Trace replay and calibration

Trace replay has two separate axes:

• Workload replay: recorded arrivals, sessions, prompt prefix structure, and optionally output token ids.
• Timing replay: either sampled from a fitted latency model, replayed verbatim from recorded step gaps, or replaced with explicit timing knobs.

Keeping those axes separate is important. You can replay a captured workload while testing a latency model fit from a different capture, or you can serve the same recorded token stream with synthetic timing for fast client tests.

The trace files used to build the committed figures live under traces/, which is gitignored. See traces/README.md for the local inventory and which captures are fitting inputs versus gate seeds.

Start with the Simulation guide for trace format, prefill, budget, and how play consumes captures. Then read Concepts for terminology, and use the scenario pages for arrival replay, prefix-cache workloads, content-identical replay, and multi-token step replay.