# 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 configurable `TimeHorizonSeconds` and `OutputTimeStepSeconds` values to the trajectory-observation MovementTest, with defaults of `6d` and `0.10d` seconds.

`TimeHorizonSeconds` controls how far into the future the ST plan covers. `OutputTimeStepSeconds` controls how many knots divide that horizon and must not exceed it. 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 `TimeHorizonSeconds` and `OutputTimeStepSeconds` in `TrajectoryObservationSettings`.
- Expose both settings in the MovementTest as public fields with defaults of `6d` and `0.10d`.
- Copy both values to the session-local `EmPlannerConfiguration.Scheduling` configuration.
- Verify custom settings reach the planning request and non-positive values are rejected.
- Add Chinese XML documentation comments to the MovementTest fields and settings properties, explaining horizon coverage, timestamp spacing, defaults, and the distinction from `ObserverPeriodSeconds`.

## Non-goals

- 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.