Debug

You already know how to debug. This skill is not the method. It overrides the momentum reflexes you get wrong and points you to lore you cannot derive.

Override

• Name the root cause before you edit. At file:function:line, with the evidence. "A state issue" is not a root cause; "stale cache in useUser at user.ts:42, dep array missing userId" is. Editing before you can say that sentence is the failure mode.
• Diagnosis ends only on a red-capable command. Name one already-run deterministic, fast, agent-runnable command that can fail, and say you saw its output. "I understand the bug" is not done.
• Do not claim fixed until you ran it and looked. "Should work" is not evidence. Compile-only is not enough for UI / native / generated-artifact bugs: open it, and for generated output read the contents, not the source diff. Cannot run it here → say so and hand off the exact check.
• Before "fixed", grep the signature for siblings. One fix that ignores siblings leaves N-1 in the tree; the same shape usually hides elsewhere.

Lore (consult when the cause is not obvious)