fix(cleanup): remove empty isolation stubs and dead symbols (P2-2 / C-3a / C-4)

.agents/skills/lib.sh

@@ -123,8 +123,6 @@ _resolve_real_herdr_path() {
   done
   IFS="$save_ifs"
   [ -n "$real_path" ] || return 1
-  _REAL_HERDR_PATH="$real_path"
-  export _REAL_HERDR_PATH
   printf '%s\n' "$real_path"
 }
 
@@ -1363,28 +1361,12 @@ capture_conversation_id() {
 #    ~/.hermes, ~/.cline user configuration and credential stores.
 # 2. Process Isolation: each agent-workspace pair runs in its own herdr pane.
 # 3. Conversation Isolation: session UUIDs discriminate conversation history.
-#
-# Stubbed isolation functions kept for backward compatibility:
+# The backward-compat stubs (provision_isolation / isolation_lever /
+# isolation_env_prefix / isolation_cmd_args) were removed in P2-2 (C-3a);
+# they had zero production callers. The `isolation.root` row field is still
+# consumed (C-3b) — see verify_session_uuid / find_workspace_uuid /
+# mam_session_iso_root / stop_session.sh purge guard.
 # ---------------------------------------------------------------------------
-provision_isolation() {
-  local agent="$1" root="$2"
-  printf ''
-}
-
-isolation_lever() {
-  case "$1" in
-    claude|agy|hermes|cline) echo "none" ;;
-    *)                       echo "" ;;
-  esac
-}
-
-isolation_env_prefix() {
-  :
-}
-
-isolation_cmd_args() {
-  :
-}
 
 # ---------------------------------------------------------------------------
 # is_already_stopped <session_name>