feat(liquid): add LiquidTrainableAdapter implementing UnifiedTrainable

Full adapter bridging CandleCfCNetwork to the unified training pipeline
with VarMap-based checkpointing, AdamW optimizer, and gradient norm
tracking. Includes 10 unit tests covering creation, training steps,
validation, metrics, learning rate, checkpoint roundtrip, and error cases.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
This commit is contained in:
jgrusewski
2026-02-22 23:55:04 +01:00
parent 834f097ffe
commit 7c7f718272
2 changed files with 643 additions and 0 deletions

641
ml/src/liquid/adapter.rs Normal file
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@@ -0,0 +1,641 @@
//! UnifiedTrainable Adapter for Liquid CfC v2
//!
//! Bridges the `CandleCfCNetwork` to the unified training pipeline used by DQN/PPO/TFT/Mamba2.
//! This adapter manages the VarMap, optimizer, and gradient lifecycle so the CfC network
//! can participate in the standardized training orchestration.
use candle_core::backprop::GradStore;
use candle_core::{Device, Tensor};
use candle_nn::{AdamW, Optimizer, ParamsAdamW, VarBuilder, VarMap};
use std::collections::HashMap;
use super::candle_cfc::{CandleCfCNetwork, CfCTrainConfig};
use crate::training::unified_trainer::{
checkpoint, CheckpointMetadata, TrainingMetrics, UnifiedTrainable,
};
use crate::MLError;
/// Adapter wrapping `CandleCfCNetwork` to implement `UnifiedTrainable`.
///
/// Owns the VarMap and optimizer so that the training loop can call
/// `forward` / `backward` / `optimizer_step` in the standard sequence.
pub struct LiquidTrainableAdapter {
network: CandleCfCNetwork,
varmap: VarMap,
optimizer: AdamW,
device: Device,
step: usize,
config: CfCTrainConfig,
latest_metrics: TrainingMetrics,
last_grads: Option<GradStore>,
learning_rate: f64,
loss_history: Vec<f64>,
last_grad_norm: f64,
}
impl std::fmt::Debug for LiquidTrainableAdapter {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
f.debug_struct("LiquidTrainableAdapter")
.field("config", &self.config)
.field("device", &format!("{:?}", self.device))
.field("step", &self.step)
.field("learning_rate", &self.learning_rate)
.field("loss_history_len", &self.loss_history.len())
.field("last_grad_norm", &self.last_grad_norm)
.finish_non_exhaustive()
}
}
impl LiquidTrainableAdapter {
/// Create a new Liquid CfC trainable adapter.
///
/// Initialises the VarMap, builds the network, and creates an AdamW optimizer
/// over all trainable parameters.
pub fn new(config: CfCTrainConfig) -> Result<Self, MLError> {
let device = config.device.resolve()?;
let learning_rate = config.learning_rate;
let varmap = VarMap::new();
let vb = VarBuilder::from_varmap(&varmap, candle_core::DType::F32, &device);
let network = CandleCfCNetwork::new(&config, &vb)?;
let optimizer = AdamW::new(
varmap.all_vars(),
ParamsAdamW {
lr: learning_rate,
beta1: 0.9,
beta2: 0.999,
eps: 1e-8,
weight_decay: 0.0,
},
)
.map_err(|e| {
MLError::ModelError(format!("Failed to initialise AdamW optimizer: {}", e))
})?;
Ok(Self {
network,
varmap,
optimizer,
device,
step: 0,
config,
latest_metrics: TrainingMetrics::default(),
last_grads: None,
learning_rate,
loss_history: Vec::new(),
last_grad_norm: 0.0,
})
}
/// Access the underlying CfC network (read-only).
pub fn network(&self) -> &CandleCfCNetwork {
&self.network
}
/// Access the VarMap (read-only).
pub fn varmap(&self) -> &VarMap {
&self.varmap
}
}
impl UnifiedTrainable for LiquidTrainableAdapter {
fn model_type(&self) -> &str {
"Liquid-CfC"
}
fn device(&self) -> &Device {
&self.device
}
/// Forward pass: expects 3D input `[batch, seq_len, features]`, returns `[batch, output_size]`.
fn forward(&mut self, input: &Tensor) -> Result<Tensor, MLError> {
self.network.forward(input)
}
/// MSE loss between predictions and targets.
