systematic-debugging

Start by reading the full error message and stack trace, then reproduce the failure consistently. Check recent changes via git diff, form a single hypothesis about the root cause, and test it with the smallest possible change before implementing a fix.

Root cause analysis traces a bug to its origin rather than patching symptoms. It involves reading errors carefully, reproducing the issue, checking recent changes, and tracing data flow up the call stack until the source of the bad value is found.

Add diagnostic instrumentation at each component boundary: log what data enters and exits each layer, then run once to gather evidence showing where the failure occurs. Investigate only the failing component instead of guessing across the whole system.

Stop after three failed fix attempts. If each fix reveals a new problem elsewhere or requires massive refactoring, the pattern itself is likely flawed. Discuss the architecture with your team before attempting a fourth fix.

Defense-in-depth adds validation at every layer data passes through: entry point checks, business logic validation, environment guards, and debug instrumentation. This makes a fixed bug structurally impossible rather than blocked at a single checkpoint.