Three debuggers. One default.
Default to /investigate.
The only one wired into the rest of gstack. It hands off naturally to /freeze, /qa and /ship, so the chain keeps moving instead of ending at a diagnosis.
Loses on a fresh lead. Its refusal to theorise before a command goes red is discipline you do not need to buy when the first look is likely to land.
When it wins: The bug is intermittent, or it is a regression between two states you believed were both healthy, or your first look already failed.
Loses on dialect. It pulls a whole method into a session that is not running that method, and two disciplines on one diff cancel out.
When it wins: The session is already superpowers end to end.
None of the three when the cause is already known. A report that gives you the file, the line and the mechanism has finished the diagnosis. Go straight to the red test.