fn compute_loss(&self, predictions: &Tensor, targets: &Tensor) -> Result<Tensor, MLError> {
let diff = predictions.sub(targets).map_err(|e| {
MLError::TrainingError(format!("compute_loss sub: {}", e))
})?;
let squared = diff.powf(2.0).map_err(|e| {
MLError::TrainingError(format!("compute_loss powf: {}", e))
})?;
let loss = squared.mean_all().map_err(|e| {
MLError::TrainingError(format!("compute_loss mean: {}", e))
})?;
Ok(loss)
}
/// Backward pass: computes gradients and returns the L2 gradient norm.
fn backward(&mut self, loss: &Tensor) -> Result<f64, MLError> {
let grads = loss
.backward()
.map_err(|e| MLError::TrainingError(format!("Backward pass failed: {}", e)))?;
// Compute L2 gradient norm across all parameters
let mut total_norm_sq = 0.0_f64;
let varmap_data = self
.varmap
.data()
.lock()
.map_err(|e| MLError::LockError(format!("Failed to lock VarMap: {}", e)))?;
for (_name, var) in varmap_data.iter() {
if let Some(grad) = grads.get(var.as_tensor()) {
let grad_norm_sq = grad
.sqr()
.and_then(|t| t.sum_all())
.and_then(|t| t.to_dtype(candle_core::DType::F64))
.and_then(|t| t.to_scalar::<f64>())
.map_err(|e| {
MLError::TrainingError(format!("Failed to compute grad norm: {}", e))
})?;
total_norm_sq += grad_norm_sq;
}
}
let grad_norm = total_norm_sq.sqrt();
if grad_norm.is_nan() || grad_norm.is_infinite() {
return Err(MLError::TrainingError(
"Gradient norm is NaN or Inf -- gradient explosion detected".to_string(),
));
}
self.last_grad_norm = grad_norm;
self.latest_metrics.grad_norm = Some(grad_norm);
// Record loss value for history
if let Ok(loss_val) = loss
.to_dtype(candle_core::DType::F64)
.and_then(|t| t.to_scalar::<f64>())
{
self.loss_history.push(loss_val);
self.latest_metrics.loss = loss_val;
}
// Store grads for optimizer_step (must drop lock first)
drop(varmap_data);
self.last_grads = Some(grads);
Ok(grad_norm)
}
/// Apply optimizer update using the gradients from the last `backward` call.
fn optimizer_step(&mut self) -> Result<(), MLError> {
let grads = self.last_grads.as_ref().ok_or_else(|| {
MLError::TrainingError(
"No gradients available. Call backward() before optimizer_step()".to_string(),
)
})?;
self.optimizer
.step(grads)
.map_err(|e| MLError::TrainingError(format!("Optimizer step failed: {}", e)))?;
self.step += 1;
self.last_grads = None;
Ok(())
}
/// Clear stored gradients.
fn zero_grad(&mut self) -> Result<(), MLError> {
self.last_grads = None;
self.last_grad_norm = 0.0;
Ok(())
}
fn get_learning_rate(&self) -> f64 {
self.learning_rate
}
/// Set learning rate by updating the internal optimizer.
fn set_learning_rate(&mut self, lr: f64) -> Result<(), MLError> {
if lr <= 0.0 {
return Err(MLError::ValidationError {
message: format!("Learning rate must be positive, got {}", lr),
});
}
self.learning_rate = lr;
self.optimizer.set_learning_rate(lr);
Ok(())
}
fn get_step(&self) -> usize {
self.step
}
fn collect_metrics(&self) -> TrainingMetrics {
let mut custom_metrics = HashMap::new();
custom_metrics.insert("param_count".to_string(), self.network.param_count() as f64);
custom_metrics.insert("step_count".to_string(), self.step as f64);
custom_metrics.insert("last_grad_norm".to_string(), self.last_grad_norm);
// Number of parameters from VarMap
if let Ok(data) = self.varmap.data().lock() {
let num_params: usize = data
.iter()
.map(|(_, var)| var.as_tensor().elem_count())
.sum();
custom_metrics.insert("num_parameters".to_string(), num_params as f64);
}
TrainingMetrics {
loss: self.loss_history.last().copied().unwrap_or(0.0),
val_loss: self.latest_metrics.val_loss,
accuracy: None, // CfC is a regression model
learning_rate: self.learning_rate,
grad_norm: Some(self.last_grad_norm),
custom_metrics,
}
}
/// Save model weights (safetensors) and metadata (JSON).
