diff --git a/scripts/deregister-room.ts b/scripts/deregister-room.ts
index 0729930..1e875c1 100644
--- a/scripts/deregister-room.ts
+++ b/scripts/deregister-room.ts
@@ -60,21 +60,45 @@ const db = new Database(path.join(STORE_DIR, 'messages.db'));
 
 interface Target {
   jid: string;
-  folder: string | null;
+  folders: string[];
   isMain: boolean;
   name: string | null;
   registered: boolean;
 }
 
+// When a room was already unregistered (room_settings gone) the group folder is
+// no longer stored there, so recover it from the group_folder recorded on the
+// chat's leftover managed rows — otherwise sessions/disk/worktrees for an
+// already-unregistered room would be missed.
+function backtraceFolders(jid: string): string[] {
+  const set = new Set<string>();
+  for (const t of [
+    'paired_tasks',
+    'work_items',
+    'scheduled_tasks',
+    'service_handoffs',
+    'paired_projects',
+  ]) {
+    const rows = db
+      .query(
+        `SELECT DISTINCT group_folder FROM ${t} WHERE chat_jid=? AND group_folder IS NOT NULL`,
+      )
+      .all(jid) as Array<{ group_folder: string | null }>;
+    for (const r of rows) if (r.group_folder) set.add(r.group_folder);
+  }
+  return [...set];
+}
+
 const targets: Target[] = jids.map((jid) => {
   const r = db
     .query('SELECT folder, is_main, name FROM room_settings WHERE chat_jid=?')
     .get(jid) as
     | { folder: string | null; is_main: number | null; name: string | null }
     | undefined;
+  const folders = r?.folder ? [r.folder] : backtraceFolders(jid);
   return {
     jid,
-    folder: r?.folder ?? null,
+    folders,
     isMain: r?.is_main === 1,
     name: r?.name ?? null,
     registered: Boolean(r),
@@ -102,15 +126,16 @@ function folderShared(folder: string): boolean {
 const safeFolders = new Set<string>();
 const sharedFolders = new Set<string>();
 for (const t of targets) {
-  if (!t.folder) continue;
-  if (folderShared(t.folder)) sharedFolders.add(t.folder);
-  else safeFolders.add(t.folder);
+  for (const folder of t.folders) {
+    if (folderShared(folder)) sharedFolders.add(folder);
+    else safeFolders.add(folder);
+  }
 }
 
 console.log('=== targets ===');
 for (const t of targets) {
   console.log(
-    `  ${t.jid} | name=${t.name ?? '(unregistered)'} | folder=${t.folder ?? '-'} | registered=${t.registered}${t.isMain ? ' | MAIN' : ''}`,
+    `  ${t.jid} | name=${t.name ?? '(unregistered)'} | folder=${t.folders.length ? t.folders.join(',') : '-'} | registered=${t.registered}${t.isMain ? ' | MAIN' : ''}`,
   );
 }
 if (sharedFolders.size) {