base container, base DB row updated,
+    # and the instance itself never installed. Every base app ships APP_NAME ==
+    # its own slug; this keeps instances to that invariant.
+    _instanceSetCfg "CFG_${slug_u}_APP_NAME"       "$slug"                  "$cfg"
     _instanceSetCfg "CFG_${slug_u}_INSTANCE_OF"    "$type"                  "$cfg"
     _instanceSetCfg "CFG_${slug_u}_MULTI_INSTANCE" "false"                  "$cfg"
     _instanceSetCfg "CFG_${slug_u}_TITLE"          "${type_title} · ${id}"  "$cfg"