jgrusewski 8f218cab24 fix(q-side): replay buffer intent→realized + Kelly warmup floor wiring (WR-plateau root causes)
Two independent bugs surfaced by Class C (frame-shift) + Class A (hardcoded
bounds) audits, both implicated in the months-long WR-stuck-at-46-48%
plateau across 11 superprojects.

## Bug 1: Replay buffer Sutton's deadly triad

experience_kernels.cu:2275 was writing the original INTENT action to
out_actions, but the reward in the replay buffer was computed from the
REALIZED position (post-enforcement: Kelly cap, capital floor, trail-stop,
broker cap can clamp Long→Flat). Replay buffer stored (s, intent, r_realized,
s'). Q(s, Long) was therefore trained against r(s, Flat) whenever env
clamped the intent.

This explains the train_active_frac=0.40 vs val_active_frac=0.05 gap:
train measures intent (40% Long/Short), eval measures realized (5%
Long/Short). The 8× gap is env physics draining intent.

Fix: after unified_env_step_core resolves actual_dir_core/actual_mag_core,
overwrite out_actions[out_off] with the realized action (same encoding as
backtest_env_kernel.cu:323-330, which has been doing it correctly all
along). Order/urgency preserved from intent.

## Bug 2: Kelly cap update kernel ignored existing ISV warmup floor

kelly_cap_update_kernel.cu:53 hardcoded the kelly_f floor at 0.0f. Cold
path (per-epoch boundary). Per project_magnitude_eval_collapse_kelly_capped,
this collapses kelly_cap to 0 → max position pinned to Quarter for cold
start. The val-mag pathology.

The warmup floor producer (ISV[KELLY_WARMUP_FLOOR_INDEX=330], SP9 Fix 37)
was already populated and consumed by the per-step path at
trade_physics.cuh:377-384, but this cold-path kernel never read it.
Partial wiring.

Fix: replace fmaxf(kelly_f, 0.0f) with fmaxf(kelly_f, isv[330]). One-line
change.

## Predicted effect

- train_active_frac and val_active_frac should converge (Bug 1 inflated
  train by counting overridden intents)
- Magnitude distribution should escape Quarter-only (Bug 2 was pinning it)
- WR ceiling at 46-48% may finally move (Bug 1 broke Bellman consistency;
  Bug 2 prevented edge realization)

Falsification: 5-epoch L40S smoke. If unmoved by ep5, the plateau is
deeper still (Class A P0-A REWARD_POS_CAP/NEG_CAP next).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-08 08:06:49 +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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