debug

# Debug Comprehensive debugging across the four disciplines you work in: software, data engineering, devops, analytics. Systematic investigation, root-cause-first, defense-in-depth, and verified-before-claimed-done. ## Iron law ``` NO FIXES WITHOUT ROOT CAUSE INVESTIGATION FIRST ``` Random fixes waste time and create new bugs. Find root cause → trace the mechanism to its source → validate at every layer → verify with fresh evidence before claiming done, then hand the fix to `vd:fix`. **No red-capable command, no hypothesizing.** Before you name a cause, you must have a command (or browser step) that is currently red and that you can re-run. Until that exists, you are gathering a repro, not debugging. Do not stack theories to fill the gap. ## Proof gate Before calling a cause confirmed: 1. Observe or reproduce the symptom at the closest realistic boundary. 2. Compare the failing case with the nearest working control and find the first divergence. 3. Show the evidence chain from trigger to mechanism to symptom. If any link is unverified, label it a hypothesis and run the smallest check that distinguishes it from the next plausible cause. Stop when the chain is proven and the requested decision is unblocked; keep unrelated findings separate. ## When to use | Surface | Triggers | |---|---| | **Software** | test failures, bugs, exceptions, build failures, integration regressions | | **System** | server 5xx, CI/CD pipeline failures, deploy failures, performance degradati...