jgrusewski dab5990287 spec(dqn): SP1 numerical stability investigation — F1 NaN root-cause
Brainstorm session 2026-04-29 produced this spec scoping Sub-project 1
of a three-sub-project decomposition addressing the F1 ep2 NaN
explosion that persists across 9+ defensive layers in Plan C Phase 2
(commits e445d07a..e9096c7be).

Decomposition:
- SP1 (this spec): F1 NaN root-cause; γ audit + β always-landing
  instrumentation + surgical fix + multi-fold validation
- SP2 (future): numerical stability framework — codify guards
- SP3 (future): Q-learning structural stability — target-Q clip,
  pessimistic ensemble, atom-range governance

Operating principles:
- No deferrals (anomalies fixed within SP1, not punted)
- Combined fixes — rich commits (per feedback_no_partial_refactor)
- Always-landing diagnostic instrumentation (24-slot nan_flags_buf
  expands to 48; permanent regression sentinel)
- F0 Best Sharpe ≥ 55 preserved (no regression on the working path)

Pass criterion: all 3 folds train 5 epochs, F0+F1+F2 Sharpe ≥ 0,
zero NaN-CLAMPED-TO-ZERO log lines, all 48 flag slots remain zero.

5 design sections approved iteratively: Architecture, Components,
Data Flow, Error Handling, Testing. Next: writing-plans produces
implementation plan.
2026-04-29 22:53:13 +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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