# MovementTest Longitudinal Time-Step Design

## Goal

Reduce the observation-test longitudinal QP size without relaxing the solver accuracy, time budget, vehicle limits, or observe-only behavior.

## Decision

Add a configurable `OutputTimeStepSeconds` to the trajectory-observation MovementTest with a default of `0.10d` seconds.

The EM time horizon remains `6d` seconds. At the parking-test speed limit of `0.20m/s`, a 0.10-second knot interval corresponds to at most 0.02m of travel between knots.

## Scope

- Add, snapshot, and validate `OutputTimeStepSeconds` in `TrajectoryObservationSettings`.
- Expose the setting in the MovementTest as a public field with a default of `0.10d`.
- Copy it to the session-local `EmPlannerConfiguration.Scheduling.OutputTimeStepSeconds`.
- Verify custom settings reach the planning request and non-positive values are rejected.

## Non-goals

- Keep `TimeHorizonSeconds = 6d`.
- Keep `ObserverPeriodSeconds = 0.05d`.
- Keep `SolverTimeoutSeconds = 0.50d`, `MaximumOsqpIterations = 12000`, and all `1e-5d` solver tolerances.
- Do not change production EM defaults, maps, vehicle constraints, or command output behavior.