Abstract: Historic context data is automatically associated with particular pieces of source code by retrieval data structures. Ephemeral information is preserved, such as how a piece of code originated operationally and was changed over time, which research sources informed the code's origination and changes, and why particular changes in the code were made. Code may be rolled back to an earlier version based on parameters such as whether code had been refactored, or results of testing or static analysis. Rollback goes beyond editor undo actions, and a developer need not specify a timestamp or a version number. Developer documentation burdens are reduced, developer understanding is increased, and code quality is enhanced, by providing ready access to the code's software development context history data. Some actions made possible include highlighting code that was generated automatically by autocompletion or otherwise, highlighting refactored code, and highlighting pasted code, among other actions.