systematic-debugging

Read the full error message and stack trace, identify which assertion failed, verify the test setup and fixtures, then trace the unexpected value back to its source. Create a failing test that reproduces the bug before implementing any fix.

Root cause analysis traces an error backward through the call chain to find where the problem actually originated, rather than patching where the symptom appears. You observe the symptom, find the immediate cause, and keep asking what called this until you reach the original trigger.

Intermittent failures usually indicate race conditions, shared mutable state, async ordering issues, or timing dependencies. Look for these patterns and add deterministic waits or proper synchronization to make the failure reproducible.

Stop after three consecutive failed fix attempts, as this signals an architectural problem rather than a simple bug. Document your findings and discuss the design with your team before attempting more patches.

Use git bisect to binary-search through commit history and identify the exact breaking change. Then compare the change with the previous working version to find which assumption was violated.