debug
debug — find the cause before you touch the fix
debug is the on-demand diagnosis discipline of the rsc-sdd chain. Something is broken — a test
went red, a crash landed, a result is wrong, a regression appeared — and the strongest pull in the
room is to change code until the symptom disappears. That pull is the enemy. A symptom that vanishes
under a guessed edit usually moved; it rarely died. This skill replaces guess-and-patch with a
short, evidence-driven loop that ends only when one confirmed cause has been named, fixed, and
proven gone.
The one rule everything else serves: no fix before a reproduced, isolated, confirmed cause. If you cannot make the bug happen on demand, you cannot know you fixed it — you can only know the symptom stopped showing, which is not the same thing.
This is a process skill: it owns the method, never the instruments. The test runner, debugger, race detector and profiler belong to whichever stack the failure lives in — pull them from the delegation table below.