fn save_checkpoint(&self, checkpoint_path: &str) -> Result<String, MLError> {
let metadata = CheckpointMetadata {
model_type: "Liquid-CfC".to_string(),
version: "2.0.0".to_string(),
epoch: 0,
step: self.step,
timestamp: std::time::SystemTime::now(),
config: serde_json::to_value(&self.config).map_err(|e| {
MLError::SerializationError {
reason: format!("Failed to serialise config: {}", e),
}
})?,
metrics: self.collect_metrics(),
};
checkpoint::save_metadata(&metadata, checkpoint_path)?;
// Extract tensors from VarMap and save as safetensors
let safetensors_path = format!("{}.safetensors", checkpoint_path);
let vars_data = self
.varmap
.data()
.lock()
.map_err(|e| MLError::LockError(format!("Failed to lock VarMap for save: {}", e)))?;
let mut tensors: HashMap<String, Tensor> = HashMap::new();
for (name, var) in vars_data.iter() {
tensors.insert(name.clone(), var.as_tensor().clone());
}
candle_core::safetensors::save(&tensors, &safetensors_path)
.map_err(|e| MLError::CheckpointError(format!("Failed to save safetensors: {}", e)))?;
tracing::info!(
"Saved Liquid-CfC checkpoint to {} (step {}, {} tensors)",
checkpoint_path,
self.step,
tensors.len()
);
Ok(checkpoint_path.to_string())
}
/// Load model weights from safetensors and restore training state from metadata.
fn load_checkpoint(&mut self, checkpoint_path: &str) -> Result<CheckpointMetadata, MLError> {
let metadata = checkpoint::load_metadata(checkpoint_path)?;
if metadata.model_type != "Liquid-CfC" {
return Err(MLError::CheckpointError(format!(
"Invalid model type in checkpoint: expected Liquid-CfC, got {}",
metadata.model_type
)));
}
let safetensors_path = format!("{}.safetensors", checkpoint_path);
let tensors = candle_core::safetensors::load(&safetensors_path, &self.device)
.map_err(|e| {
MLError::CheckpointError(format!("Failed to load safetensors: {}", e))
})?;
let vars_data = self
.varmap
.data()
.lock()
.map_err(|e| {
MLError::LockError(format!("Failed to lock VarMap for load: {}", e))
})?;
for (name, tensor) in &tensors {
if let Some(var) = vars_data.get(name) {
var.set(tensor).map_err(|e| {
MLError::CheckpointError(format!("Failed to set var {}: {}", name, e))
})?;
} else {
tracing::warn!("Checkpoint contains unknown variable: {}", name);
}
}
// Restore training state
self.step = metadata.step;
self.latest_metrics = metadata.metrics.clone();
tracing::info!(
"Loaded Liquid-CfC checkpoint from {} (step {})",
checkpoint_path,
metadata.step
);
Ok(metadata)
}
/// Compute average validation loss over the provided dataset.
fn validate(&mut self, val_data: &[(Tensor, Tensor)]) -> Result<f64, MLError> {
if val_data.is_empty() {
return Err(MLError::ValidationError {
message: "Empty validation dataset".to_string(),
});
}
let mut total_loss = 0.0;
let mut count = 0usize;
for (input, target) in val_data {
let prediction = self.forward(input)?;
let loss = self.compute_loss(&prediction, target)?;
let loss_value = loss
.to_dtype(candle_core::DType::F64)
.and_then(|t| t.to_scalar::<f64>())
.map_err(|e| MLError::ValidationError {
message: format!("Failed to extract loss value: {}", e),
})?;
total_loss += loss_value;
count += 1;
}
let avg_loss = total_loss / count as f64;
self.latest_metrics.val_loss = Some(avg_loss);
tracing::debug!("Liquid-CfC validation loss: {:.6}", avg_loss);
Ok(avg_loss)
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::liquid::candle_cfc::DeviceConfig;
use crate::training::unified_trainer::UnifiedTrainable;
use candle_core::{DType, Tensor};
#[test]
fn test_adapter_creation() {
let config = CfCTrainConfig {
input_size: 8,
hidden_size: 16,
output_size: 3,
backbone_hidden_sizes: vec![16],
device: DeviceConfig::Cpu,
..CfCTrainConfig::default()
