jgrusewski cca9dd36ae fix(dqn): replace q_mean ratio with rolling-window MAD deviation (H — kill criterion robustness)
Current criterion uses |q_mean| / |prev_q_mean| which explodes near
zero crossings (legitimate cold-start has |prev_q_mean| ≈ 0.01-0.1,
making any non-tiny current trigger the ratio threshold).
smoke-test-n9xzr fired with prev=−0.0795, curr=0.7647, ratio=9.62×
despite this being natural cold-start growth, not geometric runaway.

Replace with rolling 5-epoch window of q_means. Compute median +
MAD (Median Absolute Deviation, a 50%-breakdown estimator robust
to single outliers); kill condition becomes
  |q_mean − median(window)| > 4.0 × max(MAD(window), 0.01)
AND the existing adaptive floor.

Constants are declared `const` near the kill block:
- Q_DRIFT_WINDOW_SIZE=5 (matches smoke fold length, gives MAD a
  meaningful estimator without averaging across regime shifts)
- Q_DRIFT_WARMUP_SAMPLES=3 (skip until ≥ 3 priors — smaller window
  degenerates to half-range MAD that trips on monotonic
  trajectories)
- Q_DRIFT_DEVIATION_THRESHOLD=4.0 (4 MADs ≈ 2.7σ Gaussian-
  equivalent; clear outlier without firing on every legitimate
  dip; literal MAD count rather than σ because q_mean is non-
  Gaussian during cold-start)
- Q_DRIFT_MIN_DEVIATION=0.01 (numerical-stability floor when
  window is constant)

Window resets at fold boundary alongside prev_epoch_q_mean /
adaptive_tau (A.1 pattern — cross-fold q-stats are independent
training runs, mixing them would inflate MAD or shift the
median).

Predicted impact on smoke-test-n9xzr:
- Plan C smoke fold 0 ep2: window has only 2 priors, warmup gate
  not yet satisfied → kill stays silent (was firing on ratio=9.62×)
- Genuine geometric runaway (q_mean → 62.5 from baseline 0.5 over
  4 epochs): ep3 deviation = |62.5 − 2.5|/MAD=2.0 = 30 > 4 AND
  |62.5| > floor=3×12=36 → kill fires correctly

Both conditions ANDed (floor + deviation), preserving the
production-safety semantics of the original criterion. The floor
check is unchanged; only the divergence detector is replaced.

Per feedback_no_quickfixes.md: this is a principled robust-
statistics replacement, not a threshold relaxation.
Per feedback_no_partial_refactor.md: window field, constants,
criterion site, and fold-boundary reset land in lockstep — the
kill criterion's contract is internally consistent across
trainer/mod.rs, constructor.rs, and training_loop.rs.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-04-29 19:15:30 +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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