feat(isolation): implement Phase 1-3 session isolation with stop purge and resume safety

.agents/skills/multi-agent-mux-stop/scripts/stop_session.sh

@@ -148,7 +148,7 @@ fi
 # purge 대상 UUID 를 워크스페이스 격리해서 해결 (P0-C — 전역 참조 금지)
 PURGE_UUID=""
 if [ "$PURGE" = "1" ] && [ -n "$TARGET_CWD" ]; then
-  PURGE_UUID=$(find_workspace_uuid "$TARGET_CWD" "$AGENT" || true)
+  PURGE_UUID=$(find_workspace_uuid "$TARGET_CWD" "$AGENT" "$SESSION_NAME" || true)
 fi
 
 NOW_ISO=$(date -u +'%Y-%m-%dT%H:%M:%SZ')
@@ -167,7 +167,7 @@ fi
 # 를 알아서 시도하므로 tmux 생사와 무관하게 동작.
 CAPTURED_UUID=""
 if [ "$CAPTURE_ID" = "1" ] && [ -n "$TARGET_CWD" ]; then
-  CAPTURED_UUID=$(capture_conversation_id "$AGENT" "$TARGET_CWD" || true)
+  CAPTURED_UUID=$(capture_conversation_id "$AGENT" "$TARGET_CWD" "$SESSION_NAME" || true)
   if [ -n "$CAPTURED_UUID" ]; then
     echo "captured conversation id: $CAPTURED_UUID"
   else
@@ -270,6 +270,23 @@ if captured and not purge:
     target['resumable'] = True
 
 # --purge-conversation: 워크스페이스 격리된 UUID 의 디스크 artifact 만 삭제 (P0-C)
+# T6: stop-purge 시 격리 디렉터리 청소 및 경로 가드
+iso = target.get('isolation')
+if purge and iso:
+    iso_root = iso.get('root')
+    iso_uuid = iso.get('uuid')
+    if iso_root and iso_uuid:
+        ws_abs = os.path.abspath(ws) if ws else ""
+        expected_homes_dir = os.path.join(ws_abs, '.mam', 'agent_homes')
+        expected_iso_root = os.path.join(expected_homes_dir, iso_uuid)
+        if (os.path.abspath(iso_root) == os.path.abspath(expected_iso_root) and
+            os.path.abspath(iso_root).startswith(os.path.abspath(expected_homes_dir) + os.sep)):
+            if os.path.isdir(iso_root):
+                shutil.rmtree(iso_root)
+                print(f"purged isolated home: {iso_root}", flush=True)
+        else:
+            print(f"WARN: isolated home path check failed: {iso_root}", flush=True)
+
 if purge and purge_uuid:
     if agent == 'claude':
         key = ws.replace('/', '-').replace('_', '-')