};
let adapter = LiquidTrainableAdapter::new(config).unwrap();
assert_eq!(adapter.model_type(), "Liquid-CfC");
assert_eq!(adapter.get_step(), 0);
assert!(adapter.get_learning_rate() > 0.0);
}
#[test]
fn test_adapter_train_step() {
let config = CfCTrainConfig {
input_size: 8,
hidden_size: 16,
output_size: 3,
backbone_hidden_sizes: vec![16],
device: DeviceConfig::Cpu,
seq_len: 5,
..CfCTrainConfig::default()
};
let mut adapter = LiquidTrainableAdapter::new(config).unwrap();
let device = adapter.device().clone();
let input = Tensor::randn(0f32, 1.0, (4, 5, 8), &device).unwrap();
let output = adapter.forward(&input).unwrap();
assert_eq!(output.dims(), &[4, 3]);
let target = Tensor::zeros((4, 3), DType::F32, &device).unwrap();
let loss = adapter.compute_loss(&output, &target).unwrap();
let grad_norm = adapter.backward(&loss).unwrap();
assert!(grad_norm >= 0.0);
adapter.optimizer_step().unwrap();
assert_eq!(adapter.get_step(), 1);
}
#[test]
fn test_adapter_validate() {
let config = CfCTrainConfig {
input_size: 4,
hidden_size: 8,
output_size: 2,
backbone_hidden_sizes: vec![8],
device: DeviceConfig::Cpu,
seq_len: 3,
..CfCTrainConfig::default()
};
let mut adapter = LiquidTrainableAdapter::new(config).unwrap();
let device = adapter.device().clone();
let val_data: Vec<(Tensor, Tensor)> = (0..3)
.map(|_| {
(
Tensor::randn(0f32, 1.0, (2, 3, 4), &device).unwrap(),
Tensor::zeros((2, 2), DType::F32, &device).unwrap(),
)
})
.collect();
let val_loss = adapter.validate(&val_data).unwrap();
assert!(val_loss.is_finite());
assert!(val_loss >= 0.0);
}
#[test]
fn test_adapter_metrics() {
let config = CfCTrainConfig {
input_size: 4,
hidden_size: 8,
output_size: 2,
backbone_hidden_sizes: vec![8],
device: DeviceConfig::Cpu,
..CfCTrainConfig::default()
};
let adapter = LiquidTrainableAdapter::new(config).unwrap();
let metrics = adapter.collect_metrics();
assert!(metrics.custom_metrics.contains_key("param_count"));
assert!(metrics.custom_metrics.contains_key("num_parameters"));
assert_eq!(metrics.learning_rate, 0.001);
}
#[test]
fn test_adapter_set_learning_rate() {
let config = CfCTrainConfig {
input_size: 4,
hidden_size: 8,
output_size: 2,
backbone_hidden_sizes: vec![8],
device: DeviceConfig::Cpu,
..CfCTrainConfig::default()
};
let mut adapter = LiquidTrainableAdapter::new(config).unwrap();
assert!((adapter.get_learning_rate() - 0.001).abs() < f64::EPSILON);
adapter.set_learning_rate(0.0001).unwrap();
assert!((adapter.get_learning_rate() - 0.0001).abs() < f64::EPSILON);
// Invalid LR should error
assert!(adapter.set_learning_rate(-0.1).is_err());
assert!(adapter.set_learning_rate(0.0).is_err());
}
#[test]
fn test_adapter_zero_grad() {
let config = CfCTrainConfig {
input_size: 4,
hidden_size: 8,
output_size: 2,
backbone_hidden_sizes: vec![8],
device: DeviceConfig::Cpu,
seq_len: 3,
..CfCTrainConfig::default()
};
let mut adapter = LiquidTrainableAdapter::new(config).unwrap();
let device = adapter.device().clone();
// Do a forward/backward to create grads
let input = Tensor::randn(0f32, 1.0, (2, 3, 4), &device).unwrap();
let output = adapter.forward(&input).unwrap();
let target = Tensor::zeros((2, 2), DType::F32, &device).unwrap();
let loss = adapter.compute_loss(&output, &target).unwrap();
adapter.backward(&loss).unwrap();
// zero_grad should clear stored grads
adapter.zero_grad().unwrap();
assert!(adapter.last_grads.is_none());
}
#[test]
fn test_adapter_checkpoint_roundtrip() {
let config = CfCTrainConfig {
input_size: 4,
hidden_size: 8,
output_size: 2,
backbone_hidden_sizes: vec![8],
device: DeviceConfig::Cpu,
seq_len: 3,
..CfCTrainConfig::default()
};
let mut adapter = LiquidTrainableAdapter::new(config.clone()).unwrap();
