Coming back from an interruption
Before
You are deep in a feature when a production incident takes forty minutes. Back at the editor, what you were thinking and what you meant to touch next are gone; fifteen minutes go into rebuilding it.
What it costs: Fifteen minutes of rebuilding, and the thread you were holding
After
The state just before the interruption is held: you return to “you were writing error handling for this function, tests were next.” The rebuild is not part of the day.
