Root cause: the test never actually trained — min_replay_size=1000 but
only 800 experiences generated, so can_train()=false. Training was
entirely skipped, and the NaN error came from validation loss.
With min_replay_size=100 (from smoketest TOML), training runs properly.
But ASSERT 7 (walk-forward validation) loaded 146K bars × 15 folds ×
29K GPU forward passes = hours in debug mode.
Fixes:
- Load config from dqn-smoketest.toml (batch=64, lr=0.0003, hidden=64,
max_steps=50, min_replay=100)
- drop(trainer) before ASSERT 7 to release CUDA context — avoids GPU
command queue serialization between trainer and validation DQN
- Limit walk-forward to last 2000 bars (3 folds × 400 steps = seconds)
- Read epsilon from metrics instead of async lock (avoids RwLock
contention after training)
Test passes locally in 48s (RTX 3050, debug mode).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
3ad2344c87