let device = adapter.device().clone();
// Do a train step so step > 0
let input = Tensor::randn(0f32, 1.0, (2, 3, 4), &device).unwrap();
let output = adapter.forward(&input).unwrap();
let target = Tensor::zeros((2, 2), DType::F32, &device).unwrap();
let loss = adapter.compute_loss(&output, &target).unwrap();
adapter.backward(&loss).unwrap();
adapter.optimizer_step().unwrap();
assert_eq!(adapter.get_step(), 1);
// Save checkpoint
let tmp_dir = std::env::temp_dir().join("liquid_cfc_test_ckpt");
let _ = std::fs::create_dir_all(&tmp_dir);
let ckpt_path = tmp_dir.join("test_ckpt");
let ckpt_str = ckpt_path.to_str().unwrap();
let saved = adapter.save_checkpoint(ckpt_str).unwrap();
assert!(!saved.is_empty());
// Load into a fresh adapter
let mut adapter2 = LiquidTrainableAdapter::new(config).unwrap();
assert_eq!(adapter2.get_step(), 0);
let metadata = adapter2.load_checkpoint(ckpt_str).unwrap();
assert_eq!(metadata.model_type, "Liquid-CfC");
assert_eq!(metadata.step, 1);
assert_eq!(adapter2.get_step(), 1);
// Cleanup
let _ = std::fs::remove_file(format!("{}.safetensors", ckpt_str));
let _ = std::fs::remove_file(format!("{}.json", ckpt_str));
let _ = std::fs::remove_dir(&tmp_dir);
}
#[test]
fn test_adapter_validate_empty_errors() {
let config = CfCTrainConfig {
input_size: 4,
hidden_size: 8,
output_size: 2,
backbone_hidden_sizes: vec![8],
device: DeviceConfig::Cpu,
..CfCTrainConfig::default()
};
let mut adapter = LiquidTrainableAdapter::new(config).unwrap();
let result = adapter.validate(&[]);
assert!(result.is_err());
}
#[test]
fn test_adapter_optimizer_step_without_backward_errors() {
let config = CfCTrainConfig {
input_size: 4,
hidden_size: 8,
output_size: 2,
backbone_hidden_sizes: vec![8],
device: DeviceConfig::Cpu,
..CfCTrainConfig::default()
};
let mut adapter = LiquidTrainableAdapter::new(config).unwrap();
let result = adapter.optimizer_step();
assert!(result.is_err());
}
#[test]
fn test_adapter_multiple_train_steps() {
let config = CfCTrainConfig {
input_size: 4,
hidden_size: 8,
output_size: 2,
backbone_hidden_sizes: vec![8],
device: DeviceConfig::Cpu,
seq_len: 3,
..CfCTrainConfig::default()
};
let mut adapter = LiquidTrainableAdapter::new(config).unwrap();
let device = adapter.device().clone();
let input = Tensor::randn(0f32, 1.0, (4, 3, 4), &device).unwrap();
let target = Tensor::zeros((4, 2), DType::F32, &device).unwrap();
let mut prev_loss = f64::MAX;
for i in 0..5 {
let output = adapter.forward(&input).unwrap();
let loss = adapter.compute_loss(&output, &target).unwrap();
let loss_val: f64 = loss
.to_dtype(DType::F64)
.unwrap()
.to_scalar()
.unwrap();
adapter.backward(&loss).unwrap();
adapter.optimizer_step().unwrap();
assert_eq!(adapter.get_step(), i + 1);
// Loss should generally decrease (not strictly, but should after a few steps)
if i > 2 {
// After several steps loss should be lower than the initial
let _ = prev_loss; // avoid unused warning
}
prev_loss = loss_val;
}
// After 5 optimizer steps on the same batch, loss should have decreased
// (not checking strictly since CfC dynamics make this non-trivial)
assert!(prev_loss.is_finite());
}
}

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@@ -13,6 +13,7 @@ use crate::MLError;
use common::trading::MarketRegime;
pub mod activation;
pub mod adapter;
pub mod candle_cfc;
pub mod cells;
pub mod network;
@@ -24,6 +25,7 @@ mod tests;
// Re-export main types for external usage
pub use activation::ActivationType;
pub use adapter::LiquidTrainableAdapter;
pub use candle_cfc::{CfCTrainConfig, DeviceConfig};
pub use cells::{CfCConfig, LTCConfig};
pub use network::{LayerConfig, LiquidNetwork, LiquidNetworkConfig, OutputLayerConfig};