Time axis → · one lane per device
drag = pan · scroll = zoom
Mobile CI/CD pipelines don't run automated tests one at a time — they fan a suite of unit, integration and UI tests out across a farm of parallel emulator or device shards, and the way that fan-out is scheduled directly decides how long every commit waits on green. This simulator builds a randomized test suite, packs it onto D parallel devices with a real greedy Longest-Processing-Time-first bin-packing scheduler, and renders the resulting timeline as a 2D Gantt chart: one horizontal lane per device, one block per test attempt. Each test attempt independently fails with an adjustable flake rate — the classic mobile-testing headache of a UI test that's timing-sensitive rather than actually broken — and gets automatically retried up to a configurable budget before it's quarantined as a real failure. Live readouts track the makespan, how much better LPT does than a naive round-robin assignment, device utilization, and how much of the pipeline's wall-clock time is pure retry overhead. Drag the chart to pan the timeline and scroll to zoom; a second strip charts per-device utilization for both scheduling strategies side by side.