**Description**: Central data structure representing the complete state of the SPM system.
**Implementation**:
```rust
pub struct MachineState {
pub all_signals: Option<Vec<f32>>,
pub position: Option<(f64, f64)>
pub z_position: Option<f64>,
pub timestamp: f64,
pub signal_history: VecDeque<f32>, // !?
pub tip_state: TipState,
pub last_action: Option<String>,
}
```
**Notes**:
- Central hub updated by [[StateClassifier]] and read by [[PolicyEngine]]
- Contains signal data, spatial/temporal context, and classification results
- Designed for ML expansion with future embedding fields