# MECHMPPR.CPP / .HPP — reconstruction notes

`MechControlsMapper` (: Subsystem) is the mech's control-input subsystem,
installed at roster slot 0 via `Mech::SetMappingSubsystem`. It publishes the
control-input attributes (StickPosition..PilotArray, IDs 3–0x16) that the
streamed control mappings bind to, and — as of Phase 5.3 — interprets those raw
inputs into the locomotion/aim demands the mech drive consumes.

## Reconstructed

- The attribute table + AttributeIndex + shared-data statics (earlier wave).
- The ctor: primes the published inputs to neutral and (Phase 5.3) installs
  `InterpretControls` as the per-frame Performance.
- `InterpretControls(Scalar)` — the per-frame control interpretation
  (mechmppr.cpp @004afd10, authentic demand math):
  - throttle → forward speed: `speedDemand = topSpeed · throttle · fwdScale`
    (reverse thrust inverts and drops the forward scale). `topSpeed`/`walkSpeed`
    are read from the owner via `Mech::GetReverseStrideLength()/GetWalkStrideLength()`.
  - soft response: square the stick yaw (sign preserved), cube the pedals.
  - Basic mode: stick yaw = `turnDemand`; Standard/Veteran: pedals = `turnDemand`.
  - speed clamp while turning hard (`max_turn` ramps topSpeed → walkSpeed by
    |turnDemand|); VeteranMode has no clamp.
- Demand accessors `GetSpeedDemand()/GetTurnDemand()` (read by `Mech::Simulate`).
- `GetMech()` = `(Mech *)GetEntity()`.

The mapper ticks in the engine's `Entity::PerformAndWatch` roster walk (slot 0),
which runs BEFORE the mech's own Performance (`Simulation::PerformAndWatch` at
the tail), so the demands are same-frame — no input latency.

## DEV hook (headless verification)

`BT_FORCE_THROTTLE` / `BT_FORCE_TURN` override the pushed raw inputs (the RIO/
keyboard aren't present in the headless smoke test), so the demand math + mech
drive are exercisable without hardware. `BT_MECH_LOG` prints a 1 Hz `[mppr]`
demand trace. Verified: `throttle=1.0` → speedDemand=30; `throttle=0.3,turn=1.0`
→ the mech walks a circle; neutral → 0. See MECH.NOTES.md (Phase 5.3 inc 2).

## Deferred (the aiming wave)

The torso/free-look half of the authentic InterpretControls is not yet
reconstructed: the torso analog axes (`Torso::SetAnalogElevationAxis/
SetAnalogTwistAxis`), HUD free-aim slew (`HUD::SetFreeAimSlew`), the recenter
command, and the look/eyepoint commit (`BTCommitLookState`). These are the
aiming/camera surface, separate from locomotion; they come with the
Torso/HUD/eyepoint wave.