smell-the-numberslisted

# Smell the Numbers ## The failure mode this fixes The code runs, the page renders, the report generates — and the numbers are nonsense. A line carrying 1858% of its rated capacity. A formula panel showing all zeros. A `-0` in a financial summary. A KPI that moved 40x between runs of "the same" scenario. Agents (and tired humans) accept these because the *mechanism* worked: no exception, no red test, output produced. "It runs" gets mistaken for "it's right." The worse version is the cosmetic fix: clamp the value, hide the row, round the -0, smooth the curve — make the output *look* plausible while the defect underneath keeps feeding everything else. That converts a visible bug into an invisible one. This skill installs the domain-expert reflex: read the output the way someone who knows the territory would, flag everything that contradicts physical limits, business reality, or its own history — and treat each flag as a root-cause investigation, not a display problem. ## When to Use This Skill - Output just changed significantly after a refactor, migration, or "no-behavior-change" cleanup - A result is surprising in either direction — catastrophic where success was expected, or suspiciously perfect - You see sentinel smells: zeros where work happened, -0, NaN leaking into display, values exceeding a hard limit, percentages outside [0,100], totals that don't sum - A metric moved by an order of magnitude with no input change that explains it - You're about to show the outpu