Lambda Architecture: Reconciliation Strip Chart

Big-data systems answer queries over data that never stops arriving, which forces a tradeoff between latency and exactness. This 2D companion renders that tradeoff as a scrolling strip-chart rather than a 3D pipeline: a tape of incoming events streams across the top, each colored by its value, while below it four traces race left-to-right on a shared time axis — a fast speed-layer EMA updated on every event, a slow batch (or replayed) layer that jumps to a fresh value at each dashed recompute line, the reconciled serving estimate that anchors to the last jump and rides the speed layer's delta since, and a ghost ground-truth trace so you can watch the gap between them open and close. A one-click toggle swaps the whole pipeline from Lambda architecture (two separate engines) to Kappa architecture (one stream engine that "recomputes" by replaying the log through itself), showing exactly why Kappa is simpler but never quite as exact.