diff --git a/echo-memory-1.5.1.plugin b/echo-memory-1.5.1.plugin
index af302d8..c12f48d 100644
Binary files a/echo-memory-1.5.1.plugin and b/echo-memory-1.5.1.plugin differ
diff --git a/echo-memory.plugin b/echo-memory.plugin
index af302d8..c12f48d 100644
Binary files a/echo-memory.plugin and b/echo-memory.plugin differ
diff --git a/echo-memory.plugin.src/skills/echo-memory/references/api-reference.md b/echo-memory.plugin.src/skills/echo-memory/references/api-reference.md
index 85b78bb..fefc1d9 100644
--- a/echo-memory.plugin.src/skills/echo-memory/references/api-reference.md
+++ b/echo-memory.plugin.src/skills/echo-memory/references/api-reference.md
@@ -197,6 +197,13 @@ curl -s -X DELETE \
 
 Only on explicit operator request. Deletion is destructive.
 
+> **DELETE removes files only — never directories.** Deleting the last file in a folder
+> leaves the empty folder orphaned on disk; the REST listing then 404s (nothing left to
+> list), which falsely reads as "the tree is gone", but Obsidian's file explorer still
+> shows it. After removing a folder's last file, tell the operator the empty folder
+> needs manual deletion in Obsidian — do not claim the tree is gone from a 404 listing.
+> (Learned 2026-07-03 removing the retired `archive/` and `_agent/outputs/` trees.)
+
 ---
 
 ## URL-Encoding Notes