jgrusewski 9dbd8d7e9f docs(design): unify training and validation environments
Design document for the follow-up to the adaptive-learning-rootcause
session. Lays out the evidence, root cause, options considered, and
recommended path for closing the 70% structural gap between training
and validation Sharpe that remained after the distillation collapse
fix landed.

Key findings documented:
- Reward-shaping ablation (2026-04-20) closed ~30% of the gap; ~70%
  remains architectural
- Two env kernels (experience_env_step vs backtest_env_step) have
  drifted: spread scaling, fill model, saboteur noise, reward terms,
  action selection, position dynamics all differ
- Hint from history: experience_kernels.cu:1418 comment "Regime-
  adaptive scaling removed to eliminate train/eval mismatch" shows
  someone aligned *some* things previously

Recommended path (Option C, "unified env with layered reward"):
- Single unified_env_step kernel replaces both
- Core reward = pure P&L; shaping is additive and P&L-units-aligned
- Validation = training with exploration_scale=0 AND shaping_scale=0
- Scale factors are pinned device-mapped scalars (same pattern used by
  the distillation alpha fix)

Phased implementation plan with ~8-day budget and concrete success
criteria: validation Sharpe_raw within 0.05 of training Sharpe_raw by
epoch 30 on L40S production run.

Rejected alternatives: backtest-matches-training (hides real issue),
training-matches-backtest (regresses stability), two-environment with
divergence as metric (fallback only).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-04-21 00:22:05 +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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