jgrusewski b21c6d5cff feat: comprehensive C51 training stability overhaul — Q-stats diagnostics, adaptive atoms, gradient safety
Major architectural fixes discovered through systematic investigation:

Q-gap measurement (3 bugs):
- compute_expected_q never ran during training → q_out_buf was zeros
- epoch_q_gap reset in process_epoch_boundary before logging read it
- flush_q_stats_readback drained async readback before in-loop read

Zero-copy pinned memory (4 hot-path scalars):
- t_buf, tau_buf, v_range_buf, adaptive_clip_buf → pinned device-mapped
- GPU reads via cuMemHostGetDevicePointer, host writes directly, no HtoD

Q-stats-driven adaptive v_range:
- v_range = q_mean ± 3σ + Bellman headroom (was fixed ±1.0)
- Adaptive MIN_RANGE scales with |Q_mean| (was fixed 0.02)
- Per-step adaptation (was every 50 steps)
- 100× finer atom resolution from epoch 1

Gradient stability:
- IS-weight clamp at 10.0 in all loss/grad kernels (PER spike prevention)
- 3 power iterations in spectral norm (was 1 — underestimated sigma)
- Bottleneck w_bn added as 13th spectral-normed matrix (was missing)
- Pre-Adam grad_buf clip via clip_grad_buf_inplace (activation amplification)
- EMA-based adaptive gradient clipping (pinned device buffer)
- Consolidated grad_norm to single buffer (was 2 — eliminated grad_norm_f32_buf)

Adaptive tau from online-target Q-divergence:
- C51 loss kernel accumulates (E[Q_online] - E[Q_target])² per batch
- Tau scales with sqrt(divergence/baseline), clamped [0.5×, 10×] base
- Accelerates target convergence during discovery, stabilizes during plateau

Deterministic evaluation:
- eval_mode in action_select kernel: pure greedy argmax, no Boltzmann/RNG
- Eliminated ±40 val_Sharpe noise from near-uniform Boltzmann sampling
- Backtest evaluator uses adaptive v_range (was config v_min/v_max — 1500× mismatch)

Atom utilization metrics:
- compute_expected_q accumulates entropy + utilization per step
- q_stats_kernel extended to 7 outputs (was 5)
- Logged per epoch: atoms=98%ent/92%util

Pessimistic Q-init removed — incompatible with adaptive v_range (bias was
255× outside ±0.01 support, causing 5-epoch cold-start and late Q-value drift).

903/903 tests passing. val_Sharpe positive from epoch 1 with greedy eval.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-04-12 20:10:25 +02:00

Foxhunt

Production HFT trading system in Rust.

Architecture

The workspace contains 32 crates organized as follows:

Core Libraries (16)

Crate Purpose
trading_engine Order processing, FIX 4.4, IB TWS, SIMD, RDTSC timing
risk VaR, Kelly, circuit breakers, kill switches, compliance
risk-data Risk data types and shared structures
trading-data Trading data types
ml DQN Rainbow, PPO, TFT, Mamba2, ensemble inference
ml-data ML data types and feature definitions
data Market data ingestion and storage
backtesting Replay engine, strategy tester
adaptive-strategy Ensemble execution, microstructure analysis
common Shared types, resilience, error handling
storage S3 and local model storage
model_loader Model serialization and loading
market-data Market data feed handlers
database PostgreSQL access layer (SQLx)
config Configuration management
tli CLI commands and tooling

Services (8)

Service Purpose
backtesting_service gRPC backtesting service
broker_gateway_service FIX routing, broker connectivity
trading_service Core trading operations
ml_training_service Model training orchestration
data_acquisition_service Market data acquisition
trading_agent_service Autonomous trading agents
api_gateway gRPC API gateway with auth
web-gateway Axum REST + WebSocket gateway

Frontend

web-dashboard/ -- React 19 + TypeScript + Vite + TradingView charts.

Building

# Check compilation (no PostgreSQL required)
SQLX_OFFLINE=true cargo check --workspace

# Run tests for a specific crate
SQLX_OFFLINE=true cargo test -p <crate> --lib

# Clippy
SQLX_OFFLINE=true cargo clippy --workspace

ML Models

Four production model architectures on Candle v0.9.1 with CUDA:

  • DQN Rainbow -- Deep Q-Network with prioritized replay, dueling heads, noisy nets
  • PPO -- Proximal Policy Optimization with GAE and LSTM policies
  • TFT -- Temporal Fusion Transformer for multi-horizon forecasting
  • Mamba2 -- State space model for sequence prediction

Each model has a standalone trainer and a UnifiedTrainable adapter for the hyperopt pipeline.

Infrastructure

  • Git: Gitea at git.fxhnt.ai (Tailscale-only), Scaleway DEV1-S
  • Observability: OpenTelemetry OTLP (env OTEL_EXPORTER_OTLP_ENDPOINT)
  • Database: PostgreSQL with SQLx offline mode for CI

License

Proprietary. All rights reserved.

Description
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