prefer existing operation;

retain isolated blob nodes (amending deb2fcbda16e): avoid failure of Session.handle_change with "Missing blob", when opening theory with load command later;

clarified signature -- avoid confusion with Resources.is_hidden;

markup for deleted fragments of token source (NB: quoted tokens transform "\123" implicitly);

merged

tidying and reorganisation around Cauchy Integral Theorem

export sort algebra;

tuned;

tuned;

support 'export_files' in session ROOT;

clarified output;

support multiple patterns;

clarified cache;

tuned signature;