systematic-debugging

Follow four phases: reproduce the failure and record the exact error, isolate the scope with dbg!() or git bisect, state the root cause in one sentence, then write a failing test that captures it before applying the minimal fix.

Root cause analysis means understanding why code produces wrong behavior before fixing it. You must state the cause in one sentence, explain the faulty mechanism, and predict what a correct fix changes before writing any code.

Use git bisect during the isolation phase when a bug's origin commit is unknown. It binary-searches commit history to identify the exact change that introduced the failure, narrowing the investigation scope.

Skip the full process for typos and trivial syntax errors, which should just be fixed directly. Build configuration issues should also be handled by checking files like Cargo.toml first rather than running a four-phase investigation.

A failing test captures the root cause and proves the fix works. It should fail before the fix and pass after, and running the full test suite afterward confirms the change introduces no regressions.